CN111928512A - Cold-hot combined multi-stage compression circulating system and control method - Google Patents
Cold-hot combined multi-stage compression circulating system and control method Download PDFInfo
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- CN111928512A CN111928512A CN202010945051.7A CN202010945051A CN111928512A CN 111928512 A CN111928512 A CN 111928512A CN 202010945051 A CN202010945051 A CN 202010945051A CN 111928512 A CN111928512 A CN 111928512A
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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
- F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit
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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
- 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
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Abstract
The invention relates to a cold-heat combined multistage compression circulation system and a control method, and the system comprises low-temperature-level heat pump units and high-temperature-level heat pump units, wherein at least two high-temperature-level heat pump units are connected in series on the low-temperature-level heat pump units, the low-temperature-level heat pump units adopt CO2 as a refrigerant, at least one high-temperature-level heat pump unit adopts an R134a refrigerant, and a defrosting assembly is arranged between a high-temperature condenser of the high-temperature-level heat pump unit adopting the R134a refrigerant and a low-temperature evaporator of the low-temperature-level heat pump unit; a heat transfer assembly is arranged between the high-temperature side of a high-temperature-stage heat pump unit high-temperature condenser adopting an R134a refrigerant and a heat using space. The refrigeration efficiency is improved by overlapping at least two high-temperature-level heat pump units on the low-temperature-level heat pump unit; meanwhile, the defrosting assembly is arranged, so that a defrosting operation is performed on a frost layer of the low-temperature evaporator in the working process, the efficiency is improved, and the energy efficiency of a unit is ensured; and the heat transmission assembly is adopted for heat transmission and use, so that the utilization rate of energy is improved.
Description
Technical Field
The invention relates to the technical field of refrigeration, in particular to a cold-hot combined multi-stage compression circulation system and a control method.
Background
In the industrial field, the temperature required by each process step in the production flow of products is different at present, part of the products need low temperature, and part of the products need high temperature, and the method which is generally adopted is that a refrigerating unit is adopted to supply cold energy, and municipal steam, a boiler and electric heating are adopted as hot water sources to supply heat; in the low-temperature part, in order to reach a lower temperature, a cascade refrigeration technology is generally adopted, the cascade refrigeration technology generally consists of two separate heat pump systems, namely a high-temperature stage part and a low-temperature stage part, the high-temperature stage part uses a medium-temperature refrigerant, and the low-temperature stage part uses a low-temperature refrigerant. The evaporation of the refrigerant in the high-temperature part system is used for condensing the refrigerant in the low-temperature part system, and a condensing evaporator is used for connecting the two parts, namely the evaporator of the high-temperature part and the condenser of the low-temperature part; the bottom of an evaporator is easy to frost when the low-temperature part is refrigerated for a long time, at present, two ways are mainly adopted for defrosting, the first unit stops working and is flushed by high-pressure water, the machine needs to be stopped for operation, the thicker the frost layer is, the longer the defrosting time is, and the production efficiency is reduced; the second method utilizes cryogenic stage partial reversal defrosting, which results in increased cold side tip temperature excursion, affecting tip use.
With the increasing social energy-saving consciousness, for heat pump circulation, only the cold quantity at the evaporation side or the heat quantity at the condensation side is generally used independently at present, so that the waste is serious, the investment is high, the system is complex and the maintenance cost is high; how to ensure the normal operation of the system unit, the problem that needs to be solved by the industry is that loads on the cold side and the hot side are used at the same time.
Disclosure of Invention
The invention aims to provide a cold and hot combined multi-stage compression circulation system and a control method, which can improve the refrigeration effect and use the heat of the system.
The invention solves the problemThe technical scheme adopted by the technical problem is as follows: the cold-heat combined multistage compression circulation system comprises low-temperature-level heat pump units and high-temperature-level heat pump units, wherein at least two high-temperature-level heat pump units are connected in series on the low-temperature-level heat pump units, and the low-temperature-level heat pump units adopt CO2As a refrigerant, at least one of the high-temperature-stage heat pump units adopts R134a as the refrigerant, a defrosting assembly is arranged between a high-temperature condenser of the high-temperature-stage heat pump unit adopting R134a as the refrigerant and a low-temperature evaporator of the low-temperature-stage heat pump unit, and the defrosting assembly conveys a liquid refrigerant generated by the high-temperature condenser of the high-temperature-stage heat pump unit adopting R134a as the refrigerant to the bottom of the low-temperature evaporator of the low-temperature-stage heat pump unit for defrosting operation; a heat transmission assembly is arranged between the high-temperature side of a high-temperature-stage heat pump unit high-temperature condenser adopting R134a as a refrigerant and a heat using space, and transmits heat generated by the high-temperature condenser to the heat using space for heating operation.
More specifically, the condensing assembly and the evaporating assembly of the low-temperature stage heat pump unit are formed by serially connecting a low-temperature compressor, a low-temperature oil separator, an evaporating condensing heat exchanger of the high-temperature stage heat pump unit, a liquid storage tank and a gas return heat exchanger, and a low-temperature oil cooler and a low-temperature oil circulating pump are sequentially serially connected between a liquid outlet of the low-temperature oil separator and the low-temperature compressor; the evaporation assembly is formed by connecting a liquid circulating pump, a low-temperature throttler, a low-temperature evaporator, a circulating barrel and an air return heat exchanger in series; the refrigerant in the condensation component sequentially passes through the low-temperature compressor, the low-temperature oil separator, the evaporation condensation heat exchanger of the high-temperature heat pump unit, the liquid storage tank and the air return heat exchanger and then enters the circulating barrel; in the evaporation assembly, the refrigerant sequentially passes through the liquid circulating pump, the low-temperature throttler and the low-temperature evaporator from the circulating barrel and then returns to the circulating barrel, and the refrigerant which is changed into a gaseous state enters the gas-return heat exchanger and then enters the condensation assembly for circulation.
More specifically, a low-temperature side pressure probe and a low-temperature side temperature probe are arranged at the inlet of the low-temperature compressor, and a control electromagnetic valve is arranged at the rear end of the low-temperature evaporator.
More specifically, the high-temperature-stage heat pump unit is formed by serially connecting a high-temperature compressor, a high-temperature oil separator, a high-temperature condenser, a high-temperature restrictor and an evaporation and condensation heat exchanger, wherein a high-temperature oil cooler and a high-temperature oil circulating pump are sequentially serially connected between a liquid outlet of the high-temperature oil separator and an inlet of the high-temperature compressor.
More specifically, a high-temperature side pressure probe and a high-temperature side temperature probe are provided at an inlet of the high-temperature compressor, and an oil pressure probe and an oil temperature probe are provided at a gas outlet of the high-temperature oil separator.
Further specifically, the defrosting assembly is formed by serially connecting a coil pipe, a one-way valve and a capillary pipe fitting which are arranged at the bottom of a low-temperature evaporator of the low-temperature-level heat pump unit, and a liquid refrigerant is output by the high-temperature condenser, passes through the defrosting assembly, is output to the front end of the evaporative condensation heat exchanger, and returns to the high-temperature-level heat pump unit which adopts R134a as the refrigerant to continue to circulate.
More specifically, a high-temperature electromagnetic valve is arranged at the front end of the coil.
More specifically, at least one of the high-temperature-stage heat pump units uses R717 as a refrigerant.
A control method of a cold and hot combined multi-stage compression circulating system comprises the following steps,
s1, starting a low-temperature-level heat pump unit for refrigeration;
s2, judging whether the refrigeration temperature reaches the required temperature, if so, keeping the frequency of the low-temperature compressor unchanged; if not, increasing the frequency of the low-temperature compressor, continuing to loop to the step S2 until the low-temperature compressor runs at full frequency, and then entering the step S3;
s3, starting a high-temperature heat pump unit which does not adopt R134a as a refrigerant and continuously cooling;
s4, judging whether the refrigeration temperature reaches the required temperature, if so, keeping the frequency of the high-temperature compressor unchanged; if not, the frequency of the high-temperature compressor is increased, and the loop continues to step S4 until the required temperature is reached.
More specifically, when defrosting is required, a high-temperature-stage heat pump unit adopting R134a as a refrigerant is started, and a defrosting assembly is started to transmit a liquid refrigerant to a low-temperature evaporator; meanwhile, according to the refrigeration efficiency of the high-temperature-level heat pump unit adopting R134a as the refrigerant, the refrigeration efficiency of the high-temperature-level heat pump unit not adopting R134a as the refrigerant is reduced.
The invention has the beneficial effects that: the refrigeration efficiency is improved by overlapping at least two high-temperature-level heat pump units on the low-temperature-level heat pump unit; meanwhile, the defrosting assembly is arranged, so that a defrosting operation is performed on a frost layer of the low-temperature evaporator in the working process, the efficiency is improved, and the energy efficiency of a unit is ensured; and the heat transmission assembly is adopted for heat transmission and use, so that the utilization rate of energy is improved.
Drawings
Fig. 1 is a schematic structural view of the present invention.
In the figure: 1. a high temperature compressor; 2. a high temperature oil separator; 3. a high temperature condenser; 4. a high temperature restrictor; 5. a high temperature oil cooler; 6. a high temperature oil circulation pump; 8. a cryogenic compressor; 9. a low temperature oil separator; 10. an evaporation and condensation heat exchanger; 11. a liquid storage tank; 12. a return air heat exchanger; 13. a low temperature oil cooler; 14. a low temperature oil circulation pump; 15. a liquid state circulating pump; 16. a low temperature restrictor; 17. a low temperature evaporator; 18. a circulating barrel; 19. controlling the electromagnetic valve; 20. a coil pipe; 21. a one-way valve; 22. a capillary tube member; 23. high temperature solenoid valve.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings.
As shown in fig. 1, the cold-heat combined multistage compression cycle system includes a low-temperature stage heat pump unit and a high-temperature stage heat pump unit, at least two high-temperature stage heat pump units are connected in series to the low-temperature stage heat pump unit, and the low-temperature stage heat pump unit adopts CO2At least one high-temperature-stage heat pump unit adopts R134a as a refrigerant, a defrosting assembly is arranged between the high-temperature condenser 3 of the high-temperature-stage heat pump unit adopting R134a as the refrigerant and the low-temperature evaporator 17 of the low-temperature-stage heat pump unit, and the defrosting assembly conveys the liquid refrigerant generated by the high-temperature condenser 3 of the high-temperature-stage heat pump unit adopting R134a as the refrigerant to the low-temperature evaporator of the low-temperature-stage heat pump unit17, defrosting at the bottom; a heat transmission assembly is arranged between the high-temperature side of the high-temperature-stage heat pump unit high-temperature condenser 3 adopting R134a as a refrigerant and the heat using space, and the heat transmission assembly transmits the heat generated by the high-temperature condenser 3 to the heat using space for heating operation; the hot space can be a plurality of closed environments, such as places of shopping malls, workshops, office buildings, residential buildings, schools, hospitals and the like.
In the scheme, the high-temperature heat pump unit comprises a first high-temperature heat pump unit A and a second high-temperature heat pump unit B, wherein the first high-temperature heat pump unit A adopts R717 as a refrigerant, and the R717 is NH3，NH3The second high-temperature-stage heat pump unit B adopts R134a as a refrigerant, R134a is tetrafluoroethane, and the high-temperature-stage heat pump unit B can provide high heating temperature on the high-temperature side; the low-temperature heat pump unit carries out cooling operation through the low-temperature evaporator 17, and the first high-temperature heat pump unit A is started under the condition that the cooling efficiency of the low-temperature heat pump unit is insufficient and the cooling efficiency is enhanced; the second high-temperature-level heat pump unit B plays three roles, the first defrosting component is used for defrosting the low-temperature evaporator 17, the second heat space supplies heat, and the third heat pump unit is matched with the low-temperature-level heat pump unit to realize cooling.
The low-temperature heat pump unit comprises a condensation component and an evaporation component, wherein the condensation component is formed by serially connecting a low-temperature compressor 8, a low-temperature oil separator 9, an evaporation condensation heat exchanger 10 of the high-temperature heat pump unit, a liquid storage tank 11 and an air return heat exchanger 12, and a low-temperature oil cooler 13 and a low-temperature oil circulating pump 14 are sequentially serially connected between a liquid outlet of the low-temperature oil separator 9 and the low-temperature compressor 8; the evaporation assembly is formed by connecting a liquid circulating pump 15, a low-temperature throttler 16, a low-temperature evaporator 17, a circulating barrel 18 and a gas return heat exchanger 12 in series; in the condensing assembly, a gaseous refrigerant firstly enters a low-temperature compressor 8 to be compressed into a high-pressure high-temperature gaseous refrigerant, the gaseous refrigerant enters a low-temperature oil separator 9 to be subjected to gas-liquid separation, the gaseous refrigerant enters an evaporation condensing heat exchanger 10, and a liquid refrigerant enters a low-temperature oil cooler 13 and reenters the low-temperature compressor 8 through a low-temperature oil circulating pump 14 to be compressed; the gaseous refrigerant entering the evaporation condensation heat exchanger 10 exchanges heat with the high-temperature-level heat pump unit, the gaseous refrigerant enters the liquid storage tank 11 after being changed into the liquid refrigerant, the liquid refrigerant enters the return air heat exchanger 12 after passing through the liquid storage tank 11, the heat exchange is carried out between the gaseous refrigerant and the gaseous refrigerant which is about to enter the low-temperature compressor 8 in the return air heat exchanger 12, the temperature of the gaseous refrigerant is reduced, and the energy consumption of the gaseous refrigerant is reduced after entering the low-temperature compressor 8; at the moment, a small part of the liquid refrigerant is changed into a gas state, the refrigerant mixed with the gas state and the liquid state enters the circulating barrel 18 of the evaporation assembly, the liquid refrigerant is arranged at the bottom of the circulating barrel 18, and the gas refrigerant enters the return air heat exchanger 12 from the top of the circulating barrel 18 for heat exchange and then enters the low-temperature compressor 8 to continue compression and circulation; in the evaporation assembly, liquid refrigerant enters a low-temperature throttler 16 from the bottom of a circulating barrel 18 through a liquid circulating pump 15 and then enters a low-temperature evaporator 17 for heat exchange operation, the liquid refrigerant after heat exchange becomes gaseous, at the moment, the gaseous refrigerant is also mixed with the liquid refrigerant, the mixed refrigerant flows back to the circulating barrel 18, the liquid refrigerant and the gaseous refrigerant are separated in the circulating barrel 18, the liquid refrigerant continues to participate in circulation in the evaporation assembly downwards, and the gaseous refrigerant enters a low-temperature compressor 8 after upwards entering a gas return heat exchanger 12 to participate in circulation in a condensation assembly; the system is characterized in that a low-temperature side pressure probe and a low-temperature side temperature probe are arranged at an inlet of the low-temperature compressor 8, a control electromagnetic valve 19 is arranged at the rear end of the low-temperature evaporator 17, and in the food quick-freezing industry, an oil film is inevitably adhered to the surface of the low-temperature evaporator 17. In addition, the liquid circulation pump 15 also monitors the suction overheating condition according to the low-temperature side temperature probe at the inlet of the low-temperature compressor 8 and the low-temperature side pressure probe at the inlet of the low-temperature compressor 8 for automatic frequency conversion, so as to prevent liquid impact and over-high exhaust temperature.
The first high-temperature-stage heat pump unit A and the second high-temperature-stage heat pump unit B have the same structure, the refrigerant circulation condition is also the same, the high-temperature-stage heat pump unit is formed by serially connecting a high-temperature compressor 1, a high-temperature oil separator 2, a high-temperature condenser 3, a high-temperature restrictor 4 and an evaporative condensing heat exchanger 10, and a high-temperature oil cooler 5 and a high-temperature oil circulating pump 6 are sequentially serially connected between the liquid outlet of the high-temperature oil separator 2 and the inlet of the high-temperature compressor 1; the evaporative condenser 10 of the first high-temperature-level heat pump unit A and the evaporative condenser 10 of the second high-temperature-level heat pump unit B are simultaneously connected in series on a loop of a condensing assembly of the low-temperature-level heat pump unit; firstly, gaseous refrigerant enters a high-temperature compressor 1 to be compressed, the compressed gaseous refrigerant is changed into high-pressure high-temperature gaseous refrigerant and then enters a high-temperature oil separator 2 to be subjected to gas-liquid separation, the gaseous refrigerant enters a high-temperature condenser 3, and the liquid refrigerant enters a high-temperature oil cooler 5 and reenters the high-temperature compressor 1 through a high-temperature oil circulating pump 6 to be subjected to compression circulation; the high-temperature condenser 3 cools the gaseous refrigerant into a liquid refrigerant, the liquid refrigerant passes through the high-temperature throttler 4, the high-temperature throttler 4 sends the low-temperature liquid refrigerant into the evaporation condensation heat exchanger 10 to exchange heat with the low-temperature heat pump unit, the refrigerant after heat exchange becomes gaseous (or the gaseous state is mixed with the liquid state), and then the refrigerant enters the high-temperature compressor 1 to be compressed and circulated; a high-temperature side pressure probe and a high-temperature side temperature probe are arranged at the inlet of the high-temperature compressor 1, and an oil content pressure probe and an oil content temperature probe are arranged at the gas outlet of the high-temperature oil separator 2; the high-temperature oil circulating pump 6 adopts a variable frequency pump, and because the system is a cascade system and the low-temperature evaporator 17 can provide different temperatures, the pressure on two sides in the evaporation condensation heat exchanger 10 changes more and has large amplitude, and the high-temperature oil circulating pump 6 can automatically add frequency under the working condition that the high-temperature heat pump unit is at a high evaporation temperature, thereby ensuring smooth oil return; and when the high-temperature heat pump unit is in the low evaporation temperature working condition, the frequency is automatically reduced, and the gaseous refrigerant is prevented from returning to the high-temperature compressor 1, so that the effective air suction amount of the high-temperature compressor 1 is reduced.
The defrosting assembly is formed by connecting a coil pipe 20, a one-way valve 21 and a capillary tube 22 which are arranged at the bottom of a low-temperature evaporator 17 of the low-temperature-level heat pump unit in series, liquid refrigerant is output by a high-temperature condenser 3 and sequentially passes through the coil pipe 20, the one-way valve 21 and the capillary tube 22, the capillary tube 22 plays a throttling role, the liquid refrigerant is output to the front end of the evaporation and condensation heat exchanger 10 and returns to the second high-temperature-level heat pump unit B for continuous circulation, meanwhile, a high-temperature electromagnetic valve 23 is arranged at the front end of the coil pipe 20, and the high-temperature electromagnetic valve 23 is opened according to the specific frosting condition at the bottom of the low-temperature; the temperature of the liquid refrigerant output by the high-temperature condenser 3 of the second high-temperature stage heat pump unit B is 30-50 ℃, the temperature of the bottom of the low-temperature evaporator 17 of the low-temperature stage heat pump unit is lower, the frozen layer at the bottom of the low-temperature evaporator 17 is thawed through heat exchange, and the temperature of the liquid refrigerant in the defrosting assembly is reduced, is cooled through the capillary tube 22 and then returns to the circulation loop.
The heat transmission assembly comprises a pipeline for transmitting heat, the pipeline forms a cycle, the high-temperature side heat of the high-temperature condenser 3 in the second high-temperature stage heat pump unit B is received on the pipeline and transmitted to a heat using space, and hot water or hot air can be arranged in the pipeline; when the water is hot water, circulation is realized through a water pump, and hot water with the temperature not lower than 55 ℃ can be provided; when the hot air is used, circulation is realized through the fan.
Based on the system, a control method of the cold-heat combined multi-stage compression circulating system is provided,
s1, starting the low-temperature heat pump unit to refrigerate and cool the refrigerant CO2The circulation carries out refrigeration at the low-temperature evaporator 17, and detects the temperature of the process room through an ambient temperature probe and transmits the temperature to the control end of the system in real time.
S2, the control end receives the environment temperature signal and compares the environment temperature signal with a built-in temperature threshold value, whether the refrigeration temperature reaches the required temperature is judged, if yes, the frequency of the low-temperature compressor 8 is kept unchanged, and refrigeration is continued; if not, increasing the frequency of the low-temperature compressor 8, further reducing the temperature, collecting the environmental temperature signal, continuing to loop to the step S2, and entering the step S3 after the low-temperature compressor 8 runs at full frequency.
S3, starting the first high-temperature-stage heat pump unit A, enabling the first high-temperature-stage heat pump unit A and the low-temperature-stage heat pump unit to form a cold and hot combined multi-stage compression circulating system, continuing to cool the process chamber, and meanwhile detecting the temperature of the process chamber through the ambient temperature tower head and transmitting the temperature to the control end.
S4, judging whether the refrigerating temperature reaches the required temperature, if so, keeping the frequencies of the high-temperature compressor 1 and the low-temperature compressor 8 unchanged; if not, the frequency of the high temperature compressor 1 is increased, and the loop continues to step S4 until the desired temperature is reached.
The steps are the operation steps of integral cooling, and automatic adjustment and control are carried out on the acquisition of the environmental temperature; when defrosting or heating is required, the second high-temperature-stage heat pump unit B is started, the defrosting assembly is started to transmit liquid refrigerants to the low-temperature evaporator 17, and the heat transmission assembly transmits heat to the heat utilization space; in defrosting, defrosting is realized through the difference between the temperature of the low-temperature-level heat pump unit and the temperature of the second high-temperature-level heat pump unit B; because heat exchange is carried out between the liquid refrigerant of the second high-temperature heat pump unit B and the low-temperature evaporator 17 of the low-temperature stage heat pump unit, the temperature of the liquid refrigerant of the second high-temperature heat pump unit B is reduced while defrosting, and after the liquid refrigerant returns to the circulation loop again, the supercooling degree is increased, and the refrigerating efficiency of the second high-temperature stage heat pump unit B is obviously improved; during defrosting and heating, the refrigeration efficiency of the first high-temperature-level heat pump unit A can be correspondingly reduced according to the refrigeration efficiency of the second high-temperature-level heat pump unit B; the compressors in the first high-temperature-stage heat pump unit A and the second high-temperature-stage heat pump unit B are frequency conversion compressors, the heat loads of the evaporative condenser 10 are distributed together, and on the premise that the refrigerating capacity of the unit is met, the load proportion of the second high-temperature heat pump unit B is increased as much as possible, so that the supply of effective heat to the tail end is improved; the load distribution is automatically distributed through the low-temperature evaporation temperature and the suction superheat degree.
In summary, the refrigeration efficiency is improved by overlapping at least two high-temperature-stage heat pump units on the low-temperature-stage heat pump unit; meanwhile, the defrosting assembly is arranged, so that a defrosting operation is performed on a frost layer of the low-temperature evaporator in the working process, the efficiency is improved, and the energy efficiency of a unit is ensured; and the heat transmission assembly is adopted for heat transmission and use, so that the utilization rate of energy is improved.
It is to be emphasized that: the above embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and all simple modifications, equivalent changes and modifications made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.
Claims (10)
1. A multi-stage compression circulation system for cold and hot applications comprises a low temperature compressorThe heat pump unit comprises a stage heat pump unit and a high-temperature stage heat pump unit, and is characterized in that at least two high-temperature stage heat pump units are connected in series on a low-temperature stage heat pump unit, and the low-temperature stage heat pump unit adopts CO2The defrosting component is arranged between a high-temperature condenser (3) of the high-temperature heat pump unit which adopts R134a as the refrigerant and a low-temperature evaporator (17) of the low-temperature heat pump unit, and the liquid refrigerant generated by the high-temperature condenser (3) of the high-temperature heat pump unit which adopts R134a as the refrigerant is conveyed to the bottom of the low-temperature evaporator (17) of the low-temperature heat pump unit by the defrosting component to be defrosted; a heat transfer assembly is arranged between the high-temperature side of the high-temperature-stage heat pump unit high-temperature condenser (3) adopting R134a as a refrigerant and a heat using space, and the heat transfer assembly transfers heat generated by the high-temperature condenser (3) to the heat using space for heating operation.
2. A cold-heat combined multistage compression cycle system according to claim 1, wherein the low-temperature stage heat pump unit condensation unit and the evaporation unit are connected in series, the condensation unit is formed by connecting a low-temperature compressor (8), a low-temperature oil separator (9), an evaporation-condensation heat exchanger (10) of the high-temperature stage heat pump unit, a liquid storage tank (11) and a return-air heat exchanger (12) in series, and a low-temperature oil cooler (13) and a low-temperature oil circulation pump (14) are connected in series between a liquid outlet of the low-temperature oil separator (9) and the low-temperature compressor (8); the evaporation assembly is formed by connecting a liquid circulating pump (15), a low-temperature throttler (16), a low-temperature evaporator (17), a circulating barrel (18) and a gas return heat exchanger (12) in series; the refrigerant in the condensation component sequentially passes through a low-temperature compressor (8), a low-temperature oil separator (9), an evaporation condensation heat exchanger (10) of a high-temperature heat pump unit, a liquid storage tank (11) and an air return heat exchanger (12) and then enters a circulating barrel (18); in the evaporation assembly, the refrigerant passes through the liquid circulating pump (15), the low-temperature throttler (16) and the low-temperature evaporator (17) in sequence from the circulating barrel (18) and then returns to the circulating barrel (18), and the refrigerant which is changed into a gaseous state enters the gas return heat exchanger (12) and then enters the condensation assembly for circulation.
3. A cold-heat combined multi-stage compression cycle system according to claim 2, wherein a low-temperature side pressure probe and a low-temperature side temperature probe are provided at an inlet of the low-temperature compressor (8), and a control solenoid valve (19) is provided at a rear end of the low-temperature evaporator (17).
4. A multistage compression cycle system for combined cooling and heating according to claim 1, wherein the high-temperature stage heat pump unit is formed by connecting a high-temperature compressor (1), a high-temperature oil separator (2), a high-temperature condenser (3), a high-temperature throttle (4) and an evaporative condensing heat exchanger (10) in series, and a high-temperature oil cooler (5) and a high-temperature oil circulating pump (6) are connected in series between a liquid outlet of the high-temperature oil separator (2) and an inlet of the high-temperature compressor (1) in this order.
5. A cold-hot combination multistage compression cycle system according to claim 4, wherein a high-temperature-side pressure probe and a high-temperature-side temperature probe are provided at an inlet of the high-temperature compressor (1), and an oil pressure probe and an oil temperature probe are provided at a gas outlet of the high-temperature oil separator (2).
6. A cold and hot combined multistage compression cycle system according to claim 4, wherein the defrosting component is formed by connecting a coil pipe (20), a one-way valve (21) and a capillary pipe fitting (22) which are arranged at the bottom of the low-temperature evaporator (17) of the low-temperature stage heat pump unit in series, and liquid refrigerant is output from the high-temperature condenser (3), passes through the defrosting component, is output to the front end of the evaporative condensation heat exchanger (10), and returns to the high-temperature stage heat pump unit which adopts R134a as refrigerant for continuous circulation.
7. A multistage compression cycle system for cold and hot use according to claim 6, wherein a high temperature solenoid valve (23) is provided at a front end of the coil pipe (20).
8. A multi-stage compression cycle system for cooling and heating as claimed in claim 1, wherein at least one of the high-temperature stage heat pump units uses R717 as a refrigerant.
9. A control method of a cold and hot combined multistage compression circulation system is characterized in that the control method comprises the following steps,
s1, starting a low-temperature-level heat pump unit for refrigeration;
s2, judging whether the refrigeration temperature reaches the required temperature, if so, keeping the frequency of the low-temperature compressor (8) unchanged; if not, increasing the frequency of the low-temperature compressor (8), continuing to loop the step S2 until the low-temperature compressor (8) runs at full frequency, and then entering the step S3;
s3, starting a high-temperature heat pump unit which does not adopt R134a as a refrigerant and continuously cooling;
s4, judging whether the refrigerating temperature reaches the required temperature, if so, keeping the frequency of the high-temperature compressor (1) unchanged; if not, increasing the frequency of the high-temperature compressor (1), and continuing to loop the step S4 until the required temperature is reached.
10. The control method of a multistage compression cycle system for combined cooling and heating according to claim 9, wherein when defrosting is required, a high-temperature stage heat pump unit using R134a as a refrigerant is turned on and a defrosting component is turned on to deliver a liquid refrigerant to the low-temperature evaporator (17); meanwhile, according to the refrigeration efficiency of the high-temperature-level heat pump unit adopting R134a as the refrigerant, the refrigeration efficiency of the high-temperature-level heat pump unit not adopting R134a as the refrigerant is reduced.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010945051.7A CN111928512A (en) | 2020-09-10 | 2020-09-10 | Cold-hot combined multi-stage compression circulating system and control method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010945051.7A CN111928512A (en) | 2020-09-10 | 2020-09-10 | Cold-hot combined multi-stage compression circulating system and control method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112902282A (en) * | 2021-01-28 | 2021-06-04 | 广东芬尼克兹节能设备有限公司 | Cascade type heat pump start-stop control method and device, computer equipment and storage medium |
| WO2024017611A1 (en) * | 2022-07-20 | 2024-01-25 | Atlantic Refrigeration Consulting | De-icing system for an nh3/co2 cascade unit |
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2020
- 2020-09-10 CN CN202010945051.7A patent/CN111928512A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112902282A (en) * | 2021-01-28 | 2021-06-04 | 广东芬尼克兹节能设备有限公司 | Cascade type heat pump start-stop control method and device, computer equipment and storage medium |
| WO2024017611A1 (en) * | 2022-07-20 | 2024-01-25 | Atlantic Refrigeration Consulting | De-icing system for an nh3/co2 cascade unit |
| FR3138192A1 (en) * | 2022-07-20 | 2024-01-26 | Atlantic Refrigeration Consulting | DEFROSTING SYSTEM FOR AN NH3/CO2 CASCADE INSTALLATION |
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