CN114811986A - Refrigeration system, defrosting control method and refrigeration equipment - Google Patents
Refrigeration system, defrosting control method and refrigeration equipment Download PDFInfo
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- CN114811986A CN114811986A CN202210630723.4A CN202210630723A CN114811986A CN 114811986 A CN114811986 A CN 114811986A CN 202210630723 A CN202210630723 A CN 202210630723A CN 114811986 A CN114811986 A CN 114811986A
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- 238000005057 refrigeration Methods 0.000 title claims abstract description 145
- 238000010257 thawing Methods 0.000 title claims abstract description 134
- 238000000034 method Methods 0.000 title claims abstract description 27
- 239000007788 liquid Substances 0.000 claims abstract description 82
- 239000003507 refrigerant Substances 0.000 claims abstract description 65
- 238000001816 cooling Methods 0.000 claims abstract description 9
- 238000011084 recovery Methods 0.000 claims abstract description 3
- 230000001172 regenerating effect Effects 0.000 claims description 9
- 238000012544 monitoring process Methods 0.000 claims description 6
- 230000004913 activation Effects 0.000 claims description 2
- 230000008859 change Effects 0.000 abstract description 3
- 239000003921 oil Substances 0.000 description 12
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 4
- 229910052731 fluorine Inorganic materials 0.000 description 4
- 239000011737 fluorine Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 238000004781 supercooling Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
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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
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
- F25B1/10—Compression machines, plants or systems with non-reversible cycle with multi-stage compression
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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
- F25B31/00—Compressor 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
- F25B40/00—Subcoolers, desuperheaters or superheaters
- F25B40/06—Superheaters
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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
- F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
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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
- F25B41/40—Fluid line 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
- F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
- F25B47/02—Defrosting cycles
- F25B47/022—Defrosting cycles hot gas defrosting
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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
-
- 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
- F25B5/00—Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity
- F25B5/02—Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity arranged in parallel
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Defrosting Systems (AREA)
Abstract
The invention discloses a refrigeration system, a defrosting control method and refrigeration equipment, wherein the refrigeration system comprises: the refrigeration cycle loop is formed by connecting a compressor unit, a condenser and an evaporator unit, the compressor unit comprises a first compressor and a second compressor which are arranged in series, and a refrigerant discharged by the first compressor is sent to an air suction port of the second compressor; the heat recovery defrosting circuit is formed by connecting a compressor unit, an evaporator group, an auxiliary heat exchanger and a heat regenerator, a refrigerant flowing out of a condenser is sent to the evaporator group for refrigeration through a first heat exchange pipeline of the heat regenerator, the refrigerant flowing out of the evaporator group is sent back to an air suction port of the first compressor through a second heat exchange pipeline of the auxiliary heat exchanger and the heat regenerator, and the auxiliary heat exchanger is used for cooling the refrigerant discharged by the first compressor. According to the invention, the liquid refrigerant which is subjected to phase change after defrosting is introduced into the auxiliary heat exchanger and the heat regenerator, so that the exhaust temperature of the compressor unit is reduced while the liquid impact hidden danger is eliminated, the work of the compressor is reduced, and the refrigeration efficiency is improved.
Description
Technical Field
The invention relates to the technical field of refrigeration, in particular to a refrigeration system, a defrosting control method and refrigeration equipment.
Background
In large industrial freezer refrigeration systems, frosting is a very common phenomenon. It is believed that when air flows over the evaporator surface and the evaporator surface temperature is below 0 c, surface frosting occurs. Because the frost layer formed has low heat conductivity, the heat exchange performance of the evaporator is reduced, the energy consumption is increased, and the air absorption and liquid entrainment can be caused to a certain degree. In general, hot fluorine defrosting is adopted as a defrosting mode of a low-temperature refrigerator in the industry, sufficient heat source, namely gaseous high-pressure high-temperature refrigerant, is needed for hot fluorine defrosting, high-temperature gas generated when a compressor unit works is guided into an evaporator in a defrosting working condition in an evaporator set through shunting, and a frost layer on the surface of the evaporator is melted by using heat of the high-temperature gas.
The defrosting mode has the great advantage in defrosting speed, high-temperature gas can absorb cold of a frost layer and condense into liquid while defrosting an evaporator, a liquid refrigerant treatment scheme generated by defrosting in the prior art is to introduce the liquid refrigerant into a heat regenerator, the liquid refrigerant absorbs heat of refrigerant flowing out of a condenser through the heat regenerator and then is sent to an air suction port of a compressor unit, but due to the factors of low temperature, incomplete heat exchange and the like of the refrigerant flowing out of the condenser, the liquid refrigerant cannot be completely converted into a gaseous refrigerant after absorbing heat, and liquid impact hidden danger still exists.
Therefore, how to overcome the shortcomings of the existing hot fluorine defrosting scheme is a technical problem to be solved in the industry.
Disclosure of Invention
In order to overcome the defect of liquid impact hidden danger in the existing hot fluorine defrosting technology, the invention provides a refrigerating system, a defrosting control method and refrigerating equipment.
The technical scheme adopted by the invention is that a refrigeration system is designed, and the refrigeration system comprises:
the refrigeration cycle loop is formed by connecting a compressor unit, a condenser and an evaporator unit, the compressor unit comprises a first compressor and a second compressor which are arranged in series, and a refrigerant discharged by the first compressor is sent to an air suction port of the second compressor;
the heat recovery defrosting circuit is formed by connecting a compressor unit, an evaporator group, an auxiliary heat exchanger and a heat regenerator, a refrigerant flowing out of a condenser is sent to the evaporator group for refrigeration through a first heat exchange pipeline of the heat regenerator, the refrigerant flowing out of the evaporator group is sent back to an air suction port of the first compressor through a second heat exchange pipeline of the auxiliary heat exchanger and the heat regenerator, and the auxiliary heat exchanger is used for cooling the refrigerant discharged by the first compressor.
Furthermore, a bypass branch is arranged on the outlet side of the first heat exchange pipeline of the heat regenerator and used for returning part of the refrigerant flowing out of the first heat exchange pipeline to the inlet of the condenser, and a bypass valve for adjusting the flow of the refrigerant is arranged on the bypass branch.
Furthermore, the evaporator group is composed of at least two evaporators arranged in parallel;
the first heat exchange pipeline of the heat regenerator is connected with the refrigerating inlet end of the evaporator group through a liquid supply header, and the refrigerating outlet end of the evaporator group is connected with the exhaust port of the second compressor through a defrosting header;
a second heat exchange pipeline of the heat regenerator is connected with a refrigeration inlet end of the evaporator group through a liquid return header, and a refrigeration outlet end of the evaporator group is connected with an air suction port of the first compressor through an air return header;
the liquid supply collecting pipe, the liquid return collecting pipe, the defrosting collecting pipe and the air return collecting pipe are respectively provided with liquid distributing openings which are connected with the evaporators in a one-to-one correspondence mode, and each liquid distributing opening is provided with an independently working valve.
Further, when the evaporator is in a refrigerating working condition, the valve elements on the liquid supply collecting pipe and the air return collecting pipe corresponding to the evaporator are opened, and the valve elements on the defrosting collecting pipe and the liquid return collecting pipe corresponding to the evaporator are closed;
when the evaporator is in a defrosting working condition, the valve elements on the liquid supply collecting pipe and the air return collecting pipe corresponding to the evaporator are closed, and the valve elements on the defrosting collecting pipe and the liquid return collecting pipe corresponding to the evaporator are opened.
Furthermore, the refrigeration inlet end of each evaporator is connected with the liquid supply header and the liquid return header through two parallel branches, a throttle valve and a switching valve are installed on one branch, a one-way valve is installed on the other branch, the switching valve is opened only when the evaporator is in a refrigeration working condition, and the one-way valve only allows refrigerant to flow out of the refrigeration inlet end of the evaporator.
Furthermore, a backheating control valve is installed at the inlet side of the second heat exchange pipeline of the backheating device, the backheating control valve is kept closed when all the evaporators of the evaporator group are in a refrigeration working condition, and the backheating control valve is kept open when one evaporator is in a defrosting working condition.
The invention also provides a defrosting control method adopting the refrigeration system, which comprises the following steps:
judging whether an evaporator reaches a defrosting starting condition or not;
if yes, the evaporator which reaches the defrosting starting condition is used as an undetermined evaporator, the evaporator which is in the refrigerating condition and does not reach the defrosting starting condition is used as a refrigerating evaporator, whether the ratio of the sum of the number of the undetermined evaporators to the sum of the number of the refrigerating evaporators exceeds a set ratio is judged, if yes, part of evaporators are selected from the standby evaporators to be forced to enter the refrigerating working condition, then all the undetermined evaporators are started to enter the defrosting working condition, and if not, all the undetermined evaporators are directly started to enter the defrosting working condition.
In some embodiments, selecting a portion of the evaporators to enter a defrost condition in a standby evaporator comprises:
calculating and rounding up according to the sum of the number of the evaporators to be determined and a set proportion to obtain the sum of the number of the target refrigeration evaporators;
calculating the difference value of the sum of the number of the target refrigeration evaporators and the sum of the number of the refrigeration evaporators;
and selecting a corresponding evaporator from the standby evaporators to forcibly enter a refrigeration working condition randomly according to the difference or according to the priority.
Further, the defrosting control method further comprises the following steps:
after all the evaporators to be determined are started to enter a defrosting condition;
judging whether the opening of the throttle valve of more than half of the refrigeration evaporators is smaller than a set opening;
if yes, opening a bypass valve, and returning part of the refrigerant flowing out of the first heat exchange pipeline of the heat regenerator to an inlet of the condenser;
if not, the bypass valve is closed.
Further, the defrosting control method further comprises the following steps:
starting all evaporators to be determined to enter a defrosting working condition;
judging whether an evaporator to be determined reaches a defrosting ending condition or not;
if yes, the undetermined evaporators finish the defrosting condition, the refrigeration evaporators forcibly entering the refrigeration condition are recovered to be standby, whether all the undetermined evaporators finish the defrosting condition is judged, if not, whether the ratio of the sum of the number of the remaining undetermined evaporators to the sum of the number of the refrigeration evaporators exceeds a set ratio is judged, and if yes, whether any evaporator reaches the defrosting starting condition is judged.
In some embodiments, determining whether an evaporator has reached a defrost initiation condition comprises:
monitoring the current of the evaporator under the refrigeration working condition, and judging whether the current of the evaporator exceeds a set current value or not;
if yes, the evaporator reaches a defrosting starting condition;
if not, the evaporator does not reach the defrosting starting condition.
Further, before whether the evaporators reach the defrosting starting condition is judged, the indoor environment temperature of each evaporator in the evaporator group is monitored, whether the indoor environment temperature of the evaporator is reduced to a set temperature value is judged, and if not, the evaporators are started to enter the refrigeration working condition.
The invention also proposes a refrigeration device comprising: the defrosting control method comprises a refrigeration system and a controller for controlling the operation state of the refrigeration system, wherein the controller executes the defrosting control method.
In some embodiments, the refrigeration appliance is a freezer.
Compared with the prior art, the invention has the following beneficial effects:
1. an auxiliary heat exchanger is added in a heat return defrosting loop, liquid refrigerants which are subjected to phase change after defrosting sequentially flow through the auxiliary heat exchanger and the heat regenerator, the liquid refrigerants and the liquid refrigerants discharged by the first compressor are subjected to heat exchange through the auxiliary heat exchanger, the liquid impact hidden danger is eliminated, meanwhile, the exhaust temperature of the second compressor is reduced, the liquid supply supercooling degree is increased, the compressor work is reduced under the same pressure ratio, and the energy consumption of a refrigerating system is reduced;
2. a bypass branch is arranged between the outlet side of the first heat exchange tube of the heat regenerator and the inlet of the condenser, when the heat load of the refrigeration system is not large, a bypass valve of the bypass branch is opened, part of the refrigerant flowing out of the first heat exchange tube is sent back to the inlet of the condenser, the redundant cold energy is utilized to reduce the load of the condenser, and the refrigeration efficiency is improved.
Drawings
The invention is described in detail below with reference to examples and figures, in which:
FIG. 1 is a schematic diagram of the connection of the refrigeration system of the present invention;
FIG. 2 is a flow chart illustrating a defrosting control method according to the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present patent and are not limiting upon the present patent.
As shown in fig. 1, the present invention proposes that the refrigeration system is suitable for refrigeration equipment, especially a refrigerator and the like. The refrigeration system includes: the system comprises a compressor set, a condenser 5, an evaporator group 6, a heat regenerator 11, an auxiliary heat exchanger 12 and the like, wherein the compressor set, the condenser 5 and the evaporator group 6 are connected to form a refrigeration cycle loop, and the compressor set, the evaporator group 6, the auxiliary heat exchanger 12 and the heat regenerator 11 are connected to form a heat regeneration defrosting loop.
The compressor unit comprises a first compressor 1 and a second compressor 2 which are arranged in series, the first compressor 1 is a low-pressure compressor, the second compressor 1 is a high-pressure compressor, a refrigerant discharged from the first compressor 1 is sent to an air suction port of the second compressor 2, an air exhaust port of the first compressor 1 is connected with a first oil separator 3, an air exhaust port of the second compressor 2 is connected with a second oil separator 4, the refrigerant discharged from the air exhaust port of the first compressor 1 is separated by the first oil separator 3 and sent to the air suction port of the second compressor 2, and the refrigerant discharged from the air exhaust port of the second compressor 2 is separated by the second oil separator 4 and sent to a condenser 5.
The heat regenerator 11 and the auxiliary heat exchanger 12 both have two sets of heat exchange pipelines, a first heat exchange pipeline of the heat regenerator 11 is connected between an outlet of the condenser and a refrigeration inlet end of the evaporator group 6, the first heat exchange pipeline of the heat regenerator 11 belongs to a part of a refrigeration cycle loop, a second heat exchange pipeline of the heat regenerator 11 is connected between an outlet of the second heat exchange pipeline of the auxiliary heat exchanger 12 and an air suction port of the first compressor 1, and the second heat exchange pipeline of the heat regenerator 11 belongs to a part of a heat regeneration defrosting loop. The first heat exchange pipeline of the auxiliary heat exchanger 12 is connected between the exhaust port of the first compressor 1 and the suction port of the second compressor 2, more precisely, between the air outlet of the first oil separator 3 and the suction port of the second compressor 2, the first heat exchange pipeline of the auxiliary heat exchanger 12 belongs to a part of the refrigeration cycle loop, the second heat exchange pipeline of the auxiliary heat exchanger 12 is connected between the refrigeration inlet end of the evaporator group and the second heat exchange pipeline inlet of the heat regenerator 11, and the second heat exchange pipeline of the auxiliary heat exchanger 12 belongs to a part of the regenerative defrosting loop.
The refrigerant flowing out of the condenser 5 is sent to the evaporator in the evaporator group 6 under the refrigeration condition through the first heat exchange pipeline of the heat regenerator 11 for refrigeration, and the refrigerant flowing out after the evaporator in the defrosting condition in the evaporator group 6 is defrosted sequentially passes through the second heat exchange pipeline of the auxiliary heat exchanger 12 and the second heat exchange pipeline of the heat regenerator 11 and is sent back to the suction port of the first compressor 1. That is, the liquid refrigerant undergoing phase change after defrosting exchanges heat with the gaseous refrigerant discharged from the first compressor 1 through the auxiliary heat exchanger 12 to complete the first heat absorption, and the refrigerant flowing out of the auxiliary heat exchanger 12 exchanges heat with the refrigerant flowing out of the condenser 5 through the heat regenerator 11 to complete the second heat absorption. The design has the advantages that firstly, the liquid refrigerant generated by defrosting realizes twice heat absorption through the auxiliary heat exchanger 12 and the heat regenerator 11, the liquid refrigerant is gasified and enters the air suction port of the compressor unit, the normal operation of the system is ensured, and the liquid impact phenomenon is avoided; secondly, the gaseous refrigerant discharged by the first compressor 1 is cooled through the auxiliary heat exchanger 12, the exhaust temperature of the compressor unit and the heat load of the condenser 5 are reduced, the work of the compressor unit under the same pressure ratio is reduced, the energy consumption of the system is reduced, and the refrigeration efficiency is improved; thirdly, the refrigerant of the second heat exchange pipeline absorbs the heat of the refrigerant of the first heat exchange pipeline, the supercooling degree of the refrigerant flowing out of the first heat exchange pipeline is improved, and the refrigeration effect is optimized; and fourthly, the temperature of lubricating oil of the compressor unit is reduced, and oil return of the compressor unit is facilitated.
In some embodiments, a bypass branch is disposed at an outlet side of the first heat exchange pipeline of the heat regenerator 11, the bypass branch is configured to return a portion of the refrigerant flowing out of the first heat exchange pipeline to an inlet of the condenser 5, a bypass valve 13 for adjusting a flow rate of the bypass branch is installed in the bypass branch, the bypass valve 13 of the bypass branch is opened when a thermal load of the refrigeration system is not large, the portion of the refrigerant flowing out of the first heat exchange pipeline is returned to the inlet of the condenser 5, and the redundant cooling capacity is utilized to reduce a load of the condenser 5, thereby improving the refrigeration efficiency. For example, the thermal load condition of the refrigeration system is judged according to the opening degree of the refrigeration evaporator, when the opening degree of the throttle valve exceeding half of the refrigeration evaporators is smaller than the set opening degree, the thermal load of the refrigeration system is not large at present, the cold quantity provided by the first heat exchange pipeline of the heat regenerator is surplus, at the moment, the bypass valve is opened, part of the refrigerant flowing out of the first heat exchange pipeline of the heat regenerator is sent back to the inlet of the condenser, and the part of the refrigerant is mixed with the high-temperature refrigerant discharged by the second compressor for cooling, so that the load of the condenser is reduced.
In some embodiments, the evaporator group 6 is composed of at least two evaporators arranged in parallel, the evaporators can be installed in different rooms, each evaporator can be independently switched into a refrigeration cycle or a regenerative defrosting cycle, two ends of the evaporator group 6 are a refrigeration inlet end and a refrigeration outlet end, respectively, and since the refrigerant flow directions of the evaporators in the regenerative defrosting cycle or the refrigeration cycle are opposite, the refrigeration inlet end of the evaporator group 6 is actually a defrosting outlet end, and the refrigeration outlet end is actually a defrosting inlet end.
The connection structure of the refrigeration system is described in detail below, a first heat exchange pipeline of the heat regenerator 11 is connected to a refrigeration inlet end of the evaporator group 6 through the liquid supply header 7, a refrigeration outlet end of the evaporator group 6 is connected to an exhaust port of the second compressor 2 through the defrosting header 9, a second heat exchange pipeline of the heat regenerator 11 is connected to the refrigeration inlet end of the evaporator group 6 through the liquid return header 8, and the refrigeration outlet end of the evaporator group 6 is connected to an air suction port of the first compressor 1 through the air return header 10. The end part of each collecting pipe connected with the evaporator group 6 is provided with a plurality of liquid separating ports with the same number as the evaporators, the liquid separating ports are connected with the evaporators in a one-to-one correspondence mode, and each liquid separating port is provided with an independently working valve. When the evaporator is in a refrigeration working condition, the valve elements on the liquid supply header 7 and the air return header 10 corresponding to the evaporator are opened, and the valve elements on the defrosting header 9 and the liquid return header 8 corresponding to the evaporator are closed; when the evaporator is in a defrosting condition, the valve elements on the liquid supply header 7 and the air return header 10 corresponding to the evaporator are closed, and the valve elements on the defrosting header 9 and the liquid return header 8 corresponding to the evaporator are opened.
Specifically, a liquid supply electromagnetic valve is installed at each liquid distribution port of the liquid supply header 7, a liquid return electromagnetic valve is installed at each liquid distribution port of the liquid return header 8, a defrosting electromagnetic valve is installed at each liquid distribution port of the defrosting header 9, and a gas return electromagnetic valve is installed at each liquid distribution port of the gas return header 10, so that independent control of each evaporator is realized through a valve and the liquid distribution ports, and the refrigerant can be uniformly distributed.
In some embodiments, the refrigeration inlet end of each evaporator is connected to the liquid supply header 7 and the liquid return header 8 by two parallel branches, one branch is provided with a throttle valve and a switching valve, the other branch is provided with a check valve, the switching valve is opened only when the evaporator is in a refrigeration condition, and the check valve only allows refrigerant to flow out of the refrigeration inlet end of the evaporator. The inlet of the second heat exchange pipeline of the regenerator 11 is provided with a regenerative control valve 14, and the regenerative control valve 14 is kept closed when all the evaporators of the evaporator group 6 are in the refrigeration working condition.
As shown in FIG. 1, for example, an evaporator group comprises four evaporators 6-1 to 6-4, liquid supply electromagnetic valves of the four evaporators are 7-1 to 7-4 from left to right, liquid return electromagnetic valves are 8-1 to 8-4 from left to right, defrosting electromagnetic valves are 9-1 to 9-4 from left to right, and air return electromagnetic valves are 10-1 to 10-4 from right to left, and the working flow of the refrigeration system is as follows.
All evaporators are in a refrigeration mode, liquid supply electromagnetic valves 7-1-7-4 are opened, liquid return electromagnetic valves 8-1-8-4 are closed, defrosting electromagnetic valves 9-1-9-4 are closed, air return electromagnetic valves 10-1-10-4 are opened, and heat return control valves and bypass valves are closed. The refrigerant flow direction is as follows: high-temperature and high-pressure gaseous refrigerant discharged from the second compressor 2 → the second oil separator 4 → the condenser 5 → the regenerator 11 → the liquid supply solenoid valve → the throttle valve → the evaporator → the air return solenoid valve → the suction port of the first compressor 1 → the first oil separator 3 → the suction port of the second compressor 2.
Part of evaporators enter a defrosting working condition, and the other part of evaporators are in a refrigeration mode, taking the evaporator 5-1 for defrosting and the evaporators 5-2, 5-3 and 5-4 for refrigeration as an example: the defrosting electromagnetic valve 9-1 is opened, and the defrosting electromagnetic valves 9-2, 9-3 and 9-4 are closed; the liquid supply electromagnetic valve 7-1 is closed, and the liquid supply electromagnetic valves 7-2, 7-3 and 7-4 are opened; the liquid return electromagnetic valve 8-1 is opened, the liquid return electromagnetic valves 8-2, 8-3 and 8-4 are closed, the heat return control valve 14 is opened, and the bypass valve 13 is opened when the heat load of the refrigeration system is not large. The refrigerant flow direction in the refrigeration mode is as follows: high-temperature and high-pressure gaseous refrigerant discharged from the second compressor 2 → the second oil separator 4 → the condenser 5 → the regenerator 11 → the liquid supply solenoid valve → the throttle valve → the evaporator → the air return solenoid valve → the suction port of the first compressor 1 → the first oil separator 3 → the suction port of the second compressor 2; the refrigerant flow direction of the defrosting working condition is as follows: high-temperature and high-pressure gaseous refrigerant discharged from the second compressor 2 → the second oil separator 4 → the defrosting solenoid valve → the evaporator → the check valve → the liquid return solenoid valve → the regenerative control valve → the auxiliary heat exchanger 12 → the regenerator 11 → the suction port of the first compressor 1 → the first oil separator 3 → the suction port of the second compressor 2.
The invention also provides a defrosting control method of the refrigerating system, which comprises the following steps:
judging whether an evaporator reaches a defrosting starting condition or not;
if yes, the evaporator which reaches the defrosting starting condition is used as an undetermined evaporator, the evaporator which is in the refrigerating condition and does not reach the defrosting starting condition is used as a refrigerating evaporator, whether the ratio of the sum of the number of the undetermined evaporators to the sum of the number of the refrigerating evaporators exceeds a set ratio is judged, if yes, part of evaporators are selected from the standby evaporators to be forced to enter the refrigerating working condition, then all the undetermined evaporators are started to enter the defrosting working condition, and if not, all the undetermined evaporators are directly started to enter the defrosting working condition.
According to the defrosting control method, according to the proportional relation between the sum of the number of evaporators to be determined reaching the defrosting starting condition and the sum of the number of refrigeration evaporators, when the preset proportion is exceeded, the number of the current refrigeration evaporators is insufficient, and the provided cold quantity is insufficient to maintain the stable temperature of the refrigeration house, so that part of evaporators are selected from standby evaporators to be forced to enter a refrigeration working condition, then all evaporators to be determined are started to enter the defrosting working condition, the defrosting speed is accelerated, the stable temperature of the refrigeration house is ensured, and the use effect of the refrigeration house is improved. More importantly, the statistics of the number of the undetermined evaporators and the number of the refrigeration evaporators are easy to realize, detection parts such as sensors do not need to be additionally arranged, the calculation logic is simple, the cost is low, and the implementation and the popularization are easy.
In some embodiments, selecting a portion of the evaporators to enter a defrost condition in a standby evaporator comprises:
dividing the sum of the number of the evaporators to be determined by a set proportion to obtain a preliminary result, and rounding the preliminary result upwards to obtain the sum of the number of the target refrigeration evaporators;
calculating the difference value of the sum of the number of the target refrigeration evaporators and the sum of the number of the refrigeration evaporators;
and selecting a corresponding evaporator from the standby evaporators to forcibly enter a refrigeration working condition randomly according to the difference or according to the priority. It should be understood that, when a corresponding evaporator is selected from the standby evaporators according to the priority, the priority may be a pre-designed fixed priority, a dynamic priority sorted according to the temperature difference between the ambient temperature in the room where the evaporator is located and the set temperature value, or a dynamic priority sorted according to the size of other operating parameters of the evaporator, which is not limited in this respect.
In some embodiments, the defrost control method further comprises:
starting all evaporators to be determined to enter a defrosting working condition;
judging whether an evaporator to be determined reaches a defrosting ending condition or not;
if yes, the undetermined evaporators finish the defrosting condition, the refrigeration evaporators forcibly entering the refrigeration condition are recovered to be standby, whether all the undetermined evaporators finish the defrosting condition is judged, if not, whether the ratio of the sum of the number of the remaining undetermined evaporators to the sum of the number of the refrigeration evaporators exceeds a set ratio is judged, and if yes, whether any evaporator reaches the defrosting starting condition is judged.
It should be understood that in the defrosting control method, as the undetermined evaporators gradually complete defrosting, the number of the remaining undetermined evaporators is less and less, and the ratio of the sum of the number of all the remaining undetermined evaporators to the sum of the number of the refrigeration evaporators is inevitably smaller than or equal to a set proportion, that is, all the remaining undetermined evaporators are directly started to enter a defrosting condition in the later defrosting stage.
In some embodiments, the defrost control method further comprises:
after all the evaporators to be determined are started to enter a defrosting condition;
judging whether the opening of the throttle valve of more than half of the refrigeration evaporators is smaller than a set opening;
if so, indicating that the heat load of the current refrigerating system is not large, and the cold energy provided by the first heat exchange pipeline of the heat regenerator is surplus, opening the bypass valve at the moment, sending part of the refrigerant flowing out of the first heat exchange pipeline of the heat regenerator back to the inlet of the condenser, and mixing the part of the refrigerant with the high-temperature refrigerant discharged by the second compressor for cooling so as to reduce the load of the condenser;
if not, the thermal load of the current refrigeration system is large, the bypass valve is closed at the moment, and all refrigerants flowing out of the first heat exchange pipeline of the heat regenerator are distributed to the refrigeration evaporator so as to meet the refrigeration requirement of the refrigeration system.
The set ratio and the set opening degree can be designed according to the actual conditions of the refrigeration system, and generally speaking, the set ratio is optimal when the set ratio is one third, and the set opening degree is optimal when the set opening degree is 30%.
In some embodiments, determining whether the evaporator has reached the defrost activation condition includes:
monitoring the current of the evaporator under the refrigeration working condition, and judging whether the current of the evaporator exceeds a set current value or not;
if yes, the heat exchange state of the evaporator is poor, the frost layer on the surface of the evaporator is thick, and the evaporator reaches a defrosting starting condition;
if not, the heat exchange state of the evaporator is still acceptable, the surface of the evaporator is frostless or the frost layer is thin, and the evaporator does not reach the defrosting starting condition.
It should be noted that the current value is easy to collect and has small error, so as to determine whether the evaporator reaches the defrosting start condition is a preferred embodiment. Of course, the defrosting start condition and the defrosting end condition may adopt the existing determination condition, for example, the duration of the cooling operation of the evaporator is used as the defrosting start condition, the duration of the back-heating defrosting operation is used as the defrosting exit condition, and whether the parameters such as the tube temperature of the evaporator reach the corresponding target temperature or not may be detected as the determination condition, which is not limited in the present invention.
Taking the embodiment shown in fig. 2 as an example, the implementation process of the defrosting control method will be described in detail.
step 3, the evaporator of the room with the temperature reduced to the set temperature value enters standby, a liquid supply electromagnetic valve, an air return electromagnetic valve, a liquid return electromagnetic valve and a defrosting electromagnetic valve of the standby evaporator are closed, and the step 2 is executed again;
step 4, the evaporator of the room with the temperature exceeding the set temperature value enters a refrigeration working condition, a liquid supply electromagnetic valve of the refrigeration evaporator is opened, a liquid return electromagnetic valve is closed, a defrosting electromagnetic valve is closed, and an air return electromagnetic valve is opened, and the step 5 is executed;
step 5, monitoring the current of the evaporator under the refrigeration working condition, judging whether the current of the evaporator exceeds a set current value, if so, executing step 6, and if not, returning to step 2;
step 9, judging whether the throttle valve opening of more than half of the refrigeration evaporators is smaller than a set opening, if so, executing step 10, and if not, executing step 11;
step 10, opening a bypass valve;
and step 13, judging whether all the evaporators to be determined finish the defrosting condition, returning to execute the step 6, judging whether the ratio of the sum of the number of the remaining evaporators to be determined to the sum of the number of the refrigeration evaporators exceeds a set ratio, and if so, returning to the step 5.
The invention also proposes a refrigeration device comprising: the defrosting control method includes the steps of controlling the operation state of the refrigeration system, and controlling the defrosting control method to be executed by the controller.
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.
Claims (14)
1. A refrigeration system, comprising:
the refrigeration cycle loop is formed by connecting a compressor unit, a condenser and an evaporator unit, wherein the compressor unit comprises a first compressor and a second compressor which are arranged in series, and a refrigerant discharged by the first compressor is sent to a suction port of the second compressor;
the heat recovery defrosting circuit is formed by connecting the compressor unit, the evaporator group, the auxiliary heat exchanger and the heat regenerator, a refrigerant flowing out of the condenser is sent to the evaporator group for refrigeration through a first heat exchange pipeline of the heat regenerator, the refrigerant flowing out of the evaporator group defrosting sequentially passes through the auxiliary heat exchanger and a second heat exchange pipeline of the heat regenerator and is sent back to an air suction port of the first compressor, and the auxiliary heat exchanger is used for cooling the refrigerant discharged by the first compressor.
2. The refrigerating system of claim 1, wherein a bypass branch is disposed at an outlet side of the first heat exchange line of the heat regenerator, the bypass branch is configured to return a portion of the refrigerant flowing out of the first heat exchange line to an inlet of the condenser, and the bypass branch is provided with a bypass valve for adjusting a flow rate of the bypass branch.
3. The refrigeration system according to claim 1, wherein the evaporator group is composed of at least two evaporators arranged in parallel;
the first heat exchange pipeline of the heat regenerator is connected with the refrigerating inlet end of the evaporator group through a liquid supply header, and the refrigerating outlet end of the evaporator group is connected with the exhaust port of the second compressor through a defrosting header;
a second heat exchange pipeline of the heat regenerator is connected with a refrigeration inlet end of the evaporator group through a liquid return header, and a refrigeration outlet end of the evaporator group is connected with a suction port of the first compressor through a gas return header;
the liquid supply collecting pipe, the liquid return collecting pipe, the defrosting collecting pipe and the air return collecting pipe are respectively provided with liquid distributing openings which are connected with the evaporators in a one-to-one correspondence mode, and each liquid distributing opening is provided with an independently working valve.
4. A refrigeration system according to claim 3, wherein when said evaporator is in a refrigeration mode, valves associated with said evaporator in said supply header and said return header are open, and valves associated with said evaporator in said defrost header and said return header are closed;
when the evaporator is in a defrosting condition, the valve elements on the liquid supply header and the air return header corresponding to the evaporator are closed, and the valve elements on the defrosting header and the liquid return header corresponding to the evaporator are opened.
5. A refrigeration system as recited in claim 3 wherein the refrigeration inlet end of each of said evaporators is connected to said liquid supply header and said liquid return header by two parallel branches, one of said branches including a throttle valve and a switching valve, the other branch including a check valve, said switching valve being opened only when said evaporator is in a refrigeration mode, said check valve allowing refrigerant to flow only out of the refrigeration inlet end of said evaporator.
6. The refrigeration system according to claim 1, wherein a regenerative control valve is installed on an inlet side of the second heat exchange line of the regenerator, the regenerative control valve is kept closed when all evaporators of the evaporator group are in a cooling condition, and the regenerative control valve is kept open when any evaporator is in a defrosting condition.
7. A defrosting control method of a refrigeration system employing the refrigeration system according to any one of claims 1 to 6, characterized by comprising:
judging whether an evaporator reaches a defrosting starting condition or not;
if yes, the evaporator which reaches the defrosting starting condition is used as an undetermined evaporator, the evaporator which is in the refrigerating condition and does not reach the defrosting starting condition is used as a refrigerating evaporator, whether the ratio of the sum of the number of the undetermined evaporators to the sum of the number of the refrigerating evaporators exceeds a set ratio is judged, if yes, part of evaporators are selected from the standby evaporators to be forced to enter the refrigerating working condition, then all the evaporators to be determined are started to enter the defrosting working condition, and if not, all the evaporators to be determined are directly started to enter the defrosting working condition.
8. The defrost control method of claim 7, wherein selecting a portion of evaporators to enter a defrost condition in a standby evaporator comprises:
calculating and rounding up according to the sum of the number of the evaporators to be determined and the set proportion to obtain the sum of the number of the target refrigeration evaporators;
calculating a difference between the sum of the numbers of the target refrigeration evaporators and the sum of the numbers of the refrigeration evaporators;
and selecting a corresponding evaporator from the standby evaporators to forcibly enter a refrigeration working condition randomly or according to the priority according to the difference.
9. The frost control method of claim 7, further comprising:
after all the evaporators to be determined are started to enter a defrosting condition;
judging whether the opening of the throttle valve of more than half of the refrigeration evaporators is smaller than a set opening;
if yes, opening a bypass valve, and returning part of the refrigerant flowing out of the first heat exchange pipeline of the heat regenerator to an inlet of the condenser;
if not, the bypass valve is closed.
10. The frost control method of claim 7, further comprising:
starting all the evaporators to be determined to enter a defrosting condition;
judging whether the pending evaporator reaches a defrosting ending condition or not;
if yes, the undetermined evaporators finish the defrosting condition, the refrigeration evaporators forcibly entering the refrigeration condition are recovered to be standby, whether all the undetermined evaporators finish the defrosting condition is judged, if not, whether the ratio of the sum of the number of the remaining undetermined evaporators to the sum of the number of the refrigeration evaporators exceeds a set ratio is judged, and if yes, whether any evaporator reaches a defrosting starting condition is judged.
11. The defrost control method of claim 7, wherein determining whether an evaporator has reached a defrost activation condition comprises:
monitoring the current of an evaporator under a refrigeration working condition, and judging whether the current of the evaporator exceeds a set current value or not;
if yes, the evaporator reaches a defrosting starting condition;
if not, the evaporator does not reach the defrosting starting condition.
12. The defrosting control method of claim 11 wherein before determining whether any evaporator reaches the defrosting start condition, monitoring the indoor ambient temperature of each evaporator in the evaporator group, determining whether the indoor ambient temperature of any evaporator falls to a set temperature value, and if not, starting the evaporator to enter the cooling condition.
13. A refrigeration appliance comprising: a refrigeration system and a controller for controlling an operation state of the refrigeration system, wherein the controller performs the defrosting control method according to any one of claims 7 to 12.
14. The refrigeration appliance of claim 13 wherein the refrigeration appliance is a freezer.
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