U.S. patent application number 15/446336 was filed with the patent office on 2018-02-01 for supercritical refrigeration cycle apparatus and method for controlling supercritical refrigeration cycle apparatus.
The applicant listed for this patent is LG ELECTRONICS INC.. Invention is credited to Byeongsu KIM, Hyoungsuk WOO, Dongkeun YANG.
Application Number | 20180031282 15/446336 |
Document ID | / |
Family ID | 59285067 |
Filed Date | 2018-02-01 |
United States Patent
Application |
20180031282 |
Kind Code |
A1 |
WOO; Hyoungsuk ; et
al. |
February 1, 2018 |
SUPERCRITICAL REFRIGERATION CYCLE APPARATUS AND METHOD FOR
CONTROLLING SUPERCRITICAL REFRIGERATION CYCLE APPARATUS
Abstract
A supercritical refrigeration cycle apparatus and a method for
controlling a supercritical refrigeration cycle apparatus are
provided. The supercritical refrigeration cycle apparatus may
include a compressor; a gas cooler configured to cool the
compressed a refrigerant in a supercritical state; a pressure
control electronic expansion valve connected to the gas cooler; a
receiver configured to temporarily store the refrigerant; a flow
control electronic expansion valve connected to an outlet side of
the receiver to control a flow rate of the refrigerant; and a
controller configured to control the flow control electronic
expansion valve based on a suction superheat degree of refrigerant
suctioned into the compressor and a target suction superheat
degree, and control the pressure control electronic expansion valve
based on a target operation high pressure and a current operation
high pressure. In this way, flow control and pressure control of
refrigerant may be respectively implemented in a separate manner,
thereby enhancing reliability and operation efficiency of the
compressor, respectively.
Inventors: |
WOO; Hyoungsuk; (Seoul,
KR) ; YANG; Dongkeun; (Seoul, KR) ; KIM;
Byeongsu; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
|
KR |
|
|
Family ID: |
59285067 |
Appl. No.: |
15/446336 |
Filed: |
March 1, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 49/02 20130101;
F25B 2400/23 20130101; F25B 2600/2513 20130101; F25B 2341/0662
20130101; F25B 41/062 20130101; F25B 2700/195 20130101; F25B
2341/065 20130101; F25B 40/00 20130101; Y02B 30/70 20130101; F25B
2700/21152 20130101; F25B 2700/21175 20130101; F25B 1/10 20130101;
F25B 2309/061 20130101; F25B 2700/21151 20130101; F25B 2700/21163
20130101; F25B 43/006 20130101; F25B 9/008 20130101; Y02B 30/72
20130101; F25B 2600/2509 20130101 |
International
Class: |
F25B 9/00 20060101
F25B009/00; F25B 43/00 20060101 F25B043/00; F25B 41/06 20060101
F25B041/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 26, 2016 |
KR |
10-2016-0094970 |
Claims
1. A supercritical refrigeration cycle apparatus, comprising: a
compressor configured to compress a refrigerant in a supercritical
state; a gas cooler configured to cool the compressed refrigerant;
a pressure control electronic expansion valve connected to the gas
cooler to control a pressure of the refrigerant; a receiver
configured to temporarily store the refrigerant which has passed
through the pressure control electronic expansion valve; a flow
control electronic expansion valve connected to an outlet side of
the receiver to control a flow rate of the refrigerant; and a
controller configured to control the flow control electronic
expansion valve based on a suction superheat degree of refrigerant
suctioned into the compressor and a target suction superheat
degree, and control the pressure control electronic expansion valve
based on a target operation high pressure and a current operation
high pressure.
2. The supercritical refrigeration cycle apparatus of claim 1,
wherein the controller decreases an opening degree of the flow
control electronic expansion valve when the suction superheat
degree of the refrigerant is less than the target suction superheat
degree, and increases the opening degree of the flow control
electronic expansion valve when the suction superheat degree of the
refrigerant is greater than the target suction superheat
degree.
3. The supercritical refrigeration cycle apparatus of claim 1,
wherein the controller increases an opening degree of the pressure
control electronic expansion valve when the current operation high
pressure is greater than the target operation high pressure,
decreases the opening degree of the pressure control electronic
expansion valve when the current operation high pressure is less
than the target operation high pressure, and maintains the opening
degree of the pressure control electronic expansion valve when they
are the same.
4. The supercritical refrigeration cycle apparatus of claim 1,
further including: an intermediate heat exchanger in which
refrigerant which has passed through the gas cooler and refrigerant
which has passed through the evaporator exchange heat with each
other.
5. A supercritical refrigeration cycle apparatus, comprising: a
compressor configured to compress a refrigerant in a supercritical
state; a gas cooler configured to cool the compressed refrigerant;
a pressure control electronic expansion valve connected to the gas
cooler to control a pressure of the refrigerant; a phase separator
configured to accommodate refrigerant which has passed through the
pressure control electronic expansion valve to perform phase
separation; a flow control electronic expansion valve connected to
an outlet side of the phase separator to control a flow rate of the
refrigerant; an injection pipe, a first end of which is connected
to the phase separator and a second end of which is connected to
the compressor to provide gaseous refrigerant in the phase
separator to the compressor; a switching valve configured to open
or close the injection pipe; and a controller configured to control
the flow control electronic expansion valve based on a suction
superheat degree of refrigerant suctioned into the compressor and a
target suction superheat degree, and control the pressure control
electronic expansion valve based on a target operation high
pressure and a current operation high pressure, and control the
switching valve based on a compression ratio of the refrigerant and
a refrigerant discharge temperature of the compressor.
6. The supercritical refrigeration cycle apparatus of claim 5,
wherein the controller decreases an opening degree of the flow
control electronic expansion valve when the suction superheat
degree of the refrigerant is less than the target suction superheat
degree, and increases the opening degree of the flow control
electronic expansion valve when the suction superheat degree of the
refrigerant is greater than the target suction superheat
degree.
7. The supercritical refrigeration cycle apparatus of claim 5,
wherein the controller increases an opening degree of the pressure
control electronic expansion valve when the current operation high
pressure is greater than the target operation high pressure,
decreases the opening degree of the pressure control electronic
expansion valve when the current operation high pressure is less
than the target operation high pressure, and maintains the opening
degree of the pressure control electronic expansion valve when the
current operation high pressure is the same as the target operation
high pressure.
8. The supercritical refrigeration cycle apparatus of claim 5,
further including: an intermediate heat exchanger in which
refrigerant which has passed through the gas cooler and refrigerant
which has passed through the evaporator exchange heat with each
other.
9. The supercritical refrigeration cycle apparatus of claim 5,
wherein the controller controls the switching valve to open the
injection pipe so as to provide refrigerant in the phase separator
to the compressor when the compression ratio is above a
predetermined value, and the discharge temperature of the
compressor is above a predetermined temperature.
10. A method for controlling a supercritical refrigeration cycle
apparatus including a compressor configured to compress a
refrigerant; a gas cooler configured to cool the compressed
refrigerant in a supercritical state; a pressure control electronic
expansion valve connected to the gas cooler to control a pressure
of the refrigerant; a receiver configured to temporarily store the
refrigerant which has passed through the pressure control
electronic expansion valve; and a flow control electronic expansion
valve connected to an outlet side of the receiver to control a flow
rate of refrigerant, the method comprising: controlling an opening
degree of the flow control electronic expansion valve based on a
suction superheat degree of refrigerant in the compressor; and
controlling an opening degree of the pressure control electronic
expansion valve based on an operation high pressure of the
refrigerant.
11. The method of claim 10, wherein the controlling of the opening
degree of the flow control electronic expansion valve includes:
checking a suction superheat degree of the refrigerant in the
compressor; comparing the suction superheat degree of the
compressor with a target suction superheat degree; and maintaining
a current opening degree of the flow control electronic expansion
valve when the suction superheat degree of the compressor is the
same as the target suction superheat degree.
12. The method of claim 11, further including: increasing the
opening degree of the flow control electronic expansion valve when
the suction superheat degree of the compressor is greater than the
target suction superheat degree and decreasing the opening degree
of the flow control electronic expansion valve when the suction
superheat degree is less than the target suction superheat
degree.
13. The method of claim 11, wherein when the suction superheat
degree of the compressor is the same as the target suction
superheat degree, maintaining a current opening degree of the flow
control electronic expansion valve, and then controlling the
opening degree of the pressure control electronic expansion
valve.
14. The method of claim 11, wherein the controlling of the opening
degree of the pressure control electronic expansion valve includes:
sensing an outlet temperature of the gas cooler and an evaporation
temperature of the evaporator, respectively; calculating a target
operation high pressure using the outlet temperature of the gas
cooler and the evaporation temperature of the evaporator, and
calculating a current operation high pressure corresponding to the
outlet temperature of the gas cooler; comparing the target
operation high pressure with the current operation high pressure;
and maintaining a current opening degree of the pressure control
electronic expansion valve when the current operation high pressure
is the same as the target operation high pressure.
15. The method of claim 14, further including: increasing the
opening degree of the pressure control electronic expansion valve
when the current operation high pressure is greater than the target
operation high pressure; and decreasing the opening degree of the
pressure control electronic expansion valve when the current
operation high pressure is less than the target operation high
pressure.
16. A method for controlling a supercritical refrigeration cycle
apparatus including a compressor configured to compress a
refrigerant; a gas cooler configured to cool the compressed
refrigerant in a supercritical state; a pressure control electronic
expansion valve connected to the gas cooler to control a pressure
of the refrigerant; a phase separator configured to accommodate
refrigerant which has passed through the pressure control
electronic expansion valve to perform phase separation; a flow
control electronic expansion valve connected to an outlet side of
the phase separator to control a flow rate of the refrigerant; an
injection pipe, a first end of which is connected to the phase
separator and a second end of which is connected to the compressor
to provide gaseous refrigerant in the phase separator to the
compressor; and a switching valve configured to open or close the
injection pipe, the method comprising: controlling an opening
degree of the flow control electronic expansion valve based on a
suction superheat degree of the compressor; controlling an opening
degree of the pressure control electronic expansion valve based on
an operation high pressure of the refrigerant; and controlling the
switching valve based on a compression ratio of the refrigerant and
a refrigerant discharge temperature of the compressor.
17. The method of claim 16, wherein the controlling of the
switching valve controls the switching valve to open the injection
pipe so as to provide the refrigerant in the phase separator to the
compressor when the compression ratio is above a predetermined
value, and the discharge temperature of the compressor is above a
predetermined temperature.
18. The method of claim 16, wherein when the suction superheat
degree of the compressor is the same as the target suction
superheat degree, maintaining a current opening degree of the flow
control electronic expansion valve, and controlling an opening
degree of the pressure control electronic expansion valve.
19. The method of claim 18, wherein the controlling of the opening
degree of the flow control electronic expansion valve includes:
checking a suction superheat degree of the refrigerant in the
compressor; comparing the suction superheat degree of the
compressor with a target suction superheat degree; maintaining a
current opening degree of the flow control electronic expansion
valve when the suction superheat degree of the compressor is the
same as the target suction superheat degree, increasing the opening
degree of the flow control electronic expansion valve when the
suction superheat degree of the compressor is greater than the
target suction superheat degree, and decreasing the opening degree
of the flow control electronic expansion valve when the suction
superheat degree of the compressor is less than the target suction
superheat degree.
20. The method of claim 18, wherein the controlling of the opening
degree of the pressure control electronic expansion valve includes:
checking an outlet temperature of the gas cooler and an evaporation
temperature of the evaporator, respectively; calculating a target
operation high pressure using the outlet temperature of the gas
cooler and the evaporation temperature of the evaporator, and
calculating a current operation high pressure corresponding to the
outlet temperature of the gas cooler; comparing the target
operation high pressure with the current operation high pressure;
and maintaining a current opening degree of the pressure control
electronic expansion valve when the current operation high pressure
is the same as the target operation high pressure, increasing an
the opening degree of the pressure control electronic expansion
valve when the current operation high pressure is greater than the
target operation high pressure, and decreasing the opening degree
of the pressure control electronic expansion valve when the current
operation high pressure is less than the target operation high
pressure.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] Pursuant to 35 U.S.C. .sctn.119(a), this application claims
the benefit of earlier filing date and right of priority to Korean
Application No. 10-2016-0094970, filed in Korea on Jul. 26, 2016,
the contents of which is incorporated by reference herein in its
entirety.
BACKGROUND
1. Field
[0002] A supercritical refrigeration cycle apparatus and a method
for controlling a supercritical refrigeration cycle apparatus are
disclosed herein.
2. Background
[0003] As is known, a refrigeration cycle apparatus may be
configured to have a so-called vapor-compression refrigeration
cycle including a compressor configured to compress refrigerant, a
condenser in which refrigerant is radiated and condensed, an
expansion apparatus configured to decompress and expand
refrigerant, and an evaporator in which refrigerant is evaporated
by absorbing ambient latent heat. On the other hand, there is a
supercritical refrigeration cycle apparatus (hereinafter, referred
to as a "supercritical refrigeration cycle apparatus") using carbon
dioxide (CO.sub.2) as refrigerant.
[0004] The supercritical refrigeration cycle apparatus may include
a compressor configured to compress refrigerant in a supercritical
state, a gas cooler configured to radiate heat from the compressed
refrigerant, an expansion apparatus configured to decompress and
expand refrigerant which has passed through the gas cooler, and an
evaporator configured to allow refrigerant to absorb and evaporate
ambient latent heat. According to the supercritical refrigeration
cycle apparatus, in contrast to a condenser in the refrigeration
cycle apparatus in which a phase change typically occurs, a
refrigerating capacity and power consumption may vary according to
a pressure change due to a change in an outlet temperature of the
gas cooler.
[0005] That is, as illustrated in FIG. 1, when comparing a first
temperature, a second temperature, and a third temperature with
different ambient temperatures, it is seen that the outlet
temperature of the gas cooler relatively increases at the second
and the third temperature (t2, t3) with relatively higher ambient
temperatures compared to the first temperature (t1) with the lowest
ambient temperature, and thus, their refrigerating capacity
respectively decreases. According to the supercritical
refrigeration cycle apparatus, there may exist "an appropriate
operation high pressure" capable of maximizing a ratio of a power
consumption change rate to a change rate of the refrigerating
capacity. However, according to the related art supercritical
refrigeration cycle apparatus, liquid refrigerant may be suctioned
into the compressor, and due to this, an opening degree of the
expansion apparatus should be controlled in consideration of a
suction superheat degree of refrigerant suctioned into the
compressor and the appropriate operation high pressure at the same
time to suppress the occurrence of damage to the compressor,
thereby causing a relatively large number of constraints in
controlling the appropriate high pressure capable of enhancing the
operation efficiency of the apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Embodiments will be described in detail with reference to
the following drawings in which like reference numerals refer to
like elements, and wherein:
[0007] FIG. 1 is a graph showing a change in refrigerating capacity
according to a gas cooler outlet temperature of a supercritical
refrigeration cycle apparatus in the related art;
[0008] FIG. 2 is a schematic diagram of a supercritical
refrigeration cycle apparatus according to an embodiment;
[0009] FIG. 3 is a pressure-enthalpy diagram for the supercritical
refrigeration cycle apparatus of FIG. 2;
[0010] FIG. 4 is a control block diagram of the supercritical
refrigeration cycle apparatus of FIG. 2.
[0011] FIG. 5 is a schematic diagram of a supercritical
refrigeration cycle apparatus according to another embodiment;
[0012] FIG. 6 is a control block diagram of the supercritical
refrigeration cycle apparatus of FIG. 5;
[0013] FIG. 7 is a flow chart of a method for controlling a
supercritical refrigeration cycle apparatus according to an
embodiment; and
[0014] FIG. 8 is a flow chart of a method for controlling a
supercritical refrigeration cycle apparatus according to another
embodiment.
DETAILED DESCRIPTION
[0015] Hereinafter, embodiments will be described in detail with
reference to the accompanying drawings. Where possible, like
reference numerals have been used to indicate like elements, and
repetitive disclosure has been omitted. In describing the
embodiments, detailed description will be omitted when a specific
description for publicly known technologies to which the
embodiments pertain is judged to obscure the gist.
[0016] Further, the accompanying drawings are used to help easily
understand the technical idea of the embodiments and it should be
understood that the idea of the present disclosure is not limited
by the accompanying drawings. The idea of the present disclosure
should be construed to extend to any alterations, equivalents, and
substitutes besides the accompanying drawings.
[0017] As illustrated in FIGS. 2 through 4, a supercritical
refrigeration cycle apparatus according to an embodiment may
include a compressor 110 configured to compress refrigerant in a
supercritical state; a gas cooler 140 configured to cool the
compressed refrigerant in a supercritical state; a pressure control
electronic expansion valve 170 connected to the gas cooler 140 to
control a pressure of refrigerant; a receiver 180 configured to
temporarily store refrigerant which has passed through the pressure
control electronic expansion valve; a flow control electronic
expansion valve 190 connected to an outlet side of the receiver 180
to control a flow rate of refrigerant; and a controller 250
configured to control the flow control electronic expansion valve
190 based on a suction superheat degree of refrigerant suctioned
into the compressor 110 and a target suction superheat degree, and
control the pressure control electronic expansion valve 170 based
on a target operation high pressure and a current operation high
pressure. The refrigerant may be carbon dioxide (CO.sub.2), for
example.
[0018] The compressor 110 may include an airtight container 111, a
compression unit or device 115 provided within the airtight
container 111, and a motor unit or motor 121 configured to provide
a drive force to the compression unit 115, for example.
[0019] The compression unit 115 may include a low stage compression
unit or device 117 configured to suction and compress the
evaporated refrigerant and a high stage compression unit or device
119 configured to compress the refrigerant compressed in the low
stage compression unit 117. The high stage compression unit 119 may
be configured to compress the refrigerant at a pressure above a
critical pressure of the refrigerant.
[0020] According to this embodiment, a case in which the compressor
110 is implemented as a two-stage compressor has been described;
however, this is merely an example, and embodiments are not limited
thereto.
[0021] An accumulator 130 configured to separate refrigerant into a
gas and a liquid may be provided at a suction side of the
compressor 110, for example. The gas cooler 140 may be connected to
a discharge-side pipe of the compressor 110 to communicate
therewith. The pressure control electronic expansion valve 170,
which may be configured to reduce a pressure of refrigerant cooled
in the gas cooler 140, for example, may be provided at an
outlet-side pipe of the gas cooler 140.
[0022] The receiver 180 may be provided at an outlet side pipe of
the pressure control electronic expansion valve 170. Refrigerant
decompressed and expanded while passing through the pressure
control electronic expansion valve 170 may be temporarily stored
within the receiver 180.
[0023] The flow control electronic expansion valve 190, which may
be configured to control a flow rate of refrigerant which has
passed the receiver 180, for example, may be provided at an
outlet-side pipe of the receiver 180. An evaporator 210, in which
refrigerant may absorb and evaporate ambient latent heat, may be
provided at an outlet-side pipe of the flow control electronic
expansion valve 190.
[0024] An outlet-side pipe of the evaporator 210 may be connected
to a suction side of the compressor 110 to communicate therewith.
The outlet-side pipe of the evaporator 210 may be connected to the
accumulator 130, for example.
[0025] Refrigerant which has passed through the evaporator 210 may
exchange heat with refrigerant which has passed through the gas
cooler 140. Due to this, a suction superheat degree of refrigerant
suctioned into the compressor 110 may increase.
[0026] An outlet-side pipe of the evaporator 210 may be configured
to exchange heat with an outlet-side pipe of the gas cooler 140.
That is, an inter-refrigerant heat exchanger 150 or intermediate
heat exchanger (hereinafter, referred to as "intermediate heat
exchanger 150") configured to exchange heat between high-pressure
refrigerant and low-pressure refrigerant may be provided at an
outlet side of the gas cooler 140.
[0027] The intermediate heat exchanger 150 may include a first heat
exchanger 151 configured to receive refrigerant which has passed
through the gas cooler 140 and a second heat exchanger 153
configured to receive refrigerant which has passed the evaporator
210. The first heat exchanger 151 and second heat exchanger 153 may
be configured to exchange heat, for example.
[0028] A supercritical refrigeration cycle apparatus according to
this embodiment may include the controller 250 implemented with a
microprocessor provided with a control program, as illustrated in
FIG. 4, for example. The controller 250 may be configured to
control the flow control electronic expansion valve 190 so as to
decrease an opening degree of the flow control electronic expansion
valve 190 when the suction superheat degree of the refrigerant is
less than the target suction superheat degree, and increase an
opening degree of the flow control electronic expansion valve 190
when the suction superheat degree of the refrigerant is greater
than the target suction superheat degree.
[0029] The controller 250 may be configured to control the pressure
control electronic expansion valve 170 so as to increase an opening
degree of the pressure control electronic expansion valve 170 when
the current operation high pressure is greater than the target
operation high pressure, decrease the opening degree of the
pressure control electronic expansion valve 170 when the current
operation high pressure is less than the target operation high
pressure, and maintain the opening degree of the pressure control
electronic expansion valve 170 when the current operation high
pressure is the same as the target operation high pressure.
[0030] The controller 250 may include a operation unit (calculation
unit or calculator) 255 configured to calculate a suction superheat
degree of refrigerant in the compressor 110, for example. A
compressor suction temperature sensor 270 configured to sense a
temperature of refrigerant suctioned into the compressor 110, an
evaporator temperature sensor 265 configured to sense a temperature
of refrigerant at an outlet side of the evaporator 210, a gas
cooler temperature sensor 260 configured to sense an outlet
temperature of the gas cooler 140, and a pressure sensor 275
configured to sense a current operation high pressure may all be
connected to the controller 250 in a communicable manner. The
pressure sensor 275 may be provided at an outlet side of the gas
cooler 140, for example.
[0031] The operation unit 255 may be configured to compute the
target operation high pressure (P.sub.CT) from an outlet
temperature (T.sub.C) of the gas cooler 140 and an evaporation
temperature (T.sub.E) of the evaporator 210, for example. The
target operation high pressure (P.sub.CT) may be configured such
that a ratio of a refrigerating capacity change rate to a power
consumption change rate is a maximum (highest).
[0032] That is, the target operation high pressure (target
pressure) may be calculated using Equation 1 below, for
example.
P.sub.CT=A*T.sub.C+B*T.sub.C*T.sub.E+C, where A, B, C are preset or
predetermined constants, respectively, according to a system.
[Equation 1]
[0033] The operation unit 255 may subtract an outlet temperature of
refrigerant in the evaporator 210 from a suction temperature of
refrigerant in the compressor 110 to compute a suction superheat
degree (=suction temperature-outlet temperature) of refrigerant in
the compressor 110, for example. The controller 250 may be
configured to control an opening degree of the flow control
electronic expansion valve 190 to secure a suction superheat degree
of the compressor 110 so as to suppress the occurrence of damage to
the compressor 110 due to wet compression (liquid compression), and
then control an opening degree of the pressure control electronic
expansion valve 170 to maintain an appropriate operation high
pressure so as to enhance the operation efficiency of the
apparatus.
[0034] When an operation is started, low-pressure refrigerant may
be suctioned into the compressor 110 and compressed at a pressure
above a critical pressure and discharged in a supercritical state.
The discharged refrigerant may be cooled by exchanging heat with
air in the gas cooler 140.
[0035] Refrigerant which has passed through the gas cooler 140 may
be decompressed while passing through the pressure control
electronic expansion valve 170 via the intermediate heat exchanger
150. Refrigerant which has passed through the pressure control
electronic expansion valve 170 may be introduced into the receiver
180, and refrigerant which has passed through the receiver 180 may
be decompressed while passing through the flow control electronic
expansion valve 190. Refrigerant which has passed through the flow
control electronic expansion valve 190 may be introduced into the
compressor 110 and evaporated by absorbing ambient latent heat.
[0036] Hereinafter, a method for controlling a supercritical
refrigeration cycle apparatus according to an embodiment will be
described with reference to FIG. 7.
[0037] The operation unit 255 may calculate a suction superheat
degree of refrigerant in the compressor 110 from a difference
between a temperature sensed by the compressor suction temperature
sensor 270 and a temperature sensed by the evaporator temperature
sensor 265 (S110). The controller 250 may compare the calculated
suction superheat degree and a target suction superheat degree to
control an opening degree of the flow control electronic expansion
valve 190 (S120). When the calculated suction superheat degree is
the same as the target suction superheat degree (S110), the
controller 250 may maintain a current opening degree of the flow
control electronic expansion valve 190 (S160) and control an
opening degree of the pressure control electronic expansion valve
170.
[0038] According to this embodiment, the target suction superheat
degree may be set to prevent liquid refrigerant from being
suctioned into the compressor 110, and thus, when the calculated
suction superheat degree is maintained to be the same as the target
suction superheat degree, the wet compression (liquid compression)
of the compressor 110 may be prevented, enhancing reliability of
the compressor 110. When the calculated suction superheat degree is
greater than the target suction superheat degree (S130), the
controller 250 may control the flow control electronic expansion
valve 190 to increase an opening degree of the flow control
electronic expansion valve 190 (S140).
[0039] Further, when the calculated suction superheat degree is
less than the target suction superheat degree (S130), the
controller 250 may control the flow control electronic expansion
valve 190 to decrease an opening degree of the flow control
electronic expansion valve 190 (S150). When the calculated suction
superheat degree is the same as the target suction superheat degree
(S120), the controller 250 may control the flow control electronic
expansion valve 190 to maintain a current opening degree of the
flow control electronic expansion valve 190 (S160), and control an
opening degree of the pressure control electronic expansion valve
170.
[0040] On the other hand, the controller 250 may sense a gas cooler
temperature and an evaporator temperature from the gas cooler
temperature sensor 260 and the evaporator temperature sensor 265,
respectively, and sense a current pressure by the pressure sensor
275 (S170). The operation unit 255 may compute a target operation
high pressure using the gas cooler temperature and evaporator
temperature based on the Equation 1 (S180).
[0041] When the target operation high pressure is computed, the
controller 250 may compare the computed target operation high
pressure with the current pressure (S190), and when the current
pressure is the same as the target operation high pressure, the
controller 250 may control the pressure control electronic
expansion valve 170 to maintain a current opening degree of the
pressure control electronic expansion valve 170 (S230). When the
current pressure is greater than the target operation high pressure
(S200), the controller 250 may control the pressure control
electronic expansion valve 170 to increase an opening degree of the
pressure control electronic expansion valve 170 (S210). When the
current pressure is less than the target operation high pressure
(S200), the controller 250 may control the pressure control
electronic expansion valve 170 to decrease an opening degree of the
pressure control electronic expansion valve 170 (S220).
[0042] According to this embodiment, the target operation high
pressure may be set to maximize a ratio of the refrigerating
capacity change rate to the power consumption change rate, and
then, when the current pressure is maintained to be the same as the
target operation high pressure, the operation efficiency may be
enhanced.
[0043] Hereinafter, a supercritical refrigeration cycle apparatus
according to another embodiment will be described with reference to
FIGS. 5 and 6.
[0044] As illustrated in FIGS. 5 and 6, a supercrtical
refrigeration cycle apparatus according to this embodiment may
include compressor 110 configured to compress refrigerant in a
supercritical state; gas cooler 140 configured to cool the
compressed refrigerant; a pressure control electronic expansion
valve 170 connected to the gas cooler 140 to control a pressure of
refrigerant; a phase separator 280 configured to accommodate
refrigerant which has passed through the pressure control
electronic expansion valve to perform phase separation; a flow
control electronic expansion valve 190 connected to an outlet side
of the phase separator 280 to control a flow rate of refrigerant;
an injection pipe 285, one or a first end of which may be connected
to the phase separator 280, and the other or a second end of which
may be connected to the compressor 110 to provide gaseous
refrigerant in the phase separator 280 to the compressor 110; a
switching valve 286 configured to open or close the injection pipe
285; and controller 250 configured to control the flow control
electronic expansion valve 190 based on a suction superheat degree
of refrigerant suctioned into the compressor 110 and a target
suction superheat degree, and control the pressure control
electronic expansion valve 170 based on a target operation high
pressure and a current operation high pressure, and control the
switching valve 286 based on a compression ratio of the refrigerant
and a refrigerant discharge temperature of the compressor 110. The
refrigerant may be carbon dioxide (CO.sub.2), for example.
[0045] The compressor 110 may include airtight container 111,
compression unit or device 115 provided within the airtight
container 111, and motor unit or motor 121 configured to provide a
drive force to the compression unit 115, for example. The
compression unit 115 may include low stage compression unit or
device 117 and high stage compression unit or device 119.
[0046] Accumulator 130 may be provided at a suction side of the
compressor 110. According to this embodiment, a case in which the
accumulator 130 is provided at a suction side of the compressor 110
is illustrated, but it is merely an illustration, and the
accumulator 130 may not be provided.
[0047] The gas cooler 140 may be connected to the discharge-side
pipe of the compressor 110. Intermediate heat exchanger 150 may be
provided at the outlet side of the gas cooler 140.
[0048] The pressure control electronic expansion valve 170 may be
provided at the outlet side of the intermediate heat exchanger 150.
The phase separator 280 may be connected to the outlet side of the
pressure control electronic expansion valve 170.
[0049] The flow control electronic expansion valve 190 may be
provided at one side of the phase separator 280. The evaporator 210
may be connected to the discharge side of the flow control
electronic expansion valve 190. The phase separator 280 may be
configured to allow refrigerant decompressed while passing through
the pressure control electronic expansion valve 170, for example,
to be introduced and separated into gaseous liquid (a gas and a
liquid).
[0050] The phase separator 280 may include a case 281 configured to
form an accommodation space therein and a first outlet 282
configured to discharge gaseous refrigerant within the case 281,
for example. The phase separator 280 may further include a second
outlet 283 configured to discharge liquid refrigerant within the
case 281, for example. One or a first end of a pipe may be
connected to the evaporator 210, and the other or a second end
thereof may be connected the second outlet 283.
[0051] One or a first end of the injection pipe 285 may be
connected to the compressor 110, and the other or a second end
thereof may be connected to the first outlet 282, for example. Due
to this, gaseous refrigerant within the phase separator 280 may be
provided to the compressor 110.
[0052] The injection pipe 285 may be configured to provide gaseous
refrigerant in the phase separator 280 to a suction side of the
high stage compression unit 119 of the compressor 110. The
switching valve 286 may be provided at the injection pipe 285 to
open or close a passage of the injection pipe 285.
[0053] This embodiment may be configured to include the controller
250 implemented as a microprocessor provided with a control
program, for example. The flow control electronic expansion valve
190, the pressure control electronic expansion valve 170, and the
switching valve 286 may be respectively connected to the controller
250 in a controlled manner, as illustrated in FIG. 6. The
controller 250 may include the operation unit 255 configured to
compute a refrigerant suction superheat degree and a target
operation high pressure (target pressure) of the compressor
110.
[0054] Gas cooler temperature sensor 260 configured to sense a
temperature of the gas cooler 140 evaporator temperature sensor 265
configured to sense the evaporator temperature, compressor suction
temperature sensor 270 configured to sense a temperature of
refrigerant suctioned into the compressor 110, a compressor
discharge temperature sensor 290 configured to sense a temperature
of refrigerant discharged from the compressor 110 may be connected
to the controller 250, and pressure sensor 275 configured to sense
a current pressure (high pressure) of the refrigerant may each be
connected to the controller 250.
[0055] The operation unit 255 may be configured to subtract an
outlet temperature of the evaporator 210 from a refrigerant suction
temperature of the compressor 110 to calculate a refrigerant
suction superheat degree of the compressor 110. The operation unit
255 may be configured to compute a target operation high pressure
using Equation 1 as described above.
[0056] The operation unit 255 may be configured to compute a ratio
(compression ratio) of an operation high pressure of refrigerant to
an operation low pressure, for example. The operation high pressure
may denote a pressure of high-pressure refrigerant from a
discharge-side pipe of the compressor 110 prior to introduction to
the pressure control electronic expansion valve 170, for
example.
[0057] The operation high pressure may be a pressure value sensed
by the pressure sensor 275 provided in the gas cooler 140, for
example. The operation high pressure may be a pressure value
converted from a temperature of the gas cooler 140.
[0058] The operation low pressure may be a pressure value of
low-pressure refrigerant from a discharge side of the flow control
electronic expansion valve 190 prior to the suction of the
compressor 110, for example. The operation low pressure may be a
pressure value converted from a temperature sensed from the
evaporator temperature sensor 265, for example. The operation low
pressure may be a pressure value sensed by a pressure sensor (not
shown) configured to sense a pressure of the evaporator 210, for
example.
[0059] The controller 250 may decrease an opening degree of the
flow control electronic expansion valve 190 when the suction
superheat degree of the refrigerant is less than the target suction
superheat degree, increase an opening degree of the flow control
electronic expansion valve 190 when the suction superheat degree of
the refrigerant is greater than the target suction superheat
degree, and maintain a current opening degree of the flow control
electronic expansion valve 190 when the suction superheat degree of
the refrigerant is the same as the target suction superheat degree.
In this way, a suction superheat degree of refrigerant suctioned
into the compressor 110 may be appropriately maintained to suppress
the occurrence of damage to the compressor 110 due to wet
compression (liquid compression), thereby enhancing reliability of
the compressor 110.
[0060] The controller 250 may control the pressure control
electronic expansion valve 170 to increase an opening degree of the
pressure control electronic expansion valve 170 when the current
operation high pressure is greater than the target operation high
pressure, decrease an opening degree of the pressure control
electronic expansion valve 170 when the current operation high
pressure is less than the target operation high pressure, and
maintain an opening degree of the pressure control electronic
expansion valve 170 when the current operation high pressure is the
same as the target operation high pressure. In this way, a ratio of
a refrigerating capacity change rate to a consumption power change
rate may be maximized to enhance an operation efficiency of the
supercritical refrigeration cycle apparatus according to this
embodiment.
[0061] On the other hand, the controller 250 may be configured to
control the switching valve 286 to open a passage of the injection
pipe 285 so as to provide refrigerant in the phase separator 280 to
the compressor 110 when a ratio of the operation high pressure of
the refrigerant to the operation low pressure, namely, the
compression ratio of the refrigerant, is above a set or
predetermined value or the discharge temperature of the compressor
110 is above a set or predetermined temperature. Gaseous
refrigerant in the phase separator 280 may be provided to the
compressor 110 to reduce a temperature of the refrigerant, thereby
decreasing a work (load) of the compressor 110 (actually, the high
stage compression unit 119).
[0062] When the operation of the supercritical refrigeration cycle
apparatus according to this embodiment is started, the compressor
110 may suction and compress low-pressure refrigerant in a
supercritical state and discharge it to the gas cooler 140.
Refrigerant cooled in the gas cooler 140 may be decompressed while
passing through the flow control electronic expansion valve 190 via
the intermediate heat exchanger 150.
[0063] The refrigerant which has passed through the flow control
electronic expansion valve 190 may be introduced into the phase
separator 280, and phase-separated into a gas and a liquid. The
liquid refrigerant of the phase separator 280 may be discharged
through the second outlet 283 and decompressed while passing
through the flow control electronic expansion valve 190. The
refrigerant which has passed through the flow control electronic
expansion valve 190 may be evaporated by absorbing latent heat
while passing through the evaporator 210.
[0064] Hereinafter, a method of controlling a supercritical
refrigeration cycle apparatus according to another embodiment will
be described with reference to FIG. 8.
[0065] The controller 250 may control the operation unit 255 to
calculate a suction superheat degree of refrigerant in the
compressor 110 (S110). The controller 250 may determine whether the
suction superheat degree of the refrigerant is the same as a target
suction superheat degree (S120).
[0066] When the suction superheat degree of the refrigerant is
greater than the target suction superheat degree (S130), the
controller 250 may control the flow control electronic expansion
valve 190 to increase an opening degree of the flow control
electronic expansion valve 190 (S140). When the suction superheat
degree of the refrigerant is less than the target suction superheat
degree (S130), the controller 250 may control the flow control
electronic expansion valve 190 to decrease an opening degree of the
flow control electronic expansion valve 190 (S150).
[0067] The controller 250 may repeatedly perform an opening degree
control process of the flow control electronic expansion valve 190,
and control the flow control electronic expansion valve 190 to
maintain a current opening degree of the flow control electronic
expansion valve 190 (S160) when the suction superheat degree is the
same as the target suction superheat degree (S120). When the
current opening degree of the flow control electronic expansion
valve 190 is maintained (S160), the controller 250 may perform the
control of the pressure control electronic expansion valve 170.
[0068] The controller 250 may sense the gas cooler temperature, the
evaporator temperature, and a current pressure through the gas
cooler temperature sensor 260, the evaporator temperature sensor
265, and the pressure sensor (S170). The controller 250 may control
the operation unit 255 to calculate a target operation high
pressure (S180).
[0069] The controller 250 may compare the current pressure with the
target operation high pressure (S190), and control the pressure
control electronic expansion valve 170 to increase an opening
degree of the pressure control electronic expansion valve 170
(S210) when the current pressure is greater than the target
operation high pressure (S200). When the current pressure is less
than the target operation high pressure (S200), the controller 250
may control the pressure control electronic expansion valve 170 to
decrease an opening degree of the pressure control electronic
expansion valve 170 (S220).
[0070] The controller 250 may repeat the control process of the
pressure control electronic expansion valve 170, and control the
pressure control electronic expansion valve 170 to maintain a
current opening degree of the pressure control electronic expansion
valve 170 (S230) when the current pressure is the same as the
target operation high pressure (S190).
[0071] On the other hand, the controller 250 may sense an operation
high pressure, an operation low pressure of the refrigerant, and a
discharge temperature of the compressor 110 (S240), and control the
operation unit 255 to compute a compression ratio of the
refrigerant (S250). The controller 250 may compare the compression
ratio with a set or predetermined value (S250), and control the
switching valve 286 to open a passage of the injection pipe 285
when the compression ratio exceeds the set or predetermined value
(S260).
[0072] Further, when a refrigerant discharge temperature of the
compressor 110 exceeds a set or predetermined temperature (S255),
the controller 250 may control the switching valve 286 to open a
passage of the injection pipe 285 (S260). When the passage of the
injection pipe 285 is open, gaseous refrigerant within the phase
separator 280 may move along a passage of the injection pipe 285 to
be provided to the compressor 110. When the refrigerant discharge
temperature of the compressor 110 does not exceed the set or
predetermined temperature (S255), the controller 250 may control
the switching value 286 to close the passage of the injection pipe
285 (S265).
[0073] That is, gaseous refrigerant moved along the injection pipe
285 may be introduced to a suction side of the high stage
compression unit 119 of the compressor 110, and mixed with
refrigerant discharged from the low stage compression unit 117 and
suctioned to a suction side of the high stage compression unit 119.
Gaseous refrigerant in the receiver 180 may have a relatively low
temperature, and then when the gaseous refrigerant is mixed with
refrigerant compressed in the low stage compression unit 117, a
temperature of refrigerant suctioned into the high stage
compression unit 119 may be significantly lower compared to a
temperature of refrigerant discharged from the low stage
compression unit 117. In this way, a load of the high stage
compression unit 119 of the compressor 110 may be significantly
reduced.
[0074] With a supercritical refrigeration cycle apparatus and a
method for controlling a supercritical refrigeration cycle
apparatus in accordance with this embodiment, a suction superheat
degree of refrigerant suctioned into the compressor 110 through
control of the flow control electronic expansion valve 190 may be
appropriately secured to suppress the occurrence of wet compression
in the compressor 110, thereby enhancing reliability of the
compressor 110. Further, a ratio of a refrigerating capacity change
rate to a power consumption change rate may be appropriately
managed (maximized) through control of the pressure control
electronic expansion valve 170, thereby enhancing operation
efficiency. Furthermore, when a compression ratio of the
refrigerant exceeds a set or predetermined value or a discharge
temperature of the compressor 110 is above a set or predetermined
temperature, gaseous refrigerant in the phase separator 280 may be
provided to the compressor 110 to alleviate a load (work) of the
compressor 110, thereby further enhancing operation efficiency.
[0075] As described above, according to an embodiment, a pressure
control electronic expansion valve connected to a gas cooler to
control a pressure of refrigerant, a receiver configured to
temporarily store refrigerant which has passed through the pressure
control electronic expansion valve, and a flow control electronic
expansion valve connected to an outlet side of the receiver to
control a flow rate of refrigerant may be provided, thereby
implementing flow control and pressure control of the refrigerant
in a respectively separate manner. In this way, it may be possible
to enhance reliability of the compressor as well as enhance
refrigerating capacity.
[0076] In addition, a pressure control electronic expansion valve,
a phase separator configured to accommodate refrigerant which has
passed through the pressure control electronic expansion valve to
perform phase separation, a flow control electronic expansion valve
connected to an outlet side of the phase separator to control a
flow rate of refrigerant, an injection pipe, one or a first end of
which may be connected to the phase separator, and the other or a
second end of which may be connected to the compressor to provide
gaseous refrigerant in the phase separator to the compressor, and a
switching valve configured to open or close the injection pipe may
be provided therein to implement flow control and pressure control
of the refrigerant in a respectively separate manner, as well as
provide gaseous refrigerant within the phase separator to the
compressor so as to reduce a load of the compressor, thereby
reducing power consumption.
[0077] Accordingly, embodiments disclosed herein provide a
supercritical refrigeration cycle apparatus and a method for
controlling a supercritical refrigeration cycle apparatus capable
of implementing flow control and pressure control of refrigerant in
a respectively separate manner. Further, embodiments disclosed
herein provide a supercritical refrigeration cycle apparatus and a
method for controlling a supercritical refrigeration cycle
apparatus thereof capable of controlling flow control and pressure
control of refrigerant in a separate manner, as well as reducing a
temperature of refrigerant in the compressor to decrease load.
[0078] Embodiments disclosed herein provide a supercritical
refrigeration cycle apparatus that may include a compressor
configured to compress refrigerant in a supercritical state; a gas
cooler configured to cool the compressed refrigerant in a
supercritical state; a pressure control electronic expansion valve
connected to the gas cooler to control a pressure of refrigerant; a
receiver configured to temporarily store refrigerant which has
passed through the pressure control electronic expansion valve; a
flow control electronic expansion valve connected to an outlet side
of the receiver to control a flow rate of refrigerant; and a
controller configured to control the flow control electronic
expansion valve based on a suction superheat degree of refrigerant
suctioned into the compressor and a target suction superheat
degree, and control the pressure control electronic expansion valve
based on a target operation high pressure and a current operation
high pressure. The controller may decrease an opening degree of the
flow control electronic expansion valve when the suction superheat
degree of the refrigerant is less than the target suction superheat
degree, and increase an opening degree of the flow control
electronic expansion valve when the suction superheat degree of the
refrigerant is greater than the target suction superheat degree.
The controller may increase an opening degree of the pressure
control electronic expansion valve when the current operation high
pressure is greater than the target operation high pressure, and
decrease an opening degree of the pressure control electronic
expansion valve when the current operation high pressure is less
than the target operation high pressure, and maintain an opening
degree of the pressure control electronic expansion valve when they
are the same.
[0079] The supercritical refrigeration cycle apparatus may further
include an intermediate heat exchanger in which refrigerant which
has passed through the gas cooler and refrigerant which has passed
through the evaporator exchange heat with each other.
[0080] Embodiments disclosed herein further provide a supercritical
refrigeration cycle apparatus that may include a compressor
configured to compress refrigerant in a supercritical state; a gas
cooler configured to cool the compressed refrigerant; a pressure
control electronic expansion valve connected to the gas cooler to
control a pressure of refrigerant; a phase separator configured to
accommodate refrigerant which has passed through the pressure
control electronic expansion valve to perform phase separation; a
flow control electronic expansion valve connected to an outlet side
of the phase separator to control a flow rate of refrigerant; an
injection pipe, one or a first end of which may be connected to the
phase separator, and the other or a second end of which may be
connected to the compressor to provide gaseous refrigerant in the
phase separator to the compressor; a switching valve configured to
open or close the injection pipe; and a controller configured to
control the flow control electronic expansion valve based on a
suction superheat degree of refrigerant suctioned into the
compressor and a target suction superheat degree, and control the
pressure control electronic expansion valve based on a target
operation high pressure and a current operation high pressure, and
control the switching valve based on a compression ratio of the
refrigerant and a refrigerant discharge temperature of the
compressor. The controller may decrease an opening degree of the
flow control electronic expansion valve when the suction superheat
degree of the refrigerant is less than the target suction superheat
degree, and increase an opening degree of the flow control
electronic expansion valve when the suction superheat degree of the
refrigerant is greater than the target suction superheat degree.
The controller may increase an opening degree of the pressure
control electronic expansion valve when a current operation high
pressure is greater than the target operation high pressure,
decrease an opening degree of the pressure control electronic
expansion valve when the current operation high pressure is less
than the target operation high pressure, and maintain an opening
degree of the pressure control electronic expansion valve when the
current operation high pressure is the same as the target operation
high pressure.
[0081] The supercritical refrigeration cycle apparatus may further
include an intermediate heat exchanger in which refrigerant which
has passed through the gas cooler and refrigerant which has passed
through the evaporator exchange heat with each other.
[0082] The controller may control the switching valve to open the
injection pipe so as to provide refrigerant in the phase separator
to the compressor when the compression ratio is above a set or
predetermined value, and the discharge temperature of the
compressor is above a set or predetermined temperature.
[0083] Embodiments disclosed herein further provide a method for
controlling a supercritical refrigeration cycle apparatus including
a compressor configured to compress refrigerant; a gas cooler
configured to cool the compressed refrigerant in a supercritical
state; a pressure control electronic expansion valve connected to
the gas cooler to control a pressure of refrigerant; a receiver
configured to temporarily store refrigerant which has passed
through the pressure control electronic expansion valve; and a flow
control electronic expansion valve connected to an outlet side of
the receiver to control a flow rate of refrigerant. The method may
include controlling an opening degree of the flow control
electronic expansion valve based on a suction superheat degree of
refrigerant in the compressor; and controlling an opening degree of
the pressure control electronic expansion valve based on an
operation high pressure of the refrigerant.
[0084] The controlling the opening degree of the flow control
electronic expansion valve may include checking a suction superheat
degree of refrigerant in the compressor; comparing the suction
superheat degree of the compressor with a target suction superheat
degree, and maintaining a current opening degree of the flow
control electronic expansion valve when the suction superheat
degree of the compressor is the same as the target suction
superheat degree. The method may further include increasing an
opening degree of the flow control electronic expansion valve when
the suction superheat degree of the compressor is greater than the
target suction superheat degree, and decreasing an opening degree
of the flow control electronic expansion valve when the suction
superheat degree is less than the target suction superheat
degree.
[0085] When the suction superheat degree of the compressor is the
same as the target suction superheat degree, maintaining a current
opening degree of the flow control electronic expansion valve, and
then controlling an opening degree of the pressure control
electronic expansion valve may be carried out. The controlling the
opening degree of the pressure control electronic expansion valve
may include checking an outlet temperature of the gas cooler and an
evaporation temperature of the evaporator, respectively;
calculating a target operation high pressure using the outlet
temperature of the gas cooler and the evaporation temperature of
the evaporator, and calculating a current operation high pressure
corresponding to the outlet temperature of the gas cooler;
comparing the target operation high pressure with the current
operation high pressure; and maintaining a current opening degree
of the pressure control electronic expansion valve when the current
operation high pressure is the same as the target operation high
pressure. The method may further include increasing an opening
degree of the pressure control electronic expansion valve when the
current operation high pressure is greater than the target
operation high pressure, and decreasing an opening degree of the
pressure control electronic expansion valve when the current
operation high pressure is less than the target operation high
pressure.
[0086] Embodiments disclosed herein also provide a method for
controlling a supercritical refrigeration cycle apparatus including
a compressor configured to compress refrigerant; a gas cooler
configured to cool the compressed refrigerant in a supercritical
state; a pressure control electronic expansion valve connected to
the gas cooler to control a pressure of refrigerant; a phase
separator configured to accommodate refrigerant which has passed
through the pressure control electronic expansion valve to perform
phase separation; a flow control electronic expansion valve
connected to an outlet side of the phase separator to control a
flow rate of refrigerant; an injection pipe, one or a first end of
which may be connected to the phase separator, and the other or a
second end of which may be connected to the compressor to provide
gaseous refrigerant in the phase separator to the compressor; and a
switching valve configured to open or close the injection pipe. The
method may include controlling an opening degree of the flow
control electronic expansion valve based on a suction superheat
degree of the compressor; controlling an opening degree of the
pressure control electronic expansion valve based on an operation
high pressure of the refrigerant; and controlling the switching
valve based on a compression ratio of the refrigerant and a
refrigerant discharge temperature of the compressor.
[0087] The controlling the switching valve may include controlling
the switching valve to open the injection pipe so as to provide
refrigerant in the phase separator to the compressor when the
compression ratio is above a set or predetermined value, and a
discharge temperature of the compressor is above a set or
predetermined temperature. When the suction superheat degree of the
compressor is the same as the target suction superheat degree,
maintaining a current opening degree of the flow control electronic
expansion valve, and controlling an opening degree of the pressure
control electronic expansion valve may be carried out.
[0088] The controlling an opening degree of the flow control
electronic expansion valve may include checking a suction superheat
degree of refrigerant in the compressor; comparing the suction
superheat degree of the compressor with a target suction superheat
degree; maintaining a current opening degree of the flow control
electronic expansion valve when the suction superheat degree of the
compressor is the same as the target suction superheat degree, and
increasing an opening degree of the flow control electronic
expansion valve when the suction superheat degree of the compressor
is greater than the target suction superheat degree, and decreasing
an opening degree of the flow control electronic expansion valve
when the suction superheat degree of the compressor is less than
the target suction superheat degree. The controlling the opening
degree of the pressure control electronic expansion valve may
include checking an outlet temperature of the gas cooler and an
evaporation temperature of the evaporator, respectively;
calculating a target operation high pressure using the outlet
temperature of the gas cooler and the evaporation temperature of
the evaporator, and calculating a current operation high pressure
corresponding to the outlet temperature of the gas cooler,
comparing the target operation high pressure with the current
operation high pressure; and maintaining a current opening degree
of the pressure control electronic expansion valve when the current
operation high pressure is the same as the target operation high
pressure, and increasing an opening degree of the pressure control
electronic expansion valve when the current operation high pressure
is greater than the target operation high pressure, and decreasing
an opening degree of the pressure control electronic expansion
valve when the current operation high pressure is less than the
target operation high pressure.
[0089] It is obvious to those skilled in the art that embodiments
may be embodied in other specific forms without departing from the
concept and essential characteristics thereof. The detailed
description is, therefore, not to be construed as illustrative in
all respects but considered as restrictive. The scope of the
invention should be determined by reasonable interpretation of the
appended claims and all changes that come within the equivalent
scope are included in the scope.
[0090] Any reference in this specification to "one embodiment," "an
embodiment," "example embodiment," etc., means that a particular
feature, structure, or characteristic described in connection with
the embodiment is included in at least one embodiment. The
appearances of such phrases in various places in the specification
are not necessarily all referring to the same embodiment. Further,
when a particular feature, structure, or characteristic is
described in connection with any embodiment, it is submitted that
it is within the purview of one skilled in the art to effect such
feature, structure, or characteristic in connection with other ones
of the embodiments.
[0091] Although embodiments have been described with reference to a
number of illustrative embodiments thereof, it should be understood
that numerous other modifications and embodiments can be devised by
those skilled in the art that will fall within the spirit and scope
of the principles of this disclosure. More particularly, various
variations and modifications are possible in the component parts
and/or arrangements of the subject combination arrangement within
the scope of the disclosure, the drawings and the appended claims.
In addition to variations and modifications in the component parts
and/or arrangements, alternative uses will also be apparent to
those skilled in the art.
* * * * *