CN111623568A - Refrigerating unit and control method thereof - Google Patents
Refrigerating unit and control method thereof Download PDFInfo
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- CN111623568A CN111623568A CN202010348975.9A CN202010348975A CN111623568A CN 111623568 A CN111623568 A CN 111623568A CN 202010348975 A CN202010348975 A CN 202010348975A CN 111623568 A CN111623568 A CN 111623568A
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- heat exchanger
- compressor
- branch
- valve
- outdoor heat
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
- F25B47/02—Defrosting cycles
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
Abstract
The invention provides a refrigerating unit and a control method thereof, wherein the refrigerating unit comprises: the air conditioner comprises a compressor, an outdoor heat exchanger, an indoor heat exchanger and a first throttling device, wherein the first throttling device is arranged between the indoor heat exchanger and the outdoor heat exchanger; the refrigerating unit further comprises a first branch, one end of the first branch is communicated to a pipeline between the outdoor heat exchanger and the compressor, the other end of the first branch is communicated to a pipeline between the outdoor heat exchanger and the first throttling device, and the first branch can guide the refrigerant at the outlet end of the outdoor heat exchanger back to the inlet end of the outdoor heat exchanger when the indoor heat exchanger is defrosted. According to the invention, the flow of the refrigerant entering the air suction port of the compressor can be reduced when the indoor heat exchanger performs heating and defrosting, the air suction pressure of the compressor is reduced, the exhaust high-pressure of the compressor is reduced, the condition that the defrosting of the refrigerating unit is finished in advance due to the high pressure existing in the defrosting period of the refrigerating unit is avoided, and the defrosting process is effectively and continuously performed.
Description
Technical Field
The invention relates to the technical field of refrigeration, in particular to a refrigeration unit and a control method thereof.
Background
During the defrosting of current refrigeration defrosting unit, the evaporimeter of unit acts as the condenser, and its frost layer absorbs the heat of high temperature refrigerant and melts, and the condenser of unit acts as the evaporimeter and changes the frost in-process, because the refrigerant of condenser the inside can not evaporate completely, causes the easy liquid of compressor induction port of unit, and the high pressure of unit can rise gradually during defrosting under some abominable operating modes simultaneously, reaches the guard value for the unit changes the frost and finishes in advance.
The condition that the defrosting of the refrigerating unit is finished in advance due to the fact that high pressure exists in the refrigerating unit in the prior art and reaches a protection value during defrosting, and the defrosting process is seriously influenced; meanwhile, the suction superheat degree of a refrigerant at a suction port of a compressor of the unit is low, so that the suction is easy to carry liquid, liquid impact is formed, the use of the compressor is seriously influenced, and the like.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defect that the defrosting of the refrigerating unit is finished in advance due to the fact that the high pressure is high and the protection value is reached in the defrosting period of the refrigerating unit in the prior art, so that the refrigerating unit and the control method thereof are provided.
In order to solve the above problems, the present invention provides a refrigerator unit including:
the air conditioner comprises a compressor, an outdoor heat exchanger, an indoor heat exchanger and a first throttling device, wherein the first throttling device is arranged between the indoor heat exchanger and the outdoor heat exchanger; the refrigerating unit further comprises a first branch, one end of the first branch is communicated to a pipeline between the outdoor heat exchanger and the compressor, the other end of the first branch is communicated to a pipeline between the outdoor heat exchanger and the first throttling device, and the first branch can guide the refrigerant at the outlet end of the outdoor heat exchanger back to the inlet end of the outdoor heat exchanger when the indoor heat exchanger is defrosted.
Preferably, the first branch passage is further provided with a check valve which allows only refrigerant to be led from one end of the first branch passage communicating to a line between the outdoor heat exchanger and the compressor to the other end communicating to a line between the outdoor heat exchanger and the first throttling means; and/or the presence of a gas in the gas,
and a proportional control three-way valve is arranged at one end of the first branch communicated to a pipeline between the outdoor heat exchanger and the compressor.
Preferably, the indoor heat exchanger further comprises a four-way reversing valve, and four ends of the four-way reversing valve are respectively communicated to a gas exhaust pipeline of the compressor, a gas suction pipeline of the compressor, the indoor heat exchanger and the proportion adjusting three-way valve; and/or the presence of a gas in the gas,
and a liquid storage device and/or a drying filter are/is further arranged on a pipeline between the outdoor heat exchanger and the first throttling device.
Preferably, a control valve is further arranged on the air suction pipeline of the compressor, a second branch is further arranged in parallel with the control valve, a subcooler is arranged on the second branch, a pipeline between the first throttling device and the outdoor heat exchanger penetrates through the subcooler and exchanges heat with the second branch, and a second throttling device is further arranged at the upstream position of the subcooler on the second branch.
Preferably, a gas-liquid separator is further arranged at the air suction port of the compressor; and/or, the first throttling device is an electronic expansion valve; and/or the second throttling device is an electronic expansion valve; and/or the control valve is an electromagnetic valve; and/or, when a proportional three-way valve is further included, the proportional three-way valve is an electric proportional three-way valve.
The present invention also provides a control method for a refrigeration unit as set forth in any preceding claim, including, when a proportional three-way valve is included:
a detection step, which is used for detecting the operation mode of the refrigerating unit;
judging whether the refrigerating unit operates in a defrosting mode of the indoor heat exchanger or not;
and a control step of controlling the four-way reversing valve to enable the exhaust gas of the compressor to flow to the indoor heat exchanger and controlling the proportion adjusting three-way valve to enable the refrigerant to partially flow into the first branch when the refrigerating unit operates in an indoor heat exchanger defrosting mode.
Preferably, the detecting step is also used for detecting the high-pressure at the exhaust end of the compressor;
the judging step is also used for judging whether the high-pressure at the exhaust end of the compressor is greater than the preset pressure;
and the control step comprises the following steps that when the refrigerating unit operates in an indoor heat exchanger defrosting mode: when the high-pressure of the compressor exhaust is greater than the preset pressure, the opening degree of the proportional control three-way valve is controlled and adjusted, so that the flow of the refrigerant flowing into the first branch is increased; when the high-pressure of the compressor exhaust is smaller than the preset pressure, controlling and adjusting the opening degree of the proportional control three-way valve to increase and decrease the flow rate of the refrigerant flowing into the first branch circuit; and when the high-pressure of the exhaust gas of the compressor is equal to the preset pressure, controlling and adjusting the opening of the proportional control three-way valve to be unchanged.
Preferably, the controlling step is further configured to control the four-way reversing valve such that the discharge air of the compressor flows to the proportional three-way valve when the refrigeration unit operates in the indoor heat exchanger refrigeration mode, and control the proportional three-way valve such that the refrigerant completely flows into the outdoor heat exchanger without flowing into the first branch.
Preferably, the detecting step is further configured to detect a suction temperature at a suction port of the compressor, and calculate a suction superheat degree;
the judging step is also used for judging whether the suction superheat degree is smaller than a first preset superheat degree;
the control step is also used for controlling the control valve to be closed when the suction superheat degree is smaller than a first preset superheat degree, and controlling the refrigerant to flow into the second branch and flow into the subcooler for heat exchange; and when the suction superheat degree is larger than or equal to a first preset superheat degree, controlling the control valve to be opened, and controlling the refrigerant to directly flow back to the suction port of the compressor without flowing through the second branch.
Preferably, the judging step is further configured to judge whether the suction superheat degree is greater than a second preset superheat degree;
the control step is also used for controlling the opening degree of the second throttling device to be reduced while controlling the control valve to be closed when the suction superheat degree is larger than a second preset superheat degree; when the suction superheat degree is smaller than a second preset superheat degree, controlling the opening degree of the second throttling device to increase while controlling the control valve to be closed; when the suction superheat degree is equal to a second preset superheat degree, controlling the opening degree of the second throttling device to be unchanged while controlling the control valve to be closed; wherein the second predetermined degree of superheat is less than the first predetermined degree of superheat.
The refrigerating unit and the control method thereof provided by the invention have the following beneficial effects:
1. according to the invention, the first branch is communicated between the outlet end and the inlet end of the outdoor heat exchanger, so that the refrigerant from the outlet of the outdoor heat exchanger can be partially led back to the inlet of the outdoor heat exchanger when the indoor heat exchanger is used for heating and defrosting, the flow of the refrigerant entering the suction port of the compressor is effectively reduced, the suction pressure of the compressor is further reduced, the exhaust high-pressure of the compressor is further effectively reduced, the condition that the defrosting of the refrigerating unit is finished in advance due to the fact that the high pressure of the refrigerating unit is higher and reaches a protection value during defrosting is effectively avoided, and the defrosting process is effectively and continuously carried out.
2. The invention also comprises a second branch, a subcooler and a second throttling device which are arranged on the second branch in parallel on the air suction pipeline of the compressor, and a pipeline between the outdoor heat exchanger and the first throttling device penetrates through the subcooler and exchanges heat with the second branch, so that the refrigerant at the low-pressure air suction end enters the second branch, is throttled and depressurized, and then continuously absorbs the heat of the refrigerant in the pipeline between the outdoor heat exchanger and the first throttling device from the subcooler, thereby effectively improving the air suction superheat degree of the refrigerant at the air suction end of the compressor, effectively avoiding the phenomenon of liquid impact caused by liquid entrainment in the air suction, and effectively ensuring the normal operation without liquid of the compressor.
Drawings
Fig. 1 is a system configuration diagram of a refrigeration unit of the present invention.
The reference numerals are represented as:
1. a compressor; 2. an outdoor heat exchanger; 3. an indoor heat exchanger; 41. a first throttling device; 42. a second throttling device; 5. a one-way valve; 6. a proportional control three-way valve; 7. a reservoir; 8. drying the filter; 9. a control valve; 10. a subcooler; 11. a four-way reversing valve; 12. a gas-liquid separator; 101. a first branch; 102. a second branch.
Detailed Description
As shown in fig. 1, the present invention provides a refrigeration unit comprising:
the air conditioner comprises a compressor 1, an outdoor heat exchanger 2, an indoor heat exchanger 3 and a first throttling device 41, wherein the first throttling device 41 is arranged between the indoor heat exchanger 3 and the outdoor heat exchanger 2; the refrigerating unit further comprises a first branch 101, one end of the first branch 101 is communicated to a pipeline between the outdoor heat exchanger 2 and the compressor 1, the other end of the first branch 101 is communicated to a pipeline between the outdoor heat exchanger 2 and the first throttling device 41, and the first branch 101 can guide the refrigerant at the outlet end of the outdoor heat exchanger 2 back to the inlet end of the outdoor heat exchanger 2 when the indoor heat exchanger 3 is defrosted.
According to the invention, the first branch is communicated between the outlet end and the inlet end of the outdoor heat exchanger, so that the refrigerant from the outlet of the outdoor heat exchanger can be partially led back to the inlet of the outdoor heat exchanger when the indoor heat exchanger is used for heating and defrosting, the flow of the refrigerant entering the suction port of the compressor is effectively reduced, the suction pressure of the compressor is further reduced, the exhaust high-pressure of the compressor is further effectively reduced, the condition that the defrosting of the refrigerating unit is finished in advance due to the fact that the high pressure of the refrigerating unit is higher and reaches a protection value during defrosting is effectively avoided, and the defrosting process is effectively and continuously carried out.
Preferably, the first branch 101 is further provided with a check valve 5, and the check valve 5 only allows refrigerant to be guided from one end of the first branch 101, which is communicated to a pipeline between the outdoor heat exchanger 2 and the compressor 1, to the other end of the first branch, which is communicated to a pipeline between the outdoor heat exchanger 2 and the first throttling device 41; and/or the presence of a gas in the gas,
a proportional three-way valve 6 is provided at one end of the first branch 101 connected to a pipe between the outdoor heat exchanger 2 and the compressor 1.
According to the invention, only one end of the first branch circuit 101, which is communicated to the pipeline between the outdoor heat exchanger 2 and the compressor 1, of the refrigerant is arranged and guided to the other end of the pipeline communicated to the pipeline between the outdoor heat exchanger 2 and the first throttling device 41, so that the situation that the refrigerant directly flows back to the compressor due to the short circuit formed by the first branch circuit to the outdoor heat exchanger when the indoor heat exchanger heats and defrosts and the outdoor heat exchanger cannot play a corresponding heat exchange role is prevented; the proportion adjusting three-way valve is arranged at one end of the pipeline, which is communicated between the outdoor heat exchanger 2 and the compressor 1, of the first branch, so that the flow of the refrigerant flowing into the first branch can be adjusted or closed, whether the refrigerant flows back from the first branch or not can be selected according to different conditions, the high-pressure exhaust pressure can be effectively reduced when the indoor heat exchanger is defrosted, and the normal refrigeration can be realized when the indoor heat exchanger is used for refrigerating.
Preferably, the system further comprises a four-way reversing valve 11, and four ends of the four-way reversing valve 11 are respectively communicated to a discharge pipeline of the compressor 1, a suction pipeline of the compressor, the indoor heat exchanger 3 and the proportion adjusting three-way valve 6; and/or a liquid storage device 7 and/or a drying filter 8 are/is further arranged on a pipeline between the outdoor heat exchanger 2 and the first throttling device 41. The effective switching of refrigeration and heating mode can be realized through the setting of cross valve, and reservoir and drier-filter all are used for absorbing liquid refrigerant or other impurity.
Preferably, a control valve 9 is further disposed on the gas suction pipeline of the compressor 1, a second branch 102 is further disposed in parallel with the control valve 9, a subcooler 10 is disposed on the second branch 102, a pipeline between the first throttling device 41 and the outdoor heat exchanger 2 penetrates through the subcooler 10 and exchanges heat with the second branch 102, and a second throttling device 42 is further disposed on the second branch 102 at an upstream position of the subcooler 10.
The invention also comprises a second branch, a subcooler and a second throttling device which are arranged on the second branch in parallel on the air suction pipeline of the compressor, and a pipeline between the outdoor heat exchanger and the first throttling device penetrates through the subcooler and exchanges heat with the second branch, so that the refrigerant at the low-pressure air suction end enters the second branch, is throttled and depressurized, and then continuously absorbs the heat of the refrigerant in the pipeline between the outdoor heat exchanger and the first throttling device from the subcooler, thereby effectively improving the air suction superheat degree of the refrigerant at the air suction end of the compressor, effectively avoiding the phenomenon of liquid impact caused by liquid entrainment in the air suction, and effectively ensuring the normal operation without liquid of the compressor.
Preferably, a gas-liquid separator 12 is further arranged at the air suction port of the compressor 1; and/or, the first throttling device 41 is an electronic expansion valve; and/or, the second throttling device 42 is an electronic expansion valve; and/or the control valve 9 is an electromagnetic valve; and/or, when a proportional three-way valve 6 is further included, the proportional three-way valve 6 is an electric proportional three-way valve. The invention is a further preferable structure form, the gas-liquid separator realizes the gas-liquid separation of the refrigerant at the air suction port of the compressor, and the liquid impact is prevented; the first throttling device and the second throttling device are preferably electronic expansion valves, and intelligent control is achieved; the solenoid valve can realize the accurate control of switching, and electronic proportional control three-way valve can realize the effect to the accurate intelligent control of first branch flow.
The invention also provides a control method applicable to the refrigeration unit set forth in any one of the preceding claims, which, when including the proportional three-way valve 6, includes:
a detection step, which is used for detecting the operation mode of the refrigerating unit;
judging whether the refrigerating unit operates in a defrosting mode of the indoor heat exchanger or not;
and a control step of controlling the four-way reversing valve to make the discharge air of the compressor flow to the indoor heat exchanger 3 and controlling the proportion adjusting three-way valve 6 to make the refrigerant partially flow into the first branch 101 when the refrigeration unit operates in an indoor heat exchanger defrosting mode.
The refrigerating unit is controlled in a defrosting mode, namely the proportion adjusting three-way valve is adjusted to enable the refrigerant to partially flow into the first branch, so that the flow of the refrigerant entering the air suction end of the compressor is effectively reduced, the air suction pressure is further reduced, the exhaust high-pressure of the compressor is reduced, and the defrosting process is continuously and effectively carried out. During defrosting of the refrigerating unit, a refrigerant part at the outlet of the outdoor heat exchanger is bypassed to a pipeline at the inlet of the outdoor heat exchanger, so that the amount of the refrigerant entering the compressor is reduced, the exhaust pressure of the system compressor cannot be very high, meanwhile, the refrigerant entering the compressor is firstly throttled, so that part of liquid refrigerant is vaporized, and the heat is absorbed by the subcooler, so that the compressor is ensured to operate without liquid.
Preferably, the detecting step is also used for detecting the high-pressure at the exhaust end of the compressor;
the judging step is also used for judging whether the high-pressure at the exhaust end of the compressor is greater than the preset pressure;
and the control step comprises the following steps that when the refrigerating unit operates in an indoor heat exchanger defrosting mode: when the high-pressure of the compressor discharge air is greater than the preset pressure, the opening degree of the proportional control three-way valve 6 is controlled and adjusted, so that the flow rate of the refrigerant flowing into the first branch 101 is increased; when the high-pressure of the compressor discharge air is smaller than the preset pressure, controlling and adjusting the opening degree of the proportional control three-way valve 6 to increase and decrease the flow rate of the refrigerant flowing into the first branch circuit 101; and when the high-pressure of the compressor exhaust gas is equal to the preset pressure, controlling and adjusting the opening of the proportional control three-way valve 6 to be unchanged.
The opening of the proportional control three-way valve is further controlled by judging the high-pressure at the exhaust end of the compressor, so that the flow of the refrigerant flowing back through the first branch bypass is increased and the flow of the refrigerant flowing back to the compressor is reduced when the pressure is higher than the preset pressure, the exhaust pressure is reduced at an accelerated speed, the flow of the refrigerant flowing back through the first branch bypass is reduced and the flow of the refrigerant flowing back to the compressor is increased when the pressure is lower than the preset pressure, and the speed of reducing the exhaust pressure is reduced; when the exhaust pressure is equal to the preset pressure, the control opening is unchanged; thereby realizing the further accurate and effective control of the high pressure at the exhaust end of the compressor not to be too high.
Preferably, the controlling step is further configured to control the four-way reversing valve such that the discharge air of the compressor flows to the proportional three-way valve 6 when the refrigeration unit operates in the indoor heat exchanger cooling mode, and control the proportional three-way valve 6 such that the refrigerant completely flows into the outdoor heat exchanger 2 without flowing into the first branch 101. According to the refrigerating unit, no refrigerant flows into the first branch by controlling the proportional control three-way valve in the refrigerating mode, the refrigerant is prevented from flowing into the first branch to cause short circuit to the outdoor heat exchanger at the moment to influence normal heat exchange of the outdoor heat exchanger, and the normal refrigerating operation of the indoor heat exchanger can be effectively guaranteed at the moment.
Preferably, the detecting step is further configured to detect a suction temperature at a suction port of the compressor, and calculate a suction superheat degree;
the judging step is also used for judging whether the suction superheat degree is smaller than a first preset superheat degree;
the control step is also used for controlling the control valve to be closed when the suction superheat degree is smaller than a first preset superheat degree, and controlling the refrigerant to flow into the second branch and flow into the subcooler 10 for heat exchange; and when the suction superheat degree is larger than or equal to a first preset superheat degree, controlling the control valve to be opened, and controlling the refrigerant to directly flow back to the suction port of the compressor without flowing through the second branch.
The control valve is controlled to be opened or closed according to the relation between the superheat degree and the first preset superheat degree by detecting the suction superheat degree, so that the suction superheat degree is not required to be overheated through the subcooler when the suction superheat degree is large, the suction superheat degree directly enters the compressor through the control valve, but the phenomenon of liquid entrainment in the suction gas possibly exists when the suction superheat degree is smaller than the first preset superheat degree, so that the refrigerant flows through the subcooler to be overheated by closing the control valve, the suction superheat degree is improved, and liquid slugging is prevented.
Preferably, the judging step is further configured to judge whether the suction superheat degree is greater than a second preset superheat degree;
the control step is also used for controlling the opening degree of the second throttling device 42 to be reduced while controlling the control valve to be closed when the suction superheat degree is larger than a second preset superheat degree; when the suction superheat degree is smaller than a second preset superheat degree, controlling the control valve to be closed and controlling the opening degree of the second throttling device 42 to be increased; when the suction superheat degree is equal to a second preset superheat degree, controlling the opening degree of the second throttling device 42 to be unchanged while controlling the control valve to be closed; wherein the second predetermined degree of superheat is less than the first predetermined degree of superheat.
The invention further realizes the further control of the second throttling device by further judging the relation between the suction superheat degree and the second preset superheat degree, thereby effectively realizing the control of the opening degree of the second throttling device to be reduced when the suction superheat degree is larger, leading less refrigerant to flow through the subcooler for overheating and reducing the suction superheat degree, and the control of the opening degree of the second throttling device to be increased when the suction superheat degree is smaller, leading more refrigerant to flow through the subcooler for overheating, improving the suction superheat degree and leading the control of the suction superheat degree to be more accurate and intelligent.
The operation mode of the refrigerating unit of the invention is as follows:
refrigerating operation of the refrigerating unit:
high-temperature and high-pressure refrigerant gas flows out of the compressor, flows to the electric proportional control three-way valve through the four-way reversing valve, then enters the outdoor heat exchanger 2 for heat exchange, the opening of the electric proportional control three-way valve is adjusted, so that the refrigerant completely flows to the outdoor heat exchanger 2, the refrigerant flowing out of the outdoor heat exchanger 2 sequentially flows through the liquid storage tank and the drying filter, then passes through the subcooler, the refrigerant flowing out of the subcooler flows to the electronic expansion valve I (a first throttling device 41) and then flows to the indoor heat exchanger 3 for heat absorption, the refrigerant flowing out of the indoor heat exchanger 3 flows to the four-way reversing valve, two branches are provided at the moment, one branch enters the gas-liquid separator through the electromagnetic valve and then returns to the compressor to form a refrigeration cycle, the other branch passes through the electronic expansion valve II (namely a, without throttling), and then the refrigerant is subjected to heat exchange with the refrigerant from the outlet of the outdoor heat exchanger 2 through the subcooler, so that the superheat degree of the refrigerant is improved, and then the refrigerant returns to the gas-liquid separator and enters the compressor, so that the compressor is ensured to operate without liquid, and a refrigeration cycle is formed. The opening of the electromagnetic valve is determined according to the superheat degree of air sucked by the compressor, when the superheat degree is lower, the electromagnetic valve is in an off state, the refrigerant is overheated through the subcooler, when the superheat degree of air sucked by the compressor is higher, the electromagnetic valve is in an on state, and the refrigerant directly enters the gas-liquid separator through the electromagnetic valve and then returns to the compressor.
Defrosting operation of the refrigerating unit:
high-temperature and high-pressure refrigerant gas flows out of the compressor and flows to the indoor heat exchanger 3 of the heat pump unit through the switching of the four-way reversing valve, at the moment, the indoor heat exchanger 3 serves as a condenser, a frost layer of the indoor heat exchanger 3 absorbs heat of the high-temperature and high-pressure refrigerant gas and then melts (usually, frost easily forms in the indoor heat exchanger of a commercial air conditioner or a refrigeration house), the refrigerant flowing out of the indoor heat exchanger 3 is throttled by the electronic expansion valve I, then is subcooled by the refrigerant throttled by the electronic expansion valve II (second throttling device 42) by the subcooler, flows into the liquid reservoir through the drying filter and then flows into the outdoor heat exchanger 2, at the moment, the outdoor heat exchanger 2 serves as an evaporator, the refrigerant flowing out of the outdoor heat exchanger 2 flows to the electric proportional control three-way valve, at the moment, the, one part of refrigerant flows to the four-way reversing valve, and the other part of refrigerant flows from the third branch to the one-way valve and then flows back to a pipeline between the subcooler and the drying filter; the refrigerant flowing from the electric proportional control three-way valve to the four-way reversing valve flows to the second electronic expansion valve (the second throttling device 42) for throttling, the throttled refrigerant enters the subcooler and exchanges heat with the refrigerant flowing from the first electronic expansion valve (the first throttling device 41) to enable the refrigerant to absorb heat for overheating, at the moment, the electromagnetic valve between the four-way reversing valve and the gas-liquid separator is in a disconnected state, and the refrigerant flowing out of the subcooler flows to the gas-liquid separator and then flows back to the compressor.
Opening adjustment of the electric proportional control three-way valve:
(1) when the high pressure of the system is increased to a set value during defrosting, the opening degree of the first branch of the electric proportional control three-way valve is increased, so that more refrigerants flow away from the first branch, the amount of the refrigerants entering the compressor is reduced, and the high pressure of the system is further enabled to operate within a reasonable range.
(2) When the high pressure of the system is smaller than a set value during defrosting, the opening degree of the first branch of the electric proportional control three-way valve is reduced, so that the amount of the refrigerant flowing to the first branch is reduced.
(3) And when the high-pressure value of the system is equal to the set value during defrosting, the opening degree of the third branch of the electric proportional control three-way valve is kept unchanged.
Opening degree adjustment of the second electronic expansion valve (second throttle device 42):
(1) when the superheat degree of the refrigerant at the air suction port of the compressor is larger than a set value, the opening degree of the electronic expansion valve II is reduced, so that the superheat degree value is reduced to the set value.
(2) When the superheat degree of the refrigerant at the air suction port of the compressor is smaller than a set value, the opening degree of the electronic expansion valve II is increased, so that the superheat degree value is gradually increased to the set value.
(3) And when the superheat degree value of the air suction port of the compressor is equal to the set value, the opening degree of the second electronic expansion valve is kept unchanged.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention. The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A refrigeration unit, characterized by: the method comprises the following steps:
the air conditioner comprises a compressor (1), an outdoor heat exchanger (2), an indoor heat exchanger (3) and a first throttling device (41), wherein the first throttling device (41) is arranged between the indoor heat exchanger (3) and the outdoor heat exchanger (2); the refrigerating unit further comprises a first branch (101), one end of the first branch (101) is communicated to a pipeline between the outdoor heat exchanger (2) and the compressor (1), the other end of the first branch (101) is communicated to a pipeline between the outdoor heat exchanger (2) and the first throttling device (41), and the first branch (101) can guide the refrigerant at the outlet end of the outdoor heat exchanger (2) back to the inlet end of the outdoor heat exchanger (2) when the indoor heat exchanger (3) is defrosted.
2. The refrigeration unit as set forth in claim 1 wherein:
the first branch (101) is also provided with a check valve (5), and the check valve (5) only allows refrigerant to be guided from one end of the first branch (101) communicated to a pipeline between the outdoor heat exchanger (2) and the compressor (1) to the other end communicated to a pipeline between the outdoor heat exchanger (2) and the first throttling device (41); and/or the presence of a gas in the gas,
and a proportional control three-way valve (6) is arranged at one end of the first branch (101) communicated to a pipeline between the outdoor heat exchanger (2) and the compressor (1).
3. The refrigeration unit as set forth in claim 2 wherein:
the four-way reversing valve (11) is communicated with a gas exhaust pipeline of the compressor (1), a gas suction pipeline of the compressor, the indoor heat exchanger (3) and the proportion adjusting three-way valve (6) respectively at four ends of the four-way reversing valve (11); and/or the presence of a gas in the gas,
and a liquid storage device (7) and/or a drying filter (8) are/is further arranged on a pipeline between the outdoor heat exchanger (2) and the first throttling device (41).
4. A refrigeration unit as set forth in any of claims 1-3 wherein:
the air suction pipeline of the compressor (1) is further provided with a control valve (9), a second branch (102) is further arranged in parallel with the control valve (9), a subcooler (10) is arranged on the second branch (102), a pipeline between the first throttling device (41) and the outdoor heat exchanger (2) penetrates through the subcooler (10) and exchanges heat with the second branch (102), and a second throttling device (42) is further arranged at the upstream position of the subcooler (10) on the second branch (102).
5. The refrigeration unit as set forth in claim 4 wherein:
a gas-liquid separator (12) is also arranged at the air suction port of the compressor (1); and/or the first throttling device (41) is an electronic expansion valve; and/or the second throttling device (42) is an electronic expansion valve; and/or the control valve (9) is an electromagnetic valve; and/or when a proportional control three-way valve (6) is further included, the proportional control three-way valve (6) is an electric proportional control three-way valve.
6. A control method suitable for a refrigeration unit as set forth in any one of claims 1-5, characterized in that: when the proportional control three-way valve (6) and the four-way reversing valve (11) are included, the control method comprises the following steps:
a detection step, which is used for detecting the operation mode of the refrigerating unit;
judging whether the refrigerating unit operates in a defrosting mode of the indoor heat exchanger or not;
and a control step of controlling the four-way reversing valve (11) to enable the exhaust gas of the compressor (1) to flow to the indoor heat exchanger (3) and controlling the proportion adjusting three-way valve (6) to enable the refrigerant to partially flow into the first branch (101) when the refrigerating unit operates in an indoor heat exchanger defrosting mode.
7. The control method according to claim 6, characterized in that:
the detection step is also used for detecting the high-pressure at the exhaust end of the compressor;
the judging step is also used for judging whether the high-pressure at the exhaust end of the compressor is greater than the preset pressure;
and the control step comprises the following steps that when the refrigerating unit operates in an indoor heat exchanger defrosting mode: when the high-pressure of the compressor exhaust is greater than the preset pressure, the opening degree of the proportional control three-way valve (6) is controlled and adjusted, so that the flow rate of the refrigerant flowing into the first branch (101) is increased; when the high-pressure of the compressor discharge air is smaller than the preset pressure, controlling and adjusting the opening degree of the proportional control three-way valve (6) to increase and decrease the flow rate of the refrigerant flowing into the first branch circuit (101); and when the high-pressure of the compressor exhaust gas is equal to the preset pressure, controlling and adjusting the opening of the proportional control three-way valve (6) to be unchanged.
8. The control method according to claim 6, characterized in that:
and the control step is also used for controlling the four-way reversing valve (11) to enable the exhaust gas of the compressor to flow to the proportional adjustment three-way valve (6) when the refrigerating unit operates in the indoor heat exchanger refrigerating mode, and controlling the proportional adjustment three-way valve (6) to enable the refrigerant to completely flow into the outdoor heat exchanger (2) and not flow into the first branch circuit (101).
9. The control method according to any one of claims 6 to 8, characterized in that:
when further comprising a control valve (9):
the detection step is also used for detecting the suction temperature of the suction port of the compressor and calculating the suction superheat degree;
the judging step is also used for judging whether the suction superheat degree is smaller than a first preset superheat degree;
the control step is also used for controlling the control valve (9) to be closed when the suction superheat degree is less than a first preset superheat degree, and controlling the refrigerant to flow into the second branch and flow into the subcooler (10) for heat exchange; and when the suction superheat degree is larger than or equal to a first preset superheat degree, the control valve (9) is controlled to be opened, and the refrigerant is controlled to directly flow back to the suction port of the compressor without flowing through the second branch.
10. The control method according to claim 9, characterized in that:
the judgment step is also used for judging whether the suction superheat degree is larger than a second preset superheat degree;
the control step is also used for controlling the opening degree of the second throttling device (42) to be reduced while controlling the control valve (9) to be closed when the suction superheat degree is larger than a second preset superheat degree; when the suction superheat degree is smaller than a second preset superheat degree, controlling the control valve (9) to be closed and controlling the opening degree of the second throttling device (42) to be increased; when the suction superheat degree is equal to a second preset superheat degree, controlling the opening degree of the second throttling device (42) to be unchanged while controlling the control valve (9) to be closed; wherein the second predetermined degree of superheat is less than the first predetermined degree of superheat.
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| CN202010348975.9A CN111623568A (en) | 2020-04-28 | 2020-04-28 | Refrigerating unit and control method thereof |
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