U.S. patent application number 13/876540 was filed with the patent office on 2013-07-18 for refrigeration cycle apparatus and refrigeration cycle control method.
This patent application is currently assigned to MITSUBISHI ELECTRIC CORPORATION. The applicant listed for this patent is Makoto Saito, Shogo Tamaki. Invention is credited to Makoto Saito, Shogo Tamaki.
Application Number | 20130180274 13/876540 |
Document ID | / |
Family ID | 45993481 |
Filed Date | 2013-07-18 |
United States Patent
Application |
20130180274 |
Kind Code |
A1 |
Tamaki; Shogo ; et
al. |
July 18, 2013 |
REFRIGERATION CYCLE APPARATUS AND REFRIGERATION CYCLE CONTROL
METHOD
Abstract
An integrated air-conditioning and hot-water-supply system
includes a compressor, a plate-type water heat exchanger, a
hot-water-supply pressure-reducing mechanism, and an outdoor heat
exchanger. Moreover, the integrated air-conditioning and
hot-water-supply system includes a high-pressure sensor that
detects a high pressure in the compressor, and a controller that
calculates a condensing temperature of the plate-type water heat
exchanger based on the high pressure detected by the high-pressure
sensor. When the calculated condensing temperature is higher than
or equal to a preset target condensing-temperature value, the
controller performs condensing-temperature control for controlling
the operating frequency of the compressor based on a difference
between the calculated condensing temperature and the target
condensing-temperature value, and performs opening-degree control
for controlling the opening degree of the hot-water-supply
pressure-reducing mechanism concurrently with the
condensing-temperature control based on a difference between a
current opening degree of the hot-water-supply pressure-reducing
mechanism and a preset target opening-degree value.
Inventors: |
Tamaki; Shogo; (Tokyo,
JP) ; Saito; Makoto; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tamaki; Shogo
Saito; Makoto |
Tokyo
Tokyo |
|
JP
JP |
|
|
Assignee: |
MITSUBISHI ELECTRIC
CORPORATION
Tokyo
JP
|
Family ID: |
45993481 |
Appl. No.: |
13/876540 |
Filed: |
March 8, 2011 |
PCT Filed: |
March 8, 2011 |
PCT NO: |
PCT/JP2011/055374 |
371 Date: |
March 28, 2013 |
Current U.S.
Class: |
62/115 ;
62/126 |
Current CPC
Class: |
F25B 2313/02741
20130101; F25B 49/022 20130101; F25B 2500/07 20130101; F25B
2700/1931 20130101; F25B 2341/063 20130101; F25B 49/027 20130101;
F25B 2600/19 20130101; F25B 2313/0233 20130101; F25B 2313/003
20130101; F25B 13/00 20130101; F25B 2313/02731 20130101 |
Class at
Publication: |
62/115 ;
62/126 |
International
Class: |
F25B 49/02 20060101
F25B049/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 2010 |
JP |
2010-243200 |
Claims
1. A refrigeration cycle apparatus comprising: a refrigeration
cycle mechanism having a compressor whose operating frequency is
controllable, a first radiator, a first pressure-reducing mechanism
whose opening degree is controllable, and a first evaporator,
wherein a refrigerant sequentially circulates through the
compressor, the first radiator, the first pressure-reducing
mechanism, and the first evaporator; a high-pressure sensor that
detects a high pressure between a discharge side of the compressor
and a liquid side of the first pressure-reducing mechanism; and a
controller that controls the operating frequency of the compressor
and controlling the opening degree of the first pressure-reducing
mechanism based on a degree of subcooling of the first radiator,
wherein, when a condensing temperature of the first radiator that
is obtained based on the high pressure detected by the
high-pressure sensor is higher than or equal to a preset target
condensing-temperature value, the controller (a) performs
condensing-temperature control for reducing the operating frequency
of the compressor based on a difference between the condensing
temperature and the target condensing-temperature value, and (b)
performs opening-degree control for increasing the opening degree
of the first pressure-reducing mechanism more than opening-degree
control under the control based on the degree of the
subcooling.
2. The refrigeration cycle apparatus of claim 1, wherein the first
pressure-reducing mechanism performs the opening-degree control
based on a preset target opening degree value so as to ensure a
predetermined level of a heat-radiation capacity of the first
radiator.
3. The refrigeration cycle apparatus of claim 2, wherein the first
radiator includes an inflowing-water-pipe connection section
connected to an inflowing water pipe into which water flows, an
outflowing-water-pipe connection section connected to an outflowing
water pipe from which the water flows, and a water pipe through
which the water flowing in from the inflowing water pipe passes and
flows out to the outflowing water pipe, wherein the first radiator
heats the water passing through the water pipe by radiating heat to
the water, and wherein the target heat-radiation-capacity value of
the first radiator is set in correspondence with an upper limit
value in design for an inlet water temperature of the water flowing
into the water pipe from the inflowing water pipe.
4. The refrigeration cycle apparatus of claim 1, wherein the
controller includes a storage unit that stores
frequency/opening-degree correspondence information in which the
operating frequency of the compressor and a preset the target
opening-degree value of the first pressure-reducing mechanism are
stored in correspondence with each other, and wherein when the
controller concurrently performs the condensing-temperature control
and the opening-degree control, the controller refers to the
frequency/opening-degree correspondence information so as to
identify the target opening-degree value corresponding to a current
operating frequency of the compressor from the
frequency/opening-degree correspondence information, and uses the
identified target opening-degree value as the target opening-degree
value in the opening-degree control.
5. The refrigeration cycle apparatus of claim 1, wherein the first
evaporator is disposed outdoors, wherein the refrigeration cycle
apparatus comprises an outdoor-air temperature sensor that detects
an outdoor-air temperature around the first evaporator, and wherein
the controller includes a storage unit that stores
outdoor-air-temperature/opening-degree correspondence information
in which the outdoor-air temperature and the preset target
opening-degree value of the first pressure-reducing mechanism are
stored in correspondence with each other, and wherein when the
controller concurrently performs the condensing-temperature control
and the opening-degree control, the controller refers to the
outdoor-air-temperature/opening-degree correspondence information
so as to identify the target opening-degree value corresponding to
the outdoor-air temperature detected by the outdoor-air temperature
sensor from the outdoor-air-temperature/opening-degree
correspondence information, and uses the identified target
opening-degree value as the target opening-degree value in the
opening-degree control.
6. The refrigeration cycle apparatus of claim 1, wherein the first
evaporator is disposed outdoors, wherein the refrigeration cycle
apparatus comprises: an outdoor-air temperature sensor that detects
an outdoor-air temperature around the first evaporator; and an
evaporating temperature sensor that detects an evaporating
temperature of the refrigerant in the first evaporator, and wherein
the controller receives data of two or more sets of a temperature
difference between the outdoor-air temperature around the first
evaporator and the evaporating temperature of the first evaporator
and an evaporating capacity of the first evaporator corresponding
to the temperature difference, determines a functional relationship
between the temperature difference and the evaporating capacity
based on the received data, refers to the determined functional
relationship so as to identify the evaporating capacity
corresponding to the temperature difference between the outdoor-air
temperature detected by the outdoor-air temperature sensor and the
evaporating temperature detected by the evaporating temperature
sensor from the functional relationship, calculates a compressor
input, which indicates compressing work done on the refrigerant by
the compressor, from the operating frequency of the compressor, the
condensing temperature, and the evaporating temperature detected by
the evaporating temperature sensor, calculates a heat-radiation
capacity of the first radiator from the identified evaporating
capacity and the calculated compressor input, determines the target
opening-degree value of the first pressure-reducing mechanism in
accordance with a difference between the calculated heat-radiation
capacity and a preliminarily-stored target heat-radiation-capacity
value, and uses the determined target opening-degree value as the
target opening-degree value in the opening-degree control.
7. The refrigeration cycle apparatus of claim 1, comprising: a
branch flow path branching from the discharge side of the
compressor and having a second radiator and a second
pressure-reducing mechanism, the branch flow path being connected
to the second radiator and the second pressure-reducing mechanism
sequentially from the discharge side of the compressor and merging
with an intermediate section between the first pressure-reducing
mechanism and the first evaporator, wherein the controller performs
a concurrent heat-radiation operation in which the refrigerant
discharged from the compressor is circulated by being made to flow
into the first radiator and the second radiator, and wherein when
the condensing temperature becomes higher than or equal to the
target condensing-temperature value during the concurrent
heat-radiation operation, the controller performs a switching
process for alternately switching between a process for making the
discharged refrigerant flow into the first radiator and a process
for making the discharged refrigerant flow into the second
radiator.
8. The refrigeration cycle apparatus of claim 7, wherein the second
radiator exchanges heat with indoor air, wherein the refrigeration
cycle apparatus comprises an indoor temperature sensor that detects
an indoor temperature, and wherein the controller performs the
switching process based on a temperature difference obtained by
subtracting a preliminarily-stored preset indoor temperate from the
indoor temperature detected by the indoor temperature sensor.
9. The refrigeration cycle apparatus of claim 8, wherein when the
discharged refrigerant is made to flow only into the second
radiator due to the switching process, the controller controls the
operating frequency of the compressor and the opening degree of the
first pressure-reducing mechanism so that the temperature
difference is greater than a predetermined positive value, and
wherein when the temperature difference becomes greater than the
predetermined positive value, the controller performs the switching
process so as to make the discharged refrigerant flow only into the
first radiator.
10. The refrigeration cycle apparatus of claim 1, comprising: a
heat-absorption branch flow path that branches from a branch
section between the first pressure-reducing mechanism and the first
evaporator and merges with a suction side of the compressor, the
heat-absorption branch flow path having a second evaporator and a
pressure-reducing mechanism for the second evaporator, the
heat-absorption branch flow path being connected to the
pressure-reducing mechanism for the second evaporator and to the
second evaporator sequentially from the branch section and merging
with the suction side of the compressor, wherein the controller
performs a concurrent heat-absorption and heat-radiation operation
in which a heat-radiation operation of the first radiator and a
heat-absorption operation of the second evaporator are concurrently
performed, the heat-radiation operation being operation in which
the refrigerant discharged from the compressor is suctioned into
the compressor from the suction side thereof via the first
radiator, the first pressure-reducing mechanism, the branch
section, and the first evaporator, the heat-absorption operation
being operation in which the discharged refrigerant is suctioned
into the compressor from the suction side thereof via the first
radiator, the first pressure-reducing mechanism, the branch
section, the pressure-reducing mechanism for the second evaporator,
and the second evaporator, and wherein when the condensing
temperature becomes higher than or equal to the target
condensing-temperature value during the concurrent heat-reception
and heat-radiation operation, the controller performs a switching
process for alternately switching between the heat-radiation
operation and the heat-absorption operation.
11. The refrigeration cycle apparatus of claim 10, wherein the
second evaporator exchanges heat with indoor air, wherein the
refrigeration cycle apparatus comprises an indoor temperature
sensor that detects an indoor temperature, and wherein the
controller performs the switching process based on a temperature
difference obtained by subtracting a preliminarily-stored preset
indoor temperature from the indoor temperature detected by the
indoor temperature sensor.
12. The refrigeration cycle apparatus of claim 11, wherein when
only the heat-absorption operation is performed due to the
switching process, the controller controls the operating frequency
of the compressor and the opening degree of the first
pressure-reducing mechanism so that the temperature difference is
smaller than a predetermined negative value, and wherein when the
temperature difference becomes smaller than the predetermined
negative value, the controller performs the switching process so
that only the heat-radiation operation is performed.
13. The refrigeration cycle apparatus of claim 1, wherein the
refrigeration cycle apparatus uses a refrigerant that operates at a
critical pressure or higher, and wherein when the high pressure
detected by the high-pressure sensor is higher than or equal to a
preset target high-pressure value, the controller performs
high-pressure control for controlling the operating frequency of
the compressor based on a difference between the high pressure and
the target high-pressure value, and performs opening-degree control
for controlling the opening degree of the first pressure-reducing
mechanism concurrently with the high-pressure control based on the
difference between the current opening degree of the first
pressure-reducing mechanism and the preset target opening-degree
value.
14. A refrigeration cycle control method for performing an
operation on a refrigeration cycle apparatus, the refrigeration
cycle apparatus including a refrigeration cycle mechanism having a
compressor whose operating frequency is controllable, a first
radiator, a first pressure-reducing mechanism whose opening degree
is controllable, and a first evaporator, wherein a refrigerant
sequentially circulates through the compressor, the first radiator,
the first pressure-reducing mechanism, and the first evaporator;
and a high-pressure sensor that detects a high pressure between a
discharge side of the compressor and a liquid side of the first
pressure-reducing mechanism, the refrigeration cycle apparatus
controlling the operating frequency of the compressor and
controlling the opening degree of the first pressure-reducing
mechanism based on a degree of subcooling of the first radiator,
the method comprising: when a condensing temperature of the first
radiator corresponding to the high pressure detected by the
high-pressure sensor is higher than or equal to a preset target
condensing-temperature value, performing condensing-temperature
control for reducing the operating frequency of the compressor
based on a difference between the condensing temperature and the
preset target condensing-temperature value, and performing
opening-degree control for increasing the opening degree of the
first pressure-reducing mechanism more than opening-degree control
under the control based the degree of on the subcooling.
Description
TECHNICAL FIELD
[0001] The present invention relates to integrated air-conditioning
and hot-water-supply systems that can perform an air-conditioning
operation (i.e., cooling operation or heating operation) and a
hot-water-supply operation at the same time, and more specifically,
to an integrated air-conditioning and hot-water-supply system that
determines a high-temperature-water supply state when the
condensing temperature becomes higher than or equal to a
predetermined value during a hot-water supply and that suppresses
an excessive increase in high pressure by controlling the
condensing temperature of a compressor and the opening degree of a
pressure-reducing mechanism so as to achieve a predetermined
hot-water-supply capacity within a usage range of the
compressor.
BACKGROUND ART
[0002] In the related art, a hot-water-suppliable heat pump system
that is equipped with a refrigerant circuit formed by connecting a
hot-water-supply unit (i.e., a water heater) to a heat source unit
(i.e., an outdoor unit) by pipes and that can perform the
hot-water-supply operation is known. When the hot-water-supply
temperature becomes high (e.g., 60 degrees C.) in such a
hot-water-supply system, the condensing temperature increases,
causing an excessive increase in high pressure. This is a problem
in that it is difficult to ensure a hot-water-supply capacity. For
this reason, there have been efforts to solve this problem (e.g.,
see Patent Literature 1 and Patent Literature 2).
[0003] In a heat-pump bath hot-water-supply device discussed in
Patent Literature 1, the valve opening degree of a
pressure-reducing device is controlled in accordance with a
discharge temperature or a discharge pressure as a target. The
operation efficiency is set in accordance with a discharge
temperature or a discharge pressure that has a maximum value
relative to the valve opening degree of the pressure-reducing
device and that corresponds to the maximum operation efficiency as
a target control value. By changing the target control value in
accordance with a bathtub temperature, a boiling temperature, a
water-side inlet temperature, and a compressor frequency, high
operation efficiency can be achieved even when the bathtub
temperature, the boiling temperature, the water-side inlet
temperature, and the compressor frequency change.
[0004] In a heat-pump hot-water-supply device discussed in Patent
Literature 2, the discharge pressure is monitored during the
hot-water-supply operation, and discharge-pressure control is
performed on an expansion valve when the discharge pressure
increases, so that the operation can be continuously performed
without the discharge pressure exceeding the usage range of the
compressor.
CITATION LIST
Patent Literature
[0005] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2004-53118 [0006] Patent Literature 2: Japanese
Unexamined Patent Application Publication No. 2005-98530
SUMMARY OF INVENTION
Technical Problem
[0007] In the heat-pump bath hot-water-supply device discussed in
Patent Literature 1, the pressure-reducing device is controlled in
accordance with the discharge temperature or the discharge pressure
corresponding to the maximum operation efficiency. However, in the
case where a high-temperature-water supply is performed and the
requested hot-water-supply capacity and the compressor frequency
are high, the control is performed based on the operation
efficiency regardless of an increase in the discharge pressure of
the pressure-reducing device. This causes the discharge pressure to
increase, possibly resulting in an excessive increase in the
condensing temperature.
[0008] In the heat-pump hot-water-supply device discussed in Patent
Literature 2, in the case where the high-temperature-water supply
is performed and the requested hot-water-supply capacity and the
compressor frequency are high, an increase in high pressure
sometimes cannot be suppressed by simply controlling the
pressure-reducing device, resulting in an excessive increase in the
condensing temperature.
[0009] Furthermore, in an integrated air-conditioning and
hot-water-supply system that is equipped with a refrigerant circuit
formed by connecting a use-side unit (i.e., an indoor unit) by
pipes in addition to a hot-water-supply unit and that can perform
the air-conditioning operation and the hot-water-supply operation
at the same time, if there are an air conditioning load and a
high-temperature-water-supply request at the same time during the
high-temperature-water supply, an operation method that satisfies
both of them needs to be established.
[0010] In the present invention, when the condensing temperature
becomes higher than or equal to a predetermined value during the
hot-water supply, a high-temperature-water supply state is
determined, condensing-temperature control is performed on a
compressor, and opening-degree control is performed on a
pressure-reducing mechanism. Accordingly, an integrated
air-conditioning and hot-water-supply system that can suppress an
excessive increase in condensing temperature and can ensure a
hot-water-supply capacity within a usage range of a compressor
during the high-temperature-water supply.
Solution to Problem
[0011] A refrigeration cycle apparatus according to the present
invention includes a refrigeration cycle mechanism having a
compressor whose operating frequency is controllable, a first
radiator, a first pressure-reducing mechanism whose opening degree
is controllable, and a first evaporator, and in which a refrigerant
sequentially circulates through the compressor, the first radiator,
the first pressure-reducing mechanism, and the first evaporator; a
high-pressure sensor that detects a high pressure between a
discharge side of the compressor and a liquid side of the first
pressure-reducing mechanism; and a controller that calculates a
condensing temperature of the first radiator based on the high
pressure detected by the high-pressure sensor. When the calculated
condensing temperature of the first radiator is higher than or
equal to a preset target condensing-temperature value, the
controller performs condensing-temperature control for controlling
the operating frequency of the compressor based on a difference
between the calculated condensing temperature and the target
condensing-temperature value, and performs opening-degree control
for controlling the opening degree of the first pressure-reducing
mechanism concurrently with the condensing-temperature control
based on a difference between a current opening degree of the first
pressure-reducing mechanism and a preset target opening-degree
value.
Advantageous Effects of Invention
[0012] The present invention can provide a refrigeration cycle
apparatus that can suppress an excessive increase in condensing
temperature and can ensure a hot-water-supply capacity within a
usage range of a compressor during the high-temperature-water
supply.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 illustrates the configuration of an integrated
air-conditioning and hot-water-supply system 100 according to
Embodiment 1.
[0014] FIG. 2 schematically illustrates the flow of water from a
hot-water-supply unit 304 to a hot-water-supply tank 305 in
Embodiment 1.
[0015] FIG. 3 schematically illustrates a controller 110 in
Embodiment 1.
[0016] FIG. 4 illustrates an operation of four-way valves relative
to operation modes in Embodiment 1.
[0017] FIG. 5 illustrates a method for determining a target
evaporating-temperature value from a maximum cooled-room
temperature difference in compressor control in Embodiment 1.
[0018] FIG. 6 illustrates a method for determining a target
condensing-temperature value from a maximum heated-room temperature
difference in compressor control in Embodiment 1.
[0019] FIG. 7 illustrates the relationships among a target opening
degree, a hot-water-supply capacity, and operation efficiency in
Embodiment 1.
[0020] FIG. 8 illustrates tests performed when performing control
for changing a target opening-degree value of a hot-water-supply
pressure-reducing mechanism in accordance with a compressor
frequency in Embodiment 1.
[0021] FIG. 9 illustrates the relationship between an outdoor-air
temperature and the target opening-degree value in Embodiment
1.
[0022] FIG. 10 illustrates the relationships among the
hot-water-supply capacity, an evaporating capacity, and a
compressor input in Embodiment 1.
[0023] FIG. 11 illustrates the contents of tests performed at a
development stage when performing control for changing the target
opening-degree value in accordance with the hot-water-supply
capacity in Embodiment 1.
[0024] FIG. 12 is a flowchart illustrating the flow for determining
whether a high-temperature-water supply is to be performed or a
normal hot-water supply is to be performed in Embodiment 1.
[0025] FIG. 13 is a flowchart illustrating an operation method
during a high-temperature-water supply in a simultaneous heating
and hot-water-supply operation in Embodiment 1.
[0026] FIG. 14 is a flowchart illustrating an operation method
during a high-temperature-water supply in a simultaneous cooling
and hot-water-supply operation in Embodiment 1.
DESCRIPTION OF EMBODIMENTS
Embodiment 1
[0027] Embodiment 1 will be described below with reference to FIGS.
1 to 14.
[0028] FIG. 1 is a refrigerant circuit configuration diagram of an
integrated air-conditioning and hot-water-supply system 100
(refrigeration cycle apparatus) according to Embodiment 1. In the
following figures including FIG. 1, the dimensional relationships
among components may sometimes differ from actual dimensional
relationships. Furthermore, when a symbol used in a numerical
expression first appears in this specification, the unit of the
symbol will be written in parenthesis [ ]. If a symbol is
dimensionless (i.e., has no units), the unit will be expressed as
[-].
[0029] FIG. 2 schematically illustrates the flow of water from a
hot-water-supply unit 304 to a hot-water-supply tank 305 in the
integrated air-conditioning and hot-water-supply system 100.
[0030] FIG. 3 schematically illustrates various kinds of sensors in
the integrated air-conditioning and hot-water-supply system 100,
and a measuring unit 101, a calculating unit 102, a control unit
103, and a storage unit 104 in a controller 110. The configuration
of the integrated air-conditioning and hot-water-supply system 100
will be described below with reference to FIGS. 1 to 3. The
integrated air-conditioning and hot-water-supply system 100 is a
triple-pipe multisystem integrated air-conditioning and
hot-water-supply system that performs a vapor-compression
refrigeration cycle operation so as to simultaneously perform a
cooling operation or heating operation selected in a use-side unit
and a hot-water-supply operation in a hot-water-supply unit. The
integrated air-conditioning and hot-water-supply system 100 is an
integrated air-conditioning and hot-water-supply system that can
ensure a hot-water-supply capacity by suppressing an excessive
increase in high pressure during a supply of high-temperature water
when the hot-water-supply operation is performed in the
hot-water-supply unit. FIG. 1 illustrates the refrigerant circuit
configuration, and FIG. 2 illustrates a water circuit configuration
from the hot-water-supply unit 304 to the hot-water-supply tank
305.
[0031] System Configuration
[0032] The integrated air-conditioning and hot-water-supply system
100 has a heat source unit 301, a branch unit 302, use-side units
303a and 303b, the hot-water-supply unit 304, and the
hot-water-supply tank 305. The heat source unit 301 and the branch
unit 302 are connected by a liquid extension pipe 6 serving as a
refrigerant pipe and a gas extension pipe 12 serving as a
refrigerant pipe. The hot-water-supply unit 304 has one end
connected to the heat source unit 301 via a hot-water-supply gas
extension pipe 15 serving as a refrigerant pipe and another end
connected to the branch unit 302 via a hot-water-supply liquid pipe
18 serving as a refrigerant pipe. The use-side units 303a and 303b
and the branch unit 302 are connected by indoor gas pipes 11a and
11b serving as refrigerant pipes and indoor liquid pipes 8a and 8b
serving as refrigerant pipes. The hot-water-supply tank 305 and the
hot-water-supply unit 304 are connected by an upstream water pipe
20 serving as a water pipe and a downstream water pipe 21 serving
as a water pipe.
[0033] Although one heat source unit, two use-side units, one
hot-water-supply unit, and one hot-water-supply tank 305 are
connected as an example in Embodiment 1, the configuration is not
limited to this and the numbers thereof may be more than or fewer
than those shown. Furthermore, although a refrigerant used in the
integrated air-conditioning and hot-water-supply system 100 is
R410A, the refrigerant used in the integrated air-conditioning and
hot-water-supply system 100 is not limited to this kind of
refrigerant. Other alternatives include, for example, an HFC
(hydrofluorocarbon) refrigerant, such as R407C or R404A, an HCFC
(hydrochlorofluorocarbon) refrigerant, such as R22 or R134a, and a
refrigerant that operates at a critical pressure or higher, such as
CO.sub.2.
[0034] As shown in FIG. 1, the integrated air-conditioning and
hot-water-supply system 100 includes the controller 110. The
controller 110 includes the measuring unit 101, the calculating
unit 102, the control unit 103, and the storage unit 104.
[0035] Control to be described below is entirely performed by the
controller 110. Although the controller 110 is disposed in the heat
source unit 301 in FIG. 1, this is only an example. The position
where the controller 110 is disposed is not limited.
[0036] Operation Modes of Heat Source Unit 301
[0037] Operation modes that can be performed by the integrated
air-conditioning and hot-water-supply system 100 will be briefly
described. In the integrated air-conditioning and hot-water-supply
system 100, an operation mode of the heat source unit 301 is
determined based on whether there are a hot-water-supply load in
the connected hot-water-supply unit 304 and cooling loads or
heating loads in the use-side units 303a and 303b. The integrated
air-conditioning and hot-water-supply system 100 is capable of
performing the following five operation modes, which includes
[0038] a cooling operation mode A,
[0039] a heating operation mode B,
[0040] a hot-water-supply operation mode C,
[0041] a simultaneous heating and hot-water-supply operation mode
D, and
[0042] a simultaneous cooling and hot-water-supply operation mode
E.
[0043] (1) The cooling operation mode A is an operation mode of the
heat source unit 301 when there is no hot-water-supply request
signal (also referred to as "hot-water-supply request") and the
cooling operation is performed by the use-side units 303a and 303b.
(2) The heating operation mode B is an operation mode of the heat
source unit 301 when there is no hot-water-supply request and the
heating operation is performed by the use-side units 303a and
303b.
[0044] (3) The hot-water-supply operation mode C is an operation
mode of the heat source unit 301 when there is no air conditioning
load and the hot-water-supply operation is performed by the
hot-water-supply unit 304.
[0045] (4) The simultaneous heating and hot-water-supply operation
mode D is an operation mode of the heat source unit 301 when the
heating operation by the use-side units 303a and 303b and the
hot-water-supply operation by the hot-water-supply unit 304 are
simultaneously performed.
[0046] (5) The simultaneous cooling and hot-water-supply operation
mode E is an operation mode of the heat source unit 301 when the
cooling operation by the use-side units 303a and 303b and the
hot-water-supply operation by the hot-water-supply unit 304 are
simultaneously performed.
[0047] Use-Side Units 303a and 303b
[0048] The use-side units 303a and 303b are connected to the heat
source unit 301 via the branch unit 302. The use-side units 303a
and 303b are installed in areas (e.g., by being concealed in or
suspended from a ceiling indoors or being hung on a wall) where the
units can blow conditioned air to an air conditioning target
region. The use-side units 303a and 303b are connected to the heat
source unit 301 via the branch unit 302, the liquid extension pipe
6, and the gas extension pipe 12, and constitute a part of the
refrigerant circuit.
[0049] The use-side units 303a and 303b each include an indoor-side
refrigerant circuit that constitutes a part of the refrigerant
circuit. These indoor-side refrigerant circuits are constituted by
respective indoor heat exchangers 9a and 9b serving as use-side
heat exchangers. Furthermore, the use-side units 303a and 303b are
respectively provided with indoor air-sending devices 10a and 10b
for supplying conditioned air, after having exchanged heat with the
refrigerant in the indoor heat exchangers 9a and 9b, to the air
conditioning target region, such as an indoor space.
[0050] The indoor heat exchangers 9a and 9b may each be formed of,
for example, a cross-fin-type fin-and-tube heat exchanger
constituted of a heat transfer pipe and multiple fins.
Alternatively, the indoor heat exchangers 9a and 9b may each be
formed of a micro-channel heat exchanger, a shell-and-tube heat
exchanger, a heat-pipe heat exchanger, or a double-pipe heat
exchanger. When the operation mode performed by the use-side units
303a and 303b is the cooling operation mode A, the indoor heat
exchangers 9a and 9b function as refrigerant evaporators and cool
the air in the air conditioning target region. When the operation
mode is the heating operation mode B, the indoor heat exchangers 9a
and 9b function as refrigerant condensers (or radiators) and heat
the air in the air conditioning target region.
[0051] The indoor air-sending devices 10a and 10b have a function
of suctioning indoor air into the use-side units 303a and 303b,
making the indoor air exchange heat with the refrigerant at the
indoor heat exchangers 9a and 9b, and then supplying the indoor air
as conditioned air to the air conditioning target region.
Specifically, in the use-side units 303a and 303b, the indoor air
taken in by the indoor air-sending devices 10a and 10b and the
refrigerant flowing through the indoor heat exchangers 9a and 9b
can exchange heat with each other. The indoor air-sending devices
10a and 10b are capable of adjusting the flow rate of conditioned
air to be supplied to the indoor heat exchangers 9a and 9b and each
include a fan, such as a centrifugal fan or a multi-blade fan, and
a motor, such as a DC fan motor, for driving this fan.
[0052] The use-side units 303a and 303b are provided with the
following various kinds of sensors, which include:
(1) indoor liquid temperature sensors 206a and 206b that are
provided at the liquid side of the indoor heat exchangers 9a and 9b
and detect the temperature of a liquid refrigerant; (2) indoor gas
temperature sensors 207a and 207b that are provided at the gas side
of the indoor heat exchangers 9a and 9b and detect the temperature
of a gas refrigerant; and (3) indoor suction temperature sensors
208a and 208b that are provided at the indoor-air suction side of
the use-side units 303a and 303b and detect the temperature of
indoor air flowing into the units.
[0053] As shown in FIG. 3, the operation of the indoor air-sending
devices 10a and 10b is controlled by the control unit 103 that
functions as normal-operation control means that performs a normal
operation including the cooling operation mode A and the heating
operation mode B of the use-side units 303a and 303b.
[0054] Hot-Water-Supply Unit 304
[0055] The hot-water-supply unit 304 is connected to the heat
source unit 301 via the branch unit 302. As shown in FIG. 2, the
hot-water-supply unit 304 has a function of supplying hot water to
the hot-water-supply tank 305 installed, for example, outdoors and
boiling the water in the hot-water-supply tank 305 by heating the
water. A plate-type water heat exchanger 16 of the hot-water-supply
unit 304 includes a connection section 25 (i.e., an
inflowing-water-pipe connection section) connected to the
downstream water pipe 21 (i.e., an inflowing water pipe), a
connection section 26 (i.e., an outflowing water pipe connection
section) connected to the upstream water pipe 20 (i.e., an
outflowing water pipe), and a water pipe 27 through which water
flowing therein from the downstream water pipe 21 flows out toward
the upstream water pipe 20. Furthermore, the hot-water-supply unit
304 has one end connected to the heat source unit 301 via the
hot-water-supply gas extension pipe 15 and another end connected to
the branch unit 302 via the hot-water-supply liquid pipe 18, and
constitutes a part of the refrigerant circuit in the integrated
air-conditioning and hot-water-supply system 100.
[0056] The hot-water-supply unit 304 includes a
hot-water-supply-side refrigerant circuit that constitutes a part
of the refrigerant circuit. The hot-water-supply-side refrigerant
circuit has the plate-type water heat exchanger 16 serving as a
hot-water-supply-side heat exchanger as an elemental function.
Furthermore, the hot-water-supply unit 304 is provided with a feed
pump 17 for supplying hot water, after having exchanged heat with
the refrigerant in the plate-type water heat exchanger 16, to the
hot-water-supply tank 305, etc.
[0057] When the hot-water-supply operation mode C is performed by
the hot-water-supply unit 304, the plate-type water heat exchanger
16 functions as a refrigerant condenser and heats the water to be
supplied by the feed pump 17. The feed pump 17 has a function of
supplying the water into the hot-water-supply unit 304, making the
water exchange heat at the plate-type water heat exchanger 16 so as
to turn the water into hot water, and then supplying the hot water
into the hot-water-supply tank 305 so as to make the hot water
exchange heat with the water in the hot-water-supply tank 305.
Specifically, in the hot-water-supply unit 304, the water supplied
by the feed pump 17 and the refrigerant flowing through the
plate-type water heat exchanger 16 can exchange heat with each
other, and the water supplied by the feed pump 17 and the water in
the hot-water-supply tank 305 can exchange heat with each other.
Moreover, the flow rate of water to be supplied to the plate-type
water heat exchanger 16 can be adjusted.
[0058] The hot-water-supply unit 304 is provided with the following
various kinds of sensors, which include:
(1) a hot-water-supply liquid temperature sensor 209 that is
provided at the liquid side of the plate-type water heat exchanger
16 and detects the temperature of a liquid refrigerant.
[0059] The operation of the feed pump 17 is controlled by the
control unit 103 that functions as normal-operation control means
that performs the normal operation including the hot-water-supply
operation mode C of the hot-water-supply unit 304 (see FIG. 3).
[0060] Hot-Water-Supply Tank 305
[0061] The hot-water-supply tank 305 is installed, for example,
outdoors and has a function of storing the hot water boiled by the
hot-water-supply unit 304. Furthermore, the hot-water-supply tank
305 has one end connected to the hot-water-supply unit 304 via the
upstream water pipe 20 and another end connected to the
hot-water-supply unit 304 via the downstream water pipe 21, and
constitutes a part of a water circuit in the integrated
air-conditioning and hot-water-supply system 100. The
hot-water-supply tank 305 is of a full-water type that makes the
hot water flow out of the upper portion of the tank when the hot
water is consumed by the user and that is supplied with water from
the lower portion of the tank in accordance with the consumed
amount.
[0062] The water fed by the feed pump 17 in the hot-water-supply
unit 304 becomes hot water by being heated by the refrigerant at
the plate-type water heat exchanger 16 and then travels through the
upstream water pipe 20 so as to flow into the hot-water-supply tank
305. The hot water exchanges heat with the water in the
hot-water-supply tank 305 as intermediate water without being mixed
with the water in the tank, thereby turning into cold water.
Subsequently, the water flows out of the hot-water-supply tank 305
and travels through the downstream water pipe 21 so as to flow into
the hot-water-supply unit 304 again. After being fed by the feed
pump 17 again, the water turns into hot water at the plate-type
water heat exchanger 16. As a result of this process, the water is
boiled in the hot-water-supply tank 305.
[0063] The method for heating the water in the hot-water-supply
tank 305 is not limited to the intermediate-water-based heat
exchange method as in Embodiment 1. As an alternative heating
method, the water in the hot-water-supply tank 305 may flow
directly into a pipe, turn into hot water by exchanging heat at the
plate-type water heat exchanger 16, and then return to the
hot-water-supply tank 305.
[0064] The hot-water-supply tank 305 is provided with the following
various kinds of sensors, which include:
(1) a hot-water-supply-tank water temperature sensor 210 that is
provided on a side surface at the lower portion of the
hot-water-supply tank 305 and detects the temperature of the hot
water in the tank.
[0065] Heat Source Unit 301
[0066] The heat source unit 301 is installed, for example, outdoors
and is connected to the use-side units 303a and 303b via the liquid
extension pipe 6, the gas extension pipe 12, and the branch unit
302. Moreover, the heat source unit 301 is connected to the
hot-water-supply unit 304 via the hot-water-supply gas extension
pipe 15, the liquid extension pipe 6, and the branch unit 302, and
constitutes a part of the refrigerant circuit in the integrated
air-conditioning and hot-water-supply system 100.
[0067] The heat source unit 301 includes an outdoor-side
refrigerant circuit that constitutes a part of the refrigerant
circuit. As elemental devices, the outdoor-side refrigerant circuit
has a compressor 1 that compresses the refrigerant, two four-way
valves (i.e., a first four-way valve 2 and a second four-way valve
13) for switching the flowing direction of the refrigerant in
accordance with the outdoor operation mode, an outdoor heat
exchanger 3 as a heat-source-side heat exchanger, and an
accumulator 14 for retaining an excess refrigerant. Furthermore,
the heat source unit 301 is constituted of an outdoor air-sending
device 4 for supplying air to the outdoor heat exchanger 3 and an
outdoor pressure-reducing mechanism 5 as a heat-source-side
pressure-reducing mechanism for controlling the distributive flow
rate of the refrigerant.
[0068] The compressor 1 suctions the refrigerant and compresses
this refrigerant to a high-temperature high-pressure state. The
compressor 1 equipped in Embodiment 1 is capable of adjusting the
operation capacity and is, for example, a positive-displacement
compressor that is driven by a motor (not shown) controlled by an
inverter. Although only a single compressor 1 is shown as an
example in Embodiment 1, the configuration is not limited to this,
and two or more compressors 1 may be connected in parallel to each
other in accordance with, for example, the connected number of
use-side units 303a and 303b and hot-water-supply units 304.
Furthermore, a discharge-side pipe connected to the compressor 1 is
bifurcated at an intermediate section of the pipe and has one end
connected to the gas extension pipe 12 via the second four-way
valve 13 and another end connected to the hot-water-supply gas
extension pipe 15 via the first four-way valve 2.
[0069] The first four-way valve 2 and the second four-way valve 13
each function as a flow switching device that switches the flowing
direction of the refrigerant in accordance with the operation mode
of the heat source unit 301.
[0070] FIG. 4 illustrates the operational contents of the four-way
valves relative to the operation modes. The terms "solid line" and
"dash line" shown in FIG. 4 correspond to solid lines and dashed
lines shown in FIG. 1 that denote the switched statuses of the
first four-way valve 2 and the second four-way valve 13.
[0071] In the cooling operation mode A, the first four-way valve 2
is switched to the "solid line" state. Specifically, in the cooling
operation mode A, in order to make the outdoor heat exchanger 3
function as a condenser for the refrigerant compressed by the
compressor 1, the first four-way valve 2 is switched so as to
connect the discharge side of the compressor 1 to the gas side of
the outdoor heat exchanger 3. In the heating operation mode B, the
hot-water-supply operation mode C, the simultaneous heating and
hot-water-supply operation mode D, or the simultaneous cooling and
hot-water-supply operation mode E, the first four-way valve 2 is
switched to the "dash line" state. Specifically, in the heating
operation mode B, the hot-water-supply operation mode C, the
simultaneous heating and hot-water-supply operation mode D, or the
simultaneous cooling and hot-water-supply operation mode E, in
order to make the outdoor heat exchanger 3 function as a
refrigerant evaporator, the first four-way valve 2 is switched so
as to connect the discharge side of the compressor 1 to the gas
side of the plate-type water heat exchanger 16 and also to connect
the suction side of the compressor 1 to the gas side of the outdoor
heat exchanger 3.
[0072] In the cooling operation mode A, the hot-water-supply
operation mode C, or the simultaneous cooling and hot-water-supply
operation mode E, the second four-way valve 13 switched to the
"solid line" state. Specifically, the second four-way valve 13 is
switched so as to connect the suction side of the compressor 1 to
the gas side of the indoor heat exchangers 9a and 9b, such that the
indoor heat exchangers 9a and 9b are made to function as
evaporators for the refrigerant compressed by the compressor 1 in
the cooling operation mode A or the simultaneous cooling and
hot-water-supply operation mode E or such that the refrigerant is
prevented from flowing to the use-side units 303a and 303b in the
hot-water-supply operation mode C. In the heating operation mode B,
the hot-water-supply operation mode C, and the simultaneous heating
and hot-water-supply operation mode D, the second four-way valve 13
is switched to the "dash line" state. Specifically, in the heating
operation mode B, the hot-water-supply operation mode C, and the
simultaneous heating and hot-water-supply operation mode D, in
order to make the indoor heat exchangers 9a and 9b function as
refrigerant condensers, the second four-way valve 13 is switched so
as to connect the discharge side of the compressor 1 to the gas
side of the indoor heat exchangers 9a and 9b.
[0073] The outdoor heat exchanger 3 has its gas side connected to
the first four-way valve 2 and its liquid side connected to the
outdoor pressure-reducing mechanism 5. The outdoor heat exchanger 3
may be formed of, for example, a cross-fin-type fin-and-tube heat
exchanger constituted of a heat transfer pipe and multiple fins.
Alternatively, the outdoor heat exchanger 3 may be formed of a
micro-channel heat exchanger, a shell-and-tube heat exchanger, a
heat-pipe heat exchanger, or a double-pipe heat exchanger. In the
cooling operation mode A, the outdoor heat exchanger 3 functions as
a refrigerant condenser and cools the refrigerant. In the heating
operation mode B, the hot-water-supply operation mode C, the
simultaneous heating and hot-water-supply operation mode D, and the
simultaneous cooling and hot-water-supply operation mode E, the
outdoor heat exchanger 3 functions as a refrigerant evaporator and
heats the refrigerant.
[0074] The outdoor air-sending device 4 has a function of
suctioning outdoor air into the heat source unit 301, making the
outdoor air exchange heat at the outdoor heat exchanger 3, and then
discharging the air to the outside. Specifically, in the heat
source unit 301, the outdoor air taken in by the outdoor
air-sending device 4 and the refrigerant flowing through the
outdoor heat exchanger 3 can exchange heat with each other. The
outdoor air-sending device 4 is capable of adjusting the flow rate
of air to be supplied to the outdoor heat exchanger 3 and includes
a fan, such as a propeller fan, and a motor, such as a DC fan
motor, for driving this fan.
[0075] The accumulator 14 is provided at the suction side of the
compressor 1 and has a function of retaining the liquid refrigerant
to prevent it from flowing back to the compressor 1 when there is a
malfunction in the integrated air-conditioning and hot-water-supply
system 100 or during a transient response of an operational state
caused by a change in operation control.
[0076] The heat source unit 301 is provided with the following
various kinds of sensors, which include:
(1) a high-pressure sensor 201 that is provided at the discharge
side of the compressor 1 and detects a high-pressure side high
pressure; (2) a discharge temperature sensor 202 that is provided
at the discharge side of the compressor 1 and detects a discharge
temperature; (3) an outdoor gas temperature sensor 203 that is
provided at the gas side of the outdoor heat exchanger 3 and
detects a gas refrigerant temperature; (4) an outdoor liquid
temperature sensor 204 that is provided at the liquid side of the
outdoor heat exchanger 3 and detects a liquid refrigerant
temperature; and (5) an outdoor-air temperature sensor 205 that is
provided at the outdoor-air suction side of the heat source unit
301 and detects the temperature of outdoor air flowing into the
unit.
[0077] The operation of each of the compressor 1, the first
four-way valve 2, the outdoor air-sending device 4, the outdoor
pressure-reducing mechanism 5, and the second four-way valve 13 is
controlled by the control unit 103 that functions as
normal-operation control means that performs the normal operation
including the cooling operation mode A, the heating operation mode
B, the hot-water-supply operation mode C, the simultaneous heating
and hot-water-supply operation mode D, and the simultaneous cooling
and hot-water-supply operation mode C.
[0078] Branch Unit 302
[0079] The branch unit 302 is installed, for example, indoors, is
connected to the heat source unit 301 via the liquid extension pipe
6 and the gas extension pipe 12, is connected to the use-side units
303a and 303b via the indoor liquid pipes 8a and 8b and the indoor
gas pipes 11a and 11b, is connected to the hot-water-supply unit
304 via the hot-water-supply liquid pipe 18, and constitutes a part
of the refrigerant circuit in the integrated air-conditioning and
hot-water-supply system 100. The branch unit 302 has a function of
controlling the flow of the refrigerant in accordance with a
requested operation in the use-side units 303a and 303b and the
hot-water-supply unit 304.
[0080] The branch unit 302 includes a branch refrigerant circuit
that constitutes a part of the refrigerant circuit. As elemental
devices, the branch refrigerant circuit has indoor
pressure-reducing mechanisms 7a and 7b as use-side
pressure-reducing mechanisms for controlling the distributive flow
rate of the refrigerant, and a hot-water-supply pressure-reducing
mechanism 19 for controlling the distributive flow rate of the
refrigerant.
[0081] The indoor pressure-reducing mechanisms 7a and 7b are
respectively provided in the indoor liquid pipes 8a and 8b. The
hot-water-supply pressure-reducing mechanism 19 is provided in the
hot-water-supply liquid pipe 18 in the branch unit 302. Each of the
indoor pressure-reducing mechanisms 7a and 7b functions as a
pressure-reducing valve and an expansion valve, and reduces the
pressure of and expands the refrigerant flowing through the liquid
extension pipe 6 in the cooling operation mode A and reduces the
pressure of and expands the refrigerant flowing through the
hot-water-supply pressure-reducing mechanism 19 in the simultaneous
cooling and hot-water-supply operation mode E. In the heating
operation mode B and the simultaneous heating and hot-water-supply
operation mode D, the indoor pressure-reducing mechanisms 7a and 7b
reduce the pressure of and expand the refrigerant flowing through
the indoor liquid pipes 8a and 8b. The hot-water-supply
pressure-reducing mechanism 19 functions as a pressure-reducing
valve and an expansion valve and reduces the pressure of and
expands the refrigerant flowing through the hot-water-supply liquid
pipe 18 in the hot-water-supply operation mode C and the
simultaneous heating and hot-water-supply operation mode D. The
indoor pressure-reducing mechanisms 7a and 7b and the
hot-water-supply pressure-reducing mechanism 19 may each be of a
type whose opening degree is variably controllable, such as precise
flow control means using an electronic expansion valve or
inexpensive refrigerant flow control means such as a capillary
tube.
[0082] As shown in FIG. 3, the operation of the hot-water-supply
pressure-reducing mechanism 19 is controlled by the control unit
103 of the controller 110, which functions as normal-operation
control means that performs the normal operation including the
hot-water-supply operation mode C of the hot-water-supply unit 304.
The operation of each of the indoor pressure-reducing mechanisms 7a
and 7b is controlled by the control unit 103 functioning as
normal-operation control means that performs the normal operation
including the cooling operation mode A and the heating operation
mode B of the use-side units 303a and 303b.
[0083] Controller 110
[0084] As shown in FIG. 3, the values detected by the various kinds
of temperature and pressure sensors are input to the measuring unit
101 and are processed by the calculating unit 102. Then, based on
the processed result of the calculating unit 102, the control unit
103 controls the compressor 1, the first four-way valve 2, the
outdoor air-sending device 4, the outdoor pressure-reducing
mechanism 5, the indoor pressure-reducing mechanisms 7a and 7b, the
indoor air-sending devices 10 and 10b, the second four-way valve
13, the feed pump 17, and the hot-water-supply pressure-reducing
mechanism 19. Specifically, the overall operation of the integrated
air-conditioning and hot-water-supply system 100 is controlled by
the controller 110 equipped with the measuring unit 101, the
calculating unit 102, and the control unit 103. The controller 110
may be constituted of a microcomputer. Calculation expressions to
be described in Embodiment 1 below are calculated by the
calculating unit 102, and the control unit 103 controls each of the
devices, such as the compressor 1, in accordance with the
calculation results. The storage unit 104 stores data to be used in
the calculating unit 102 and the calculation results.
[0085] Specifically, based on commands, such as an operation mode
(e.g., a cooling request signal for requesting the cooling
operation of the use-side units 303) received via a remote
controller, a hot-water-supply request signal, to be described
below, and a preset temperature, and information detected by the
various sensors, the control unit 103 performs each operation mode
by controlling the following:
[0086] the operating frequency of the compressor 1,
[0087] the switching of the first four-way valve 2,
[0088] the rotation speed (including an on/off operation) of the
outdoor air-sending device 4,
[0089] the opening degree of the outdoor pressure-reducing
mechanism 5,
[0090] the opening degrees of the indoor pressure-reducing
mechanisms 7a and 7b,
[0091] the rotation speeds (including an on/off operation) of the
indoor air-sending devices 10a and 10b,
[0092] the switching of the second four-way valve 13,
[0093] the rotation speed (including an on/off operation) of the
feed pump 17, and
[0094] the opening degree of the hot-water-supply pressure-reducing
mechanism 19.
[0095] The measuring unit 101, the calculating unit 102, and the
control unit 103 may be integrally provided or may be provided
independently of each other. Furthermore, the measuring unit 101,
the calculating unit 102, and the control unit 103 may be provided
in any one of the units. Moreover, the measuring unit 101, the
calculating unit 102, and the control unit 103 may be provided in
each of the units.
[0096] Operation Modes
[0097] The integrated air-conditioning and hot-water-supply system
100 controls each of the devices equipped in the heat source unit
301, the branch unit 302, the use-side units 303a and 303b, and the
hot-water-supply unit 304 in accordance with requested air
conditioning loads of the use-side units 303a and 303b and a
requested hot-water-supply load of the hot-water-supply unit 304.
With this control, the integrated air-conditioning and
hot-water-supply system 100 performs the cooling operation mode A,
the heating operation mode B, the hot-water-supply operation mode
C, the simultaneous heating and hot-water-supply operation mode D,
or the simultaneous cooling and hot-water-supply operation mode
E.
[0098] The simultaneous cooling and hot-water-supply operation mode
E further includes a "hot-water-supply priority mode" in which the
operating frequency of the compressor 1 is controlled in accordance
with a hot-water-supply request signal from the hot-water-supply
unit 304 and a "cooling priority mode" in which the operating
frequency of the compressor 1 is controlled in accordance with
cooling loads of the use-side units 303a and 303b. The
hot-water-supply request signal is output from the hot-water-supply
unit 304 when the temperature of the water stored in the
hot-water-supply tank 305 is lower than a preset hot-water-supply
temperature. When the hot-water-supply request signal is output,
the control unit 103 estimates a cooling load and a heating load
from a temperature difference (i.e., an indoor temperature
difference) between an indoor suction temperature and a preset
indoor temperature and performs control based on an assumption that
the larger the indoor temperature difference, the larger the
cooling load and the heating load.
[0099] Operation
[0100] Specific refrigerant flowing methods and normal control
methods in the cooling operation mode A, the heating operation mode
B, the hot-water-supply operation mode C, the simultaneous heating
and hot-water-supply operation mode D, and the simultaneous cooling
and hot-water-supply operation mode E performed by the integrated
air-conditioning and hot-water-supply system 100 will now be
described. The operation of each four-way valve in each of the
operation modes is as shown in FIG. 4. For each of the
hot-water-supply operation mode C, the simultaneous heating and
hot-water-supply operation mode D, and the simultaneous cooling and
hot-water-supply operation mode E, a control method for
high-temperature-water supply will be described in addition to a
normal control method.
[0101] Cooling Operation Mode A
[0102] In the cooling operation mode, the hot-water-supply
pressure-reducing mechanism 19 is completely closed. In the cooling
operation mode A, the first four-way valve 2 is in the solid-line
state, meaning that the discharge side of the compressor 1 is
connected to the gas side of the outdoor heat exchanger 3.
Furthermore, the second four-way valve 13 is in the solid-line
state, meaning that the suction side of the compressor 1 is
connected to the indoor heat exchangers 9a and 9b via the gas
extension pipe 12.
[0103] While the refrigerant circuit is in this state, the
compressor 1, the outdoor air-sending device 4, and the indoor
pressure-reducing mechanisms 7a and 7b are activated. This causes a
low-pressure gas refrigerant to be suctioned into and compressed by
the compressor 1, thereby becoming a high-temperature high-pressure
gas refrigerant. Subsequently, the high-temperature high-pressure
gas refrigerant travels through the first four-way valve 2 and
flows into the outdoor heat exchanger 3 where the gas refrigerant
condenses by exchanging heat with outdoor air supplied by the
outdoor air-sending device 4, thereby becoming a high-pressure
liquid refrigerant. After flowing out of the outdoor heat exchanger
3, the high-pressure liquid refrigerant flows to the outdoor
pressure-reducing mechanism 5 where the high-pressure liquid
refrigerant is reduced in pressure. Subsequently, the liquid
refrigerant travels through the liquid extension pipe 6 and flows
into the branch unit 302. At this time, the outdoor
pressure-reducing mechanism 5 is controlled to a maximum opening
degree. The refrigerant flowing into the branch unit 302 is reduced
in pressure by the indoor pressure-reducing mechanisms 7a and 7b so
as to become a low-pressure two-phase gas-liquid refrigerant.
Subsequently, the refrigerant flows out of the branch unit 302 and
travels through the indoor liquid pipes 8a and 8b so as to flow
into the use-side units 303a and 303b.
[0104] The refrigerant flowing into the use-side units 303a and
303b flows into the indoor heat exchangers 9a and 9b where the
refrigerant evaporates by exchanging heat with indoor air supplied
by the indoor air-sending devices 10a and 10b, thereby becoming a
low-pressure gas refrigerant. In this case, each of the indoor
pressure-reducing mechanisms 7a and 7b is controlled such that a
temperature difference (i.e., a cooled-room temperature difference)
obtained by subtracting a preset temperature from an indoor suction
temperature detected by the indoor suction temperature sensor 208a
or 208b in corresponding use-side unit 303a or 303b is eliminated.
Therefore, the flow rate of refrigerant flowing through the indoor
heat exchangers 9a and 9b corresponds to the cooling load requested
in the air-conditioned space where the use-side units 303a and 303b
are installed.
[0105] The refrigerant flowing out of the indoor heat exchangers 9a
and 9b flows out of the use-side units 303a and 303b and then
travels through the indoor gas pipes 11a and 11b and the branch
unit 302 so as to flow into the gas extension pipe 12. The
refrigerant then travels through the second four-way valve 13 and
passes through the accumulator 14 so as to be suctioned into the
compressor 1 again.
[0106] The operating frequency of the compressor 1 is controlled by
the control unit 103 such that the evaporating temperature is made
equal to a predetermined value. The predetermined
evaporating-temperature value is the temperature detected by the
indoor liquid temperature sensor 206a or 206b. The predetermined
evaporating-temperature value is determined from a temperature
difference (i.e., a cooled-room temperature difference), which is
obtained by subtracting a preset temperature from an indoor suction
temperature detected by the indoor suction temperature sensor 208a
or 208b, in the use-side unit 303a or 303b that has the maximum
temperature difference in the use-side units 303a and 303b.
[0107] FIG. 5 illustrates a method for determining a
target-evaporating-temperature value from a maximum cooled-room
temperature difference in compressor control. Specifically, as
shown in FIG. 5, a target-evaporating-temperature value in a
corresponding range is set on the basis of a maximum cooled-Room
Temperature difference .DELTA.Tje [-].
Target-evaporating-temperature values A1 to A4 in respective
maximum cooled-room temperature difference ranges are determined
from tests, etc. Furthermore, the quantity of air from the outdoor
air-sending device 4 is controlled by the control unit 103 such
that the condensing temperature is made equal to a predetermined
value in accordance with the outdoor-air temperature detected by
the outdoor-air temperature sensor 205. The condensing temperature
in this case is a saturation temperature calculated based on the
pressure detected by the high-pressure sensor 201.
[0108] Heating Operation Mode B
[0109] In the heating operation mode, the hot-water-supply
pressure-reducing mechanism 19 (i.e., a first pressure-reducing
mechanism) is completely closed. Therefore, the refrigerant does
not flow to the first four-way valve 2 and the hot-water-supply
unit 304. In the heating operation mode B, the first four-way valve
2 is in the dash-line state, meaning that the discharge side of the
compressor 1 is connected to the gas side of the plate-type water
heat exchanger 16 (i.e., a first radiator) and the suction side of
the compressor 1 is connected to the gas side of the outdoor heat
exchanger 3 (i.e., a first evaporator). The second four-way valve
13 is in the dash-line state, meaning that the discharge side of
the compressor 1 is connected to the gas side of the indoor heat
exchangers 9a and 9b.
[0110] While the refrigerant circuit is in this state, the
compressor 1, the outdoor air-sending device 4, the indoor
air-sending devices 10a and 10b, and the feed pump 17 are
activated. This causes a low-pressure gas refrigerant to be
suctioned into and compressed by the compressor 1, thereby becoming
a high-temperature high-pressure gas refrigerant. Subsequently, the
high-temperature high-pressure gas refrigerant flows through the
second four-way valve 13.
[0111] The refrigerant flowing into the second four-way valve 13
flows out of the heat source unit 301 and travels through the gas
extension pipe 12 so as to flow into the branch unit 302.
Subsequently, the refrigerant travels through the indoor gas pipes
11a and 11b so as to flow into the use-side units 303a and 303b.
The refrigerant flowing into the use-side units 303a and 303b flows
into the indoor heat exchangers 9a and 9b where the refrigerant
condenses by exchanging heat with indoor air supplied by the indoor
air-sending devices 10a and 10b so as to become a high-pressure
liquid refrigerant, which then flows out of the indoor heat
exchangers 9a and 9b. The refrigerant having heated the indoor air
at the indoor heat exchangers 9a and 9b flows out of the use-side
units 303a and 303b and travels through the indoor liquid pipes 8a
and 8b so as to flow into the branch unit 302. The refrigerant is
then reduced in pressure by the indoor pressure-reducing mechanisms
7a and 7b, thereby becoming a low-pressure, two-phase gas-liquid or
liquid-phase refrigerant. Subsequently, the refrigerant flows out
of the branch unit 302.
[0112] Each of the indoor pressure-reducing mechanisms 7a and 7b is
controlled such that a temperature difference (i.e., a heated-room
temperature difference) obtained by subtracting a preset indoor
temperature from an indoor suction temperature detected by the
indoor suction temperature sensor 208a or 208b in corresponding
use-side unit 303a or 303b is eliminated. Therefore, the flow rate
of refrigerant flowing through the indoor heat exchangers 9a and 9b
corresponds to the heating load requested in the air-conditioned
space where the use-side units 303a and 303b are installed.
[0113] The refrigerant flowing out of the branch unit 302 travels
through the liquid extension pipe 6, flows into the heat source
unit 301, passes through the outdoor pressure-reducing mechanism 5,
and then flows into the outdoor heat exchanger 3. The opening
degree of the outdoor pressure-reducing mechanism 5 is controlled
so that it is in a completely open state. The refrigerant flowing
into the outdoor heat exchanger 3 evaporates by exchanging heat
with outdoor air supplied by the outdoor air-sending device 4,
thereby becoming a low-pressure gas refrigerant. This refrigerant
flows out of the outdoor heat exchanger 3, travels through the
first four-way valve 2, passes through the accumulator 14, and is
then suctioned into the compressor 1 again.
[0114] The operating frequency of the compressor 1 is controlled by
the control unit 103 such that the condensing temperature is made
equal to a target value. The method for determining the condensing
temperature is the same as that in the cooling operation. The
target condensing-temperature value is determined from a
temperature difference (i.e., a heated-room temperature
difference), which is obtained by subtracting a preset indoor
temperature from an indoor suction temperature detected by the
indoor suction temperature sensor 208a or 208b, in the use-side
unit 303a or 303b that has the maximum heated-room temperature
difference in the use-side units 303a and 303b.
[0115] FIG. 6 illustrates a method for determining a
target-condensing-temperature value from a maximum heated-room
temperature difference in compressor control. Specifically, as
shown in FIG. 6, a target-condensing-temperature value in a
corresponding range is set on the basis of a maximum heated-room
temperature difference .DELTA.Tjc [-].
Target-condensing-temperature values B1 to B4 in respective maximum
heated-room temperature difference ranges are determined from
tests, etc. Furthermore, the quantity of air from the outdoor
air-sending device 4 is controlled by the control unit 103 such
that the evaporating temperature is made equal to a predetermined
value in accordance with the outdoor-air temperature detected by
the outdoor-air temperature sensor 205. The evaporating temperature
in this case is determined based on the temperature detected by the
outdoor liquid temperature sensor 204.
[0116] Hot-Water-Supply Operation Mode C
[0117] In the hot-water-supply operation mode C, the first four-way
valve 2 is in the dash-line state, meaning that the discharge side
of the compressor 1 is connected to the gas side of the plate-type
water heat exchanger 16 and the suction side of the compressor 1 is
connected to the gas side of the outdoor heat exchanger 3. The
second four-way valve 13 is in the solid-line state, meaning that
the suction side of the compressor 1 is connected to the indoor
heat exchangers 9a and 9b via the gas extension pipe 12.
[0118] While the refrigerant circuit is in this state, the
compressor 1, the outdoor air-sending device 4, the indoor
air-sending devices 10a and 10b, and the feed pump 17 are
activated. This causes a low-pressure gas refrigerant to be
suctioned into and compressed by the compressor 1, thereby becoming
a high-temperature high-pressure gas refrigerant. Subsequently, the
high-temperature high-pressure gas refrigerant flows through the
first four-way valve 2.
[0119] The refrigerant flowing into the first four-way valve 2
flows out of the heat source unit 301 and travels through the
hot-water-supply gas extension pipe 15 so as to flow into the
hot-water-supply unit 304. The refrigerant flowing into the
hot-water-supply unit 304 flows into the plate-type water heat
exchanger 16 where the refrigerant condenses by exchanging heat
with water supplied by the feed pump 17 so as to become a
high-pressure liquid refrigerant, which then flows out of the
plate-type water heat exchanger 16. The refrigerant having heated
the water at the plate-type water heat exchanger 16 flows out of
the hot-water-supply unit 304, travels through the hot-water-supply
liquid pipe 18, flows into the branch unit 302, and is then reduced
in pressure by the hot-water-supply pressure-reducing mechanism 19,
thereby becoming a low-pressure two-phase gas-liquid refrigerant.
Subsequently, the refrigerant flows out of the branch unit 302 and
flows into the heat source unit 301 via the liquid extension pipe
6.
[0120] In the hot-water-supply operation mode, the opening degree
of the hot-water-supply pressure-reducing mechanism 19 is
controlled by the control unit 103 such that the degree of
subcooling at the liquid side of the plate-type water heat
exchanger 16 is made equal to a predetermined value. The degree of
subcooling at the liquid side of the plate-type water heat
exchanger 16 is determined by calculating a saturation temperature
(i.e., a calculated condensing temperature) from a pressure (i.e.,
a high pressure) detected by the high-pressure sensor 201 (i.e., a
high-pressure sensor) and then subtracting a temperature detected
by the hot-water-supply liquid temperature sensor 209 therefrom.
The hot-water-supply pressure-reducing mechanism 19 controls the
flow rate of refrigerant flowing through the plate-type water heat
exchanger 16 so that the degree of subcooling of the refrigerant at
the liquid side of the plate-type water heat exchanger 16 is made
equal to the predetermined value. Therefore, the high-pressure
liquid refrigerant condensed by the plate-type water heat exchanger
16 turns into a state with a predetermined degree of subcooling.
Accordingly, the flow rate of refrigerant flowing through the
plate-type water heat exchanger 16 corresponds to a
hot-water-supply request according to the usage condition of hot
water in a facility where the hot-water-supply unit 304 is
installed.
[0121] The refrigerant flowing out of the branch unit 302 travels
through the liquid extension pipe 6, flows into the heat source
unit 301, passes through the outdoor pressure-reducing mechanism 5,
and then flows into the outdoor heat exchanger 3. The opening
degree of the outdoor pressure-reducing mechanism 5 is controlled
so that it is in a completely open state. The refrigerant flowing
into the outdoor heat exchanger 3 evaporates by exchanging heat
with outdoor air supplied by the outdoor air-sending device 4,
thereby becoming a low-pressure gas refrigerant. This refrigerant
flows out of the outdoor heat exchanger 3, travels through the
first four-way valve 2, passes through the accumulator 14, and is
then suctioned into the compressor 1 again.
[0122] The operating frequency of the compressor 1 is controlled to
a high value by the control unit 103. Specifically, in the case of
the hot-water-supply operation, the controller 110 ensures a high
hot-water-supply capacity so as to increase the water temperature
in the hot-water-supply tank 305 to a preset hot-water-supply
temperature as quickly as possible in response to a
hot-water-supply request signal detected by the
hot-water-supply-tank water temperature sensor 210. Furthermore,
the quantity of air from the outdoor air-sending device 4 is
controlled by the control unit 103 such that the evaporating
temperature is made equal to a predetermined value in accordance
with the outdoor-air temperature detected by the outdoor-air
temperature sensor 205. The evaporating temperature in this case is
the temperature detected by the outdoor liquid temperature sensor
204.
[0123] If the hot-water-supply temperature is high (e.g., 60
degrees C.), the inlet water temperature (i.e., the temperature of
water flowing into the connection section 25) of the plate-type
water heat exchanger 16 also becomes high, causing the condensing
temperature to increase. In this case, if the operating frequency
of the compressor 1 is controlled to a high value, the high
pressure increases to a value outside an appropriate operating
range of the compressor 1. Therefore, if a condensing temperature
calculated from a detected value of the high-pressure sensor 201
reaches an upper limit value (e.g., 60 degrees C.),
condensing-temperature control shown in expressions (1) and (2) is
performed on the compressor 1 so as to prevent the condensing
temperature from increasing.
[Math. 1]
Fm=F+.DELTA.F (1)
[Math. 2]
.DELTA.F=(CTm-CT).times.k.sub.CT-comp (2)
[0124] In this case, Fm denotes a target operating frequency [Hz]
of the compressor 1, F denotes a current operating frequency [Hz]
of the compressor 1, .DELTA.F denotes a change [Hz] in the
operating frequency of the compressor 1, CTm denotes a target
condensing-temperature value [degrees C], CT denotes a calculated
condensing temperature [degrees C], and k.sub.CT,comp denotes gain
compensation [-] for a change in the operating frequency of the
compressor.
[0125] The target condensing-temperature value CTm is, for example,
a maximum condensing-temperature value (e.g., 60 degrees C.)
allowable in an appropriate usage range of the compressor 1. The
condensing temperature CT is a saturation temperature calculated
from the pressure detected by the high-pressure sensor 201. The
gain compensation k.sub.CT,comp for a change in the operating
frequency of the compressor is set to a value based on tests or
simulation such that the condensing temperature CT does not
increase from the target condensing-temperature value CTm and that
the frequency does not decrease rapidly. Although the high-pressure
sensor 201 is provided between the compressor 1 and the first
four-way valve 2 in Embodiment 1, the configuration is not limited
to this. The high-pressure sensor 201 may be provided at any
position between the liquid side of the hot-water-supply
pressure-reducing mechanism 19 and the discharge side of the
compressor 1, which is located at the high-pressure side of the
refrigeration cycle. If the high-pressure sensor 201 is disposed
between the first four-way valve 2 and the liquid side of the
hot-water-supply pressure-reducing mechanism 19, an additional
pressure sensor for determining the condensing temperature in the
heating operation mode B is disposed between the compressor 1 and
the second four-way valve 13.
[0126] If the calculated condensing temperature CT reaches the
target condensing-temperature value CTm during the
high-temperature-water supply, CT becomes higher than CTm. In that
case, the operating frequency of the compressor 1 is decreased in
accordance with expressions (1) and (2), whereby the condensing
temperature CT can be prevented from being higher than the target
condensing-temperature value CTm. When the operating frequency of
the compressor 1 decreases, the hot-water-supply capacity
decreases. In order to adjust the amount of decrease in the
hot-water-supply capacity, pressure-reducing-mechanism
opening-degree control is performed so that a predetermined
hot-water-supply capacity can be ensured. In Embodiment 1, the
opening degree of the hot-water-supply pressure-reducing mechanism
19 is controlled. Specifically, the opening degree of the
hot-water-supply pressure-reducing mechanism 19 is controlled in
accordance with expressions (3) and (4) so that the predetermined
hot-water-supply capacity can be ensured.
[Math. 3]
S.sub.j=S.sub.j-1+.DELTA.S.sub.j (3)
[Math. 4]
.DELTA.S.sub.j=(S.sub.jm-S.sub.j-1) (4)
[0127] In this case, S.sub.j denotes an opening degree [pulse] of
the pressure-reducing mechanism after changing the opening degree
thereof, S.sub.j-1 denotes a current opening degree [pulse] of the
pressure-reducing mechanism, .DELTA.S.sub.j denotes a change
[pulse] in the opening degree of the pressure-reducing mechanism,
and S.sub.jm denotes a target opening degree [pulse] of the
pressure-reducing mechanism (sometimes referred to as "target
pressure-reducing-mechanism opening-degree value").
[0128] The target opening degree S.sub.jm [pulse] of the
pressure-reducing mechanism can be determined at the development
stage in the following manner.
[0129] FIG. 7 illustrates the relationship between the
hot-water-supply capacity and the operation efficiency. FIG. 7(a)
illustrates the hot-water-supply capacity of the plate-type water
heat exchanger 16 relative to the opening degree of the
hot-water-supply pressure-reducing mechanism 19. The abscissa axis
denotes the opening degree of the hot-water-supply
pressure-reducing mechanism 19, whereas the ordinate axis denotes a
target hot-water-supply capacity value of the plate-type water heat
exchanger 16. FIG. 7(b) illustrates the operation efficiency (COP)
relative to the opening degree of the hot-water-supply
pressure-reducing mechanism 19. The abscissa axis denotes the
opening degree of the hot-water-supply pressure-reducing mechanism
19, whereas the ordinate axis denotes the operation efficiency.
When the inlet water temperature during high-temperature-water
supply increases and condensing-temperature control is to be
performed on the compressor 1, the hot-water-supply capacity of the
plate-type water heat exchanger 16 and the operation efficiency
(COP) change as shown in FIGS. 7(a) and 7(b) relative to the
opening degree of the hot-water-supply pressure-reducing mechanism
19. Because the operating frequency of the compressor 1 becomes
higher as the opening degree of the hot-water-supply
pressure-reducing mechanism 19 increases, the hot-water-supply
capacity increases. In contrast, the operation efficiency
decreases. The target opening degree S.sub.jm of the
pressure-reducing mechanism can be set based on FIG. 7 as an
opening degree that achieves a minimum-required hot-water-supply
capacity to be ensured. Specifically, the target opening-degree
value is set in correspondence with a target value for the
hot-water-supply capacity (i.e., heat-radiation capacity) of the
plate-type water heat exchanger 16 (i.e., first radiator). The
target opening degree S.sub.jm of the pressure-reducing mechanism
is determined based on tests or simulation at the development
stage. Furthermore, as the hot-water-supply temperature becomes
higher and the inlet water temperature increases (i.e., as CT
increases when CT>CTm), the operating frequency of the
compressor 1 is decreased by performing the condensing-temperature
control (i.e., expressions (1) and (2)) on the compressor 1,
causing the hot-water-supply capacity to decrease. Therefore, the
target opening degree is determined when the inlet water
temperature is at the maximum. The inlet water temperature is
estimated such that, for example, when the maximum value of the
hot-water-supply temperature is 60 degrees C. and the
hot-water-supply capacity is a rated hot-water-supply capacity, the
amount of flowing water causes the temperature difference between
the inlet water temperature and the outlet water temperature of the
plate-type water heat exchanger 16 to be 5 degrees C. In this case,
since the hot-water-supply temperature is 60 degrees C., the outlet
water temperature is 60 degrees C. and the inlet water temperature
is 55 degrees C. In other words, the maximum inlet water
temperature is 55 degrees C. Because the hot-water-supply capacity
increases as the inlet water temperature decreases, the
minimum-required hot-water-supply capacity (i.e., the
heat-radiation capacity of the plate-type water heat exchanger 16)
can be ensured by determining the target opening degree when the
inlet water temperature is at the maximum. Furthermore, it is
obvious from FIG. 7 that, by lowering the target hot-water-supply
capacity and lowering the target opening degree S.sub.jm, the
operation efficiency can be increased.
[0130] The target hot-water-supply capacity value of the plate-type
water heat exchanger 16 may be set in correspondence with an upper
limit value in design for the inlet water temperature of the water
flowing into the water pipe of the plate-type water heat exchanger
16 from the downstream water pipe 21.
[0131] When an operation is actually performed with the target
opening degree S.sub.jm of the pressure-reducing mechanism
described above, the condensing-temperature control is performed on
the compressor 1, and the operation is performed with the target
opening degree S.sub.jm of the pressure-reducing mechanism as a
fixed value regardless of the operating frequency of the compressor
1. Therefore, the minimum-required hot-water-supply capacity can be
ensured when the inlet water temperature is 55 degrees C., and the
operating frequency of the compressor is increased when the inlet
water temperature is low at 54 degrees C. or 53 degrees C. Because
the hot-water-supply capacity increases in proportion to the
operating frequency of the compressor, the hot-water-supply
capacity is excessive when the inlet water temperature is low,
leading to reduced operating efficiency even though the time
required for completing the hot-water-supply operation can be
shortened. If the minimum-required hot-water-supply capacity can be
ensured, it is desirable that the hot-water-supply operation be
performed at the highest possible operation efficiency. Therefore,
when the inlet water temperature is low at 54 degrees C. or 53
degrees C., the opening degree of the hot-water-supply
pressure-reducing mechanism 19 may be reduced to suppress an
excessive hot-water-supply capacity, so that the minimum-required
hot-water-supply capacity can be ensured. Reducing the opening
degree of the hot-water-supply pressure-reducing mechanism 19
causes a pressure difference in the hot-water-supply
pressure-reducing mechanism 19 to increase and the condensing
temperature to increase, resulting in a lower operating frequency
of the compressor 1.
[0132] FIG. 8 illustrates tests performed when performing control
for changing the target opening-degree value of the
hot-water-supply pressure-reducing mechanism in accordance with the
frequency of the compressor. The contents of the tests are shown in
FIG. 8 for explaining how the control is performed in detail. For
determining the target opening degree of the pressure-reducing
mechanism at the development stage mentioned above, the tests are
performed when the inlet water temperature is at the maximum at 55
degrees C. and also when the inlet water temperature is 54 degrees
C. and 53 degrees C., and target opening degrees S.sub.jm of the
pressure-reducing mechanism that achieve the minimum-required
hot-water-supply capacity to be ensured when the
condensing-temperature control is performed on the compressor 1
(the target condensing temperature is set to, for example, 60
degrees C.) are determined. In this case, a compressor frequency F
is also recorded, and a function f(F) of the target opening degree
S.sub.jm of the pressure-reducing mechanism relative to the
compressor frequency F is created from a point obtained from each
test. The function of the target opening degree S.sub.jm of the
pressure-reducing mechanism can be obtained with higher accuracy by
increasing the number of tested inlet-water-temperature points.
Furthermore, because the operating frequency of the compressor 1
becomes higher and the refrigerant flow rate increases as the inlet
water temperature decreases, the target opening degree S.sub.jm of
the pressure-reducing mechanism also increases. In the actual
operation, when the condensing-temperature control is performed on
the compressor 1, the target opening degree S.sub.jm of the
pressure-reducing mechanism is determined from the function f(F)
shown in expression (5), which is created at the development stage.
The controller 110 stores the following expression (5) in the
storage unit 104 as frequency/opening-degree correspondence
information.
[Math. 5]
S.sub.jm=f(F) (5)
[0133] By performing the operation in this manner, high operating
efficiency can be achieved while the minimum-required
hot-water-supply capacity is ensured.
[0134] FIG. 9 illustrates the relationship between the outdoor-air
temperature and the target opening-degree value. As shown in FIG.
9, since the pressure at the low-pressure side increases and the
pressure at the high-pressure side increases as the outdoor-air
temperature increases, the operating frequency of the compressor 1
decreases, causing the target opening-degree value S.sub.jm for
ensuring the hot-water-supply capacity to increase. By changing the
target opening-degree value S.sub.jm in accordance with the
outdoor-air temperature, a constant hot-water-supply capacity can
also be ensured relative to a change in the outdoor-air
temperature, such as an increase in the outdoor-air
temperature.
[0135] The controller 110 stores the relationship between the
outdoor-air temperature and the target opening-degree value shown
in FIG. 9 in the storage unit 104 as
outdoor-air-temperature/opening-degree correspondence information.
When the condensing-temperature control and the opening-degree
control are concurrently performed, the control unit 103 of the
controller 110 refers to the outdoor-air-temperature/opening-degree
correspondence information so as to identify a target
opening-degree value corresponding to an outdoor-air temperature
detected by the outdoor-air temperature sensor 205 from the
outdoor-air-temperature/opening-degree correspondence information,
and uses the identified target opening-degree value as a target
opening-degree value in the opening-degree control.
[0136] For determining the target opening degree S.sub.jm of the
pressure-reducing mechanism, a target opening degree is determined
from tests performed at the development stage so as to achieve a
constant hot-water-supply capacity. However, because there are
individual differences among pressure-reducing mechanisms in
actuality, a constant hot-water-supply capacity is sometimes not
achieved even if the same pressure-reducing mechanism is used. The
following configuration can be used to solve this problem. By
determining the hot-water-supply capacity directly from the
operational state of the actual system in operation and setting a
target opening degree of the pressure-reducing mechanism that can
at least ensure a "target constant hot-water-supply capacity" by
using the determined hot-water-supply capacity, variations in
hot-water-supply capacity caused by individual differences among
pressure-reducing mechanisms or degradation over time can be
prevented, thereby preventing an unexpected decrease in
hot-water-supply capacity.
[0137] FIG. 10 illustrates the relationships among a
hot-water-supply capacity Qc, an evaporating capacity Qe, and a
compressor input W. The following description relates to a specific
method. A sum of the evaporating capacity of the outdoor heat
exchanger 3 and the input of the compressor 1 is equal to the
hot-water-supply capacity of the plate-type water heat exchanger
16. Therefore, the hot-water-supply capacity is determined by
determining the evaporating capacity of the outdoor heat exchanger
3 and the input of the compressor 1 (i.e., compressing work done on
the refrigerant by the compressor 1). A table showing the
evaporating capacity relative to a temperature difference between
the outdoor-air temperature and the evaporating temperature is
created based on tests, and the evaporating capacity of the outdoor
heat exchanger 3 is determined by using the table.
[0138] FIG. 11 illustrates the contents of tests performed at the
development stage when performing control for changing the target
opening-degree value in accordance with the hot-water-supply
capacity. The contents of the tests are shown in FIG. 11. The
condensing-temperature control is performed on the compressor 1,
and the opening degree of the hot-water-supply pressure-reducing
mechanism 19 that can ensure the hot-water-supply capacity at a
maximum inlet water temperature of 55 degrees C. is determined. The
"difference between the outdoor-air temperature and the evaporating
temperature" and the "evaporating capacity" of the outdoor heat
exchanger 3 at that point are recorded. In Embodiment 1, the
evaporating temperature is based on a detected value of the outdoor
liquid temperature sensor 204. Subsequently, in a state where the
opening degree is slightly changed (to, for example, about 50
pulses) from the previously-determined opening degree of the
hot-water-supply pressure-reducing mechanism 19, the "difference
between the outdoor-air temperature and the evaporating
temperature" and the evaporating capacity of the outdoor heat
exchanger 3 at that point are recorded. The blanks in FIG. 11 are
filled in this manner. By completing the table in FIG. 11 and
applying it to the actual operation, the evaporating capacity can
be calculated from the outdoor-air temperature and the evaporating
temperature. If a difference between the outdoor-air temperature
and the evaporating temperature that is not determined in the tests
is detected in the actual operation, the values on the table are
linearly-interpolated so as to determine the evaporating capacity.
Specifically, the relationship between the "difference between the
outdoor-air temperature and the evaporating temperature" and the
evaporating capacity obtained in FIG. 11 is input to the controller
110. The controller 110 interpolates the results of the
relationship (three sets thereof in FIG. 11) between the
"difference between the outdoor-air temperature and the evaporating
temperature" and the evaporating capacity and calculates a function
of the evaporating capacity and the "difference between the
outdoor-air temperature and the evaporating temperature".
[0139] The input W [kW] of the compressor 1 can be calculated from
the operating frequency F [Hz] of the compressor 1, the condensing
temperature CT [degrees C], and an evaporating temperature ET
[degrees C] by using the following expression (6). The degree of
superheat at the inlet of the compressor is simply set to zero.
[Math. 6]
W=f(F,CT,ET) (6)
[0140] The operating frequency F of the compressor 1 is obtained as
operation information. The condensing temperature CT is obtained as
a saturation pressure detected by the high-pressure sensor 201. The
evaporating temperature ET is determined in a manner similar to how
the evaporating capacity is calculated. Accordingly, since the
evaporating capacity Qe [kW] and the input W [kW] of the compressor
1 can be determined, the hot-water-supply capacity Qc [kW] can be
determined from expression (7).
[Math. 7]
Qc=Qe+W (7)
[0141] The target opening degree S.sub.jm of the pressure-reducing
mechanism can be determined from the determined hot-water-supply
capacity Qc and a target minimum-required hot-water-supply capacity
value Qcm [kW].
[Math. 8]
Sj,m=(Qcm-Qc).times.k.sub.Q.sub.c.sub.,S.sub.jm (8)
[0142] In this case, k.sub.Q.sub.c.sub.,S.sub.jm denotes gain
compensation [-] for a change in the target opening degree of the
pressure-reducing mechanism and is determined from tests or
simulation. By determining the hot-water-supply capacity from the
evaporating capacity and the input of the compressor 1 in this
manner, the target opening degree S.sub.jm of the pressure-reducing
mechanism is determined. Accordingly, variations in
hot-water-supply capacity caused by individual differences among
pressure-reducing mechanisms can be suppressed, so that the
minimum-required hot-water-supply capacity can be ensured during
the high-temperature-water supply in any actual system. Because the
target opening degree S.sub.jm of the pressure-reducing mechanism
is calculated by determining the hot-water-supply capacity by using
the outdoor-air temperature in this method, the outdoor-air
temperature compensation shown in FIG. 9 is not necessary.
[0143] This will be described in detail below. The controller 110
receives data of two or more sets of a temperature difference
between the outdoor-air temperature around the outdoor heat
exchanger 3 and the evaporating temperature of the outdoor heat
exchanger 3 and the evaporating capacity of the outdoor heat
exchanger 3 corresponding to this temperature difference. Based on
the input data, the controller 110 determines a functional
relationship between the temperature difference and the evaporating
capacity by interpolation and refers to the determined functional
relationship so as to identify, from the functional relationship,
the evaporating capacity that corresponds to the temperature
difference between the outdoor-air temperature detected by the
outdoor-air temperature sensor 205 and the evaporating temperature
detected by the outdoor liquid temperature sensor 204. Then, the
controller 110 calculates a compressor input W, which indicates the
compressing work done on the refrigerant by the compressor, from
the operating frequency of the compressor 1, the calculated
condensing temperature, and the evaporating temperature detected by
the outdoor liquid temperature sensor 204 (expression (6)).
Furthermore, the controller 110 calculates the hot-water-supply
capacity Qc of the plate-type water heat exchanger 16 from the
identified evaporating capacity Qe and the calculated compressor
input W (expression (7)). The controller 110 determines a target
opening-degree value in accordance with a difference between the
calculated hot-water-supply capacity Qc and a preliminarily-stored
target hot-water-supply-capacity value Qcm, and uses the determined
target opening-degree value as a target opening-degree value in the
opening-degree control (expression (8)).
[0144] FIG. 12 is a flowchart illustrating the flow for determining
whether the high-temperature-water supply is to be performed or the
hot-water-supply (i.e., normal hot-water supply) other than the
high-temperature-water-supply is to be performed. First, in step
S11, the controller 110 determines whether the condensing
temperature has increased to a value higher than a predetermined
value CTm. The predetermined value CTm for the condensing
temperature is, for example, a maximum value (e.g., 60 degrees C.)
of an appropriate usage range of the compressor 1. If the
condensing temperature CT has increased to a value higher than the
predetermined value, the process proceeds to step S12 where the
high-temperature-water-supply operation is performed by performing
the condensing-temperature control shown in expressions (1) and (2)
on the compressor 1 and performing the opening-degree control shown
in expressions (3) and (4) on the hot-water-supply
pressure-reducing mechanism 19. If the condensing temperature CT is
lower than the predetermined value, the process proceeds to step
S13 where the normal hot-water-supply operation is performed by
performing normal control on the compressor 1 and the
hot-water-supply pressure-reducing mechanism 19. This reliably
allows for switching to high-temperature-water supply control in
response to an increase in the condensing temperature CT, thereby
suppressing an increase in the condensing temperature.
[0145] With the above process, the hot-water-supply operation is
performed in response to a hot-water-supply request, and
condensing-temperature control is performed on the compressor and
opening-degree control is performed on the pressure-reducing
mechanism during the high-temperature-water supply in which the
condensing temperature becomes higher than the predetermined value
CTm, thereby suppressing an excessive increase in high pressure and
achieving a predetermined hot-water-supply capacity.
[0146] Although the hot-water-supply pressure-reducing mechanism 19
is used as a pressure-reducing mechanism whose opening degree is
controlled during the high-temperature-water supply in which the
condensing temperature CT becomes higher than or equal to the
predetermined value CTm in Embodiment 1, this is merely an example.
The controlled subject is not limited to the hot-water-supply
pressure-reducing mechanism 19, and the opening-degree control may
alternatively be performed on the outdoor pressure-reducing
mechanism 5. In this case, similar to how the opening degree of the
outdoor pressure-reducing mechanism 5 is controlled so that it is
in a completely open state when the hot-water-supply
pressure-reducing mechanism 19 is used as a pressure-reducing
mechanism whose opening degree is controlled, the opening degree of
the hot-water-supply pressure-reducing mechanism 19 is controlled
so that it is in a completely open state.
[0147] Furthermore, although the integrated air-conditioning and
hot-water-supply system 100 is described as an example in
Embodiment 1, the high-temperature-water-supply control according
to the technology developed in the present invention can also be
applied to the hot-water-supply operation in a hot-water-supply
system in which the heat source unit 301 and the hot-water-supply
unit 304 are connected by a refrigerant communication pipe,
specifically, a hot-water-supply system that does not have an
air-conditioning function but is only capable of performing the
hot-water-supply operation.
[0148] Furthermore, although an R410A refrigerant whose operating
pressure becomes lower than or equal to the critical pressure is
used as the refrigerant in Embodiment 1, the refrigerant is not
limited to an R410A refrigerant and may alternatively be, for
example, a refrigerant, such as a CO.sub.2 refrigerant, whose
operating pressure becomes higher than or equal to the critical
pressure (i.e., a refrigerant whose pressure at the high-pressure
side, such as the pressure at the discharge side of the compressor,
becomes higher than or equal to the critical pressure). In this
case, when the pressure (high pressure) detected by the
high-pressure sensor 201 of the controller becomes higher than or
equal to a predetermined high pressure (e.g., 14.5 MPaG when a
CO.sub.2 refrigerant is used), high-pressure control shown in
expressions (9) and (10) is performed on the compressor 1 so as to
prevent the high pressure from increasing.
[Math. 9]
Fm=F+.DELTA.F (9)
[Math. 10]
.DELTA.F=(Pm.sub.high-P.sub.high).times.k.sub.P,comp (10)
[0149] In this case, Fm denotes a target operating frequency [Hz]
of the compressor 1, F denotes a current operating frequency [Hz]
of the compressor 1, AF denotes a change [Hz] in the operating
frequency of the compressor 1, Pm.sub.high denotes a target
high-pressure value [MPaG], P.sub.high denotes a calculated
condensing temperature [MPaG], and k.sub.P,comp denotes gain
compensation [-] for a change in the operating frequency of the
compressor.
[0150] The target high-pressure value Pm.sub.high is, for example,
a maximum high-pressure value (e.g., 14.5 MPaG when a CO.sub.2
refrigerant is used) allowable in the appropriate usage range of
the compressor 1. Furthermore, in order to adjust the amount of
decrease in hot-water-supply capacity, the opening degree of the
hot-water-supply pressure-reducing mechanism 19 is controlled based
on expressions (3) and (4) so that a predetermined hot-water-supply
capacity can be ensured. By performing the control in this manner,
the technology according to the present invention can be applied to
a refrigerant that operates at the critical pressure or higher,
similar to a refrigerant that operates at the critical pressure or
lower, such as an R410A refrigerant, thereby suppressing an
excessive increase in high pressure during the
high-temperature-water supply so as to achieve the predetermined
hot-water-supply capacity.
[0151] Simultaneous Heating and Hot-Water-Supply Operation Mode
D
[0152] In the simultaneous heating and hot-water-supply operation
mode D (i.e., concurrent heat-radiation operation), the first
four-way valve 2 is in the "dash-line" state in FIG. 4. This means
that the discharge side of the compressor 1 is connected to the gas
side of the plate-type water heat exchanger 16, and the suction
side of the compressor 1 is connected to the gas side of the
outdoor heat exchanger 3. The second four-way valve 13 is in the
"dash-line" state. This means that the discharge side of the
compressor 1 is connected to the gas side of the indoor heat
exchangers 9a and 9b. Although both the first four-way valve 2 and
the second four-way valve 13 are in the "dash-line" state, as in
the "heating operation mode", the hot-water-supply
pressure-reducing mechanism 19 is open in the simultaneous heating
and hot-water-supply operation mode D, unlike in the "heating
operation mode" in which the hot-water-supply pressure-reducing
mechanism 19 is closed.
[0153] While the refrigerant circuit is in this state, the
compressor 1, the outdoor air-sending device 4, the indoor
air-sending devices 10a and 10b, and the feed pump 17 are
activated. This causes a low-pressure gas refrigerant to be
suctioned into and compressed by the compressor 1, thereby becoming
a high-temperature high-pressure gas refrigerant. Subsequently, the
high-temperature high-pressure gas refrigerant is distributed so as
to flow through the first four-way valve 2 and the second four-way
valve 13.
[0154] The refrigerant flowing into the first four-way valve 2
flows out of the heat source unit 301 and travels through the
hot-water-supply gas extension pipe 15 so as to flow into the
hot-water-supply unit 304. The refrigerant flowing into the
hot-water-supply unit 304 flows into the plate-type water heat
exchanger 16 where the refrigerant condenses by exchanging heat
with water supplied by the feed pump 17 so as to become a
high-pressure liquid refrigerant, which then flows out of the
plate-type water heat exchanger 16. The refrigerant having heated
the water at the plate-type water heat exchanger 16 flows out of
the hot-water-supply unit 304, travels through the hot-water-supply
liquid pipe 18, flows into the branch unit 302, and is then reduced
in pressure by the hot-water-supply pressure-reducing mechanism 19,
thereby becoming a low-pressure two-phase gas-liquid refrigerant.
Subsequently, the refrigerant merges with the refrigerant flowing
from the indoor pressure-reducing mechanisms 7a and 7b and flows
out of the branch unit 302. A flow path branching from the
discharge side of the compressor 1 and extending through the second
four-way valve 13, the indoor heat exchangers 9a and 9b, and the
indoor pressure-reducing mechanisms 7a and 7b serves as a branch
flow path relative to a flow path for the hot-water-supply
operation.
[0155] The opening degree of the hot-water-supply pressure-reducing
mechanism 19 is controlled by the control unit 103 such that the
degree of subcooling at the liquid side of the plate-type water
heat exchanger 16 is made equal to a predetermined value. The
degree of subcooling at the liquid side of the plate-type water
heat exchanger 16 is similar to that in the hot-water-supply
operation. The hot-water-supply pressure-reducing mechanism 19
controls the flow rate of refrigerant flowing through the
plate-type water heat exchanger 16 so that the degree of subcooling
of the refrigerant at the liquid side of the plate-type water heat
exchanger 16 is made equal to the predetermined value. Therefore,
the high-pressure liquid refrigerant condensed by the plate-type
water heat exchanger 16 turns into a state with a predetermined
degree of subcooling. Accordingly, the flow rate of refrigerant
flowing through the plate-type water heat exchanger 16 corresponds
to a hot-water-supply request according to the usage condition of
hot water in the facility where the hot-water-supply unit 304 is
installed.
[0156] On the other hand, the refrigerant flowing into the second
four-way valve 13 flows out of the heat source unit 301 and travels
through the gas extension pipe 12 so as to flow to the branch unit
302. Subsequently, the refrigerant travels through the indoor gas
pipes 11a and 11b so as to flow into the use-side units 303a and
303b. The refrigerant flowing into the use-side units 303a and 303b
flows into the indoor heat exchangers 9a and 9b where the
refrigerant condenses by exchanging heat with indoor air supplied
by the indoor air-sending devices 10a and 10b so as to become a
high-pressure liquid refrigerant, which then flows out of the
indoor heat exchangers 9a and 9b. The refrigerant having heated the
indoor air at the indoor heat exchangers 9a and 9b flows out of the
use-side units 303a and 303b and travels through the indoor liquid
pipes 8a and 8b so as to flow into the branch unit 302. The
refrigerant is then reduced in pressure by the indoor
pressure-reducing mechanisms 7a and 7b, thereby becoming a
low-pressure, two-phase gas-liquid or liquid-phase refrigerant.
Subsequently, the refrigerant flowing out of the indoor
pressure-reducing mechanisms 7a and 7b merges with the refrigerant
flowing from the hot-water-supply pressure-reducing mechanism 19
and flows out of the branch unit 302.
[0157] Each of the indoor pressure-reducing mechanisms 7a and 7b is
controlled such that a temperature difference (i.e., a heated-room
temperature difference) obtained by subtracting a preset indoor
temperature from an indoor suction temperature detected by the
indoor suction temperature sensor 208a or 208b (i.e., an indoor
temperature sensor) in corresponding use-side unit 303a or 303b is
eliminated. Therefore, the flow rate of refrigerant flowing through
the indoor heat exchangers 9a and 9b corresponds to the heating
load requested in the air-conditioned space where the use-side
units 303a and 303b are installed.
[0158] The refrigerant flowing out of the branch unit 302 travels
through the liquid extension pipe 6, flows into the heat source
unit 301, passes through the outdoor pressure-reducing mechanism 5,
and then flows into the outdoor heat exchanger 3. The opening
degree of the outdoor pressure-reducing mechanism 5 is controlled
so that it is in a completely open state. The refrigerant flowing
into the outdoor heat exchanger 3 evaporates by exchanging heat
with outdoor air supplied by the outdoor air-sending device 4,
thereby becoming a low-pressure gas refrigerant. This refrigerant
flows out of the outdoor heat exchanger 3, travels through the
first four-way valve 2, passes through the accumulator 14, and is
then suctioned into the compressor 1 again.
[0159] Since there is a hot-water-supply request signal detected by
the hot-water-supply-tank water temperature sensor 210, the
operating frequency of the compressor 1 is controlled to a high
value by the control unit 103 so that a high hot-water-supply
capacity can be ensured. The quantity of air from the outdoor
air-sending device 4 is controlled by the control unit 103 such
that the evaporating temperature is made equal to a predetermined
value in accordance with the outdoor-air temperature detected by
the outdoor-air temperature sensor 205. The evaporating temperature
in this case is the temperature detected by the outdoor liquid
temperature sensor 204.
[0160] If the hot-water-supply temperature is a high temperature
(e.g., 60 degrees C.), the inlet water temperature of the
plate-type water heat exchanger 16 also becomes high, causing the
condensing temperature to increase. Unlike the case of the
hot-water-supply operation, the heating operation is performed in
the use-side units 303a and 303b in the simultaneous heating and
hot-water-supply operation mode D. Therefore, even if the
condensing-temperature control shown in expressions (1) and (2) is
performed on the compressor 1 and the opening-degree control shown
in expressions (3) and (4) is performed on the hot-water-supply
pressure-reducing mechanism 19, the hot-water-supply capacity
sometimes cannot be ensured, and the opening degree of the
hot-water-supply pressure-reducing mechanism 19 is controlled
regardless of the state in the heated room. Consequently, a heating
capacity cannot be ensured in the use-side units 303a and 303b,
possibly resulting in a non-heated state. Therefore, in the case of
the simultaneous heating and hot-water-supply operation, the
simultaneous heating and hot-water-supply operation is stopped if
the condensing temperature CT increases to a value higher than a
predetermined value. Then, the controller 110 performs a switching
process for alternately switching between the heating operation and
the hot-water-supply operation so that the heating operation and
the hot-water-supply operation are performed.
[0161] FIG. 13 is a flowchart illustrating the flow of an operation
method during the high-temperature-water supply in the simultaneous
heating and hot-water-supply operation. Specifically, the operation
is performed in accordance with the flowchart shown in FIG. 13.
First, in step S21, it is determined whether or not the condensing
temperature has increased to a value higher than a predetermined
value. Similar to the case of the hot-water-supply temperature, the
predetermined value for the condensing temperature CT is, for
example, a maximum condensing-temperature value (e.g., 60 degrees
C.) allowable in the appropriate usage range of the compressor 1.
If the condensing temperature CT is lower than or equal to the
predetermined value, normal control is continuously performed in
the simultaneous heating and hot-water-supply operation in step
S22. If the condensing temperature is above the predetermined
value, the mode is changed to a heating operation mode in step S23.
In this case, the use-side units 303a and 303b are set in a heating
thermostat OFF state, and the following control is performed for
the purpose of changing to a hot-water-supply operation mode. In
the heating operation, the indoor pressure-reducing mechanisms 7a
and 7b are normally controlled so that a "heated-room temperature
difference", which is equal to "indoor suction temperature
(detected by indoor suction temperature sensor)-preset indoor
temperature", is eliminated. The indoor pressure-reducing
mechanisms 7a and 7b are controlled so that the "heated-room
temperature difference" is a positive value, such as +1 degree C.
(i.e., a predetermined positive value) (S23). Moreover, the
operating frequency of the compressor 1 is controlled so that the
condensing temperature CT is made equal to the target value CTm.
Normally, the target value CTm for the condensing temperature is
determined from a "heated-room temperature difference" in the
use-side unit 303a or 303b that has the maximum heated-room
temperature difference. However, the target value CTm for the
condensing temperature is determined from a "heated-room
temperature difference of -1 degree C." in the use-side unit 303a
or 303b that has the maximum heated-room temperature difference of
-1 degree C. By performing the control in this manner, the
"heated-room temperature difference" (i.e., indoor suction
temperature-preset indoor temperature) can be made equal to +1
degree C.
[0162] Subsequently, in step S24, it is determined whether the
heated-room temperature difference is greater than or equal to +1
degree C. If the heated-room temperature difference is smaller than
+1 degree C., the process returns to step S23. If the heated-room
temperature difference is greater than or equal to +1 degree C.,
the process proceeds to step S25 where the use-side units 303a and
303b are set in a thermostat OFF state and the hot-water-supply
unit 304 is set in a thermostat ON state, thereby commencing the
hot-water-supply operation mode C. Specifically, the simultaneous
heating and hot-water-supply operation mode D is changed to the
hot-water-supply operation mode C. In other words, the first
four-way valve 2 and the second four-way valve 13 are set to the
hot-water-supply operation mode C in FIG. 4. This state is a
high-temperature-water-supply state since the condensing
temperature CT is higher than or equal to the predetermined value,
and the controller 110 performs the condensing-temperature control
on the compressor 1 and the opening-degree control on the
hot-water-supply pressure-reducing mechanism 19. In step S26, the
controller 110 determines whether the heated-room temperature
difference (i.e., indoor suction temperature-preset indoor
temperature) is greater than or equal to 0 degrees C. If the
heated-room temperature difference is smaller than 0 degrees C.,
the process returns to step S23 where the controller 110 performs
the heating operation mode B. If the heated-room temperature
difference is greater than or equal to 0 degrees C., the process
proceeds to step S27 where the controller 110 determines whether or
not there is a hot-water-supply request (i.e., whether the
hot-water supply is completed). If there is a hot-water-supply
request, the process returns to step S25 where the controller 110
continues to perform the hot-water-supply operation mode C. If
there is no hot-water-supply request, the process proceeds to step
S28 where the controller 110 stops the hot-water-supply unit 304
and sets the use-side units 303a and 303b to a heating thermostat
ON state so as to commence the normal heating operation.
[0163] By performing the above procedure, a constant heating
capacity and a constant hot-water-supply capacity can be ensured
when there is a heating load and a hot-water-supply request at the
same time and when the inlet water temperature is high in the
high-temperature-water supply.
[0164] Simultaneous Cooling and Hot-Water-Supply Operation Mode
E
[0165] In the simultaneous cooling and hot-water-supply operation
mode E (i.e., concurrent heat-absorption and heat-radiation
operation), the use-side units 303a and 303b perform the cooling
operation, and the hot-water-supply unit 304 performs the
hot-water-supply operation. As shown in FIG. 4, in the simultaneous
cooling and hot-water-supply operation mode E, the first four-way
valve 2 is in the dash-line state, and the second four-way valve 13
is in the solid-line state. This means that the discharge side of
the compressor 1 is connected to the plate-type water heat
exchanger 16 via the hot-water-supply gas extension pipe 15, and
the suction side of the compressor 1 is connected to the gas side
of the outdoor heat exchanger 3. The refrigerant flowing out of the
plate-type water heat exchanger 16 travels through the
hot-water-supply pressure-reducing mechanism 19 and subsequently
diverges therefrom so as to flow into the indoor pressure-reducing
mechanisms 7a and 7b and into the liquid extension pipe 6.
[0166] While the refrigerant circuit is in this state, the
compressor 1, the outdoor air-sending device 4, the indoor
air-sending devices 10a and 10b, and the feed pump 17 are
activated, so that a low-pressure gas refrigerant is suctioned into
and compressed by the compressor 1, thereby becoming a
high-temperature high-pressure gas refrigerant. Subsequently, the
high-temperature high-pressure gas refrigerant flows into the first
four-way valve 2.
[0167] The refrigerant flowing into the first four-way valve 2
flows out of the heat source unit 301 and travels through the
hot-water-supply gas extension pipe 15 so as to flow into the
hot-water-supply unit 304. The refrigerant flowing into the
hot-water-supply unit 304 flows into the plate-type water heat
exchanger 16 where the refrigerant condenses by exchanging heat
with water supplied by the feed pump 17 so as to become a
high-pressure liquid refrigerant, which then flows out of the
plate-type water heat exchanger 16. The refrigerant having heated
the water at the plate-type water heat exchanger 16 flows out of
the hot-water-supply unit 304 and travels through the
hot-water-supply liquid pipe 18, so as to flow into the branch unit
302.
[0168] The refrigerant flowing into the branch unit 302 is reduced
in pressure by the hot-water-supply pressure-reducing mechanism 19,
thereby becoming an intermediate-pressure, two-phase gas-liquid or
liquid-phase refrigerant. In this case, the hot-water-supply
pressure-reducing mechanism 19 is controlled to a maximum opening
degree. Subsequently, the refrigerant is distributed so as to flow
into the liquid extension pipe 6 and into the indoor
pressure-reducing mechanisms 7a and 7b. As shown in FIG. 1, the
refrigeration traveling toward the indoor units diverges at a
branch section 28. Furthermore, in FIG. 1, flow paths constituted
by the indoor pressure-reducing mechanisms 7a and 7b (i.e., second
pressure-reducing mechanisms), the indoor heat exchangers 9a and 9b
(i.e., second evaporators), and the second four-way valve 13
constitute heat-absorption branch flow paths.
[0169] The refrigerant flowing into the indoor pressure-reducing
mechanisms 7a and 7b is reduced in pressure into a low-pressure
two-phase gas-liquid state and travels through the indoor liquid
pipes 8a and 8b so as to flow into the use-side units 303a and
303b. The refrigerant flowing into the use-side units 303a and 303b
flows into the indoor heat exchangers 9a and 9b where the
refrigerant evaporates by exchanging heat with indoor air supplied
by the indoor air-sending devices 10a and 10b, thereby becoming a
low-pressure gas refrigerant.
[0170] In this case, each of the indoor pressure-reducing
mechanisms 7a and 7b is controlled such that a temperature
difference (i.e., a cooled-room temperature difference) obtained by
subtracting a preset temperature from an indoor suction temperature
detected by the indoor suction temperature sensor 208a or 208b in
corresponding use-side unit 303a or 303b is eliminated. Therefore,
the flow rate of refrigerant flowing through the indoor heat
exchangers 9a and 9b corresponds to the cooling load requested in
the air-conditioned space where the use-side units 303a and 303b
are installed.
[0171] The refrigerant flowing out of the indoor heat exchangers 9a
and 9b flows out of the use-side units 303a and 303b and then
travels through the indoor gas pipes 11a and 11b, the branch unit
302, and the gas extension pipe 12 so as to flow into the heat
source unit 301. The refrigerant flowing into the heat source unit
301 passes through the second four-way valve 13 and then merges
with the refrigerant having passed through the outdoor heat
exchanger 3.
[0172] On the other hand, the refrigerant flowing into the liquid
extension pipe 6 flows into the heat source unit 301 and is reduced
in pressure by the outdoor pressure-reducing mechanism 5, thereby
becoming a low-pressure two-phase gas-liquid refrigerant.
Subsequently, the refrigerant flows into the outdoor heat exchanger
3 where the refrigerant evaporates by exchanging heat with outdoor
air supplied by the outdoor air-sending device 4. Then, the
refrigerant travels through the first four-way valve 2 and merges
with the refrigerant having passed through the indoor heat
exchangers 9a and 9b. Subsequently, the refrigerant passes through
the accumulator 14 and is suctioned into the compressor 1
again.
[0173] In the case where the simultaneous cooling and
hot-water-supply operation mode E is in the hot-water-supply
priority mode, the water temperature in the hot-water-supply tank
305 is increased to a preset hot-water-supply temperature as
quickly as possible in response to a hot-water-supply request of
the hot-water-supply unit 304. Thus, in order to ensure a high
hot-water-supply capacity, the control unit 103 controls the
compressor 1 so as to increase the operating frequency thereof.
Therefore, heat absorption is necessary in the outdoor heat
exchanger 3 for achieving an equal cooling capacity for the cooling
loads of the use-side units 303a and 303b. The opening degree of
the outdoor pressure-reducing mechanism 5 is controlled by the
control unit 103 such that the degree of superheat at the gas side
of the outdoor heat exchanger 3 is made equal to a predetermined
value. The degree of superheat at the gas side of the outdoor heat
exchanger 3 is determined by subtracting the temperature detected
by the outdoor liquid temperature sensor 204 from the temperature
detected by the outdoor gas temperature sensor 203. The quantity of
air from the outdoor air-sending device 4 is controlled such that
the evaporating temperature is made equal to a predetermined
value.
[0174] The evaporating temperature is the temperature detected by
the indoor liquid temperature sensor 206a or 206b. The
predetermined evaporating-temperature value is determined from a
temperature difference (i.e., a cooled-room temperature
difference), which is obtained by subtracting a preset temperature
from an indoor suction temperature detected by the indoor suction
temperature sensor 208a or 208b, in the use-side unit 303a or 303b
that has the maximum heated-room temperature difference in the
use-side units 303a and 303b.
[0175] In the case where the simultaneous cooling and
hot-water-supply operation mode E is the cooling priority mode, the
operating frequency of the compressor 1 is controlled by the
control unit 103 such that the evaporating temperature is made
equal to a predetermined value in accordance with the cooling loads
of the use-side units 303a and 303b. The predetermined
evaporating-temperature value is determined from a temperature
difference (i.e., a cooled-room temperature difference), which is
obtained by subtracting a preset temperature from an indoor suction
temperature detected by the indoor suction temperature sensor 208a
or 208b, in the use-side unit 303a or 303b that has the maximum
heated-room temperature difference in the use-side units 303a and
303b. Because the operating frequency of the compressor 1 is set in
accordance with the cooling loads of the use-side units 303a and
303b, there is no need to perform heat absorption in the outdoor
heat exchanger 3. Therefore, the outdoor pressure-reducing
mechanism 5 is controlled to a small opening degree by the control
unit 103, and the outdoor air-sending device 4 is stopped by the
control unit 103.
[0176] In the simultaneous cooling and hot-water-supply operation
mode E, the operation is normally performed in the cooling priority
mode and is performed in accordance with the cooling load so as to
achieve a favorable level of comfort inside. However, if the
cooling load is small, the operating frequency of the compressor 1
becomes low. If this causes the hot-water-supply capacity to be low
for a long time, the time that it takes to complete the
hot-water-supply operation increases, causing a shortage of hot
water. In order to prevent such a shortage of hot water, if a
hot-water-supply request is detected continuously for a certain
period of time (e.g., two consecutive hours), the simultaneous
cooling and hot-water-supply operation mode E is performed in the
hot-water-supply priority mode so as to prevent the shortage of hot
water.
[0177] If the hot-water-supply temperature is a high temperature
(e.g., 60 degrees C.), the inlet water temperature of the
plate-type water heat exchanger 16 also becomes high, causing the
condensing temperature CT to increase. Unlike the case of the
hot-water-supply operation, the cooling operation is performed in
the use-side units 303a and 303b in the simultaneous cooling and
the hot-water-supply operation. Therefore, when the
condensing-temperature control shown in expressions (1) and (2) is
performed on the compressor 1 and the opening-degree control shown
in expressions (3) and (4) is performed on the hot-water-supply
pressure-reducing mechanism 19, the operating frequency of the
compressor 1 becomes low in the condensing-temperature control.
Thus, a cooling capacity cannot be ensured in the use-side units
303a and 303b, sometimes resulting in a "non-cooled" state.
Therefore, if the condensing temperature increases to a value
higher than a predetermined value during the simultaneous cooling
and hot-water-supply operation, the simultaneous operation is
stopped, and the cooling operation and the hot-water-supply
operation are performed by alternately switching between the
cooling operation and the hot-water-supply operation, as in the
simultaneous heating and hot-water-supply operation.
[0178] FIG. 14 is a flowchart illustrating the flow of an operation
method during the high-temperature-water supply in the simultaneous
cooling and hot-water-supply operation mode. Specifically, the
operation is performed in accordance with the flowchart shown in
FIG. 14. First, in step S31, it is determined whether or not the
condensing temperature has increased to a value higher than a
predetermined value. Similar to the case of the hot-water-supply
temperature, the predetermined value for the condensing temperature
is, for example, a maximum condensing-temperature value (e.g., 60
degrees C.) allowable in the appropriate usage range of the
compressor 1. If the condensing temperature is lower than or equal
to the predetermined value, normal control is continuously
performed in the simultaneous cooling and hot-water-supply
operation in step S32. If the condensing temperature is higher than
or equal to the predetermined value, the process proceeds to the
cooling operation mode A in step S33. In this case, the use-side
units 303a and 303b are set in a cooling thermostat OFF state, and
the following control is performed for the purpose of changing to
the hot-water-supply operation mode C. In the cooling operation,
the indoor pressure-reducing mechanisms 7a and 7b are normally
controlled so that a "cooled-room temperature difference", which is
equal to "indoor suction temperature (detected by indoor suction
temperature sensor)-preset indoor temperature", is eliminated. The
indoor pressure-reducing mechanisms 7a and 7b are controlled so
that the cooled-room temperature difference is a negative value,
such as -1 degree C. (i.e., a predetermined negative value).
Moreover, the operating frequency of the compressor 1 is controlled
so that the evaporating temperature is made equal to a target
value. Normally, the target value for the evaporating temperature
is determined from a cooled-room temperature difference in the
use-side unit 303a or 303b that has the maximum cooled-room
temperature difference in the use-side units 303a and 303b.
However, the target evaporating-temperature value for the operating
frequency of the compressor 1 is determined from a cooled-room
temperature difference of +1 degree C. in the use-side unit 303a or
303b that has the maximum heated-room temperature difference of +1
degree C. By performing the control in this manner, the cooled-room
temperature difference can be made equal to -1 degree C.
[0179] Subsequently, in step S34, it is determined whether the
cooled-room temperature difference is smaller than or equal to -1
degree C. If the cooled-room temperature difference is not smaller
than or equal to -1 degree C., the process returns to step S33. If
the cooled-room temperature difference is smaller than or equal to
-1 degree C., the process proceeds to step S35 where the use-side
units 303a and 303b are set in a cooling thermostat OFF state and
the mode is changed to the hot-water-supply operation mode C. In
the hot-water-supply operation mode C, this state is a
high-temperature-water-supply state since the condensing
temperature is higher than or equal to the predetermined value, and
the condensing-temperature control is performed on the compressor
1, and the opening-degree control is performed on the
hot-water-supply pressure-reducing mechanism 19. In step S36, it is
determined whether the cooled-room temperature difference is
smaller than or equal to 0 degrees C. If the cooled-room
temperature difference is greater than or equal to 0 degrees C.,
the process returns to step S33 where the mode is set to the
cooling operation mode A. If the cooled-room temperature difference
is smaller than or equal to 0 degrees C., the process proceeds to
step S37 where it is determined whether or not there is a
hot-water-supply request (i.e., whether the hot-water supply is
completed). If there is a hot-water-supply request, the process
returns to step S35 where the hot-water-supply operation mode C is
continuously performed. If there is no hot-water-supply request,
the process proceeds to step S38 where the hot-water-supply unit
304 is stopped and the use-side units 303a and 303b are set to a
cooling thermostat ON state, thereby commencing the normal cooling
operation.
[0180] By performing the above procedure, a constant
hot-water-supply capacity can be ensured and the cooling operation
can be performed when there is a cooling load and a
hot-water-supply request at the same time and when the inlet water
temperature is high in the high-temperature-water supply.
[0181] With the integrated air-conditioning and hot-water-supply
system 100 according to Embodiment 1, an excessive increase in
condensing temperature during the high-temperature-water supply can
be suppressed, and a hot-water-supply capacity can be ensured
within a usage range of the compressor.
[0182] Although the integrated air-conditioning and
hot-water-supply system 100 (refrigeration cycle apparatus) is
described in Embodiment 1, the operation of the integrated
air-conditioning and hot-water-supply system 100 can be construed
as a refrigeration cycle control method.
REFERENCE SIGNS LIST
[0183] 1: compressor, 2: first four-way valve, 3: outdoor heat
exchanger, 4: outdoor air-sending device, 5: outdoor
pressure-reducing mechanism, 6: liquid extension pipe, 7a, 7b:
indoor pressure-reducing mechanism, 8a, 8b: indoor liquid pipe, 9a,
9b: indoor heat exchanger, 10a, 10b: indoor air-sending device,
11a, 11b: indoor gas pipe, 12: gas extension pipe, 13: second
four-way valve, 14: accumulator, 15: hot-water-supply gas extension
pipe, 16: plate-type water heat exchanger, 17: feed pump, 18:
hot-water-supply liquid pipe, 19: hot-water-supply
pressure-reducing mechanism, 20: upstream water pipe, 21:
downstream water pipe, 100: integrated air-conditioning and
hot-water-supply system, 110: controller, 101: measuring unit, 102:
calculating unit, 103: control unit, 104: storage unit, 201:
high-pressure sensor, 202: discharge temperature sensor, 203:
outdoor gas temperature sensor, 204: outdoor liquid temperature
sensor, 205: outdoor-air temperature sensor, 206a, 206b: indoor
liquid temperature sensor, 207a, 207b: indoor gas temperature
sensor, 208a, 208b: indoor suction temperature sensor, 209:
hot-water-supply liquid temperature sensor, 210:
hot-water-supply-tank water temperature sensor, 301: heat source
unit, 302: branch unit, 303a, 303b: use-side unit, 304:
hot-water-supply unit, 305: hot-water-supply tank
* * * * *