CN111780444B - Vapor compression cascade heat pump cycle and single-stage heat pump cycle combined system - Google Patents
Vapor compression cascade heat pump cycle and single-stage heat pump cycle combined system Download PDFInfo
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- CN111780444B CN111780444B CN202010494499.1A CN202010494499A CN111780444B CN 111780444 B CN111780444 B CN 111780444B CN 202010494499 A CN202010494499 A CN 202010494499A CN 111780444 B CN111780444 B CN 111780444B
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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
- F25B13/00—Compression machines, plants or systems, with reversible cycle
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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
- F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
- F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
- F25B2313/02741—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using one four-way valve
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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
- F25B2347/00—Details for preventing or removing deposits or corrosion
- F25B2347/02—Details of defrosting cycles
- F25B2347/022—Cool gas defrosting
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Abstract
The invention relates to a vapor compression cascade heat pump cycle and single-stage heat pump cycle combined system, which comprises a cascade heat pump cycle, a single-stage heat pump cycle and a water supply flow path; the cascade heat pump cycle comprises a low-temperature stage cycle and a high-temperature stage cycle which are in heat exchange connection with each other; the low-temperature stage circulation is structurally connected with the single-stage heat pump circulation; the water supply flow path is respectively connected with the high-temperature stage cycle and the single-stage heat pump cycle in a heat exchange mode, and the water supply flow path can output hot water/cold water outwards so as to realize external heating/cooling. Compared with the prior art, the heat pump cycle combined system can adaptively switch different heating modes according to the environmental working condition and the heating requirement, comprehensively meets the heating requirement in the whole heating season, and has high total energy efficiency; the heat pump cycle combined system can provide a refrigeration function in summer at the same time, and the utilization rate of the unit is high; the heat pump circulation combined system has the advantages that the heat exchange area is increased and the system energy efficiency is improved in the single-stage heat pump heating/cooling mode.
Description
Technical Field
The invention relates to a heat pump system, in particular to a vapor compression cascade heat pump cycle and single-stage heat pump cycle combined system.
Background
The traditional coal-fired heating has low utilization rate of primary energy and also causes serious environmental pollution. In order to realize energy conservation and emission reduction, the state strongly puts forward a clean heating policy of changing coal into electricity in northern areas. The air source heat pump takes outdoor air as a heat source, has high heating efficiency and wide adaptability, and is one of common heating alternatives. Meanwhile, the reverse circulation of the air source heat pump can realize refrigeration in summer, the utilization rate of the unit is high, and the initial investment is saved.
The outdoor temperature span in winter in northern severe cold areas is large and can be changed from-30 ℃ to 15 ℃. When the ambient temperature is lower than-5 ℃, the single-stage air source heat pump is adopted to generate serious heating quantity attenuation, and the compressor is difficult to operate due to the overlarge pressure ratio. Compared with the prior art, the cascade heat pump cycle comprises a low-temperature stage cycle and a high-temperature stage cycle, has a small pressure ratio, and is more suitable for the heating requirement under the low-temperature working condition. However, when the ambient temperature is higher than 0 ℃, the advantage of the small pressure ratio of the cascade heat pump is reduced. Because the heat exchange temperature difference of one layer is increased, the overall heating efficiency of the cascade heat pump is lower than that of a single-stage heat pump. Therefore, it is difficult to ensure efficient heating throughout the winter only by using the cascade heat pump or the single-stage heat pump.
The problem of frosting at low temperature of the air source heat pump is also an important problem influencing the performance of the unit. Common defrosting methods are electric heating defrosting, reverse cycle defrosting and hot gas bypass defrosting. The electric heating defrosting energy consumption is large. The cascade heat pump adopts a reverse circulation defrosting structure, and has complex structure and high control difficulty. The hot gas bypass defrosting is to introduce high-temperature exhaust gas of the compressor into the evaporator to defrost, and the mode has the advantages of high power consumption of the compressor, long defrosting time under a low-temperature working condition and low efficiency.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a combined system of a vapor compression cascade heat pump cycle and a single-stage heat pump cycle, and the heat pump cycle combined system meets the requirements of winter heating and summer cooling in severe cold areas.
The purpose of the invention can be realized by the following technical scheme:
the vapor compression cascade heat pump cycle and single-stage heat pump cycle combined system comprises a cascade heat pump cycle, a single-stage heat pump cycle and a water supply flow path;
the cascade heat pump cycle comprises a low-temperature stage cycle and a high-temperature stage cycle which are in heat exchange connection with each other;
the low-temperature stage circulation is structurally connected with the single-stage heat pump circulation;
the water supply flow path is respectively connected with the high-temperature stage cycle and the single-stage heat pump cycle in a heat exchange mode, and the water supply flow path can output hot water/cold water outwards so as to realize external heating/cooling.
Further, the low-temperature stage cycle and the high-temperature stage cycle are in heat exchange connection through a condensing evaporator;
the low-temperature stage circulation is connected with the single-stage heat pump circulation through a first evaporator and a second evaporator in a structural mode;
the first evaporator and the second evaporator are mutually independent and structurally have an integral structure.
The water supply pipeline is in heat exchange type connection with the low-temperature stage circulation through a first condenser;
the water supply flow path is connected with the single-stage heat pump in a circulating heat exchange manner through a second condenser.
Further, the low-temperature stage circulation comprises a low-temperature compressor, a first heat exchange channel of a first evaporator, a first throttle valve and a first heat exchange channel of a condensation evaporator which are sequentially connected, wherein the first heat exchange channel of the condensation evaporator is connected with the low-temperature compressor to form the low-temperature stage circulation.
Further, the first heat exchange channel of the first evaporator is a refrigerant channel, and the second heat exchange channel of the first evaporator is an air channel. The first heat exchange channel of the second evaporator is a refrigerant channel, and the second heat exchange channel is an air channel. The refrigerant channels of the first evaporator and the second evaporator are independent.
Further, the high-temperature stage circulation comprises a high-temperature compressor, a first heat exchange channel of a first condenser, a second throttling valve and a second heat exchange channel of a condensation evaporator which are sequentially connected, wherein the second heat exchange channel of the condensation evaporator is connected with the high-temperature compressor to form the high-temperature stage circulation.
Further, the single-stage heat pump cycle comprises a single-stage compressor, a first heat exchange channel of the second evaporator, a third throttle valve and a first heat exchange channel of the second condenser which are connected in sequence.
Furthermore, the single-stage heat pump cycle further comprises a four-way reversing valve, an exhaust port 8B of the single-stage compressor is connected with a connecting port 9B of the four-way reversing valve, a connecting port 9C of the four-way reversing valve is connected with a first heat exchange channel of the second condenser, the first heat exchange channel of the second condenser is connected with the third throttle valve, the first heat exchange channel of the second evaporator is connected with a connecting port 9A of the four-way reversing valve, and a connecting port 9D of the four-way reversing valve is connected with an air suction port 8A of the single-stage compressor, so that the single-stage heat pump cycle is formed.
Further, the water supply flow path comprises a first water pump, a second water pump, a flow dividing valve, a water tank, a third water pump, a second heat exchange channel of the first condenser and a second heat exchange channel of the second condenser;
the return water of the water supply flow path is divided into two paths by the flow dividing valve, one path of the return water is sent into the second heat exchange channel of the first condenser through the first water pump to be heated and then enters the water tank, the other path of the return water is sent into the second heat exchange channel of the second condenser through the second water pump to be heated and then is sent into the water tank, and the hot water in the water tank is sent into the heating tail end through the third water pump.
The first evaporator and the second evaporator are refrigerant-air heat exchangers, are provided with refrigerant channels and air channels, and are commonly of finned tube heat exchangers. The first evaporator and the second evaporator are combined into an integral heat exchanger, the integral heat exchanger shares the same group of heat exchange fins, and heat exchange pipelines are distributed in a crossed and staggered manner.
The first condenser and the second condenser are refrigerant-secondary refrigerant heat exchangers and are provided with refrigerant channels and secondary refrigerant channels, and the common types of the first condenser and the second condenser are plate heat exchangers, sleeve heat exchangers and the like.
The condensing evaporator is a refrigerant-refrigerant heat exchanger and is provided with double refrigerant channels, and common types of the condensing evaporator are a plate heat exchanger, a sleeve type heat exchanger and the like. An inlet of a high-temperature channel of the condensation evaporator is communicated with the low-temperature grade exhaust port through a refrigerant connecting pipe, and an outlet of the high-temperature channel is communicated with the first throttling valve through the refrigerant connecting pipe; the inlet of the low-temperature channel of the condensing evaporator is communicated with the second throttling valve through a refrigerant connecting pipe, and the outlet of the low-temperature channel is communicated with the air suction port of the high-temperature compressor through the refrigerant connecting pipe.
The first throttle valve, the second throttle valve and the third throttle valve can be common throttle devices such as electronic expansion valves and the like and are used for adjusting the flow of the refrigerant by controlling the superheat degree of the outlet.
Two interfaces of the four-way reversing valve are respectively communicated with an air suction port and an air exhaust port of the single-stage compressor, and the other two interfaces are communicated with a refrigerant channel at one end of the second evaporator and one end of the second condenser.
In an embodiment of the present invention, the compressor of the single-stage heat pump cycle is an air-make enthalpy-increasing compressor. The air-supplying enthalpy-increasing compressor comprises an air suction port, an air supply port and an air exhaust port. Wherein, the air supplement port is communicated with the air supplement tank through a refrigerant connecting pipe.
The combined system can realize three functions of heating in winter, refrigerating in summer and defrosting.
In the winter heating mode, the overlapping heat pump cycle and the single-stage heat pump cycle can simultaneously or independently heat according to the environmental working condition and the load requirement. The working principle of the overlapping heat pump circulation heating mode is as follows: in the low-temperature stage circulation loop, low-temperature and low-pressure refrigerant liquid is vaporized in a first evaporator to absorb heat, low-grade heat energy of ambient air is absorbed, the low-temperature and low-pressure refrigerant liquid is compressed by a low-temperature compressor to become high-temperature and high-pressure gas, the high-temperature gas is condensed in a condensing evaporator to release heat, and finally the high-temperature gas is changed into low-temperature and low-pressure liquid again through a first throttling valve. In the high-temperature stage circulation loop, low-temperature low-pressure refrigerant liquid is vaporized in the condensation evaporator to absorb heat, the condensation of low-temperature stage gaseous refrigerant is absorbed to release heat, the low-temperature low-pressure refrigerant liquid is compressed by the high-temperature compressor to become high-temperature high-pressure gas, the high-temperature high-pressure gas enters the first condenser to be condensed to release heat, heating backwater is heated, and the high-temperature high-pressure gas is changed into low-temperature low-pressure liquid again through the second throttling valve.
The working principle of the single-stage heat pump circulation heating mode is as follows: the low-temperature low-pressure refrigerant liquid is vaporized in the second evaporator to absorb heat, low-grade heat energy of ambient air is absorbed, the low-temperature low-pressure refrigerant liquid enters the single-stage compressor through the four-way reversing valve and is compressed into high-temperature high-pressure gas, the high-temperature gas enters the second condenser through the four-way reversing valve and is condensed to release heat, heating backwater is heated, and finally the high-temperature high-pressure gas is changed into low-temperature low-pressure liquid again through the third throttle valve.
Two channels of the flow divider are opened, heating backwater is divided into two channels, one channel is sent into the first condenser through the first water pump to be heated and then enters the water tank, the other channel is sent into the second condenser through the second water pump to be heated and then is sent into the water tank, and hot water in the water tank is sent into the heating tail end through the third water pump.
In the summer refrigeration mode, the cascade heat pump cycle stops working, and the single-stage heat pump cycle is switched to the refrigeration mode. The unit is mainly used in low-temperature severe cold areas, so that the refrigeration load is lower. Although the cascade circulation cannot be switched to a refrigeration mode, the single-stage circulation can reduce the condensation temperature by utilizing the heat exchange area which is not used by the cascade circulation, and improve the refrigeration capacity and the refrigeration efficiency, thereby basically meeting the cooling demand of a use area.
The working principle of the single-stage heat pump circulating refrigeration mode is as follows: the four-way reversing valve is turned, high-temperature and high-pressure gas discharged from the single-stage compressor enters the second evaporator to be condensed and released heat, the high-temperature and high-pressure gas exchanges heat with outdoor air, the high-pressure gas is changed into low-temperature and low-pressure liquid through the third throttling valve, then enters the second condenser to be evaporated and absorbed heat, the refrigeration backwater is reduced to a set temperature, and finally the refrigeration backwater enters the single-stage compressor through the four-way reversing valve to be compressed again into high-temperature and high-pressure gas.
And when a channel of the flow divider is closed, the refrigerating return water is sent to the first condenser through the first water pump for refrigeration and then enters the water tank, and the cold water in the water tank is sent to the refrigerating tail end through the third water pump.
In the defrosting mode, the cascade heat pump cycle stops working, the single-stage heat pump cycle four-way reversing valve turns, high-temperature and high-pressure gas discharged from the single-stage compressor enters the second evaporator to be condensed and released, an evaporator coil is defrosted, the high-pressure gas is changed into low-temperature and low-pressure liquid through the third throttling valve, then enters the second condenser to be evaporated and absorbed, heat of heating return water is absorbed, and finally enters the single-stage compressor through the four-way reversing valve to be recompressed into high-temperature and high-pressure gas.
And when the channel I of the flow divider is closed, the heating backwater enters the second condenser through the second water pump to be cooled and then is sent into the water tank.
The heating/refrigerating (defrosting) mode of the single-stage heat pump cycle is realized by switching the four-way reversing valve.
The invention has the following core innovation points: 1. the overlapping circulation and the single-stage heat pump circulation are combined into a combined system, so that three functions of heating in winter, refrigerating in summer and defrosting can be realized; 2. the evaporator of the cascade circulation and the evaporator of the single-stage heat pump circulation are combined into an integral heat exchanger, and share the same group of heat exchange fins; 3. during defrosting, the four-way reversing valve of the single-stage heat pump circulation is turned to defrost the integral evaporator.
Compared with the prior art, the invention has the following advantages:
1. the heat pump cycle combined system can adaptively switch different heating modes according to the environmental working condition and the heating requirement, comprehensively meets the heating requirement in the whole heating season, and has high total energy efficiency.
2. The heat pump cycle combined system can provide a refrigeration function in summer at the same time, the utilization rate of the unit is high, and the initial investment of equipment is saved.
3. In the heat pump circulation combined system, under the single-stage heat pump independent heating/cooling mode, the heat exchange area is increased due to the sharing of the fins, so that the heat exchange temperature difference is reduced, and the system energy efficiency is improved.
4. The heat pump cycle combination system provided by the invention absorbs the heat of heating backwater through single-stage heat pump reverse cycle defrosting, has stable heating quantity and high defrosting efficiency, and can ensure quick defrosting under severe working conditions in winter.
Drawings
FIG. 1 is a schematic structural view of a heat pump circulation combination system in embodiment 1 of the present invention;
FIG. 2 is a schematic piping diagram of the integral evaporator of the present invention;
fig. 3 is a schematic structural view of a heat pump circulation combination system in embodiment 2 of the present invention.
In fig. 1, 1 is a low-temperature compressor, 2 is a high-temperature compressor, 3 is a first condenser, 4 is a second throttle valve, 5 is a first throttle valve, 6 is a condensing evaporator, 7 is a first evaporator, 8 is a single-stage compressor (8A is an air inlet and 8B is an air outlet), 9 is a four-way reversing valve, 10 is a second condenser, 11 is a third throttle valve, 12 is a first water pump, 13 is a second water pump, 14 is a flow dividing valve, 15 is a water tank, 16 is a third water pump, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 30 and 31 are connecting pipes, and 25 is a second evaporator.
In fig. 2, 41 is a heat exchange tube, 42 and 43 are inlets of a low-temperature stage circulating refrigerant of the cascade system, 44 is an inlet of a single-stage heat pump circulating refrigerant, 45 is a heat exchange tube connecting tube, 46 and 48 are outlets of the low-temperature stage circulating refrigerant of the cascade system, 47 is a heat exchange fin, and 49 is an outlet of the single-stage heat pump circulating refrigerant.
In fig. 3, 1 is a low-temperature compressor, 2 is a high-temperature compressor, 3 is a first condenser, 4 is a second throttle valve, 5 is a first throttle valve, 6 is a condensing evaporator, 7 is a first evaporator, 8 is an air-make enthalpy-increasing compressor (8A is an air inlet, 8B is an air outlet, and 8C is an air supplement port), 9 is a four-way reversing valve, 10 is a second condenser, 11 is a third throttle valve, 12 is a first water pump, 13 is a second water pump, 14 is a flow dividing valve, 15 is a water tank, 16 is a third water pump, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 30, 31, 34 are connecting pipes, 25 is a second evaporator, 32 is an air supplement tank, and 33 is a fourth throttle valve.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Example 1
The combined system of the vapor compression cascade heat pump cycle and the single-stage heat pump cycle in the embodiment includes a cascade heat pump cycle, a single-stage heat pump cycle and a water supply flow path, and the structure is shown in fig. 1.
The cascade heat pump cycle consists of a low temperature stage cycle and a high temperature stage cycle. The low-temperature stage cycle comprises a low-temperature compressor 1, a condensation evaporator 6, a first throttling valve 5 and a first evaporator 7, wherein the connection relations of the components are as follows: the air outlet of the low-temperature compressor 1 is connected with the inlet of a high-temperature channel of the condensation evaporator 6 through a connecting pipe 21, the outlet of the high-temperature channel of the condensation evaporator 2 is connected with the inlet of the first throttling valve 5 through a connecting pipe 22, the outlet of the first throttling valve 5 is connected with the inlet of the first evaporator 7 through a connecting pipe 23, and the outlet of the first evaporator 7 is connected with the air suction port of the low-temperature compressor 1 through a connecting pipe 24, so that low-temperature stage circulation is formed. The high-temperature stage cycle comprises a high-temperature compressor 2, a first condenser 3, a second throttling valve 4 and a condensation evaporator 6; the connection relationship of each component is as follows: the air outlet of the high-temperature compressor 2 is connected with the inlet of the first condenser 3 through a connecting pipe 17, the outlet of the first condenser 3 is connected with the inlet of the second throttling valve 4 through a connecting pipe 18, the outlet of the second throttling valve 4 is connected with the inlet of the low-temperature channel of the condensation evaporator 6 through a connecting pipe 19, the outlet of the low-temperature channel of the condensation evaporator 6 is connected with the air suction port of the high-temperature compressor 2 through a connecting pipe 20, and therefore high-temperature stage circulation is formed.
A condensing evaporator 6 is arranged between the high-temperature stage circulation and the low-temperature stage circulation.
The single-stage heat pump cycle comprises a single-stage compressor 8, a second condenser 10, a third throttle 11, a second evaporator 25; the connection relationship of each component is as follows: the exhaust port 8B of the single-stage compressor 8 is connected with the connecting port 9B of the four-way reversing valve 9 through a connecting pipe 28, the connecting port 9C of the four-way reversing valve 9 is connected with the inlet of the second condenser 10 through a connecting pipe 29, the outlet of the second condenser 10 is connected with the third throttle valve 11 through a connecting pipe 30, the third throttle valve 11 is connected with the second evaporator 25 through a connecting pipe 31, the second evaporator 25 is connected with the connecting port 9A of the four-way reversing valve through a connecting pipe 26, and the connecting port 9D of the four-way reversing valve is connected with the air suction port 8A of the single-stage compressor 8 through a connecting pipe 27, so that a single-stage heat pump cycle is formed.
The first condenser 3 and the second condenser 10 each have a refrigerant-coolant passage.
The condenser-evaporator 6 has a double refrigerant passage.
The first evaporator 7, the first evaporator 25 each have a refrigerant-air passage. The first evaporator 7 and the first evaporator 25 are both fin tube heat exchangers, and are combined into an integral heat exchanger, and share the same group of heat exchange fins.
Figure 2 shows a tube connection of an integral heat exchanger. The flow path of the single-stage circulation and the flow path of the overlapping low-temperature stage circulation are distributed in a crossed and staggered manner, so that the defrosting efficiency is improved. The refrigerant of the cascade low-temperature stage circulation flows in from the inlets 42 and 43, exchanges heat with air and then flows out from the outlets 46 and 48; the refrigerant of the single cycle flows in from the inlet 44, exchanges heat with the air, and flows out from the outlet 49. The two circulating heat exchange tubes share the same set of heat exchange fins 47, thereby forming an integral heat exchanger.
The water supply flow path includes a first water pump 12, a second water pump 13, a flow dividing valve 14, a water tank 15, and a third water pump 16. Heating backwater is divided into two paths by a diverter valve 14, one path of the heating backwater is sent into a first condenser 3 through a first water pump 12 to be heated and then enters a water tank 15, the other path of the heating backwater is sent into a second condenser 10 through a second water pump 13 to be heated and then is sent into the water tank 15, and hot water in the water tank 15 is sent into the heating tail end through a third water pump 16.
The vapor compression cascade heat pump cycle and single-stage heat pump cycle combined system of the embodiment can realize three functions of heating in winter, refrigerating in summer and defrosting, and the detailed working flow is as follows:
winter heating
The working principle of the overlapping heat pump circulation heating mode is as follows: in the low-temperature stage circulation loop, low-temperature and low-pressure refrigerant liquid is vaporized in the first evaporator 7 to absorb heat, low-grade heat energy of ambient air is absorbed, the low-temperature and low-pressure refrigerant liquid is compressed into high-temperature and high-pressure gas through the low-temperature compressor 1, the high-temperature gas is condensed in the condensing evaporator 6 to release heat, and finally the high-temperature and low-pressure gas is changed into low-temperature and low-pressure liquid again through the first throttling valve 5. In the high-temperature stage circulation loop, low-temperature and low-pressure refrigerant liquid is vaporized in the condensation evaporator 6 to absorb heat, the condensation heat release of the low-temperature stage gaseous refrigerant is absorbed, the low-temperature stage gaseous refrigerant is compressed into high-temperature and high-pressure gas through the high-temperature compressor 2, the high-temperature and high-pressure gas enters the first condenser 3 to be condensed and released, heating backwater is heated, and the high-temperature and low-pressure gas is changed into low-temperature and low-pressure liquid again through the second throttling valve 4.
The working principle of the single-stage heat pump circulation heating mode is as follows: the four-way reversing valve 9A is communicated with 9D, and the four-way reversing valve 9B is communicated with 9C. The low-temperature low-pressure refrigerant liquid is vaporized in the second evaporator 7 to absorb heat, low-grade heat energy of ambient air is absorbed, the low-temperature low-pressure refrigerant liquid enters the single-stage compressor 8 through the four-way reversing valve 9 and is compressed into high-temperature high-pressure gas, the high-temperature gas enters the second condenser 10 through the four-way reversing valve 9 and is condensed to release heat, heating backwater is heated, and finally the high-temperature high-pressure gas is changed into low-temperature low-pressure liquid again through the third throttle valve 11.
According to the environmental condition and the heating demand, three different heating modes can be realized.
Firstly, a single-stage heat pump circulation independent heating mode. When the ambient temperature is higher (such as higher than 0 ℃), the cascade heat pump cycle stops working, and the single-stage heat pump cycle independently supplies heat. The water supply flow path is: the diverter valve 14A is closed, and the heating backwater flows out from an outlet 14B of the diverter valve 14, is sent into the second condenser 10 through the second water pump 13 for heating, and is sent into the water tank 15. The third water pump 16 feeds the hot water in the water tank 15 to the heating terminal.
And secondly, overlapping a heat pump circulation single heating mode. But when the ambient temperature is lower (such as lower than 0 ℃), the single-stage heat pump cycle stops working, and the overlapping heat pump cycle is used for heating independently. The water supply flow path is: the diverter valve 14B is closed, and the heating backwater flows out from the outlet 14A of the diverter valve 14, is sent into the first condenser 3 through the first water pump 12 for heating, and then is sent into the water tank 15. The third water pump 16 feeds the hot water in the water tank 15 to the heating terminal.
And thirdly, a combined heating mode of overlapping heat pump circulation and single-stage heat pump circulation. When the environment temperature is low and the heating demand is high, the overlapping heat pump cycle and the single-stage heat pump cycle work simultaneously to perform combined heating. The water supply flow path is: the diverter valves 14A and 14B are opened, heating backwater is divided into two paths through the diverter valve 14, one path of heating backwater is sent into the second condenser 10 through the second water pump 13 to be heated, and then is sent into the water tank 15; the other path is sent to the first condenser 3 for heating through the first water pump 12 and then sent to the water tank 15. The third water pump 16 feeds the hot water in the water tank 15 to the heating terminal.
Refrigerating in summer:
the cascade heat pump cycle stops working. Because the refrigeration load in severe cold areas is lower, the refrigeration requirement can be met only by adopting a single-stage heat pump. The single-stage heat pump circulation four-way reversing valve 9A is communicated with the single-stage heat pump circulation four-way reversing valve 9B, and the single-stage heat pump circulation four-way reversing valve 9C is communicated with the single-stage heat pump circulation four-way reversing valve 9D. The working principle of the single-stage heat pump circulating refrigeration mode is as follows: high-temperature and high-pressure gas discharged from the single-stage compressor 8 enters the second evaporator 25 to be condensed and released heat, exchanges heat with outdoor air, is changed into low-temperature and low-pressure liquid through the third throttling valve 11, enters the second condenser 10 to be evaporated and absorbed heat, returns refrigeration water to a set temperature, and finally enters the single-stage compressor 8 through the four-way reversing valve 9 to be recompressed into high-temperature and high-pressure gas.
The diverter valve 14A is closed, and the refrigeration backwater flows out from an outlet 14B of the diverter valve 14, is sent into the second condenser 10 for refrigeration through the second water pump 13, and is sent into the water tank 15. The third water pump 16 sends the cold water in the water tank 15 to the cooling end.
Thirdly, defrosting:
and in the defrosting mode, the cascade heat pump cycle stops working. The single-stage heat pump circulation four-way reversing valve 9A is communicated with the single-stage heat pump circulation four-way reversing valve 9B, and the single-stage heat pump circulation four-way reversing valve 9C is communicated with the single-stage heat pump circulation four-way reversing valve 9D. The working principle of the single-stage heat pump circulating defrosting mode is as follows: high-temperature and high-pressure gas discharged from the single-stage compressor 8 enters the second evaporator 25 to be condensed and released heat, an evaporator coil is defrosted, the high-pressure gas is changed into low-temperature and low-pressure liquid through the third throttling valve 11, then enters the second condenser 10 to be evaporated and absorbed to absorb heat of heating return water, and finally enters the single-stage compressor 8 through the four-way reversing valve 9 to be recompressed into high-temperature and high-pressure gas.
The diverter valve 14A is closed, and the heating backwater flows out from the outlet 14B of the diverter valve 14, is sent into the second condenser 10 through the second water pump 13, and is sent into the water tank 15.
Example 2
The vapor compression cascade heat pump cycle and single-stage heat pump cycle combined heating system in the embodiment comprises a cascade heat pump cycle, a single-stage heat pump cycle and a water supply flow path, and the structure is shown in fig. 3. The main structure of the system comprises a low-temperature compressor 1, a high-temperature compressor 2, a first condenser 3, a second throttle valve 4, a first throttle valve 5, a condensation evaporator 6, a first evaporator 7, an air-supplying and enthalpy-increasing compressor 8(8A is an air suction port, 8B is an air exhaust port, and 8C is an air supplement port), a four-way reversing valve 9, a second condenser 10, a third throttle valve 11, a first water pump 12, a second water pump 13, a flow dividing valve 14, a water tank 15, a third water pump 16, connecting pipes 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 30, 31 and 34, a second evaporator 25, an air supplement tank 32 and a fourth throttle valve 33.
Compared with embodiment 1, in this embodiment, the single-stage compressor is replaced with an enthalpy-increasing vapor injection compressor, and in addition to the inlet port 8A and the outlet port 8B, an inlet port 8C is added. The air inlet 8A is connected to a connection port 9D of the four-way selector valve 9 via a connection pipe 27, the air outlet 8B is connected to a connection port 9B of the four-way selector valve 9 via a connection pipe 28, and the air supply port 8C is connected to an air supply tank 32 via a connection pipe 34. And a fourth throttle valve 33 is added for throttling the supercooled liquid in the air supply tank. The use of the air-supplying enthalpy-increasing compressor 8 can realize two-stage compression, thereby reducing the exhaust temperature and improving the heating capacity of the single-stage heat pump cycle.
The embodiment 2 can also realize three heating modes of winter heating, summer cooling and defrosting, and the principle is the same as that of the embodiment 1.
It should be noted that in embodiment 2, the enthalpy increase for gas supply is not limited to be realized by adding a gas supply tank, and can also be realized by adding an economizer.
In the above embodiments, all components of the refrigeration cycle are not completely shown, and in the implementation process, common refrigeration accessories such as a liquid reservoir, a filter, a dryer, a gas-liquid separator and the like are arranged in the refrigerant circuit, which cannot be regarded as substantial improvements made in the present invention, and shall fall into the protection scope of the present invention.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (3)
1. A vapor compression cascade heat pump cycle and single-stage heat pump cycle combined system is characterized by comprising a cascade heat pump cycle, a single-stage heat pump cycle and a water supply flow path;
the cascade heat pump cycle comprises a low-temperature stage cycle and a high-temperature stage cycle which are in heat exchange connection with each other;
the low-temperature stage circulation is structurally connected with the single-stage heat pump circulation;
the water supply flow path is respectively connected with the high-temperature stage cycle and the single-stage heat pump cycle in a heat exchange manner, and can output hot water/cold water outwards so as to realize external heating/cooling;
the low-temperature stage circulation and the high-temperature stage circulation are connected in a heat exchange manner through a condensing evaporator (6);
the low-temperature stage cycle and the single-stage heat pump cycle are structurally connected through a first evaporator (7) and a second evaporator (25);
the water supply flow path is in heat exchange type connection with the high-temperature stage circulation through a first condenser (3);
the water supply flow path is in circulating heat exchange connection with the single-stage heat pump through a second condenser (10);
the low-temperature stage circulation comprises a low-temperature compressor (1), a first heat exchange channel of a first evaporator (7), a first throttling valve (5) and a first heat exchange channel of a condensation evaporator (6) which are connected in sequence, wherein the first heat exchange channel of the condensation evaporator (6) is connected with the low-temperature compressor (1) to form the low-temperature stage circulation;
the high-temperature stage cycle comprises a high-temperature compressor (2), a first heat exchange channel of a first condenser (3), a second throttling valve (4) and a second heat exchange channel of a condensation evaporator (6) which are connected in sequence, wherein the second heat exchange channel of the condensation evaporator (6) is connected with the high-temperature compressor (2) to form the high-temperature stage cycle;
the single-stage heat pump cycle comprises a single-stage compressor (8), a first heat exchange channel of a second evaporator (25), a third throttle valve (11) and a first heat exchange channel of a second condenser (10) which are connected in sequence;
the single-stage heat pump cycle further comprises a four-way reversing valve (9), an exhaust port 8B of the single-stage compressor (8) is connected with a connecting port 9B of the four-way reversing valve (9), a connecting port 9C of the four-way reversing valve (9) is connected with a first heat exchange channel of a second condenser (10), the first heat exchange channel of the second condenser (10) is connected with a third throttle valve (11), the first heat exchange channel of a second evaporator (25) is connected with a connecting port 9A of the four-way reversing valve, and a connecting port 9D of the four-way reversing valve (9) is connected with an air suction port 8A of the single-stage compressor (8), so that the single-stage heat pump cycle is formed;
the water supply flow path comprises a first water pump (12), a second water pump (13), a flow dividing valve (14), a water tank (15), a third water pump (16), a second heat exchange channel of the first condenser (3) and a second heat exchange channel of the second condenser (10);
the return water of the water supply flow path is divided into two paths by a diverter valve (14), one path of the return water is sent into a second heat exchange channel of a first condenser (3) through a first water pump (12) to exchange heat and then enters a water tank (15), the other path of the return water is sent into a second heat exchange channel of a second condenser (10) through a second water pump (13) to exchange heat and then is sent into the water tank (15), and hot water in the water tank (15) is sent into the heating/refrigerating tail end through a third water pump (16);
the vapor compression cascade heat pump cycle and single-stage heat pump cycle combined system can realize the switching of three functions of heating in winter, refrigerating in summer and defrosting;
according to the environmental working condition and the heating requirement, the vapor compression overlapping heat pump cycle and single-stage heat pump cycle combined system can realize three different heating modes, including a single-stage heat pump cycle independent heating mode, an overlapping heat pump cycle independent heating mode and an overlapping heat pump cycle and single-stage heat pump cycle combined heating mode.
2. A combined vapor compression cascade heat pump cycle and single stage heat pump cycle system according to claim 1, wherein the single stage heat pump cycle comprises a vapor-supplementing enthalpy-increasing compressor, a first heat exchange channel of the second evaporator (25), the third throttle valve (11), a first heat exchange channel of the second condenser (10) connected in series.
3. A combined vapor compression cascade heat pump cycle and single stage heat pump cycle system according to claim 1 wherein the first evaporator (7) and the second evaporator (25) are combined to form an integral heat exchanger, sharing a common set of heat exchange fins, and the heat exchange tubes are arranged in a cross-row and cross-row configuration.
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| CN112344553A (en) * | 2020-11-18 | 2021-02-09 | 天津五洲同创空调制冷设备有限公司 | Air cooling cascade water heater in negative 50 ℃ environment |
| CN112629054A (en) * | 2020-12-29 | 2021-04-09 | 清华大学 | Multi-connected temperature-changing refrigeration house refrigeration system with single-stage and cascade circulation free conversion |
| CN113551330A (en) * | 2021-06-03 | 2021-10-26 | 广东智科电子股份有限公司 | Refrigerant exchange cascade heating control method, controller and system |
| CN114754430A (en) * | 2022-04-12 | 2022-07-15 | 新科环保科技有限公司 | Air-conditioning heat pump system for preparing high-temperature hot water at low ambient temperature |
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