U.S. patent application number 13/882779 was filed with the patent office on 2013-09-12 for air-conditioning apparatus.
This patent application is currently assigned to MITSUBISHI ELECTRIC CORPORATION. The applicant listed for this patent is Hiroyuki Morimoto, Koji Yamashita. Invention is credited to Hiroyuki Morimoto, Koji Yamashita.
Application Number | 20130233006 13/882779 |
Document ID | / |
Family ID | 46580289 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130233006 |
Kind Code |
A1 |
Morimoto; Hiroyuki ; et
al. |
September 12, 2013 |
AIR-CONDITIONING APPARATUS
Abstract
An air-conditioning apparatus that includes a refrigeration
cycle in which a compressor, a heat-source side heat exchanger, an
expansion unit, and a load-side heat exchanger are included and are
connected with refrigerant pipes, includes cutoff units capable of
flowing or cut off a refrigerant circulating in the refrigeration
cycle; a detection unit detecting leaking of the refrigerant on the
basis of a resistance that changes with densities of plural kinds
of leaked refrigerants; a concentration calculation unit
calculating a concentration of a refrigerant that has leaked, on
the basis of the resistance of the detection unit; a concentration
detection unit outputting a calculation result of the concentration
calculation unit in order that the calculation result is used for
controlling the cutoff units; and a cutoff control unit controlling
the cutoff units on the basis of an output of the concentration
detection unit.
Inventors: |
Morimoto; Hiroyuki; (Tokyo,
JP) ; Yamashita; Koji; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Morimoto; Hiroyuki
Yamashita; Koji |
Tokyo
Tokyo |
|
JP
JP |
|
|
Assignee: |
MITSUBISHI ELECTRIC
CORPORATION
Tokyo
JP
|
Family ID: |
46580289 |
Appl. No.: |
13/882779 |
Filed: |
January 26, 2011 |
PCT Filed: |
January 26, 2011 |
PCT NO: |
PCT/JP2011/000411 |
371 Date: |
May 1, 2013 |
Current U.S.
Class: |
62/126 |
Current CPC
Class: |
F25B 2500/222 20130101;
F25B 2600/2519 20130101; F25B 25/005 20130101; F25B 2313/0272
20130101; F25B 9/008 20130101; F25B 2313/02732 20130101; F25B
2313/0231 20130101; F25B 13/00 20130101; F25B 49/005 20130101 |
Class at
Publication: |
62/126 |
International
Class: |
F25B 9/00 20060101
F25B009/00 |
Claims
1. An air-conditioning apparatus that includes a refrigeration
cycle in which a compressor, a heat-source side heat exchanger, an
expansion unit, and a load-side heat exchanger are included and are
connected with refrigerant pipes, the air-conditioning apparatus
comprising: a cutoff unit capable of flowing or cutting off a
refrigerant circulating in the refrigeration cycle; a detection
unit detecting a resistance that changes with densities of plural
kinds of leaked refrigerants; a concentration calculation unit
calculating a concentration of the refrigerant that has leaked, on
the basis of the resistance of the detection unit; a concentration
detection unit outputting a calculation result of the concentration
calculation unit in order that the calculation result is used for
controlling the cutoff unit; and a cutoff control unit controlling
the cutoff unit on the basis of an output of the concentration
detection unit, wherein at least R410A, R407C, R32, R404A,
HFO1234yf, HFO1234ze, a refrigerant mixture including R32 and
HFO1234yf, and all refrigerant mixtures including at least one of
these refrigerants as a component are detectable by the single
detection unit.
2. The air-conditioning apparatus of claim 1, wherein the detection
unit is formed using a stannic oxide semiconductor (SnO.sub.2).
3. (canceled)
4. The air-conditioning apparatus of claim 1, wherein the
concentration calculation unit is capable of calculating the
concentration of the refrigerant that has leaked, by using a single
relational expression regarding changes in the resistance and in
concentration, for R410A, R407C, R32, HFO1234yf, HFO1234ze, a
refrigerant mixture including R32 and HFO1234yf, and all
refrigerant mixtures including at least one of these refrigerants
as a component.
5. The air-conditioning apparatus of claim 1, wherein the
concentration detection unit outputs a predetermined signal that
makes the cutoff unit cut off circulation of the refrigerant to the
cutoff control unit in a case where a calculation result regarding
the concentration of the refrigerant from the concentration
calculation unit is greater than or equal to a predetermined
value.
6. The air-conditioning apparatus of claim 5, wherein the
predetermined signal is within 1 (V) to 24 (V).
7. The air-conditioning apparatus of claim 1, further comprising an
outdoor unit including the compressor and the heat-source side heat
exchanger, wherein the cutoff unit is provided in the outdoor unit
or near the outdoor unit.
8. The air-conditioning apparatus of claim 1, wherein the cutoff
control unit is a non-contact relay formed with a semiconductor
element.
9. The air-conditioning apparatus of claim 1, wherein the cutoff
unit is in an open state when energized and in a closed state when
not energized.
10. The air-conditioning apparatus of claim 7, wherein the cutoff
unit is one of a plurality of cutoff units and at least one cutoff
unit is provided at each of an outlet out of which the refrigerant
flows from the outdoor unit and an inlet into which the refrigerant
flows toward the outdoor unit.
11. The air-conditioning apparatus of claim 1, wherein the cutoff
unit is a two-way valve including a valve body, a sealing material
that seals the valve body, and a coil that opens and closes the
valve body by electromagnetic force.
12. The air-conditioning apparatus of claim 11, wherein the sealing
material is composed of rubber or PTFE
(polytetrafluoroethylene).
13. The air-conditioning apparatus of claim 1, wherein the cutoff
unit is designed to accept leakage of 1.0.times.10.sup.-6
(m.sup.3/sec) or smaller for the heat-source side refrigerant in a
closed state.
14. The air-conditioning apparatus of claim 1, wherein assuming
that a discharge side of the compressor is an upstream, a value of
a flow coefficient Cv is set to 5 or higher for a cutoff unit
provided on a downstream side of a heat exchanger related to heat
medium, among the cutoff units, and a value of the flow coefficient
Cv is set to 1 or higher for a cutoff unit provided on an upstream
side of the heat exchanger related to heat medium, among the cutoff
units.
15. The air-conditioning apparatus of claim 11, wherein a
direct-current voltage is applied to the coil.
16. The air-conditioning apparatus of claim 15, wherein the
direct-current voltage applied to the coil is within 12 (V) to 24
(V).
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a U.S. national stage application of
International Patent Application No. PCT/JP2011/000411 filed on
Jan. 26, 2011.
TECHNICAL FIELD
[0002] The present invention relates to an air-conditioning
apparatus applied to, for example, multi air-conditioners for
buildings, and the like.
BACKGROUND
[0003] Some air-conditioning apparatuses, such as multi
air-conditioners for buildings, have a heat source unit (an outdoor
unit) provided outside a building and an indoor unit provided
inside the building. The refrigerant circulating in a refrigerant
circuit of such an air-conditioning apparatus transfers heat to (or
removes heat from) air supplied to a heat exchanger of the indoor
unit, thereby heating or cooling the air. Then, the heated or
cooled air is sent to an air-conditioned space, and consequently,
heating or cooling is performed.
[0004] Since a building usually has a plurality of indoor spaces,
such an air-conditioning apparatus has a plurality of indoor units
in accordance with the number of the indoor spaces. Moreover, when
a building is large, a refrigerant pipe that connects an outdoor
unit and an indoor unit may be as long as 100 m long. When the
refrigerant pipe that connects the outdoor unit and the indoor unit
is long, the amount of refrigerant used to fill the refrigerant
circuit increases in accordance with the length.
[0005] If the refrigerant used to fill the refrigerant circuit
leaks for some reason, the refrigerant that has leaked may flow
into an indoor space. In this case, if the refrigerant is
flammable, the refrigerant may lead to a fire. Moreover, if the
refrigerant is poisonous, the refrigerant may harm the human
body.
[0006] As a result, an existing air-conditioning apparatus has been
proposed, in which when the refrigerant leaks, the operation of a
compressor is stopped (for example, see Patent Literature 1). In a
technology described in Patent Literature 1, carbon dioxide is used
as the refrigerant and the compressor is stopped when the
refrigerant, carbon dioxide, leaks.
CITATION LIST
Patent Literature
[0007] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2000-320936 (for example, see paragraphs [0024] to
[0033] and FIGS. 2 to 4 in the specification)
TECHNICAL PROBLEM
[0008] In the technology described in Patent Literature 1, carbon
dioxide is used as the refrigerant and the system is designed to
stop in the case where the carbon dioxide refrigerant leaks in the
same way that other existing refrigerants leak; however, the system
takes no measures against leaking of the carbon dioxide
refrigerant. That is, in the case where carbon dioxide is used as
the refrigerant, it is regarded as a major prerequisite that the
refrigerant does not harm the human body and it is necessary to
take some measures for decreasing leakage of the refrigerant.
Moreover, similarly, a flammable refrigerant is flammable, and thus
it is necessary to have some type of safety apparatuses in order to
obtain a high degree of safety, similarly to as in the case of
carbon dioxide.
[0009] Recently, there has been a tendency to restrict use of HFC
refrigerants that have a high global warming potential (for
example, R410A and R404A, R407C, R134a, and the like).
Air-conditioning apparatuses that use a refrigerant that has a low
global warming potential (for example, HFO1234yf, R32, HC, carbon
dioxide, and the like) in terms of global warming have been
proposed. Also in the case where a flammable refrigerant
(HFO1234yf, R32, and HC) or carbon dioxide is used as the
refrigerant in multi air-conditioners for buildings, a large amount
of refrigerant is necessary. Thus, some measures need to be taken
against leaking of the refrigerant into an indoor space.
SUMMARY
[0010] An air-conditioning apparatus according to the present
invention has been made in light of the above-described issues and
aims to provide effective measures against leaking of a refrigerant
in refrigeration cycle apparatuses.
[0011] An air-conditioning apparatus according to the present
invention includes a refrigeration cycle in which a compressor, a
heat-source side heat exchanger, an expansion unit, and a load-side
heat exchanger are included and are connected with refrigerant
pipes, and includes: a cutoff unit capable of flowing or cutting
off a refrigerant circulating in the refrigeration cycle; a
detection unit detecting leaking of the refrigerant on the basis of
a resistance that changes with densities of plural kinds of leaked
refrigerants; a concentration calculation unit calculating a
concentration of the refrigerant that has leaked, on the basis of
the resistance of the detection unit; a concentration detection
unit outputting a calculation result of the concentration
calculation unit in order that the calculation result is used for
controlling the cutoff unit; and a cutoff control unit controlling
the cutoff unit on the basis of an output of the concentration
detection unit. At least R410A, R407C, R32, R404A, HFO1234yf,
HFO1234ze, a refrigerant mixture including R32 and HFO1234yf, and
all refrigerant mixtures including at least one of these
refrigerants as a component are detectable by the single detection
unit.
[0012] An air-conditioning apparatus according to the present
invention has the above-described structure, and thus the degree of
safety of the air-conditioning apparatus can be improved.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a schematic diagram illustrating an installation
example of an air-conditioning apparatus according to Embodiment of
the present invention.
[0014] FIG. 2 illustrates an example of the structure of a
refrigerant circuit of the air-conditioning apparatus according to
Embodiment of the present invention.
[0015] FIG. 3 is a diagram of a refrigerant circuit illustrating a
flow of a refrigerant in the air-conditioning apparatus illustrated
in FIG. 2 in a cooling only operation mode.
[0016] FIG. 4 is a diagram of a refrigerant circuit illustrating a
flow of the refrigerant in the air-conditioning apparatus
illustrated in FIG. 2 in a heating only operation mode.
[0017] FIG. 5 is a diagram of a refrigerant circuit illustrating a
flow of the refrigerant in the air-conditioning apparatus
illustrated in FIG. 2 in a cooling main operation mode.
[0018] FIG. 6 is a diagram of a refrigerant circuit illustrating a
flow of the refrigerant in the air-conditioning apparatus
illustrated in FIG. 2 in a heating main operation mode.
[0019] FIG. 7 illustrates relationships between the resistance of a
detection member of a concentration detection unit and the
concentration of the refrigerant according to types of
refrigerants.
[0020] FIG. 8 is a diagram illustrating an example of the structure
of another refrigerant circuit of the air-conditioning apparatus
according to Embodiment of the present invention.
DETAILED DESCRIPTION
[0021] In the following, Embodiment according to the present
invention will be described with reference to the drawings.
Embodiment
[0022] FIG. 1 is a schematic diagram illustrating an installation
example of an air-conditioning apparatus 100 according to
Embodiment of the present invention. With reference to FIG. 1, the
installation example of the air-conditioning apparatus 100 will be
described.
[0023] In the case where a refrigerant leaks, the air-conditioning
apparatus 100 according to Embodiment has functions of detecting
leaking and cutting off a flow of the refrigerant flowing out from
an outdoor unit 1 (a heat source unit) and flowing into the outdoor
unit 1. As a result, an amount of the refrigerant that will leak
from the air-conditioning apparatus 100 is decreased, thereby
assuring users' safety.
[0024] Moreover, the air-conditioning apparatus 100 according to
Embodiment includes a refrigerant circuit A (see FIG. 2), which is
a refrigeration cycle which circulates a heat-source side
refrigerant, and a heat medium circulation circuit B (see FIG. 2),
which circulates a heat medium. In each indoor unit, a cooling
operation mode or a heating operation mode is selectable as an
operation mode.
[0025] The air-conditioning apparatus 100 uses a method (an
indirect method) in which the refrigerant (the heat-source side
refrigerant) is indirectly utilized. That is, the air-conditioning
apparatus 100 according to Embodiment transmits cooling energy or
heating energy stored in the heat-source side refrigerant to a
refrigerant (hereinafter referred to as a heat medium) different
from the heat-source side refrigerant, and performs cooling or
heating of an air-conditioned space by using the cooling energy or
heating energy stored in the heat medium.
[0026] In FIG. 1, the air-conditioning apparatus 100 includes the
outdoor unit 1, which is a heat source unit, a plurality of indoor
units 2, and a heat medium relay unit 3 transmitting cooling energy
or heating energy of the heat-source side refrigerant that flows in
the outdoor unit 1 to the heat medium that flows in the indoor
units 2. The heat medium relay unit 3 is a unit that exchanges heat
from the heat-source side refrigerant to the heat medium. The
outdoor unit 1 and the heat medium relay unit 3 are connected with
refrigerant pipes 4 for conducting the heat-source side
refrigerant. The heat medium relay unit 3 and the indoor units 2
are connected with heat medium pipes 5 for conducting the heat
medium. The cooling energy or heating energy generated by the
outdoor unit 1 is transmitted to the heat medium of the heat medium
relay unit 3 and is distributed to the indoor units 2. The
air-conditioning apparatus 100 according to Embodiment includes a
first cutoff unit 37 and a second cutoff unit 38 (see FIG. 2)
inside the outdoor unit 1, which will be described again with
reference to FIG. 2.
[0027] The outdoor unit 1 is usually provided in outdoor space 6,
which is space (for example, on the roof and the like) outside a
building 9 such as buildings, and supplies cooling energy or
heating energy to the indoor units 2 through the heat medium relay
unit 3. The indoor units 2 are provided at positions so as to
supply air for cooling or air for heating into a room space 7,
which is an internal space (for example, a room and the like) of
the building 9, and supply air for cooling or air for heating into
the room space 7, which is an air-conditioned space. The heat
medium relay unit 3 is configured to be able to be provided as a
separate unit from the outdoor unit 1 and the indoor units 2 at a
position that is not in the outdoor space 6 or in the room space 7.
The heat medium relay unit 3 is connected to the outdoor unit 1 and
the indoor units 2 by the refrigerant pipes 4 and the heat medium
pipes 5, respectively, and transmits cooling energy or heating
energy supplied from the outdoor unit 1 to the indoor units 2.
[0028] As illustrated in FIG. 1, in the air-conditioning apparatus
100 according to Embodiment, the outdoor unit 1 and the heat medium
relay unit 3 are connected through the refrigerant pipes 4, and the
heat medium relay unit 3 and each of the indoor units 2 are
connected through the respective heat medium pipes 5. In this way,
units (the outdoor unit 1, the indoor units 2, and the heat medium
relay unit 3) are connected using the refrigerant pipes 4 and the
heat medium pipes 5 in the air-conditioning apparatus 100, and thus
construction is easy.
[0029] Note that, in FIG. 1, a state in which the heat medium relay
unit 3 is provided in a space different from the room space 7 but
in the inside the building 9, such a space above a ceiling (for
example, a space such as a space above a ceiling in the building 9,
hereinafter referred to simply as a space 8) is illustrated as an
example. In addition, the heat medium relay unit 3 may be provided,
for example, in a common space such as elevators and the like.
Moreover, in FIG. 1, a case in which the indoor units 2 are ceiling
cassette units is illustrated as an example; however, the indoor
units 2 are not limited thereto. The indoor units 2 may be ceiling
concealed units, ceiling suspended units, or the like, and are not
particularly limited as long as supplying air for cooling or air
for heating into the room space 7 directly or through ducts and the
like into the room space 7.
[0030] Moreover, in FIG. 1, a case in which the outdoor unit 1 is
provided in the outdoor space 6 is illustrated as an example;
however, the outdoor unit 1 is not limited thereto. For example,
the outdoor unit 1 may be provided in a closed space such as a
machine room with a ventilating hole, and may also be provided
inside the building 9 if waste heat may be exhausted to the outside
the building 9 through an exhaust duct. Alternatively, in the case
where a water-cooled outdoor unit 1 is used, the water-cooled
outdoor unit 1 may also be provided inside the building 9.
[0031] The heat medium relay unit 3 may be provided at a position
near the outdoor unit 1 and away from the indoor units 2. Note that
if the distance from the heat medium relay unit 3 to each of the
indoor units 2 is long, power (energy) needed to transfer the heat
medium becomes quite large. Thus, the heat medium relay unit 3 is
desirably provided under the consideration that the effect of
energy conservation decreases. Furthermore, the number of outdoor
units 1 to be connected, that of the indoor units 2 to be
connected, and that of heat medium relay units 3 to be connected
are not particularly predetermined, and the number of units is
desirably set depending on the building 9.
[0032] FIG. 2 illustrates an example of the structure of a
refrigerant circuit of the air-conditioning apparatus 100 according
to Embodiment 1 of the present invention. With reference to FIG. 2,
the structure of the refrigerant circuit of the air-conditioning
apparatus 100 will be described. As illustrated in FIG. 2, a heat
exchanger related to heat medium 15a and a heat exchanger related
to heat medium 15b that are included in the heat medium relay unit
3 and the outdoor unit 1 are connected through the refrigerant
pipes 4 (a high-pressure side refrigerant pipe 4a(2) and a
low-pressure side refrigerant pipe 4b(2)). Moreover, the heat
exchanger related to heat medium 15a and the heat exchanger related
to heat medium 15b are connected to indoor units 2a to 2d (which
may be simply referred to as the indoor unit 2) through the heat
medium pipes 5.
[Structure of Outdoor Unit 1]
[0033] In the outdoor unit 1, a compressor 10, a first refrigerant
channel switch unit 11, a heat-source side heat exchanger 12, an
accumulator 19, the first cutoff unit 37, and the second cutoff
unit 38 are connected with the refrigerant pipes and provided.
[0034] The compressor 10 sucks and compresses the refrigerant and
makes the refrigerant be in a high-temperature high-pressure state,
and then transfers the refrigerant to the refrigerant circuit A.
The discharge side of the compressor 10 is connected to the first
refrigerant channel switch unit 11 and the suction side thereof is
connected to the accumulator 19. It is desirable that the
compressor 10 be formed with, for example, an inverter compressor
capable of controlling a capacity, or the like.
[0035] The first refrigerant channel switch unit 11 connects the
discharge side of the compressor 10 and a check valve 13b and
connects the heat-source side heat exchanger 12 and the suction
side of the accumulator 19 in a heating only operation mode and in
a heating main operation mode of a cooling and heating mixed
operation mode. Moreover, the first refrigerant channel switch unit
11 connects the discharge side of the compressor 10 and the
heat-source side heat exchanger 12 and connects a check valve 13d
and the suction side of the accumulator 19 in a cooling only
operation mode and in a cooling main operation mode of the cooling
and heating mixed operation mode. It is desirable that the first
refrigerant channel switch unit 11 be formed with, for example, a
four-way valve and the like.
[0036] The heat-source side heat exchanger 12 functions as an
evaporator when a heating operation is performed, functions as a
radiator (a gas cooler) when a cooling operation is performed, and
exchanges heat between air supplied from an air-sending device such
as a fan, not illustrated in the drawings, and a refrigerant. In
the heating operation mode, one side of the heat-source side heat
exchanger 12 is connected to a check valve 13c and the other side
thereof is connected to the suction side of the accumulator 19.
Moreover, in the cooling operation mode, one side of the
heat-source side heat exchanger 12 is connected to the discharge
side of the compressor 10 and the other side thereof is connected
to a check valve 13a. It is desirable that the heat-source side
heat exchanger 12 be formed with a plate-fin-and-tube type heat
exchanger, which may exchange heat, for example, between the
refrigerant that flows in the refrigerant pipes and air that passes
through the fan.
[0037] The accumulator 19 holds an excessive refrigerant resulting
due to a difference between the heating operation mode and the
cooling operation mode and an excessive refrigerant for a
transitive change in operation (for example, a change in the number
of operating indoor units 2). In the heating operation mode, the
suction side of the accumulator 19 is connected to the heat-source
side heat exchanger 12 and the discharge side thereof is connected
to the suction side of the compressor 10. Moreover, in the cooling
operation mode, the suction side of the accumulator 19 is connected
to the check valve 13d and the discharge side thereof is connected
to the suction side of the compressor 10.
[0038] Moreover, the outdoor unit 1 includes a first connection
pipe 42a, a second connection pipe 42b, the check valve 13a, the
check valve 13b, the check valve 13c, and the check valve 13d. By
including the first connection pipe 42a, the second connection pipe
42b, the check valve 13a, the check valve 13b, the check valve 13c,
and the check valve 13d, the heat-source side refrigerant that
flows from the outdoor unit 1 into the heat medium relay unit 3 can
keep in a certain direction regardless of whether in the heating
operation mode or in the cooling operation mode.
[0039] That is, the refrigerant discharged from the compressor 10
flows into the high-pressure side refrigerant pipe 4a(2). The
refrigerant that has flown into the high-pressure side refrigerant
pipe 4a(2) flows into the heat medium relay unit 3. The refrigerant
that has flown in the heat medium relay unit 3 flows from the
low-pressure side refrigerant pipe 4b(2) into the outdoor unit
1.
[0040] Here, a high-pressure side refrigerant pipe 4a(1) is a pipe
in the outdoor unit 1, and is a pipe on a downstream side from a
point P2 illustrated in FIG. 4. The high-pressure side refrigerant
pipe 4a(2) is a pipe connected to the high-pressure side
refrigerant pipe 4a(1) among the refrigerant pipes 4.
[0041] Moreover, a low-pressure side refrigerant pipe 4b(1) is a
pipe in the outdoor unit 1, and is a pipe on an upstream side from
a point P3 illustrated in FIG. 4. The low-pressure side refrigerant
pipe 4b(2) is a pipe connected to the low-pressure side refrigerant
pipe 4b(1) among the refrigerant pipes 4.
[0042] The first cutoff unit 37 and the second cutoff unit 38 are
capable of flowing the refrigerant (in an open state) or cutting
off the flow of the refrigerant (in a closed state) on the basis of
operation of a cutoff control unit 40 to be described below.
[0043] It is preferable to provide the first cutoff unit 37 and the
second cutoff unit 38 in the outdoor unit 1 or near the outdoor
unit 1. That is, it is desirable that the first cutoff unit 37 be
connected to the high-pressure side refrigerant pipe 4a(1) and the
second cutoff unit 38 is connected to the low-pressure side
refrigerant pipe 4b(1). Moreover, it is also desirable that the
first cutoff unit 37 be connected to the high-pressure side
refrigerant pipe 4a(2) and the second cutoff unit 38 is connected
to the low-pressure side refrigerant pipe 4b(2).
[0044] It is desirable that the first cutoff unit 37 and the second
cutoff unit 38 be each formed with, for example, a two-way valve
that includes a valve body, a sealing material that seals the valve
body, a coil that opens and closes the valve body by
electromagnetic force, and the like. In the following description,
the first cutoff unit 37 and the second cutoff unit 38 are each
assumed to be a two-way valve that includes a valve body, and a
sealing material that seals the valve body, and a coil that opens
and closes the valve body by electromagnetic force, and the
description will be made.
[Concentration Detection Mechanism of Outdoor Unit 1]
[0045] This air-conditioning apparatus 100 includes a concentration
detection unit 39 that has a detection member (not illustrated)
whose resistance changes in accordance with the concentration of
the refrigerant, a concentration calculation unit 41 that
calculates the concentration of the refrigerant on the basis of the
resistance of the detection member, and the cutoff control unit 40
that controls opening and closing of the first cutoff unit 37 and
the second cutoff unit 38 on the basis of the calculated
concentration of the refrigerant.
[0046] Moreover, the concentration detection unit 39 outputs a
predetermined signal to the cutoff control unit 40 on the basis of
a calculation result regarding the concentration of the refrigerant
from the concentration calculation unit 41.
[0047] Specifically, the concentration calculation unit 41 is
designed not to output the predetermined signal to the cutoff
control unit 40 in the case where the calculation result regarding
the concentration of the refrigerant from the concentration
calculation unit 41 is smaller than a predetermined concentration
value.
[0048] On the other hand, the concentration calculation unit 41 is
designed to output the predetermined signal to the cutoff control
unit 40 in the case where the calculation result regarding the
concentration of the refrigerant from the concentration calculation
unit 41 is greater than or equal to the predetermined concentration
value.
[0049] The concentration detection unit 39 is electrically
connected to the concentration calculation unit 41 and the cutoff
control unit 40. An output to the cutoff control unit 40 is not
particularly limited; however, for example, a direct-current
voltage (5 V, 12 V, 24 V, and the like), an alternating-current
voltage, a current, or other output is available. Note that, in the
air-conditioning apparatus 100 according to Embodiment, a
description will be made by considering the output to the cutoff
control unit 40 to be DC 5 V.
[0050] Note that the predetermined concentration corresponds to a
leak limiting concentration of or a lower explosive limit of the
refrigerant used in the air-conditioning apparatus 100. For
example, in the case where carbon dioxide is used as the
refrigerant, it is preferable to set the predetermined
concentration to about 1/10 of the leak limiting concentration.
Moreover, in the case where a flammable refrigerant (HFO1234yf,
R32, or HC) is used, it is preferable to set the predetermined
concentration to about 1/10 of the lower explosive limit.
[0051] The position at which the detection member of the
concentration detection unit 39 is provided is not particularly
limited; however, for example, it is desirable to arrange the
detection member in the outdoor unit 1 as illustrated in FIG. 1,
near the outdoor unit 1, in the heat medium relay unit 3, in the
outdoor space 6, in the room space 7, in the space 8, and the
like.
[0052] FIG. 7 illustrates relationships between the resistance of
the detection member of the concentration detection unit 39 and the
concentration of the refrigerant according to different types of
refrigerants. It is desirable that the detection member be formed
with, for example, a stannic oxide semiconductor (SnO.sup.2). As
illustrated in FIG. 7, it is clear that as the gas concentration of
the refrigerant increases, the resistance of the stannic oxide
semiconductor (SnO.sup.2) gradually decreases. That is, the
concentration of the refrigerant can be uniquely obtained by
calculating the resistance of the detection member.
[0053] Note that it is clear that in the case where the detection
member is formed with the stannic oxide semiconductor (SnO.sup.2),
relationships between the resistance of major refrigerants (R410A,
R407C, R32, and HFO1234yf) and the concentration of the refrigerant
tend to be almost the same. That is, for the major refrigerants,
the concentration of the refrigerant can be detected by using the
same calibration curve. In other words, a single detection member
makes it possible to detect densities of a plurality of
refrigerants, and thus the concentration detection unit 39 can be
standardized.
[0054] Moreover, in the case where the concentration detection unit
39 can be standardized in this way, there is no need to provide a
plurality of detecting members for the kinds of refrigerant,
thereby reducing the cost of the air-conditioning apparatus
100.
[0055] HFO1234yf has the chemical formula
CF.sub.3--CF.dbd.CH.sub.2. HFO1234ze, which is an isomer of
HFO1234yf, has the chemical formula CHF.sub.2--CF.dbd.CHF. Since
HFO1234ze has similar chemical characteristics to HFO1234yf, the
characteristics of the electrical resistance of the detection unit
of the concentration detection unit 39 according to the present
invention show almost the same characteristics. Thus, the
concentration detection unit 39 according to Embodiment can perform
a detection operation.
[0056] Moreover, in the case where R32 and HFO1234yf are mixed, a
non-azeotropic refrigerant mixture is obtained. In the case where
such a refrigerant leaks, R32, which is a low boiling point
component, has a greater leakage. That is, since R32 reaches the
limiting concentration faster than HFO1234yf, leaking of the
refrigerant can be detected in the safe side by detecting leaking
of the refrigerant through measuring of leakage of R32.
[0057] Moreover, even in the case where other refrigerant mixtures
are used, if any one among R410A, R407C, R32, HFO1234yf, and
HFO1234ze is included as a component, the electrical resistance of
the detection member changes and then the concentration detection
unit 39 can perform the detection operation. That is, leaking of
refrigerant mixtures containing HFC, HFO, and HFC and HFO can be
detected by using the concentration detection unit 39 according to
Embodiment.
[0058] On the other hand, in order to further improve the detection
accuracy of the concentration detection unit 39, such an
improvement can be achieved by generating calibration curves
varying from refrigerant to refrigerant instead of the calibration
curve used in FIG. 7. In other words, it is desirable that the
calibration curves varying from refrigerant to refrigerant be
utilized instead of using single calibration curve.
[0059] The concentration calculation unit 41 calculates (computes)
the concentration of the refrigerant on the basis of the resistance
of the detection member of the concentration detection unit 39. The
concentration calculation unit 41 is electrically connected to the
concentration detection unit 39.
[0060] The relationship between the concentration of the
refrigerant and the resistance of the detection member, as
illustrated in FIG. 7, is stored in the concentration calculation
unit 41. As a result of this, the concentration of the refrigerant
used in the air-conditioning apparatus 100 can be calculated on the
basis of the resistance of the detection member of the
concentration detection unit 39.
[0061] Note that the position at which the concentration
calculation unit 41 is provided is not particularly limited;
however, it is desirable that the concentration calculation unit 41
be provided, for example, in the outdoor unit 1, near the outdoor
unit 1, or the like. In the following, the air-conditioning
apparatus 100 will be described with reference to FIG. 2 again.
[0062] The cutoff control unit 40 controls opening and closing of
the first cutoff unit 37 and the second cutoff unit 38 on the basis
of an output (the predetermined signal) from the concentration
detection unit 39.
[0063] In the case where the concentration of the refrigerant is
greater than or equal to the predetermined concentration value, the
concentration detection unit 39 outputs the predetermined signal to
the cutoff control unit 40. As a result of this, the electrical
connection between a voltage supply (not illustrated) and the first
cutoff unit 37 and second cutoff unit 38 is cut off. That is, a
voltage is not applied to the first cutoff unit 37 and the second
cutoff unit 38 (feeding is not performed). Then, the coil of the
first cutoff unit 37 and the second cutoff unit 38 are not excited,
and thus the valve bodies close. That is, both the first cutoff
unit 37 and the second cutoff unit 38 are in the closed state.
[0064] On the other hand, in the case where the concentration of
the refrigerant is smaller than the predetermined concentration
value, the predetermined signal is not output from the
concentration detection unit 39 to the cutoff control unit 40. As a
result of this, the voltage supply (not illustrated) and the first
cutoff unit 37 and second cutoff unit 38 are electrically
connected. That is, a voltage is applied to the first cutoff unit
37 and the second cutoff unit 38 (feeding is performed). Then, the
coils of the first cutoff unit 37 and the second cutoff unit 38 are
excited, and thus the valve bodies open. That is, both the first
cutoff unit 37 and the second cutoff unit 38 are in the open
state.
[0065] Note that the position at which the cutoff control unit 40
is provided is not particularly limited; however, it is desirable
that the cutoff control unit 40 be provided, for example, in the
outdoor unit 1, near the outdoor unit 1, or the like.
[0066] As described above, the first cutoff unit 37 and the second
cutoff unit 38 are two-way valves that each include a valve body, a
sealing material that seals the valve body, and a coil that opens
and closes the valve body by electromagnetic force.
[0067] The coil of each of the first cutoff unit 37 and the second
cutoff unit 38 is connected to the voltage supply through the
cutoff control unit 40. When the air-conditioning apparatus 100 is
in normal operation, the cutoff control unit 40 puts in a state (an
energized state) in which the voltage supply is electrically
connected to the first cutoff unit 37 and second cutoff unit 38. As
a result of this, the coil of each of the first cutoff unit 37 and
the second cutoff unit 38 is applied with a voltage by the voltage
supply and becomes an electromagnet. Then, each valve body is
attracted by electromagnetic force, and the first cutoff unit 37
and the second cutoff unit 38 are in the open state.
[0068] On the other hand, when detecting leaking of the refrigerant
of the air-conditioning apparatus 100, the cutoff control unit 40
electrically cuts off the connection between the voltage supply and
the first cutoff unit 37 and second cutoff unit 38 (a non-energized
state). As a result of this, the coil of each of the first cutoff
unit 37 and the second cutoff unit 38 is not applied with a voltage
by the voltage supply. Then, each valve body is not attracted by
the coil, and the first cutoff unit 37 and the second cutoff unit
38 are in the closed state.
[0069] Note that, when a mechanical electromagnetic relay is
employed to perform switching between electrical connection and
disconnection between the voltage supply and the first cutoff unit
37 and second cutoff unit 38, in the case where a flammable
refrigerant (HFO1234yf, R32, or HC) is used as the refrigerant,
sparks may be emitted and may ignite the refrigerant. Thus, in the
case where a flammable refrigerant is used, it is desirable to
employ, as the cutoff control unit 40, an SSR (solid state relay),
which is a non-contact relay using a semiconductor element. As a
result of this, there is no mechanical operation, and thus it is
possible to reduce the possibility of sparking. As a result of
this, even if a flammable refrigerant leaks into the outdoor unit
1, switching between electrical connection and disconnection
between the voltage supply and the first cutoff unit 37 and second
cutoff unit 38 may be safely performed.
[0070] Moreover, it is desirable that the coils for opening and
closing the valve bodies of the first cutoff unit 37 and the second
cutoff unit 38 be excited by a direct current. It is because the
lifetime of the coils can be sustained longer when excitation is
performed with a direct-current voltage. Thus, a description will
be made by considering that a direct-current voltage is applied to
the first cutoff unit 37 and the second cutoff unit 38 as an
operation voltage. Note that a description will be made by assuming
that the operation voltage is DC 12 V; however, the operation
voltage may be DC 24 V or the like and is not limited thereto.
Moreover, the cutoff control unit 40 also includes a converter that
can convert an output from a commercial power supply (an
alternating-current voltage, AC 200 V in Embodiment) into a
predetermined direct-current voltage (DC 12V in Embodiment). The
above-described voltage supply corresponds to the commercial power
supply and the converter.
[0071] Since the first cutoff unit 37 and the second cutoff unit 38
are provided in main pipes (the refrigerant pipes 4) of the
refrigerant circuit, the main pipes need to have a large aperture.
That is, the main pipes need to have a large value of a flow
coefficient Cv. Thus, it is desirable to employ not a direct-acting
valve but a pilot valve as the first cutoff unit 37 and the second
cutoff unit 38.
[0072] It is desirable that the value of Cv for the first cutoff
unit 37 through which a high-pressure refrigerant flows be set to,
for example, 1 or higher, and the value of Cv for the second cutoff
unit 38 through which a low-pressure refrigerant flows be set to,
for example, 5 or higher.
[0073] Even if the first cutoff unit 37 and the second cutoff unit
38 are provided in the refrigerant circuit, the values of Cv
described above can make a pressure loss small, and make
performance degradation small. That is, the amount of the
refrigerant circulating in the refrigerant circuit A decreases in
normal operation.
[0074] Moreover, it is desirable that the sealing material that
seals the valve body be composed of rubber or PTFE
(polytetrafluoroethylene). As a result of this, in case of
emergency, the sealing material immediately conforms (closely
adheres) to the valve body. That is, in the case where the first
cutoff unit 37 and the second cutoff unit 38 are closed, the
possibility of the refrigerant leak decreases.
[0075] Note that the first cutoff unit 37 and the second cutoff
unit 38 do not open or close as often as a normal valve. Thus, it
is not always necessary to employ a metal seal, which has a high
durability, as the sealing material.
[0076] Moreover, it is desirable that the first cutoff unit 37 and
the second cutoff unit 38 be designed in such a manner that leakage
of the refrigerant in the closed state is set to, for example,
1.0.times.10.sup.-6 [m.sup.3/s] or smaller. The reason will be
described below.
[0077] When a large amount of a refrigerant leaks into a space,
there is a danger of burning, an oxygen deficiency, and the like.
For each kind of refrigerant, a corresponding limiting
concentration is defined, which is the maximum concentration for
leakage of the refrigerant so as to safely use the refrigerant. The
limiting concentration is, for example, 0.44 [m.sup.3/kg] for
R410A, 0.061 [m.sup.3/kg] for R32, 0.0578 [m.sup.3/kg] for
HFO1234yf, and 0.008 [m.sup.3/kg] for propane.
[0078] When a refrigerant leaks into a room, leaking of the
refrigerant is stopped by closing the first cutoff unit 37 and the
second cutoff unit 38 provided in the refrigerant pipes. In this
case, if a measure to stop leaking of the refrigerant is taken when
the refrigerant reaches the limiting concentration, it is late.
Thus, when the concentration of the refrigerant in a room reaches
95% of the limiting concentration, the first cutoff unit 37 and the
second cutoff unit 38 are designed to be closed. That is, after the
first cutoff unit 37 and the second cutoff unit 38 are closed and
until the concentration of the refrigerant reaches the limiting
concentration, the amount of the refrigerant that may further leak
is 5%.
[0079] Here, in the case where a location in which the multi
air-conditioners for buildings is expected to be installed is the
smallest room, which is a single room of a hotel, it is assumed
that the room has a capacity of 25 m.sup.3, the pressure difference
between before and after the first cutoff unit 37 and the second
cutoff unit 38 operate is 1.0 MPa, a substantial space capacity of
the room except for the unit bath and other items is
0.5.times.25=12.5 m.sup.3. In this case, the amount of the
refrigerant that may leak after the first cutoff unit 37 and the
second cutoff unit 38 are closed is 12.5 m.sup.3.times.0.05=0.625
m.sup.3. It is expected that users do not notice the refrigerant
leaking while sleeping or the like and that the space is closed in
a state in which windows are closed. Thus, leakage that does not
reach the limiting concentration within 24 hours after the first
cutoff unit 37 and the second cutoff unit 38 are operated is
calculated to be 0.625/(24.times.60.times.60)=7.2.times.10.sup.-6
[m.sup.3/s]. If leakage after the first cutoff unit 37 and the
second cutoff unit 38 are closed is smaller than this value, the
safety is considered to be kept.
[0080] Moreover, a position is unpredictable where the refrigerant
leaks in a high-pressure pipe or in a fluid pipe. Thus, assuming
that leaking occurs in a high-pressure pipe, leakage needs to be
smaller than the limiting concentration described above, at a
pressure difference of about 5 MPa. Leakage of the refrigerant is
in proportion to the pressure difference to the power of 0.5
according to Bernoulli's theorem, which is commonly known in the
field of fluid dynamics. Thus, leakage of the refrigerant is
7.2.times.10.sup.-6 [m.sup.3/s]/(5/1).sup.0.5=3.2.times.10.sup.-6.
If leakage is smaller than this value, the safety is ensured. In
order to achieve a higher degree of safety, leakage should be
1.0.times.10.sup.-6 [m.sup.3/s] or smaller.
[0081] Note that it is desirable that the first cutoff unit 37 and
the second cutoff unit 38 have a minimum operation pressure
difference of about 0 (kgf/cm.sup.2).
[0082] In the case where the heat-source side refrigerant leaks
from a channel (the refrigerant circuit A) in which the heat-source
side refrigerant circulates, the concentration of the refrigerant
increases in an external portion (see the outdoor space 6, the room
space 7, and the space 8 in FIG. 1) affected by leaking. The
resistance of the detecting member of the concentration detection
unit 39 changes in accordance with the concentration of the
refrigerant that has leaked. Then, the concentration calculation
unit 41 calculates the concentration of the refrigerant that has
leaked, on the basis of the resistance.
[0083] In the case where the calculation result from the
concentration calculation unit 41 is smaller than a predetermined
concentration value, which means that the refrigerant does not
leak, the concentration detection unit 39 does not output the
predetermined signal to the cutoff control unit 40. Thus, since the
predetermined signal is not output to the cutoff control unit 40,
the cutoff control unit 40 maintains an electrical connection
between the voltage supply and the first cutoff unit 37 and second
cutoff unit 38. That is, a voltage is applied to the coil of each
of the first cutoff unit 37 and the second cutoff unit 38 by the
voltage supply. As a result of this, the first cutoff unit 37 and
the second cutoff unit 38 stay in a state in which the valve bodies
of the first cutoff unit 37 and the second cutoff unit 38 are
opened. That is, both the first cutoff unit 37 and the second
cutoff unit 38 are in the open state.
[0084] In the case where the calculation result from the
concentration calculation unit 41 is greater than or equal to a
predetermined concentration value, which means that the refrigerant
leaks, the concentration detection unit 39 outputs the
predetermined signal to the cutoff control unit 40. The cutoff
control unit 40 cuts off the electrical connection between the
voltage supply and the first cutoff unit 37 and second cutoff unit
38 on the basis of this output (the predetermined signal). That is,
no voltage is applied to the coil of each of the first cutoff unit
37 and the second cutoff unit 38 by the voltage supply. As a result
of this, the valve bodies of the first cutoff unit 37 and the
second cutoff unit 38 are closed. That is, both the first cutoff
unit 37 and the second cutoff unit 38 are in the closed state.
[0085] As a result of this, the refrigerant flow that flows out
from the outdoor unit 1 and the refrigerant flow that flows into
the outdoor unit 1 are cut off. That is, the heat-source side
refrigerant is prevented from circulating in the refrigerant
circuit A. As a result of this, the amount of the refrigerant that
will leak is decreased, thereby improving the degree of safety of
the air-conditioning apparatus 100.
[Indoor Unit 2]
[0086] The indoor unit 2 includes use-side heat exchangers 26a to
26d (also simply referred to as use-side heat exchangers 26). The
use-side heat exchangers 26 are designed to be connected to heat
medium flow control devices 25a to 25d (also simply referred to as
heat medium flow control devices 25) through the second heat medium
pipes 5 and to second heat medium channel switch units 23a to 23d
(also simply referred to as second heat medium channel switch units
23) through the heat medium pipes 5. The use-side heat exchangers
26 each exchange heat between air supplied from the air-sending
device such as a fan, not illustrated, and the heat medium, and
generate air for heating or air for cooling to be supplied to the
room space 7.
[0087] FIG. 2 illustrates an example in the case where four indoor
units 2a to 2d are connected to the heat medium relay unit 3
through the heat medium pipes 5. Moreover, the use-side heat
exchangers 26 are the use-side heat exchanger 26a, the use-side
heat exchanger 26b, the use-side heat exchanger 26c, and the
use-side heat exchanger 26d from the bottom of the sheet in
accordance with the indoor units 2a to 2d, respectively. Note that
the number of the indoor units 2 to be connected is not limited to
four.
[Heat Medium Relay Unit 3]
[0088] The heat medium relay unit 3 includes two heat exchangers
related to heat medium 15a and 15b (also simply referred to as heat
exchangers related to heat medium 15), two expansion units 16a and
16b (also simply referred to as expansion units 16), two on-off
units 17a and 17b (also simply referred to as on-off units 17), two
second refrigerant channel switch units 18a and 18b (also simply
referred to as second refrigerant channel switch units 18), two
pumps 21a and 21b (also simply referred to as pumps 21), four first
heat medium channel switch units 22a to 22d (also simply referred
to as first heat medium channel switch units 22), the four second
heat medium channel switch units 23a to 23d (also simply referred
to as second heat medium channel switch units 23), and the four
heat medium flow control devices 25a to 25d (also simply referred
to as heat medium flow control devices 25).
[0089] The heat exchangers related to heat medium 15 (load-side
heat exchangers) function as condensers (radiators) or evaporators,
and exchange heat between the heat-source side refrigerant and the
heat medium. The heat exchangers related to heat medium 15 transmit
cooling energy or heating energy generated by the outdoor unit 1
and stored in the heat-source side refrigerant, to the heat medium.
The heat exchanger related to heat medium 15a is connected to a
pipe that connects the expansion unit 16a and the second
refrigerant channel switch unit 18a in the refrigerant circuit A
illustrated in FIG. 2, and cools the heat medium in the cooling and
heating mixed operation mode. The heat exchanger related to heat
medium 15b is connected to a pipe that connects the expansion unit
16b and the second refrigerant channel switch unit 18b in the
refrigerant circuit A illustrated in FIG. 2, and heats the heat
medium in the cooling and heating mixed operation mode.
[0090] The expansion units 16 function as pressure reducing valves
or expansion valves, and reduce pressure to expand the heat-source
side refrigerant. The expansion unit 16a is provided on an upstream
side of the heat exchanger related to heat medium 15a in the flow
of the heat-source side refrigerant in the cooling only operation
mode. The expansion unit 16b is provided on an upstream side of the
heat exchanger related to heat medium 15b in the flow of the
heat-source side refrigerant in the cooling only operation mode. It
is desirable that the expansion units 16 be formed with something
that may variably control its opening degree; for example, an
electronic expansion valve or the like.
[0091] The on-off units 17 open and close channels to which the
on-off units 17 are provided. The on-off unit 17a is provided on an
upstream side of the expansion units 16 in the flow of the
heat-source side refrigerant in the cooling only operation mode.
The on-off unit 17b is provided on a downstream side of the
expansion unit 16a in the flow of the heat-source side refrigerant
in the heating only operation mode. It is desirable that the on-off
units 17 be formed with, for example, a two-way valve or the
like.
[0092] The second refrigerant channel switch units 18 select the
flow of the refrigerant in the heating only operation mode, the
flow of the refrigerant in the cooling only operation mode, or the
flow of the refrigerant in the cooling and heating mixed operation
mode. The second refrigerant channel switch unit 18b connects the
high-pressure side refrigerant pipe 4a(2) and the heat exchanger
related to heat medium 15b in the heating only operation mode. The
second refrigerant channel switch unit 18a connects the heat
exchanger related to heat medium 15a and the low-pressure side
refrigerant pipe 4b(2) in the cooling only operation mode and in
the cooling and heating mixed operation mode. It is desirable that
the second refrigerant channel switch units 18 be formed with, for
example, a four-way valve or the like.
[0093] The pumps 21 make the heat medium that flows in the heat
medium pipes 5 circulate. The pump 21a is connected to a pipe that
connects the heat exchanger related to heat medium 15a and the
second heat medium channel switch units 23, among the heat medium
pipes 5. The pump 21b is connected to a pipe that connects the heat
exchanger related to heat medium 15b and the second heat medium
channel switch units 23, among the heat medium pipes 5. It is
desirable that the two pumps 21 be formed with, for example, a pump
that may control its capacity, or the like. Note that the pump 21a
may be connected to a pipe that connects the heat exchanger related
to heat medium 15a and the first heat medium channel switch units
22, among the heat medium pipes 5. Moreover, the pump 21b may be
connected to a pipe that connects the heat exchanger related to
heat medium 15b and the first heat medium channel switch units 22,
among the heat medium pipes 5.
[0094] The first heat medium channel switch units 22 perform
switching between channels of the heat medium. The first heat
medium channel switch units 22, the number of which corresponds to
the number (here, four) of the indoor units 2 provided, are
provided. One of three-way terminals of each of the first heat
medium channel switch units 22 is connected to the heat exchanger
related to heat medium 15a, another one of three-way terminals
thereof is connected to the heat exchanger related to heat medium
15b, and the other one of three-way terminals thereof is connected
to a corresponding one of the heat medium flow control devices 25.
The first heat medium channel switch units 22 are each provided on
an outlet side of a corresponding heat medium passage of the
use-side heat exchangers 26. Note that the first heat medium
channel switch units are the first heat medium channel switch unit
22a, the first heat medium channel switch unit 22b, the first heat
medium channel switch unit 22c, and the first heat medium channel
switch unit 22d from the bottom of the sheet in accordance with the
indoor units 2. It is desirable that the first heat medium channel
switch units 22 be formed with, for example, a three-way valve or
the like.
[0095] The second heat medium channel switch units 23 perform
switching between channels of the heat medium. The second heat
medium channel switch units 23, the number of which corresponds to
the number (here, four) of the indoor units 2 provided, are
provided. One of three-way terminals of each of the second heat
medium channel switch units 23 is connected to the heat exchanger
related to heat medium 15a, another one of three-way terminals
thereof is connected to the heat exchanger related to heat medium
15b, and the other one of three-way terminals thereof is connected
to a corresponding one of the use-side heat exchangers 26. The
second heat medium channel switch units 23 are each provided on an
inlet side of the corresponding heat medium passage of the use-side
heat exchangers 26. Note that the second heat medium channel switch
units are the second heat medium channel switch unit 23a, the
second heat medium channel switch unit 23b, the second heat medium
channel switch unit 23c, and the second heat medium channel switch
unit 23d from the bottom of the sheet in accordance with the indoor
units 2. It is desirable that the second heat medium channel switch
units 23 be formed with, for example, a three-way valve or the
like.
[0096] The heat medium flow control devices 25 control the amount
of the heat medium that flows in the heat medium pipes 5. The heat
medium flow control devices 25, the number of which corresponds to
the number (here, four) of the indoor units 2 provided, are
provided. One terminal of each of the heat medium flow control
devices 25 is connected to a corresponding one of the use-side heat
exchangers 26, and the other terminal thereof is connected to a
corresponding one of the first heat medium channel switch units 22.
The heat medium flow control devices 25 are each provided on the
outlet side of the corresponding heat medium passage of the
use-side heat exchangers 26. Note that the heat medium flow control
devices are illustrated as the heat medium flow control device 25a,
the heat medium flow control device 25b, the heat medium flow
control device 25c, and the heat medium flow control device 25d
from the bottom of the sheet in accordance with the indoor units 2.
Moreover, the heat medium flow control devices 25 may be each
provided on the inlet side of the corresponding heat medium passage
of the use-side heat exchangers 26. It is desirable that the heat
medium flow control devices 25 be formed with, for example, a
two-way valve that may control, for example, its opening area or
the like.
[0097] Moreover, the heat medium relay unit 3 includes various
detection units (two first temperature sensors 31a and 31b, four
second temperature sensors 34a to 34d, four third temperature
sensors 35a to 35d, and a pressure sensor 36 in FIG. 5).
Information (temperature information and pressure information)
detected by these detection units is sent to a control device (not
illustrated) that performs central control on the operation of the
air-conditioning apparatus 100, and is used to control a driving
frequency of the compressor 10, the rotation speed of the
air-sending device, which is not illustrated in the drawings but
provided near the heat-source side heat exchanger 12 and the
use-side heat exchangers 26, switching performed by the first
refrigerant channel switch unit 11, a driving frequency of the
pumps 21, switching performed by the second refrigerant channel
switch units 18, switching between channels of heat medium
circuits, and the like.
[0098] The two first temperature sensors 31a and 31b (also simply
referred to as first temperature sensors 31) detect the temperature
of the heat medium that has flown out from the heat exchangers
related to heat medium 15, that is, the temperature of the heat
medium at the outlets of the heat exchangers related to heat medium
15. The first temperature sensor 31a is provided on the heat medium
pipe 5 that is on the inlet side of the pump 21a. The first
temperature sensor 31b is provided on the heat medium pipe 5 that
is on the inlet side of the pump 21b. It is desirable that the
first temperature sensors 31 be formed with, for example, a
thermistor or the like.
[0099] The four second temperature sensors 34a to 34d (also simply
referred to as second temperature sensors 34) are provided between
the first heat medium channel switch units 22 and the heat medium
flow control devices 25, and detect temperatures of the heat medium
that flows out from the use-side heat exchangers 26. The second
temperature sensors 34 are provided in accordance with the number
(here, four) of the provided indoor units 2. Note that the second
temperature sensors are illustrated as the second temperature
sensor 34a, the second temperature sensor 34b, the second
temperature sensor 34c, and the second temperature sensor 34d from
the bottom of the sheet in accordance with the indoor units 2. It
is desirable that the second temperature sensors 34 be formed with,
for example, a thermistor or the like.
[0100] The four third temperature sensors 35a to 35d (also simply
referred to as third temperature sensors 35) are provided on inlet
sides or outlet sides of the heat exchangers related to heat medium
15 through which the heat-source side refrigerant flows, and detect
the temperatures of the heat-source side refrigerant that flows
into the heat exchangers related to heat medium 15 or the
temperatures of the heat-source side refrigerant that flows out
from the heat exchangers related to heat medium 15. The third
temperature sensor 35a is provided between the heat exchanger
related to heat medium 15a and the second refrigerant channel
switch unit 18a. The third temperature sensor 35b is provided
between the heat exchanger related to heat medium 15a and the
expansion unit 16a. The third temperature sensor 35c is provided
between the heat exchanger related to heat medium 15b and the
second refrigerant channel switch unit 18b. The third temperature
sensor 35d is provided between the heat exchanger related to heat
medium 15b and the expansion unit 16b. It is desirable that the
third temperature sensors 35 be formed with, for example, a
thermistor or the like.
[0101] The pressure sensor 36 is provided between the heat
exchanger related to heat medium 15b and the expansion unit 16b,
similarly to the setting position of the third temperature sensor
35d, and detects the pressure applied on the heat-source side
refrigerant that flows between the heat exchanger related to heat
medium 15b and the expansion unit 16b.
[0102] Moreover, a main controller, not illustrated, is configured
with a microcomputer and the like to be provided, and controls the
driving frequency of the compressor 10, the rotation speed
(including ON/OFF) of the air-sending device (not illustrated),
switching performed by the first refrigerant channel switch unit,
driving of the pumps 21, the opening degree of the expansion units
16, opening and closing of the on-off units 17, switching performed
by the second refrigerant channel switch units 18, switching
performed by the first heat medium channel switch units 22,
switching performed by the second heat medium channel switch units
23, and the opening degree of the heat medium flow control devices
25 and the like, on the basis of the information detected by the
various detection units and instructions sent from a remote
controller, thereby executing each operation mode described below.
Note that a controller may be provided in each unit, or may be
provided in the outdoor unit 1 or in the heat medium relay unit
3.
[0103] The heat medium pipes 5 in which the heat medium flows
include a pipe that is connected to the heat exchanger related to
heat medium 15a and a pipe that is connected to the heat exchanger
related to heat medium 15b. The heat medium pipes 5 is divided into
channels (here, each into four channels), the number of which
corresponds to the number of indoor units 2 connected to the heat
medium relay unit 3. Then, the heat medium pipes 5 are connected to
the first heat medium channel switch units 22 and the second heat
medium channel switch units 23. Whether the heat medium from the
heat exchanger related to heat medium 15a flows into the use-side
heat exchangers 26 or the heat medium from the heat exchanger
related to heat medium 15b flows into the use-side heat exchangers
26 is set by controlling the first heat medium channel switch units
22 and the second heat medium channel switch units 23.
[0104] Then, the air-conditioning apparatus 100 includes the
refrigerant circuit A, which has a structure in which the
compressor 10, the first refrigerant channel switch unit 11, the
heat-source side heat exchanger 12, the on-off units 17, the
expansion units 16, passages of the heat exchangers related to heat
medium 15 for the heat-source side refrigerant, the second
refrigerant channel switch units 18, and the accumulator 19 are
connected with the refrigerant pipes 4. Moreover, the heat medium
circulation circuit B has a structure in which passages of the heat
exchangers related to heat medium 15 for the heat medium, the pumps
21, the first heat medium channel switch units 22, the heat medium
flow control devices 25, the use-side heat exchangers 26, and the
second heat medium channel switch units 23 are connected with the
heat medium pipes 5. That is, each of the heat exchangers related
to heat medium 15 is connected to a plurality of use-side heat
exchangers 26 in parallel, and thus the heat medium circulation
circuit B has a plurality of systems.
[0105] Thus, in the air-conditioning apparatus 100, the outdoor
unit 1 and the heat medium relay unit 3 are connected through the
heat exchanger related to heat medium 15a and the heat exchanger
related to heat medium 15b provided in the heat medium relay unit
3, and the heat medium relay unit 3 and the indoor units 2 are
connected through the heat exchanger related to heat medium 15a and
the heat exchanger related to heat medium 15b. That is, in the
air-conditioning apparatus 100, the heat exchanger related to heat
medium 15a and the heat exchanger related to heat medium 15b
exchange heat between the heat-source side refrigerant circulating
in the refrigerant circuit A and the heat medium that circulates in
the heat medium circulation circuit B.
[0106] On the basis of instructions from each of indoor units 2,
this air-conditioning apparatus 100 enable to perform a cooling
operation or a heating operation possible by using the indoor unit
2. That is, the air-conditioning apparatus 100 can perform the same
operation in the indoor units 2 or can perform individual operation
in each of the indoor units 2 differently.
[0107] Operation modes performed by the air-conditioning apparatus
100 contain the cooling only operation mode in which all driving
indoor units 2 execute the cooling operation, the heating only
operation mode in which all driving indoor units 2 execute the
heating operation, the cooling main operation mode as the cooling
and heating mixed operation mode with a greater cooling load, and
the heating main operation mode as the cooling and heating mixed
operation mode with a greater heating load. In the following, each
of the operation modes will be described in terms of the flow of
the heat-source side refrigerant and that of the heat medium.
[Cooling Only Operation Mode]
[0108] FIG. 3 is a diagram of a refrigerant circuit illustrating a
flow of the refrigerant in the air-conditioning apparatus 100 in
the cooling only operation mode. In FIG. 3, the cooling only
operation mode is described in an example of the case where a
cooling load is generated only in the use-side heat exchanger 26a
and the use-side heat exchanger 26b. Note that, in FIG. 3, pipes
drawn with a thick line indicate pipes in which the refrigerant
(the heat-source side refrigerant and the heat medium) flows.
Moreover, in FIG. 3, the direction in which the heat-source side
refrigerant flows is indicated by arrows drawn with a solid line,
and the direction in which the heat medium flows is indicated by
arrows drawn with a broken line.
[0109] In the case of the cooling only operation mode illustrated
in FIG. 3, the outdoor unit 1 makes the first refrigerant channel
switch unit 11 perform switching in such a manner that the
heat-source side refrigerant discharged from the compressor 10
flows into the heat-source side heat exchanger 12. The heat medium
relay unit 3 drives the pump 21a and the pump 21b, opens the heat
medium flow control device 25a and the heat medium flow control
device 25b, fully opens the heat medium flow control device 25c and
the heat medium flow control device 25d, and circulates the heat
medium between the heat exchanger related to heat medium 15a and
both the use-side heat exchanger 26a and use-side heat exchanger
26b and between the heat exchanger related to heat medium 15b and
both the use-side heat exchanger 26a and use-side heat exchanger
26b.
[0110] At first, the flow of the heat-source side refrigerant in
the refrigerant circuit A is described.
[0111] A low-temperature low-pressure refrigerant is compressed by
the compressor 10, and becomes a high-temperature high-pressure
refrigerant gas, which is then discharged. The high-temperature
high-pressure refrigerant gas that has been discharged from the
compressor 10 flows into the heat-source side heat exchanger 12
through the first refrigerant channel switch unit 11. The heat is
transferred to the outside air in the heat-source side heat
exchanger 12, and consequently, the high-temperature high-pressure
refrigerant gas becomes a high-pressure liquid refrigerant.
[0112] The liquid refrigerant that has flown out from the
heat-source side heat exchanger 12 flows out from the outdoor unit
1 through the pipe that is provided with the check valve 13a and
the high-pressure side refrigerant pipe 4a(1), and flows into the
heat medium relay unit 3 through the high-pressure side refrigerant
pipe 4a(2).
[0113] The high-pressure liquid refrigerant that has flown into the
heat medium relay unit 3 flows through the on-off unit 17a, then is
divided and flows into the expansion unit 16a and the expansion
unit 16b to be expanded. As a result, a low-temperature
low-pressure two-phase refrigerant is obtained. Note that the
on-off unit 17b is closed.
[0114] The low-temperature low-pressure two-phase refrigerant flows
into each of the heat exchanger related to heat medium 15a and heat
exchanger related to heat medium 15b that function as an
evaporator. Then, the low-temperature low-pressure two-phase
refrigerant becomes a low-temperature low-pressure refrigerant gas
while absorbing heat from the heat medium that circulates in the
heat medium circulation circuit B, and consequently, cooling the
heat medium.
[0115] The refrigerant gas that has flown out from the heat
exchanger related to heat medium 15a and the heat exchanger related
to heat medium 15b flows out from the heat medium relay unit 3
through the second refrigerant channel switch unit 18a and the
second refrigerant channel switch unit 18b, and then flows again
into the outdoor unit 1 through the low-pressure side refrigerant
pipe 4b(2).
[0116] The refrigerant gas that has flown into the outdoor unit 1
is sucked again by the compressor 10 through the low-pressure side
refrigerant pipe 4b(1), the pipe to which the check valve 13d is
connected, the first refrigerant channel switch unit 11, and the
accumulator 19.
[0117] The opening degree of the expansion unit 16a is controlled
in such a manner that superheating (a degree of superheat) obtained
as the difference between the temperature detected by the third
temperature sensor 35a and the temperature detected by the third
temperature sensor 35b is constant. Similarly, the opening degree
of the expansion unit 16b is controlled in such a manner that
superheating obtained as the difference between the temperature
detected by the third temperature sensor 35c and the temperature
detected by the third temperature sensor 35d is constant.
[0118] Next, the flow of the heat medium in the heat medium
circulation circuit B will be described.
[0119] In the cooling only operation mode, the cooling energy of
the heat-source side refrigerant is transferred to the heat medium
in both the heat exchanger related to heat medium 15a and the heat
exchanger related to heat medium 15b, and the cooled heat medium is
made to flow in the heat medium pipes 5 by the pump 21a and pump
21b. The heat medium that has flown out by being compressed by the
pump 21a and the pump 21b flows into the use-side heat exchanger
26a and the use-side heat exchanger 26b through the second heat
medium channel switch unit 23a and the second heat medium channel
switch unit 23b. Then, the heat medium removes heat from the room
air in the use-side heat exchanger 26a and the use-side heat
exchanger 26b, and consequently, cooling for the room space 7 is
performed.
[0120] Then, the heat medium flows out from the use-side heat
exchanger 26a and the use-side heat exchanger 26b and flows into
the heat medium flow control device 25a and the heat medium flow
control device 25b. In this case, the amount of the flowing heat
medium is controlled by the operation of the heat medium flow
control device 25a and heat medium flow control device 25b so as to
be the amount that is necessary to meet an air conditioning load
that is needed in the room, and flows into the use-side heat
exchanger 26a and the use-side heat exchanger 26b.
[0121] The heat medium that has flown out from the heat medium flow
control device 25a flows into the heat exchanger related to heat
medium 15a and the heat exchanger related to heat medium 15b
through the first heat medium channel switch unit 22a, and is
sucked again by the pump 21a and the pump 21b.
[0122] Note that, in the heat medium pipes 5 of the use-side heat
exchangers 26, the heat medium flows in the direction from the
second heat medium channel switch units 23 to the first heat medium
channel switch units 22 via the heat medium flow control devices
25. Moreover, the air conditioning load can meet an amount needed
in the room space 7 by performing control in such a manner that the
differences between the temperature detected by the first
temperature sensor 31a and the temperatures detected by the second
temperature sensors 34 or the differences between the temperature
detected by the first temperature sensor 31b and the temperatures
detected by the second temperature sensors 34 are to have a target
value. As an output temperature of the heat exchangers related to
heat medium 15, either the temperature detected by the first
temperature sensor 31a or that detected by the first temperature
sensor 31b may be used, or the average of these temperatures may be
used. In this case, the first heat medium channel switch units 22
and the second heat medium channel switch units 23 have an
intermediate opening degree in such a manner that the heat medium
flows in both channels for the heat exchanger related to heat
medium 15a and channels for the heat exchanger related to heat
medium 15b.
[0123] In the case where the cooling only operation mode is
performed, since no heat medium need to flow into the use-side heat
exchangers 26 that have no heating load (thermostat off is
included), the heat medium flow control devices 25 close the
channels so that the heat medium does not flow into the use-side
heat exchangers 26. In FIG. 3, since the use-side heat exchanger
26a and the use-side heat exchanger 26b have a heating load, the
heat medium flows into the use-side heat exchanger 26a and the
use-side heat exchanger 26b, while the use-side heat exchanger 26c
and the use-side heat exchanger 26d have no heating load, and the
corresponding heat medium flow control device 25c and the
corresponding heat medium flow control device 25d are fully closed.
In the case where a heating load is generated in the use-side heat
exchanger 26c, the heat medium flow control device 25c is to be
opened so as to circulate the heat medium. In the case where a
heating load is generated in the use-side heat exchanger 26d, the
heat medium flow control device 25d is to be opened so as to
circulate the heat medium.
[0124] Note that this operation may be similarly applied in other
operation modes.
[Heating Only Operation Mode]
[0125] FIG. 4 is a diagram of a refrigerant circuit illustrating a
flow of the refrigerant in the air-conditioning apparatus 100 in
the heating only operation mode. In FIG. 4, the heating only
operation mode is described in an example of the case where a
heating load is generated only in the use-side heat exchanger 26a
and the use-side heat exchanger 26b. Note that, in FIG. 4, pipes
drawn with a thick line indicate pipes in which the refrigerant
(the heat-source side refrigerant and the heat medium) flows.
Moreover, in FIG. 4, the direction in which the heat-source side
refrigerant flows is indicated by arrows drawn with a solid line,
and the direction in which the heat medium flows is indicated by
arrows drawn with a broken line.
[0126] In the case of the heating only operation mode illustrated
in FIG. 4, the outdoor unit 1 makes the first refrigerant channel
switch unit 11 perform switching in such a manner that the
heat-source side refrigerant discharged from the compressor 10
flows into the heat medium relay unit 3 without flowing through the
heat-source side heat exchanger 12. The heat medium relay unit 3
drives the pump 21a and the pump 21b, opens the heat medium flow
control device 25a and the heat medium flow control device 25b,
fully closes the heat medium flow control device 25c and the heat
medium flow control device 25d, and circulates the heat medium
between the heat exchanger related to heat medium 15a and both the
use-side heat exchanger 26a and use-side heat exchanger 26b and
between the heat exchanger related to heat medium 15b and both the
use-side heat exchanger 26a and use-side heat exchanger 26b.
[0127] At first, the flow of the heat-source side refrigerant in
the refrigerant circuit A is described.
[0128] A low-temperature low-pressure refrigerant is compressed by
the compressor 10, and becomes a high-temperature high-pressure
refrigerant gas, which is then discharged. The high-temperature
high-pressure refrigerant gas that has been discharged from the
compressor 10 flows out from the outdoor unit 1 through the first
refrigerant channel switch unit 11, the first connection pipe 42a,
and the high-pressure side refrigerant pipe 4a(1). The
high-temperature high-pressure refrigerant gas that has flown out
from the outdoor unit 1 flows into the heat medium relay unit 3
through the high-pressure side refrigerant pipe 4a(2). The
high-temperature high-pressure refrigerant gas that has flown into
the heat medium relay unit 3 is divided and flows into the heat
exchanger related to heat medium 15a and the heat exchanger related
to heat medium 15b through the second refrigerant channel switch
unit 18a and the second refrigerant channel switch unit 18b.
[0129] The high-temperature high-pressure refrigerant that has
flown into the heat exchanger related to heat medium 15a and the
heat exchanger related to heat medium 15b becomes a high-pressure
refrigerant whose temperature has decreased while transferring heat
to the heat medium that circulates in the heat medium circulation
circuit B. The liquid refrigerant that has flown out from the heat
exchanger related to heat medium 15a and the heat exchanger related
to heat medium 15b is expanded by the expansion unit 16a and the
expansion unit 16b, and becomes a low-temperature low-pressure
two-phase refrigerant. The low-temperature low-pressure two-phase
refrigerant flows out from the heat medium relay unit 3 through the
on-off unit 17b and flows again into the outdoor unit 1 through the
low-pressure side refrigerant pipe 4b(2). Note that the on-off unit
17a is closed and the on-off unit 17b is opened.
[0130] The refrigerant that has flown into the outdoor unit 1 flows
into the heat-source side heat exchanger 12, which operates as an
evaporator, through the low-pressure side refrigerant pipe 4b(1)
and the second connection pipe 42b. Then, the refrigerant that has
flown into the heat-source side heat exchanger 12 removes heat from
the outside air in the heat-source side heat exchanger 12, and
becomes a low-temperature low-pressure refrigerant gas. The
low-temperature low-pressure refrigerant gas that has flown out
from the heat-source side heat exchanger 12 is sucked again by the
compressor 10 through the first refrigerant channel switch unit 11
and the accumulator 19.
[0131] Note that the refrigerant that has flown into the
low-pressure side refrigerant pipe 4b(1) flows into the second
connection pipe 42b (the check valve 13c) but does not flow into
the check valve 13d. This is because the refrigerant that flows at
a point P1 illustrated in FIG. 4 is a higher pressure refrigerant
than the refrigerant that flows at a point P3, and thus the check
valve 13d closes.
[0132] The refrigerant that has flown into the second connection
pipe 42b flows into the heat-source side heat exchanger 12 but does
not flow into the check valve 13a. This is because the refrigerant
that flows at a point P4 illustrated in FIG. 4 is a higher-pressure
refrigerant than the refrigerant that flows at a point P2, and thus
the check valve 13a closes.
[0133] The opening degree of the expansion unit 16a is controlled
in such a manner that subcooling (a degree of subcooling) obtained
as the difference between a saturation temperature, into which the
pressure detected by the pressure sensor 36 is converted, and the
temperature detected by the third temperature sensor 35b is
constant. Similarly, the opening degree of the expansion unit 16b
is controlled in such a manner that subcooling obtained as the
difference between the saturation temperature, into which the
pressure detected by the pressure sensor 36 is converted, and the
temperature detected by the third temperature sensor 35d is
constant. Note that, in the case where the temperature at a middle
position of the heat exchangers related to heat medium 15 is
measured, the temperature at the middle position may be used
instead of using the pressure sensor 36, thereby reducing the cost
of the system.
[0134] Next, the flow of the heat medium in the heat medium
circulation circuit B will be described.
[0135] In the heating only operation mode, the heating energy of
the heat-source side refrigerant is transferred to the heat medium
in both the heat exchanger related to heat medium 15a and the heat
exchanger related to heat medium 15b, and the heated heat medium is
made to flow in the heat medium pipes 5 by the pump 21a and pump
21b. The heat medium that has flown out by being compressed by the
pump 21a and the pump 21b flows into the use-side heat exchanger
26a and the use-side heat exchanger 26b through the second heat
medium channel switch unit 23a and the second heat medium channel
switch unit 23b. Then, the heat medium transfers heat to the room
air in the use-side heat exchanger 26a and the use-side heat
exchanger 26b, and consequently, heating for the room space 7 is
performed.
[0136] Then, the heat medium flows out from the use-side heat
exchanger 26a and the use-side heat exchanger 26b and flows into
the heat medium flow control device 25a and the heat medium flow
control device 25b. In this case, the amount of the flowing heat
medium is controlled by the operation of the heat medium flow
control device 25a and heat medium flow control device 25b so as to
be the amount that is necessary to meet an air conditioning load
that is needed in the room, and flows into the use-side heat
exchanger 26a and the use-side heat exchanger 26b. The heat medium
that has flown out from the heat medium flow control device 25a and
the heat medium flow control device 25b flows into the heat
exchanger related to heat medium 15a and the heat exchanger related
to heat medium 15b through the first heat medium channel switch
unit 22a and the first heat medium channel switch unit 22b, and is
sucked again by the pump 21a and the pump 21b.
[0137] Note that, in the heat medium pipes 5 of the use-side heat
exchangers 26, the heat medium flows in the direction from the
second heat medium channel switch units 23 to the first heat medium
channel switch units 22 via the heat medium flow control devices
25. Moreover, the air conditioning load can meet an amount needed
in the room space 7 by performing control in such a manner that the
differences between the temperature detected by the first
temperature sensor 31a and the temperatures detected by the second
temperature sensors 34 or the differences between the temperature
detected by the first temperature sensor 31b and the temperatures
detected by the second temperature sensors 34 are to have a target
value. As a temperature at the outlets of the heat exchangers
related to heat medium 15, either the temperature detected by the
first temperature sensor 31a or that detected by the first
temperature sensor 31b may be used, or the average of these
temperatures may be used.
[0138] In this case, the first heat medium channel switch units 22
and the second heat medium channel switch units 23 have an
intermediate opening degree in such a manner that the heat medium
flows in both the channels for the heat exchanger related to heat
medium 15a and the heat exchanger related to heat medium 15b.
Moreover, it is primarily desirable that the use-side heat
exchanger 26a is controlled by the difference between the
temperature at the inlet and the temperature at the outlet thereof;
however, the temperatures of the heat medium on the inlet sides of
the use-side heat exchangers 26 are almost the same as the
temperature detected by the first temperature sensor 31b. The
number of temperature sensors may be reduced by using the first
temperature sensor 31b, thereby reducing the cost of the
system.
[Cooling Main Operation Mode]
[0139] FIG. 5 is a diagram of a refrigerant circuit illustrating a
flow of the refrigerant in the air-conditioning apparatus 100 in
the cooling main operation mode. In FIG. 5, the cooling main
operation mode is described in an example of the case where a
cooling load is generated in the use-side heat exchanger 26a and a
heating load is generated in the use-side heat exchanger 26b. Note
that, in FIG. 5, pipes drawn with a thick line indicate pipes in
which the refrigerant (the heat-source side refrigerant and the
heat medium) flows. Moreover, in FIG. 5, the direction in which the
heat-source side refrigerant flows is indicated by arrows drawn
with a solid line, and the direction in which the heat medium flows
is indicated by arrows drawn with a broken line.
[0140] In the case of the cooling main operation mode illustrated
in FIG. 5, the outdoor unit 1 makes the first refrigerant channel
switch unit 11 perform switching in such a manner that the
heat-source side refrigerant discharged from the compressor 10
flows into the heat-source side heat exchanger 12. The heat medium
relay unit 3 drives the pump 21a and the pump 21b, opens the heat
medium flow control device 25a and the heat medium flow control
device 25b, fully closes the heat medium flow control device 25c
and the heat medium flow control device 25d, and circulates the
heat medium between the heat exchanger related to heat medium 15a
and the use-side heat exchanger 26a and between the heat exchanger
related to heat medium 15b and the use-side heat exchanger 26b.
[0141] At first, the flow of the heat-source side refrigerant in
the refrigerant circuit A is described.
[0142] A low-temperature low-pressure refrigerant is compressed by
the compressor 10, and becomes a high-temperature high-pressure
refrigerant gas, which is then discharged. The high-temperature
high-pressure refrigerant gas that has been discharged from the
compressor 10 flows into the heat-source side heat exchanger 12
through the first refrigerant channel switch unit 11. The
high-temperature high-pressure refrigerant gas becomes a liquid
refrigerant while transferring heat to the outside air in the
heat-source side heat exchanger 12.
[0143] The high-pressure liquid refrigerant that has flown out from
the heat-source side heat exchanger 12 flows out from the outdoor
unit 1 through the pipe that is provided with the check valve 13a
and the high-pressure side refrigerant pipe 4a(1), and flows into
the heat medium relay unit 3 through the high-pressure side
refrigerant pipe 4a(2). The high-pressure liquid refrigerant that
has flown into the heat medium relay unit 3 flows through the
second refrigerant channel switch unit 18b and flows into the heat
exchanger related to heat medium 15b, which functions as a
condenser. Note that the on-off units 17 are closed.
[0144] The refrigerant that has flown into the heat exchanger
related to heat medium 15b becomes a further low-temperature
refrigerant while transferring heat to the heat medium that
circulates in the heat medium circulation circuit B. The
refrigerant that has flown out from the heat exchanger related to
heat medium 15b is expanded by the expansion unit 16b and becomes a
low-pressure two-phase refrigerant. The low-pressure two-phase
refrigerant flows into the heat exchanger related to heat medium
15a, which functions as an evaporator, through the expansion unit
16a. The low-pressure two-phase refrigerant that has flown into the
heat exchanger related to heat medium 15a becomes a low-pressure
refrigerant gas while cooling the heat medium that circulates in
the heat medium circulation circuit B by absorbing heat from the
heat medium. The refrigerant gas that has flown out from the heat
exchanger related to heat medium 15a flows out from the heat medium
relay unit 3 through the second refrigerant channel switch unit
18a, and flows again into the outdoor unit 1 through the
low-pressure side refrigerant pipe 4b(2). The refrigerant that has
flown into the outdoor unit 1 is sucked again by the compressor 10
through the low-pressure side refrigerant pipe 4b(1); the pipe that
is provided with the check valve 13d; the first refrigerant channel
switch unit 11; and the accumulator 19.
[0145] The opening degree of the expansion unit 16b is controlled
in such a manner that superheating obtained as the difference
between the temperature detected by the third temperature sensor
35a and the temperature detected by the third temperature sensor
35b is constant. Here, the expansion unit 16a is fully opened, the
on-off unit 17a and the on-off unit 17b are closed. Note that the
opening degree of the expansion unit 16b may be controlled in such
a manner that subcooling obtained as the difference between a
saturation temperature, into which the pressure detected by the
pressure sensor 36 is converted, and the temperature detected by
the third temperature sensor 35d is constant. Moreover, the
expansion unit 16b may be fully opened, and superheating or
subcooling may be controlled by the expansion unit 16a.
[0146] Next, the flow of the heat medium in the heat medium
circulation circuit B will be described.
[0147] In the cooling main operation mode, the heating energy of
the heat-source side refrigerant is transferred to the heat medium
in the heat exchanger related to heat medium 15b, and the heated
heat medium is made to flow in the heat medium pipes 5 by the pump
21b. Moreover, in the cooling main operation mode, the cooling
energy of the heat-source side refrigerant is transferred to the
heat medium in the heat exchanger related to heat medium 15a, and
the cooled heat medium is made to flow in the heat medium pipes 5
by the pump 21a. The heat medium that has flown out by being
compressed by the pump 21a and the pump 21b flows into the use-side
heat exchanger 26a and the use-side heat exchanger 26b through the
second heat medium channel switch unit 23a and the second heat
medium channel switch unit 23b.
[0148] The heat medium transfers heat to the room air in the
use-side heat exchanger 26b, and consequently, heating for the room
space 7 is performed. Moreover, the heat medium removes heat from
the room air in the use-side heat exchanger 26a, and consequently,
cooling for the room space 7 is performed. In this case, the amount
of the flowing heat medium is controlled by the operation of the
heat medium flow control device 25a and heat medium flow control
device 25b so as to be the amount that is necessary to meet an air
conditioning load that is needed in the room, and flows into the
use-side heat exchanger 26a and the use-side heat exchanger 26b.
The heat medium that has flown through the use-side heat exchanger
26b and whose temperature has slightly decreased flows into the
heat exchanger related to heat medium 15b through the heat medium
flow control device 25b and the first heat medium channel switch
unit 22b, and is sucked again by the pump 21b. The heat medium that
has flown through the use-side heat exchanger 26a and the whose
temperature has slightly increased flows into the heat exchanger
related to heat medium 15a through the heat medium flow control
device 25a and the first heat medium channel switch unit 22a, and
is sucked again by the pump 21a.
[0149] During this time, the warm heat medium is not mixed with the
cold heat medium by the operation of the first heat medium channel
switch units 22 and second heat medium channel switch units 23. The
warm heat medium is guided to the use-side heat exchanger 26 that
has a heating load, and the cold heat medium is guided to the
use-side heat exchanger 26 that has a cooling load. Note that, in
the heat medium pipes 5 of the use-side heat exchangers 26, the
heat medium flows in the direction from the second heat medium
channel switch units 23 to the first heat medium channel switch
units 22 via the heat medium flow control devices 25 on both
heating and cooling sides. Moreover, the air conditioning load can
meet an amount needed in the room space 7 by performing control in
such a manner that the differences between the temperature detected
by the first temperature sensor 31b and the temperatures detected
by the second temperature sensors 34 on the heating side and the
differences between the temperatures detected by the second
temperature sensors 34 and the temperature detected by the first
temperature sensor 31a on the cooling side are kept as a target
value.
[Heating Main Operation Mode]
[0150] FIG. 6 is a diagram of a refrigerant circuit illustrating a
flow of the refrigerant in the air-conditioning apparatus 100 in
the heating main operation mode. In FIG. 6, the heating main
operation mode is described in an example of the case where a
heating load is generated in the use-side heat exchanger 26a and a
cooling load is generated in the use-side heat exchanger 26b. Note
that, in FIG. 6, pipes drawn with a thick line indicate pipes in
which the refrigerant (the heat-source side refrigerant and the
heat medium) flows. Moreover, in FIG. 6, the direction in which the
heat-source side refrigerant flows is indicated by arrows drawn
with a solid line, and the direction in which the heat medium flows
is indicated by arrows drawn with a broken line.
[0151] In the case of the heating main operation mode illustrated
in FIG. 6, the outdoor unit 1 makes the first refrigerant channel
switch unit 11 perform switching in such a manner that the
heat-source side refrigerant discharged from the compressor 10
flows into the heat medium relay unit 3 without flowing through the
heat-source side heat exchanger 12. The heat medium relay unit 3
drives the pump 21a and the pump 21b, opens the heat medium flow
control device 25a and the heat medium flow control device 25b,
fully closes the heat medium flow control device 25c and the heat
medium flow control device 25d, and circulates the heat medium
between the heat exchanger related to heat medium 15a and the
use-side heat exchanger 26b and between the heat exchanger related
to heat medium 15b and the use-side heat exchanger 26a.
[0152] At first, the flow of the heat-source side refrigerant in
the refrigerant circuit A is described.
[0153] A low-temperature low-pressure refrigerant is compressed by
the compressor 10, and becomes a high-temperature high-pressure
refrigerant gas, which is then discharged. The high-temperature
high-pressure refrigerant gas that has been discharged from the
compressor 10 flows out from the outdoor unit 1 through the first
refrigerant channel switch unit 11, the first connection pipe 42a,
and the high-pressure side refrigerant pipe 4a(1). The
high-temperature high-pressure refrigerant gas that has flown out
from the outdoor unit 1 flows into the heat medium relay unit 3
through the high-pressure side refrigerant pipe 4a(2). The
high-temperature high-pressure refrigerant gas that has flown into
the heat medium relay unit 3 flows into the heat exchanger related
to heat medium 15b, which functions as a condenser, through the
second refrigerant channel switch unit 18b. Note that the on-off
units 17 are closed.
[0154] The refrigerant gas that has flown into the heat exchanger
related to heat medium 15b becomes a low-temperature refrigerant in
a supercritical state while the refrigerant gas transfers heat to
the heat medium that circulates in the heat medium circulation
circuit B. The refrigerant that has flown out from the heat
exchanger related to heat medium 15b is expanded by the expansion
unit 16b and becomes a low-pressure two-phase refrigerant. The
low-pressure two-phase refrigerant flows into the heat exchanger
related to heat medium 15a, which functions as an evaporator,
through the expansion unit 16a. The low-pressure two-phase
refrigerant that has flown into the heat exchanger related to heat
medium 15a evaporates by absorbing heat from the heat medium that
circulates in the heat medium circulation circuit B, and
consequently, cools the heat medium. The low-pressure two-phase
refrigerant flows out from the heat exchanger related to heat
medium 15a, flows out from the heat medium relay unit 3 through the
second refrigerant channel switch unit 18a, and flows again into
the outdoor unit 1 through the low-pressure side refrigerant pipe
4b(2).
[0155] The refrigerant that has flown into the outdoor unit 1 flows
into the heat-source side heat exchanger 12, which functions as an
evaporator, through the low-pressure side refrigerant pipe 4b(1)
and the second connection pipe 42b. The refrigerant that has flown
into the heat-source side heat exchanger 12 removes heat from the
outside air in the heat-source side heat exchanger 12, and
consequently, becomes a low-temperature low-pressure refrigerant
gas. The low-temperature low-pressure refrigerant gas that has
flown out from the heat-source side heat exchanger 12 is sucked
again by the compressor 10 through the first refrigerant channel
switch unit 11 and the accumulator 19.
[0156] The opening degree of the expansion unit 16b is controlled
in such a manner that subcooling obtained as the difference between
a saturation temperature, into which the pressure detected by the
pressure sensor 36 is converted, and the temperature detected by
the third temperature sensor 35b is constant. Here, the expansion
unit 16a is fully opened, and the on-off unit 17b is closed. Note
that the expansion unit 16b may be fully opened and subcooling may
be controlled by the expansion unit 16a.
[0157] Next, the flow of the heat medium in the heat medium
circulation circuit B will be described.
[0158] In the heating main operation mode, the heating energy of
the heat-source side refrigerant is transferred to the heat medium
in the heat exchanger related to heat medium 15b, and the heated
heat medium is made to flow in the heat medium pipes 5 by the pump
21b. Moreover, in the heating main operation mode, the cooling
energy of the heat-source side refrigerant is transferred to the
heat medium in the heat exchanger related to heat medium 15a, and
the cooled heat medium is made to flow in the heat medium pipes 5
by the pump 21a. The heat medium that has flown out by being
compressed by the pump 21a and the pump 21b flows into the use-side
heat exchanger 26a and the use-side heat exchanger 26b through the
second heat medium channel switch unit 23a and the second heat
medium channel switch unit 23b.
[0159] The heat medium removes heat from the room air in the
use-side heat exchanger 26b, and consequently, cooling for the room
space 7 is performed. Moreover, the heat medium transfers heat to
the room air in the use-side heat exchanger 26a, and consequently,
heating for the room space 7 is performed. In this case, the amount
of the heat medium that flows is controlled by the operation of the
heat medium flow control device 25a and heat medium flow control
device 25b so as to be the amount that is necessary to meet an air
conditioning load that is needed in the room, and flows into the
use-side heat exchanger 26a and the use-side heat exchanger 26b.
The heat medium that has flown through the use-side heat exchanger
26b and the whose temperature has slightly increased flows into the
heat exchanger related to heat medium 15a through the heat medium
flow control device 25b and the first heat medium channel switch
unit 22b, and is sucked again by the pump 21a. The heat medium that
has flown through the use-side heat exchanger 26a and the whose
temperature has slightly decreased flows into the heat exchanger
related to heat medium 15b through the heat medium flow control
device 25a and the first heat medium channel switch unit 22a, and
is sucked again by the pump 21b.
[0160] During this time, the warm heat medium is not mixed with the
cold heat medium by the operation of the first heat medium channel
switch units 22 and second heat medium channel switch units 23. The
warm heat medium is guided to the use-side heat exchanger 26 that
has a heating load, and the cold heat medium is guided to the
use-side heat exchanger 26 that has a cooling load. Note that, in
the heat medium pipes 5 of the use-side heat exchangers 26, the
heat medium flows in the direction from the second heat medium
channel switch units 23 to the first heat medium channel switch
units 22 via the heat medium flow control devices 25 on both
heating and cooling sides. Moreover, the air conditioning load can
meet an amount needed in the room space 7 by performing control in
such a manner that the differences between the temperature detected
by the first temperature sensor 31b and the temperatures detected
by the second temperature sensors 34 on the heating side and the
differences between the temperatures detected by the second
temperature sensors 34 and the temperature detected by the first
temperature sensor 31a on the cooling side are kept as a target
value.
[Refrigerant Pipes 4]
[0161] As described above, the air-conditioning apparatus 100
according to Embodiment is provided with some operation modes. In
these operation modes, the heat-source side refrigerant flows in
the refrigerant pipes 4 that connect the outdoor unit 1 and the
heat medium relay unit 3.
[Heat Medium Pipes 5]
[0162] In some of the operation modes performed by the
air-conditioning apparatus 100 according to Embodiment, a heat
medium such as water and an antifreezing solution flows in the heat
medium pipes 5 that connect the heat medium relay unit 3 and the
indoor units 2.
[Heat-Source Side Refrigerant]
[0163] In the air-conditioning apparatus 100 according to
Embodiment, a refrigerant that has a small global warming potential
is used as the heat-source side refrigerant. Examples of such a
refrigerant include HFO1234yf, refrigerant mixture using HFO1234yf,
HFO1234ze, other tetrafluoropropene-based refrigerants, R32, HC,
carbon dioxide, a refrigerant mixture containing at least one of
the above-described refrigerants as a component, and the like.
[Heat Medium]
[0164] As the heat medium, for example, brine (an antifreezing
solution), water, a mixed solution of brine and water, a mixed
solution in which water and an additive that has a high
anti-corrosive effect are mixed, and the like may be used. Thus, in
the air-conditioning apparatus 100, even in the case where the heat
medium leaks into the room space 7 through the indoor unit 2, since
the heat medium with a high degree of safety is used, the degree of
safety is improved.
[0165] The air-conditioning apparatus 100 which employs the
above-described structure makes it possible to detect leaking of
the refrigerant from the refrigerant circuit (the refrigerant
circuit A), and consequently, the degree of safety is greatly
improved. Moreover, by using a refrigerant that can transition into
a supercritical state, the air-conditioning apparatus 100 can
reduce the environmental load.
[0166] The air-conditioning apparatus 100 has been described as an
air-conditioning apparatus that can perform the cooling and heating
mixed operation; however, the air-conditioning apparatus 100 is not
limited thereto. For example, the present invention may be applied
to air-conditioning apparatuses that have a structure in which one
heat exchanger related to heat medium 15 and one expansion unit 16
are included and a plurality of use-side heat exchangers 26 and a
plurality of heat medium flow control devices 25 are connected to
the heat exchanger related to heat medium 15 and the expansion unit
16 in parallel and that may only perform either the cooling
operation or the heating operation.
[0167] Moreover, the present invention may be applied to the case
in which one use-side heat exchanger 26 and one heat medium flow
control device 25 are connected. Furthermore, it is clear that, a
plurality of units that function the same as the heat exchangers
related to heat medium 15 and the expansion units 16 may be
provided. Furthermore, the example in which the heat medium flow
control devices 25 are built in the heat medium relay unit 3 has
been described; however, the structure is not limited thereto and
the heat medium flow control devices 25 may be built in the indoor
units 2. The heat medium relay unit 3 and the indoor units 2 may
also be separately provided.
[0168] Moreover, in general, the heat-source side heat exchanger 12
and the use-side heat exchangers 26 are equipped with an
air-sending device to accelerate condensation and evaporation by
blowing air; however, the structure is not limited thereto. For
example, something like a panel heater that utilizes eradiation may
also be used as the use-side heat exchangers 26 or water-cooled
type heat exchangers in which heat is transferred by using water or
an antifreezing solution may also be used as the heat-source side
heat exchanger 12. That is, a structure that can transfer or remove
heat, regardless of the kind of units, may be used as the
heat-source side heat exchanger 12 and the use-side heat exchangers
26.
[0169] In the air-conditioning apparatus 100 according to
Embodiment, the examples in which four use-side heat exchangers 26
are used has been described; however the number of the use-side
heat exchangers 26 is not limited thereto. Moreover, the examples
in which two heat exchangers related to heat medium 15 are used has
been described; however, as a matter of course, the number of the
heat exchangers related to heat medium 15 is not limited thereto.
If the air-conditioning apparatus 100 is configured to be able to
cool or/and heat the heat medium, the number of the heat exchangers
related to heat medium 15 does not matter. Furthermore, the number
of the pump 21a and that of the pump 21b do not have to be one, and
a plurality of pumps, each of which has a small capacity, may be
arranged and connected in parallel.
[0170] FIG. 8 is a diagram illustrating an example of the structure
of another refrigerant circuit of the air-conditioning apparatus
100 according to Embodiment of the present invention. A difference
between FIG. 8 and FIGS. 2 to 6 is that a direct expansion type
air-conditioning apparatus that does not have the heat medium
circulation circuit B is used. Furthermore, four expansion units
14a to 14d are provided. Even in the air-conditioning apparatus 100
having this structure, the effects similar in the cases of FIGS. 2
to 6 are obtained by the operation of the concentration detection
unit 39, the concentration calculation unit 41, the first cutoff
unit 37, the second cutoff unit 38 and the cutoff control unit
40.
[0171] Note that the examples in which the concentration detection
unit 39 is arranged in or near the outdoor unit 1 (a heat source
unit) have been described; however, the concentration detection
unit 39 may be arranged in or near the indoor units 2. As a result,
leaking of the refrigerant from the indoor units 2 may also be
handled.
* * * * *