U.S. patent application number 11/283694 was filed with the patent office on 2006-05-25 for air conditioning system and method for controlling the same.
This patent application is currently assigned to LG Electronics Inc.. Invention is credited to Se Dong Chang, Baik Young Chung, Ju Won Kim, Sai Kee Oh, Bong Soo Park, Chi Woo Song.
Application Number | 20060107683 11/283694 |
Document ID | / |
Family ID | 35840122 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060107683 |
Kind Code |
A1 |
Song; Chi Woo ; et
al. |
May 25, 2006 |
Air conditioning system and method for controlling the same
Abstract
The present invention relates to air conditioning systems, and
more particularly, to an air conditioning system which can control
a refrigerant flow rate to a heat exchanger exchanging heat with
room air to be optimum; and a method for controlling the same. The
air conditioning system includes an outdoor heat exchange part
including a compressor for compressing refrigerant, an outdoor heat
exchanger for making the refrigerant to heat exchange with outdoor
air, and an expansion device for expanding the refrigerant, an
indoor heat exchange part including a pump for making refrigerant
in a flow path independent from the outdoor heat exchange part to
flow, at least one indoor heat exchanger for making the refrigerant
heat exchange with room air, and a flow rate control device for
controlling a flow rate of the refrigerant, and a hybrid heat
exchange part for making the outdoor heat exchange part and the
indoor heat exchange part, which are independent from each other,
to heat exchange with each other. According to this, the air
conditioning system can be installed on a multistory building
without limitation of a height of the building as far as a capacity
of the pump permits. Moreover, even if a refrigerant pipe is long,
the air conditioning system is applicable even to a system with a
refrigerant pipe line longer than the related art as far as the
capacity of the pump permits, and fine control of a room air
temperature is possible.
Inventors: |
Song; Chi Woo; (Incheon-si,
KR) ; Park; Bong Soo; (Seoul, KR) ; Kim; Ju
Won; (Changwon-si, KR) ; Chang; Se Dong;
(Gwangmyeong-si, KR) ; Chung; Baik Young;
(Incheon-si, KR) ; Oh; Sai Kee; (Anyang-si,
KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
LG Electronics Inc.
|
Family ID: |
35840122 |
Appl. No.: |
11/283694 |
Filed: |
November 22, 2005 |
Current U.S.
Class: |
62/324.1 ;
62/434; 62/513 |
Current CPC
Class: |
F24F 2140/20 20180101;
F24F 11/83 20180101; F25B 2700/2117 20130101; F25B 2700/21174
20130101; F24F 3/06 20130101; F25B 25/005 20130101; F25B 2600/2513
20130101; F25B 13/00 20130101; F25B 2700/21175 20130101 |
Class at
Publication: |
062/324.1 ;
062/513; 062/434 |
International
Class: |
F25B 13/00 20060101
F25B013/00; F25D 17/02 20060101 F25D017/02; F25B 41/00 20060101
F25B041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 23, 2004 |
KR |
P2004-0096315 |
Claims
1. An air conditioning system comprising: an outdoor heat exchange
part including a compressor for compressing refrigerant, an outdoor
heat exchanger for making the refrigerant to heat exchange with
outdoor air, and an expansion device for expanding the refrigerant;
an indoor heat exchange part including a pump for making
refrigerant in a flow path independent from the outdoor heat
exchange part to flow, an indoor heat exchanger for making the
refrigerant heat exchange with room air, and a flow rate control
device for controlling a flow rate of the refrigerant; and a hybrid
heat exchange part for making the outdoor heat exchange part and
the indoor heat exchange part, which are independent from each
other, to heat exchange with each other.
2. The system as claimed in claim 1, wherein the flow rate control
device includes; a temperature sensor for measuring temperatures of
refrigerant flowing in the indoor heat exchanger, a controller for
determining a degree of superheat or subcooling of the refrigerant
with the temperatures measured at the temperature sensors, and a
flow rate control valve for controlling a refrigerant flow rate to
the indoor heat exchanger according to the determination of the
controller.
3. The system as claimed in claim 2, wherein the flow rate control
valve is mounted on a refrigerant inlet end of the indoor heat
exchanger.
4. The system as claimed in claim 2, wherein the flow rate control
valve is mounted on a refrigerant outlet end of the indoor heat
exchanger.
5. The system as claimed in claim 2, wherein the temperature
sensors are mounted on the refrigerant inlet end, the refrigerant
outlet end, and a predetermined portion between the refrigerant
inlet end and the refrigerant outlet end of the indoor heat
exchanger.
6. The system as claimed in claim 5, wherein the predetermined
portion between the refrigerant inlet end and the refrigerant
outlet end of the indoor heat exchanger is a section in which the
refrigerant flowing in the indoor heat exchanger is in a saturated
state.
7. A method for controlling an air conditioning system comprising
the steps of: setting an ideal degree of superheat, and an ideal
degree of subcooling at a controller; comparing the degree of
superheat or subcooling set thus with a degree of superheat or
subcooling measured thus; and controlling a flow rate of
refrigerant flowing in an indoor heat exchanger according to a
result of the step of comparing the degree of superheat or
subcooling set thus with a degree of superheat or subcooling
measured thus.
8. The method as claimed in claim 7, wherein the degree of
superheat or subcooling is a difference between a temperature of
the refrigerant at the refrigerant outlet of the indoor heat
exchanger and a saturation temperature of the refrigerant flowing
in the indoor heat exchanger.
9. The method as claimed in claim 7, wherein the step of
controlling a flow rate of refrigerant flowing in an indoor heat
exchanger includes the steps of; increasing the flow rate of the
refrigerant flowing in the indoor heat exchanger if the degree of
superheat measured is higher than the degree of superheat set, and
decreasing the flow rate of the refrigerant flowing in the indoor
heat exchanger if the degree of superheat measured is lower than
the degree of superheat set.
10. The method as claimed in claim 7, wherein the step of
controlling a flow rate of refrigerant flowing in an indoor heat
exchanger includes the steps of; increasing the flow rate of the
refrigerant flowing in the indoor heat exchanger if the degree of
subcooling measured is higher than the degree of subcooling set,
and decreasing the flow rate of the refrigerant flowing in the
indoor heat exchanger if the degree of subcooling measured is lower
than the degree of subcooling set.
11. An air conditioning system comprising: at least one first heat
exchanger for heat exchange with room air; a second heat exchanger
for transferring heat from the first heat exchanger to an outside
of a refrigerant flow path having the first heat exchanger mounted
therein; a pump for circulating the refrigerant to the first heat
exchanger and the second heat exchanger; a third heat exchanger in
a flow path independent both from the first heat exchanger and the
second heat exchanger for heat exchange with the second heat
exchanger; a fourth heat exchanger for transferring heat from the
third heat exchanger to outdoor air; a compressor for compressing
the refrigerant and circulating the refrigerant to the third heat
exchanger and the fourth heat exchanger; a plurality of temperature
sensors for measuring temperatures of the refrigerant flowing in
the first heat exchanger; and at least one flow rate control valve
for controlling a flow rate of the refrigerant flowing in the first
heat exchanger according to temperatures measured at the
temperature sensors.
12. The system as claimed in claim 11, wherein the temperature
sensors are provided at a refrigerant inlet end and a refrigerant
outlet end of the first heat exchanger, and at a predetermined
portion between the refrigerant inlet end and the refrigerant
outlet end, respectively.
13. The system as claimed in claim 11, wherein the temperature
sensor provided at a predetermined portion between the refrigerant
inlet end and the refrigerant outlet end measures a saturation
temperature of the refrigerant flowing in the first heat
exchanger.
14. The system as claimed in claim 11, wherein the flow rate
control valves are provided to a refrigerant inlet end and a
refrigerant outlet end of the indoor heat exchanger.
15. The system as claimed in claim 14, wherein, at the time of
controlling a refrigerant flow rate, an opening of the flow rate
control valve at the refrigerant inlet end of the first heat
exchanger is adjusted, and an opening of the flow rate control
valve at the refrigerant outlet end is opened to the maximum.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of Korean Application
No. P2004-96315 filed on Nov. 23, 2004, which is hereby
incorporated by reference as if fully set forth herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to air conditioning systems,
and more particularly, to an air conditioning system which can
control a refrigerant flow rate to a heat exchanger exchanging heat
with room air to be optimum; and a method for controlling the
same.
[0004] 2. Discussion of the Related Art
[0005] In general, the air conditioning system cools or heats a
room by compressing, condensing, expanding, and evaporating
refrigerant. In general, the air conditioning system is provided
with a compressor, an indoor heat exchanger, an expansion device,
and an outdoor heat exchanger.
[0006] In the air conditioning systems, there are a cooling system
in which a refrigerating cycle is operated only in one direction,
to supply only cold air to the room, and a heating/cooling system
in which the refrigerating cycle is operated in two directions
selectively, to supply cold air or warm air to the room.
[0007] Moreover, in the air conditioning systems, depending on a
number of indoor units connected thereto, there are single air
conditioning systems in each of which one indoor unit is connected
to one outdoor unit, and multiple air conditioning systems in each
of which a plurality of indoor units are connected to one outdoor
unit.
[0008] The air conditioning system uses the compressor as a driving
source for making the refrigerant to flow, and oil for lubricating
the compressor.
[0009] However, if a height difference or a distance between the
indoor heat exchanger, and the outdoor heat exchanger is great
significantly, since the related art air conditioning system has a
poor oil recovery rate, to fail in supply of an adequate rate of
oil to the compressor, which is liable to result in damage to the
compressor, development of an air conditioning system that can
solve such a problem has been required.
SUMMARY OF THE INVENTION
[0010] Accordingly, the present invention is directed to an air
conditioning system and a method for controlling the same that
substantially obviates one or more problems due to limitations and
disadvantages of the related art.
[0011] An object of the present invention is to provide a an air
conditioning system and a method for controlling the same, which is
applicable even to a case a height difference or a distance between
an indoor heat exchanger, and an outdoor heat exchanger is great
significantly.
[0012] Another object of the present invention is to provide an air
conditioning system and a method for controlling the same, which
enables a fine control of a room temperature.
[0013] Additional advantages, objects, and features of the
invention will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objectives and other
advantages of the invention may be realized and attained by the
structure particularly pointed out in the written description and
claims hereof as well as the appended drawings.
[0014] To achieve these objects and other advantages and in
accordance with the purpose of the invention, as embodied and
broadly described herein, an air conditioning system includes an
outdoor heat exchange part including a compressor for compressing
refrigerant, an outdoor heat exchanger for making the refrigerant
to heat exchange with outdoor air, and an expansion device for
expanding the refrigerant, an indoor heat exchange part including a
pump for making refrigerant in a flow path independent from the
outdoor heat exchange part to flow, a indoor heat exchanger for
making the refrigerant heat exchange with room air, and a flow rate
control device for controlling a flow rate of the refrigerant, and
a hybrid heat exchange part for making the outdoor heat exchange
part and the indoor heat exchange part, which are independent from
each other, to heat exchange with each other.
[0015] The flow rate control device may include a temperature
sensor for measuring temperatures of refrigerant flowing in the
indoor heat exchanger, a controller for determining a degree of
superheat or subcooling of the refrigerant with the temperatures
measured at the temperature sensor, and a flow rate control valve
for controlling a refrigerant flow rate to the indoor heat
exchanger according to the determination of the controller.
[0016] The flow rate control valve may be mounted on a refrigerant
inlet end of the indoor heat exchanger.
[0017] The flow rate control valve may be mounted on a refrigerant
outlet end of the indoor heat exchanger.
[0018] The temperature sensors are mounted on the refrigerant inlet
end, the refrigerant outlet end, and a predetermined portion
between the refrigerant inlet end and the refrigerant outlet end of
the indoor heat exchanger. Preferably, the predetermined portion
between the refrigerant inlet end and the refrigerant outlet end of
the indoor heat exchanger is a section in which the refrigerant
flowing in the indoor heat exchanger is in a saturated state.
[0019] In the meantime, in another aspect of the present invention,
a method for controlling an air conditioning system includes the
steps of setting an ideal degree of superheat, and an ideal degree
of subcooling at a controller, comparing the degree of superheat or
subcooling set thus with a degree of superheat or subcooling
measured thus, and controlling a flow rate of refrigerant flowing
in an indoor heat exchanger according to a result of the step of
comparing the degree of superheat or subcooling set thus with a
degree of or subcooling measured thus.
[0020] The degree of superheat or subcooling is a difference
between a temperature of the refrigerant at the refrigerant outlet
of the indoor heat exchanger and a saturation temperature of the
refrigerant flowing in the indoor heat exchanger.
[0021] The step of controlling a flow rate of refrigerant flowing
in an indoor heat exchanger includes the steps of increasing the
flow rate of the refrigerant flowing in the indoor heat exchanger
if the degree of superheat measured is higher than the degree of
superheat set, and decreasing the flow rate of the refrigerant
flowing in the indoor heat exchanger if the degree of superheat
measured is lower than the degree of superheat set.
[0022] The step of controlling a flow rate of refrigerant flowing
in an indoor heat exchanger includes the steps of increasing the
flow rate of the refrigerant flowing in the indoor heat exchanger
if the degree of subcooling measured is higher than the degree of
subcooling set, and decreasing the flow rate of the refrigerant
flowing in the indoor heat exchanger if the degree of subcooling
measured is lower than the degree of subcooling set.
[0023] In another aspect of the present invention, an air
conditioning system includes at least one first heat exchanger for
heat exchange with room air, a second heat exchanger for
transferring heat from the first heat exchanger to an outside of a
refrigerant flow path having the first heat exchanger mounted
therein, a pump for circulating the refrigerant to the first heat
exchanger and the second heat exchanger, a third heat exchanger in
a flow path independent both from the first heat exchanger and the
second heat exchanger for heat exchange with the second heat
exchanger, a fourth heat exchanger for transferring heat from the
third heat exchanger to outdoor air, a compressor for compressing
the refrigerant and circulating the refrigerant to the third heat
exchanger and the fourth heat exchanger, a plurality of temperature
sensors for measuring temperatures of the refrigerant flowing in
the first heat exchanger, at least one flow rate control valve for
controlling a flow rate of the refrigerant flowing in the first
heat exchanger according to temperatures measured at the
temperature sensors.
[0024] The temperature sensors are provided at a refrigerant inlet
end and a refrigerant outlet end of the first heat exchanger, and
at a predetermined portion between the refrigerant inlet end and
the refrigerant outlet end, respectively. The temperature sensor
provided at a predetermined portion between the refrigerant inlet
end and the refrigerant outlet end measures a saturation
temperature of the refrigerant flowing in the first heat
exchanger.
[0025] The flow rate control valves are provided to a refrigerant
inlet end and a refrigerant outlet end of the indoor heat
exchanger. At the time of controlling a refrigerant flow rate, an
opening of the flow rate control valve at the refrigerant inlet end
of the first heat exchanger is adjusted, and an opening of the flow
rate control valve at the refrigerant outlet end is opened to the
maximum.
[0026] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings;
[0028] FIG. 1 illustrates a diagram of an air conditioning system
in accordance with a preferred embodiment of the present invention,
schematically;
[0029] FIG. 2 illustrates a diagram of an indoor heat exchange part
in the air conditioning system in FIG. 1, schematically;
[0030] FIG. 3 illustrates a flow chart showing the steps of a
method for controlling an air conditioning system in accordance
with a preferred embodiment of the present invention;
[0031] FIG. 4 illustrates a P-h diagram showing a state change of
refrigerant in cooling operation of the air conditioning system in
FIG. 1; and
[0032] FIG. 5 illustrates a P-h diagram showing a state change of
refrigerant in heating operation of the air conditioning system in
FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers will be used throughout the drawings to
refer to the same or like parts.
[0034] FIGS. 1 and 2 illustrate diagrams each showing an air
conditioning system in accordance with a preferred embodiment of
the present invention.
[0035] Referring to FIGS. 1 and 2, the air conditioning system
includes an indoor heat exchange part 10 for heat exchange with
room air, an outdoor heat exchange part 20 for heat exchange with
outdoor air, and a hybrid heat exchanger 30 for making refrigerant
in the indoor heat exchange part 10 and refrigerant in the outdoor
heat exchange part 20 to heat exchange with each other.
[0036] The indoor heat exchange part 10 includes a first heat
exchanger 14 for heat exchange with the room air, a pump 12 for
circulating the refrigerant to the first heat exchanger 14, and a
flow rate control device for controlling a flow rate of the
refrigerant to the first heat exchanger 14.
[0037] The outdoor heat exchange part 20 has a refrigerant flow
path independent from the indoor heat exchange part 10, and
includes a fourth heat exchanger 24 for making the refrigerant to
heat exchange with outdoor air, and a compressor 22 for
compressing, and circulating the refrigerant to the fourth heat
exchanger 24.
[0038] The outdoor heat exchange part 20 includes an expansion
device 28 for expanding the refrigerant to drop a pressure of the
refrigerant, and a flow controller 23 for controlling a flow
direction of the refrigerant, additionally.
[0039] In the meantime, the outdoor heat exchange part 20 may have
many variations as far as the part can transfer heat to the
refrigerant in the indoor heat exchange part 10. As an example, the
part may use warm water or waste heat as a heat source.
[0040] The hybrid heat exchange part 30 is configured such that the
indoor heat exchange part 10 and the outdoor heat exchange part 20
having refrigerant flow paths independent from each other can heat
exchange with each other, without mix of the refrigerant between
the indoor heat exchange part 10 and the outdoor heat exchange part
20.
[0041] In order to enable the indoor heat exchanger 10 and the
outdoor heat exchanger 20 make heat exchange with each other, the
hybrid heat exchange part 30 includes a second heat exchanger 16 in
a flow path of the indoor heat exchange part 10, and a third heat
exchanger 26 in a flow path of the outdoor heat exchange part 20
for heat exchange with the second heat exchanger 16.
[0042] That is, the second heat exchanger 16 exchanges heat with
the third heat exchanger 26 so that the indoor heat exchange part
10 and the outdoor heat exchange part 20 make heat exchange.
[0043] Moreover, the second heat exchanger 16 forms a refrigerant
circulating flow path as a portion of the indoor heat exchange part
10, and the third heat exchanger 26 forms a refrigerant circulating
flow path as a portion of the outdoor heat exchange part 20.
[0044] That is, the outdoor heat exchange part 20 forms a
refrigerant flow path with the third heat exchanger 26, the fourth
heat exchanger 24, the compressor 22, and the expansion device 28,
and the indoor heat exchange part 10 forms a refrigerant flow path
with the first heat exchanger 14, the second heat exchanger 16, the
pump 12, and a flow rate control device.
[0045] The second heat exchanger 16 and the third heat exchanger 26
may have many variations. That is, the second heat exchanger 16 and
the third heat exchanger 26 may be constructed of heat dissipation
plates, or refrigerant tubes.
[0046] The hybrid heat exchange part 30 is configured to enable the
second heat exchanger 16, and the third heat exchanger 26 in the
outdoor heat exchange part to make thermal contact with each
other.
[0047] For an example, the hybrid heat exchange part 30 may be
constructed of a stack of a plurality of plate type heat conductive
fins having the second heat exchanger 16 and the third heat
exchanger 26 placed therebetween so as to be thermally in contact
with each other.
[0048] Or alternatively, the hybrid heat exchange part 30 may has a
structure in which the second heat exchanger and the third heat
exchanger heat exchange with each other through a heat conductive
fluid. Or, the second heat exchanger 16 and the third heat
exchanger 26 are configured to have a form of a double tube.
[0049] In the meantime, the indoor heat exchange part 10 will be
described in more detail.
[0050] As described before, the indoor heat exchange part 10 has a
flow path independent from the outdoor heat exchange part 20, and
includes a first heat exchanger 14, a pump 12, a flow rate control
device, and a second heat exchanger 16 of the hybrid heat exchange
part 30.
[0051] The indoor heat exchange part 10 has a pump 12 instead of a
compressor as a driving source for making the refrigerant to flow,
and has no separate expansion device for expanding the refrigerant.
Owing to this, the indoor heat exchange part 10 requires no oil for
operation of the compressor, and consequently, no operation for
recovery of the refrigerant is required.
[0052] It is preferable that the pump 12 includes a pumping motor
(not shown) and an impeller (not shown). Moreover, it is preferable
that liquid refrigerant is supplied to the pump 12, for which,
though not shown, a separate refrigerant storage tank may be
provided between the hybrid heat exchange part 30 and the pump 12,
for supplying refrigerant to the pump 12.
[0053] It is preferable that an inverter motor is employed as the
pumping motor for controlling a rotation speed of the motor, to
control a flow rate of the refrigerant. Of course, a constant speed
motor having a constant rotation speed may be used.
[0054] In general, the first heat exchanger 14 is mounted in an
indoor unit 15 installed in a room which requires cooling/heating.
That is, the first heat exchanger 14 is an indoor heat exchanger
for heat exchange with room air to cool or heat the room.
[0055] There may be a plurality of indoor units 15 installed in a
room if required, and according to this, a plurality of indoor heat
exchangers 14 may be mounted thereon.
[0056] The flow rate control device includes a plurality of
temperature sensors 17a, 17b, and 17c for measuring temperatures of
the refrigerant flowing through the indoor heat exchanger 14, a
controller (not shown) for determining a degree of superheat or
subcooling of the refrigerant in the indoor heat exchanger 14 with
reference to the temperatures measured at the temperature sensors
17a, 17b, and 17c, and flow rate control valves 13a, and 13b for
controlling a flow rate of the refrigerant to the indoor heat
exchanger 14 according to the determination of the controller.
[0057] It is preferable that the flow rate control valve 13a, and
13b are solenoid valves each for controlling an opening of a flow
passage with an electromagnetic force. Of course, there can be a
variety of the flow rate control valves 13a, and 13b as far as the
valve can control the opening of the flow passage.
[0058] Moreover, though it is preferable that the flow rate control
valve 13a, and 13b are mounted on opposite ends of the indoor heat
exchanger 14 into which the refrigerant flows in/out, the mounting
positions of the flow rate control valve 13a, and 13b are not
limited to this, but the flow rate control valve 13a, and 13b may
be mounted only one of the opposite ends.
[0059] Mounting positions of the temperature sensors will be
described with reference to FIG. 2.
[0060] It is preferable that the temperature sensors 17a, 17b, and
17c are mounted on an inlet 17a through which the refrigerant is
introduced into the indoor heat exchanger 14, an outlet 17b through
which the refrigerant is discharged from the indoor heat exchanger
14, and a predetermined portion 17c between the inlet 17a, and the
outlet 17b, respectively.
[0061] That is, at least three temperature sensors 17a, 17b, and
17c are mounted on every indoor heat exchanger 14 mounted on the
indoor unit 15.
[0062] Of the three temperature sensors 17a, 17b, and 17c, it is
preferable that the temperature sensor 17c mounted on the
predetermined portion between the inlet 17a, and the outlet 17b is
mounted on one point where refrigerant in the indoor heat exchanger
14 is in a saturated state, so that the temperature sensor 17c can
measure a temperature at a saturated state of the refrigerant.
[0063] The temperature at a saturated state is a temperature when
there is no temperature change even if a phase of the refrigerant
changes following heat exchange of the refrigerant.
[0064] The controller has an ideal degree of superheat and an ideal
degree of subcooling preset thereto at a pressure of the
refrigerant, and an actual degree of superheat and an actual degree
of subcooling are calculated with temperatures measured at
respective portions of the indoor heat exchanger 14 with the
temperature sensors 17a, 17b, and 17c.
[0065] The degrees of superheat or subcooling is a temperature
difference measured between the temperature sensor 17b at the
outlet and the temperature sensor 17c at the middle of the indoor
heat exchanger 14.
[0066] The degree of superheat is a temperature difference at the
time of cooling, and the degree of subcooling is a temperature
difference at the time of heating.
[0067] A method for controlling a flow rate of refrigerant with
reference to the degree of superheat or subcooling in the air
conditioning system will be described.
[0068] FIG. 3 illustrates a flow chart showing the steps of a
method for controlling an air conditioning system in accordance
with a preferred embodiment of the present invention.
[0069] Referring to FIG. 3, the method for controlling an air
conditioning system includes the steps of setting an ideal degree
of subcooling and an ideal degree of superheat at a controller
(S1), measuring the degree of subcooling or superheat of the
refrigerant flowing in an indoor heat exchanger (S2), comparing the
degree of subcooling or superheat set thus to the degree of
subcooling or superheat measured (S3), and controlling a flow rate
of the refrigerant flowing in the indoor heat exchanger according
to a result in the step S3 in which the degree of subcooling or
superheat set thus is compared to the degree of subcooling or
superheat measured.
[0070] As described, the degree of superheat or the degree of
subcooling is a difference between a temperature of the refrigerant
at the outlet of the indoor heat exchanger 14, and a temperature of
the refrigerant at a saturation state of the refrigerant flowing in
the indoor heat exchanger 14.
[0071] Moreover, as described, the temperatures of the refrigerant
are measured with a plurality of temperature sensors 17a, 17b, and
17c mounted on the indoor heat exchanger 14.
[0072] At first, a setting step (S1) is performed, in which an
ideal degree of superheat and an ideal degree of subcooling at the
time of operation of the indoor heat exchanger are set at the
controller. The ideal degree of superheat and the ideal degree of
subcooling vary with a pressure of the refrigerant and an
environmental temperature.
[0073] Then, a measuring step (S2) is performed, in which an actual
degree of superheat or an actual degree of subcooling of the
refrigerant flowing in the indoor heat exchanger 14 is measured. In
the measuring step (S2), the temperatures of the refrigerant are
measured with the temperature sensors 17a, 17b, and 17c mounted on
the indoor heat exchanger 14.
[0074] That is, since the degree of superheat or the degree of
subcooling is a difference of a temperature of the refrigerant at
the outlet of the indoor heat exchanger 14 and a saturation
temperature of the refrigerant flowing in the indoor heat
exchanger, the controller can calculate the degree of superheat or
the degree of subcooling with the temperatures measured at the
temperature sensors 17a, 17b, and 17c.
[0075] Then, a determination step (S3) is performed, in which a
measured degree of superheat or subcooling is compared to a preset
degree of superheat or subcooling. In the determination step (S3),
it is determined whether the measured degree of superheat or
subcooling converges to the preset degree of superheat or
subcooling, or not, or if not, which one has how much
difference.
[0076] Then, an adjusting step (S4) is performed, in which a flow
rate of the refrigerant flowing in the indoor heat exchanger 14 is
adjusted according to a result of determination in the
determination step (S3).
[0077] In the adjusting step (S4), the flow rate of the refrigerant
is adjusted by controlling the flow rate control valve 13a, and 13b
at opposite ends of the indoor heat exchange part 10.
[0078] In more detail, if the degree of superheat measured is
higher than the preset degree of superheat at the time of room
cooling, opening of the flow rate control valves 13a, and 13b are
adjusted, to increase a flow rate of the refrigerant flowing in the
indoor heat exchanger 14 (S4a), and if the degree of superheat
measured is lower than the preset degree of superheat at the time
of room cooling, opening of the flow rate control valves 13a, and
13b are adjusted, to decrease a flow rate of the refrigerant
flowing in the indoor heat exchanger 14 (S4c).
[0079] If the degree of superheat measured is the same with the
preset degree of superheat the time of room cooling, the flow rate
of the refrigerant flowing in the indoor heat exchanger 14 is
maintained (S(S4b).
[0080] In the meantime, if the degree of subcooling measured is
higher than the preset degree of subcooling at the time of room
heating, opening of the flow rate control valves 13a, and 13b are
adjusted, to increase a flow rate of the refrigerant flowing in the
indoor heat exchanger 14 (S4a), and if the degree of subcooling
measured is lower than the preset degree of subcooling at the time
of room cooling, opening of the flow rate control valves 13a, and
13b are adjusted, to decrease a flow rate of the refrigerant
flowing in the indoor heat exchanger 14 (S4c).
[0081] If the degree of superheat measured is the same with the
preset degree of superheat the time of room cooling, the flow rate
of the refrigerant flowing in the indoor heat exchanger 14 is
maintained (S(S4b).
[0082] The operation of the air conditioning system will be
described.
[0083] FIGS. 4 and 5 illustrate graphs showing variations of a
pressure `P` and enthalpy `h` of refrigerant at the outdoor heat
exchange part 20 and the indoor heat exchange part 10 at the time
of room cooling and room heating of the air conditioning system,
respectively.
[0084] The air conditioning system cools or heats the room
depending on an operation.
[0085] At the time of cooling or heating, the hybrid heat exchange
part 30 exchanges heat between the outdoor heat exchange part 20
and the indoor heat exchange part 10.
[0086] The cooling operation will be described with reference to
FIGS. 1 and 2.
[0087] The refrigerant in the outdoor heat exchange part 20 is
compressed at the compressor 22, and forwarded to the flow
controller 23 (A-B section). The flow controller 23 changes over
the refrigerant to a side of the fourth heat exchanger 24. In this
instance, the refrigerant introduced to the fourth heat exchanger
24 is condensed as the refrigerant heat exchanges with outdoor air
(B-C section). The condensed refrigerant changes to a refrigerant
of a low temperature and low pressure as the refrigerant passes
through the expansion device 28 (C-D section). After cooling down
the third heat exchanger 26 of the hybrid heat exchange part 30,
the low temperature and low pressure refrigerant is introduced into
the compressor 22 through the flow controller 23 (D-A section). In
the outdoor heat exchange part 20, the compressor 22 serves as a
driving source if the refrigerant flow.
[0088] Then, the refrigerant in the indoor heat exchange part 10 is
cooled down as the second heat exchanger 16 and the third heat
exchanger 26 in the hybrid heat exchange part 30 exchange heat (e-a
section). The refrigerant cooled down thus is pumped to a side of
the first heat exchanger by the pump 12 (a-b section). In this
instance, the refrigerant is neither in a two phase state, nor at a
saturated temperature. The pumped refrigerant is introduced to the
first heat exchanger 14 through the flow rate control valves 13a,
and 13b at an inlet of the first heat exchanger 14, and discharged
from the first heat exchanger 14 after heat exchanger with room air
(b-c-d section).
[0089] The refrigerant in the indoor heat exchange part 10 reaches
to a saturation temperature at which the refrigerant is involved no
temperature change, but a phase change as the refrigerant heat
exchanges with room air (c point). In this step, the temperature
sensor 17c between opposite ends of the first heat exchanger 14
measures a saturation temperature of the refrigerant, and the
temperature sensor 17b at the outlet of the first heat exchanger 14
(corresponding to `d` point) measures a superheated temperature of
the refrigerant.
[0090] According to this, the controller determines a difference
between the saturation temperature and the superheated temperature,
to derive the degree of superheat, compares the derived degree of
superheat to the preset degree of superheat of the refrigerant, and
adjusts opening of the flow rate control valves 13a, and 13b.
[0091] That is, if it is determined that the measured degree of
superheat is higher than the preset degree of superheat, opening of
the flow rate control valves 13a, and 13b on the first heat
exchanger 14 is made greater, to increase a flow rate of the
refrigerant.
[0092] Opposite to this, if it is determined that the measured
degree of superheat is lower than the preset degree of superheat,
opening of the flow rate control valves 13a, and 13b on the first
heat exchanger 14 is made smaller, to decrease a flow rate of the
refrigerant.
[0093] In this instance, of the flow rate control valves 13a, and
13b on opposite ends of the first heat exchanger 14, though it is
preferable that opening of the flow rate control valve 13a at an
inlet end of the first heat exchanger 14 is made greater or
smaller, and opening of the flow rate control valve 13b at an
outlet end of the first heat exchanger 14 is opened to the maximum,
the way of opening of the flow rate control valves 13a, and 13b is
not limited to this one.
[0094] According to this, the flow rate of the refrigerant to the
first heat exchanger 14 can be controlled to the optimum.
[0095] After making heat exchange at the first heat exchanger 14,
the refrigerant is discharged from the first heat exchanger 14 to
the second heat exchanger 16 of the hybrid heat exchange part 30,
and cooled therein again, to circulate therefrom.
[0096] Next, heating operation will be described with reference to
FIGS. 1, 2, and 5.
[0097] After compressed at the compressor 22 in the outdoor heat
exchange part 20, the refrigerant is forwarded to the flow
controller 23 (A-B). The flow controller 23 changes over the
refrigerant to a side of the third heat exchanger 26 of the hybrid
heat exchange part 30. In this instance, the refrigerant introduced
into the hybrid heat exchange part 30 discharges heat, and
condensed at the third heat exchanger 26 (B-C). The condensed
refrigerant is changed to refrigerant of a low pressure and a low
temperature as the refrigerant passes through the expansion device
28 (C-D), introduced into the fourth heat exchanger 24, heat
exchanges with outdoor air, and is introduced into the compressor
through the flow controller 23 (D-A). A circulation direction of
the refrigerant in the outdoor heat exchange part 20 is opposite to
the cooling operation.
[0098] Then, the refrigerant at the indoor heat exchange part 10
has a pressure boosted by pumping of the pump 12 (a-b). The pumped
refrigerant is heated as the refrigerant heat exchanges at the
second heat exchanger 16 of the hybrid heat exchange part 30 with
the third heat exchanger 26 of the outdoor heat exchange part 20
(b-c).
[0099] The refrigerant heated thus is forwarded to a side of the
first heat exchanger 14 by the pump 12. The refrigerant introduced
into the first heat exchanger 14 heat exchanges with room air to
heat the room, while the refrigerant itself is condensed (c-a).
[0100] In this instance, as the refrigerant in the first heat
exchanger 14 heat exchanges with the room air, the refrigerant
reaches to a saturation temperature at which the refrigerant is
involved in no temperature change, but a phase change (d-e). In
such a step, the temperature sensor 17c between the refrigerant
inlet/outlet of the first heat exchanger 14 measures the saturation
temperature of the refrigerant (`e` point), and the temperature
sensor 17b at the outlet of the first heat exchanger 14 measures a
superheated temperature of the refrigerant (`a` point).
[0101] According to this, the controller derives the degree of
superheat as a difference between the saturation temperature and
the superheated temperature, compares the derived degree of
superheat to the preset degree of superheat of the refrigerant, and
adjusts opening of the flow rate control valves 13a, and 13b.
[0102] That is, if it is determined that the measured degree of
superheat is higher than the preset degree of superheat, opening of
the flow rate control valves 13a on the refrigerant inlet of the
first heat exchanger 14 is made greater, to increase the flow rate
of the refrigerant to the first heat exchanger 14.
[0103] Opposite to this, if it is determined that the measured
degree of superheat is lower than the preset degree of superheat,
opening of the flow rate control valves 13a is made smaller, to
decrease a flow rate of the refrigerant. According to this, the
flow rate to the first heat exchanger 14 is adjusted.
[0104] The refrigerant having room air heat exchanged therewith at
the first heat exchanger 14 makes circulation in which the
refrigerant is introduced into, and heated again at the second heat
exchanger 16 of the hybrid heat exchange part 30.
[0105] As has been described, the air conditioning system and the
method for controlling the same of the present invention have the
following advantages.
[0106] The supply of refrigerant to the indoor heat exchange part
by using a pump as a driving source that requires no oil permits to
dispense with an oil recovery operation at the indoor heat exchange
part.
[0107] According to this, the air conditioning system can be
installed on a multistory building without limitation of a height
of the building as far as a capacity of the pump permits. Moreover,
even if a refrigerant pipe is long, the air conditioning system is
applicable even to a system with a refrigerant pipe line longer
than the related art as far as the capacity of the pump
permits.
[0108] Moreover, the compressor and the expansion device of the
outdoor heat exchange part may be placed outside of a room mounted
on the outdoor unit. Therefore, even if the compressor and the
expansion device generate noise, the noise can not reach to the
user.
[0109] Furthermore, since the outdoor heat exchange part is
connected to the indoor heat exchange part through the hybrid heat
exchange part, a length of the refrigerant pipeline of the outdoor
heat exchange part can be shortened significantly regardless of a
height of the building. According to this, a refrigerant recovery
ratio can be improved significantly, to prevent the compressor
suffering from damage caused by a poor refrigerant recovery
ratio.
[0110] Since the saturation temperature of the refrigerant can be
measured at the first heat exchanger in the indoor heat exchange
part, control of the refrigerant flow rate to the first heat
exchanger can be optimized.
[0111] The optimum control of the refrigerant flow rate from the
first heat exchanger permits fine control of the room
temperature.
[0112] The no provision of the compressor and the expansion device
to the indoor heat exchange part to be installed in a room permits
simple structure of the indoor heat exchange part, which enables to
reduce price of the indoor unit.
[0113] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the inventions. Thus,
it is intended that the present invention covers the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *