Double-stage heat pump triple co-generation system

Abstract

The utility model discloses a double-stage heat pump triple co-generation system which comprises a first-stage heat pump, a buffer water tank energy storage system, a second-stage heat pump, a double-stage operation heat supply loop, a double-stage operation hot water preheating loop, a first-stage operation heat supply loop, a first-stage operation cold supply loop and a second-stage hot water supply loop. The requirements of cooling, heating and hot water supply can be met by adjusting the circulation state of the heat pump, the heating / refrigerating circulation of the first-stage heat pump, the starting and stopping conditions of the second-stage heat pump and opening and closing of all the valves. The utility model has the advantages that the single-stage and double-stage switching heat supply and hot water supply can be realized when heat is needed in winter, cold supply can be realized when cold is needed in summer, and hot water supply can be realized as required.

Description

Technical Field

[0001] The utility model relates to the field of heat pumps, in particular to a two-stage heat pump trigeneration system. Background Art

[0002] As an efficient and environmentally friendly way of utilizing energy, heat pump technology has developed rapidly in China in recent years. With the country's emphasis on energy conservation, emission reduction and utilization of renewable energy, as well as the sustained development of China's economy and society and the continuous improvement of people's living standards, the heat pump industry has shown a booming development trend under the dual impetus of policy support and market demand, and the market demand for heat pump technology will continue to expand. Especially in the northern region, with the arrival of the heating season, the market demand for heat pump equipment will be even stronger. At the same time, with the increasing demand for energy conservation and emission reduction in the industrial field, the application of heat pumps in industrial refrigeration, drying and other fields will also be further expanded.

[0003] Existing heat pumps include heat pump trigeneration system and two-stage coupled cascade heat pump system. The heat pump trigeneration system operates as follows:

[0004] When heating in winter, the high-pressure steam discharged from the compressor enters the condenser. The latent heat released when the refrigerant steam condenses heats the indoor air to achieve the purpose of indoor heating. The condensed liquid refrigerant flows through the expansion valve (throttling device) into the evaporator, absorbs external heat and evaporates. The evaporated steam passes through the reversing valve and is sucked into the compressor to complete the heating cycle.

[0005] When cooling down in the summer, it operates according to the refrigeration condition. In the heat exchanger on the indoor side, the refrigerant absorbs heat and evaporates, and the indoor temperature drops. The evaporated refrigerant enters the compressor through the four-way reversing valve to form high-temperature and high-pressure steam, and then releases heat and cools down (i.e. condenses) in the heat exchanger on the outdoor side. After the pressure is reduced by the throttling device, it returns to the indoor side to absorb heat, forming a cycle.

[0006] The two-stage coupled cascade heat pump system uses two groups of refrigerants. The first group of refrigerants can achieve from ultra-low temperature to medium-low temperature, and the second group of refrigerants can achieve from medium-low temperature to high temperature, which can achieve high-temperature heating in ultra-low temperature environment.

[0007] The heat pump trigeneration system is operated by a single unit, so it has the disadvantages of limited operating range, low low-temperature outlet water temperature, and attenuated low-temperature operating capacity. The two-stage coupled cascade heat pump system can only operate in two stages and cannot make adjustments when the ambient temperature rises, resulting in energy waste. In addition, the simple cascade two-stage heat pump cannot achieve the cooling function. Utility Model Content

[0008] The purpose of the embodiments of the utility model is to address the defects of the above-mentioned prior art and provide a two-stage heat pump trigeneration system that realizes the functions of single-stage and double-stage switching heating and cooling.

[0009] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0010] A two-stage heat pump trigeneration system, comprising a primary heat pump, a buffer water tank energy storage system, a secondary heat pump, a two-stage operation heating circuit, a two-stage operation hot water preheating circuit, a primary operation heating circuit, a primary operation cooling circuit and a secondary hot water supply circuit;

[0011] The primary heat pump comprises a primary compressor, the outlet of the primary compressor is connected to one side inlet of the primary condenser through a four-way reversing valve, one side outlet of the primary condenser is connected to the primary evaporator through a primary main electronic expansion valve, and the primary evaporator is connected to the inlet of the primary compressor through the four-way reversing valve to form a first circulation loop;

[0012] The buffer water tank energy storage system comprises a buffer water tank, the outlet of the buffer water tank is connected to the other side inlet of the primary condenser through a first pipe, the other side outlet of the primary condenser is connected to a second pipe, the second pipe is connected to a third pipe through a first circulation pump, the third pipe is connected to one side inlet of the secondary evaporator, and one side outlet of the secondary evaporator is connected to the inlet of the buffer water tank through a fourth pipe, forming a second circulation loop;

[0013] The secondary heat pump comprises a secondary evaporator, the other side outlet of the secondary evaporator is connected to a secondary compressor, the secondary compressor is connected to one side inlet of the secondary condenser, and one side outlet of the secondary condenser is connected to the other side inlet of the secondary evaporator through a secondary electronic expansion valve to form a third circulation loop.

[0014] The two-stage operation heating circuit includes a secondary condenser, the other side outlet of the secondary condenser is connected to the first valve through a fifth pipeline, the first valve is connected to the inlet of the user end through a sixth pipeline, the outlet of the user end is connected to a seventh pipeline, the seventh pipeline is connected to a second circulation pump, the second circulation pump is connected to a third valve through an eighth pipeline, the third valve is connected to the other side inlet of the secondary condenser through a ninth pipeline, forming a fourth circulation circuit;

[0015] The two-stage operation hot water preheating loop includes a secondary condenser, and the other side outlet of the secondary condenser is sequentially connected to the fifth pipeline, the thirteenth pipeline, the second valve, the third circulation pump, the tenth pipeline, one side inlet of the heat exchanger, one side of the heat exchanger, one side outlet of the heat exchanger, the eleventh pipeline, the ninth pipeline and the other side inlet of the secondary condenser to form a fifth circulation loop;

[0016] The primary operation heating circuit includes a primary condenser, and the other side outlet of the primary condenser is sequentially connected to the second pipeline, the twelfth pipeline, the sixth pipeline, the user terminal, the seventh pipeline, the second circulation pump, the eighth pipeline, the fifteenth pipeline, the fourth valve, the thirteenth pipeline, the buffer water tank, the first pipeline and the other side inlet of the primary condenser to form a sixth circulation loop;

[0017] The primary operation cooling circuit is the same as the primary operation heating circuit, and the primary condenser is used as an evaporator to form a seventh circulation circuit;

[0018] The secondary hot water supply loop includes a secondary condenser, and the other side outlet of the secondary condenser is sequentially connected to the fifth pipeline, the thirteenth pipeline, the second valve, the third circulation pump, the tenth pipeline, the heat exchanger, the eleventh pipeline, the ninth pipeline and the other side inlet of the secondary condenser to form an eighth circulation loop;

[0019] The outlet on the other side of the heat exchanger is connected to the inlet of the domestic hot water storage tank, and the outlet of the domestic hot water storage tank is connected to the inlet on the other side of the heat exchanger.

[0020] The four-way reversing valve is connected to the inlet of the first-stage compressor through the first-stage gas-liquid separator; the pipeline connecting one side outlet of the first-stage condenser and the first-stage main electronic expansion valve is connected with a first-stage liquid reservoir, one side inlet of the economizer, one side outlet of the economizer, a drying filter and the sixteenth pipeline in sequence; one outlet on the other side of the economizer is connected to the first-stage compressor, and the other outlet on the other side of the economizer is connected to the first filter through the auxiliary electronic expansion valve, the first filter is connected to the sixteenth pipeline, and a second filter is provided on the pipeline connecting the main electronic expansion valve and the inlet of the first-stage evaporator.

[0021] The other side outlet of the secondary evaporator is connected to the secondary compressor through a secondary gas-liquid separator, and the pipeline connecting the one side outlet of the secondary condenser and the secondary electronic expansion valve is sequentially connected to a secondary liquid reservoir and a third filter.

[0022] The first valve, the second valve, the third valve and the fourth valve are all electric valves.

[0023] The third pipeline, the fifth pipeline, the eleventh pipeline and the twelfth pipeline are provided with check valves.

[0024] An electric heater is arranged in the buffer water tank, and a drain valve is arranged at the bottom of the buffer water tank.

[0025] The lower part of the domestic hot water storage tank is connected with a water replenishing device.

[0026] The beneficial effects brought by the technical solution provided by the embodiment of the utility model are:

[0027] The system of the present invention adopts two-stage compression technology and is equipped with a buffer water tank energy storage system. It can realize high-temperature heating and hot water supply of the system under severe cold conditions in winter; when the ambient temperature is not very low, it switches to single-stage operation to ensure heating and reduce energy waste. The system defrosts using the heat of the buffer water tank, without extracting the terminal heat, to improve the heating comfort. The two-stage heat pumps of the two-stage heat pump trigeneration system of the utility model are independent heat pumps, which can be operated in series in a two-stage mode, or in a single-stage mode with the first-stage heat pump running and the second-stage heat pump stopped. When the two-stage mode is in operation, external heating and hot water supply can be realized in winter, and the first-stage heat pump can provide cooling and the second-stage heat pump can provide hot water in summer. When the single-stage mode is in operation, external heating can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a two-stage heat pump trigeneration system provided by an embodiment of the utility model;

[0029] Figure 2 It is a diagram of a single-stage heating / cooling system provided by an embodiment of the utility model;

[0030] Figure 3 This is a diagram of a two-stage heating and hot water system provided by an embodiment of the utility model;

[0031] Figure 4 This is a diagram of a primary heat pump cooling and a secondary heat pump hot water system provided by an embodiment of the utility model;

[0032] Figure 5 It is a defrost mode system diagram provided by an embodiment of the utility model.

[0033] In the figure:

[0034] 1-1 primary evaporator, 1-2 four-way reversing valve, 1-3 gas-liquid separator, 1-4 primary compressor, 1-5 primary condenser, 1-6 primary liquid storage, 1-7 economizer, 1-8 drying filter, 1-9 primary main electronic expansion valve, 1-10 auxiliary electronic expansion valve, 1-11 first filter, 1-12 second filter, 2-1 buffer water tank, 3-1 secondary evaporator, 3-2 gas-liquid separator, 3-3 secondary compressor, 3-4 secondary condenser, 3-5 secondary liquid storage, 3-6 third filter, 3-7 secondary electronic expansion valve, 4-1 heat exchanger, 4-2 domestic hot water storage tank, 4-3 user terminal;

[0035] 1 the first valve, 2 the second valve, 3 the third valve, 4 the fourth valve, 5 the first pipeline, 6 the second pipeline, 7 the third pipeline, 8 the fourth pipeline, 9 the fifth pipeline, 10 the sixth pipeline, 11 the seventh pipeline, 12 the eighth pipeline, 13 the ninth pipeline, 14 the tenth pipeline, 15 the eleventh pipeline, 16 the twelfth pipeline, 17 the thirteenth pipeline, 18 the first circulation pump, 19 the second circulation pump, 20 the third circulation pump, 21 the check valve, 22 the drain valve, 23 the fourteenth pipeline, 24 the fifteenth pipeline, 25 the sixteenth pipeline. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clear, the implementation mode of the present invention will be further described in detail below with reference to the accompanying drawings.

[0037] See also Figure 1 , a two-stage heat pump trigeneration system, comprising a primary heat pump, a buffer water tank energy storage system, a secondary heat pump, a two-stage operation heating circuit, a two-stage operation hot water preheating circuit, a primary operation heating circuit, a primary operation cooling circuit and a secondary hot water supply circuit;

[0038] The primary heat pump comprises a primary compressor 1-4, the outlet of the primary compressor 1-4 is connected to one side inlet of the primary condenser 1-5 through a four-way reversing valve 1-2, one side outlet of the primary condenser 1-5 is connected to the primary evaporator 1-1 through a primary main electronic expansion valve 1-9, and the primary evaporator 1-1 is connected to the inlet of the primary compressor 1-4 through the four-way reversing valve 1-2, forming a first circulation loop, i.e., a primary heat pump system;

[0039] The buffer water tank energy storage system includes a buffer water tank 2-1, the outlet of the buffer water tank 2-1 is connected to the other side inlet of the primary condenser 1-5 through a first pipe 5, the other side outlet of the primary condenser 1-5 is connected to a second pipe 6, the second pipe 6 is connected to a third pipe 7 through a first circulation pump 18, the third pipe 7 is connected to one side inlet of the secondary evaporator 3-1, and one side outlet of the secondary evaporator 3-1 is connected to the inlet of the buffer water tank 2-1 through a fourth pipe 8, forming a second circulation loop, that is, the buffer water tank energy storage system;

[0040] The secondary heat pump comprises a secondary evaporator 3-1, the other side outlet of the secondary evaporator 3-1 is connected to the secondary compressor 3-3, the secondary compressor 3-3 is connected to one side inlet of the secondary condenser 3-4, and one side outlet of the secondary condenser 3-4 is connected to the other side inlet of the secondary evaporator 3-1 through a secondary electronic expansion valve 3-7, forming a third circulation loop, i.e., a secondary heat pump system;

[0041] The two-stage operation heating circuit includes a secondary condenser 3-4, the other side outlet of the secondary condenser 3-4 is connected to the first valve 1 through a fifth pipeline 9, the first valve 1 is connected to the inlet of the user terminal 4-3 through a sixth pipeline 10, the outlet of the user terminal 4-3 is connected to a seventh pipeline 11, the seventh pipeline 11 is connected to a second circulation pump 19, the second circulation pump 19 is connected to the third valve 3 through an eighth pipeline 12, and the third valve 3 is connected to the other side inlet of the secondary condenser 3-4 through a ninth pipeline 13, forming a fourth circulation loop;

[0042] The two-stage operation hot water preheating circuit includes a secondary condenser 3-4, and the other side outlet of the secondary condenser 3-4 is sequentially connected to the fifth pipeline 9, the fourteenth pipeline 23, the second valve 2, the third circulation pump 20, the tenth pipeline 14, one side inlet of the heat exchanger 4-1, one side of the heat exchanger 4-1, one side outlet of the heat exchanger 4-1, the eleventh pipeline 15, the ninth pipeline 13 and the other side inlet of the secondary condenser 3-4 to form a fifth circulation loop;

[0043] The primary operation heating circuit includes a primary condenser 1-5, and the other side outlet of the primary condenser 1-5 is sequentially connected to the second pipeline 6, the twelfth pipeline 16, the sixth pipeline 10, the user terminal 4-3, the seventh pipeline 11, the second circulation pump 19, the eighth pipeline 12, the fifteenth pipeline 24, the fourth valve 4, the thirteenth pipeline 17, the buffer water tank 2-1, the first pipeline 5 and the other side inlet of the primary condenser 1-5 to form a sixth circulation loop;

[0044] The first-stage operation cooling circuit includes a first-stage condenser 1-5 (acting as an evaporator), and the other side outlet of the first-stage condenser 1-5 is connected in sequence to the second pipeline 6, the twelfth pipeline 16, the sixth pipeline 10, the user terminal 4-3, the seventh pipeline 11, the second circulation pump 19, the eighth pipeline 12, the fifteenth pipeline 24, the fourth valve 4, the thirteenth pipeline 17, the buffer water tank 2-1, the first pipeline 5 and the other side inlet of the first-stage condenser 1-5 to form a seventh circulation loop; the user terminal here uses the cold terminal, and the other user terminals all use the hot terminal.

[0045] The secondary hot water supply loop includes a secondary condenser 3-4, and the other side outlet of the secondary condenser 3-4 is sequentially connected to the fifth pipeline 9, the fourteenth pipeline 23, the second valve 2, the third circulation pump 20, the tenth pipeline 14, the heat exchanger 4-1, the eleventh pipeline 15, the ninth pipeline 13 and the other side inlet of the secondary condenser 3-4 to form an eighth circulation loop;

[0046] The outlet on the other side of the heat exchanger 4-1 is connected to the inlet of the domestic hot water storage tank 4-2, and the outlet of the domestic hot water storage tank 4-2 is connected to the inlet on the other side of the heat exchanger 4-1.

[0047] The utility model can realize the requirements of cooling, heating and hot water supply by adjusting the circulation state of the heat pump, such as the heating / cooling cycle of the first-stage heat pump, the start and stop status of the second-stage heat pump and the switching of each valve. It has the advantages of single-stage and double-stage switching of heating and hot water supply in winter, and cooling and hot water supply in summer.

[0048] Furthermore, the four-way reversing valve 1-2 is connected to the inlet of the first-stage compressor 1-4 through the first-stage gas-liquid separator 1-3, and the pipeline connecting one side outlet of the first-stage condenser 1-5 and the first-stage main electronic expansion valve 1-9 is connected in sequence with the first-stage liquid storage device 1-6, one side inlet of the economizer 1-7, one side outlet of the economizer 1-7, the drying filter 1-8 and the sixteenth pipeline 25; one outlet on the other side of the economizer 1-7 is connected to the first-stage compressor 1-4, and the other outlet on the other side of the economizer 1-7 is connected to the first filter 1-11 through the auxiliary electronic expansion valve 1-10, and the first filter 1-11 is connected to the sixteenth pipeline 25, and the second filter 1-12 is provided on the pipeline connecting the main electronic expansion valve 1-9 and the inlet of the first-stage evaporator 1-1.

[0049] A part of the refrigerant is first cooled at the auxiliary circuit electronic expansion valve 1-10, and then passes downward through the first filter 1-11 to return to the main circuit to supercool the other part of the refrigerant.

[0050] Furthermore, the other side outlet of the secondary evaporator 3-1 is connected to the secondary compressor 3-3 through the secondary gas-liquid separator 3-2, and the pipeline connecting the one side outlet of the secondary condenser 3-4 and the secondary electronic expansion valve 3-7 is connected in sequence to the secondary liquid reservoir 3-5 and the third filter 3-6.

[0051] The primary liquid reservoir 1-6 and the secondary liquid reservoir 3-5 are specially used to store refrigerant liquid, provide the liquid supply required for the refrigeration system circulation, and ensure the stable operation of the refrigeration system; the main function of the liquid reservoir in the refrigeration system is to store refrigerant. Generally speaking, the liquid reservoir can be divided into a high-pressure circulation liquid reservoir and a low-pressure circulation liquid reservoir. Storing the liquid component in the refrigerant can avoid the heat transfer area being reduced due to excessive accumulation of refrigerant in the condenser, effectively reducing the load of the condenser, and at the same time providing a continuous supply of refrigerant to the evaporator, so that the refrigerant that has not been completely cooled can be cooled again to a completely liquid state. The liquid reservoir also plays a liquid seal role to prevent gas from entering the low-pressure compressor to produce liquid hammer. Liquid hammer mainly occurs in piston compressors, because the refrigerant liquid (or lubricant) is sucked into the compressor, causing abnormal shock accidents of the compressor.

[0052] The primary gas-liquid separator 1-3 and the secondary gas-liquid separator 3-2 are used to separate gas and liquid and remove the liquid entering the compressor, so as to prevent the compressor from sucking in lubricating oil or refrigerant at the air inlet, and to prevent liquid lubricating oil or refrigerant from causing liquid hammer and damaging the internal components of the compressor. The basic function of the gas-liquid separator in the heat pump or refrigeration system is to separate and store the liquid in the return air pipe, and to regulate the flow to prevent the compressor from causing liquid hammer. Therefore, the gas-liquid separator can temporarily store excess refrigerant liquid, and also prevent excess refrigerant from flowing into the compressor crankcase to cause oil dilution. During the separation process, the cold-refined oil will also be separated and stored at the bottom. There will be an oil hole filter at the outlet pipe and the bottom of the gas-liquid separator to return the cold-refined oil to the compressor, effectively avoiding oil shortage in the compressor. There is a U-shaped elbow design inside the gas-liquid separator, and there is a protective net and a small hole assembly on the U-shaped tube to prevent foreign matter and dirt from affecting the operation of the separator.

[0053] The function of economizer 1-7 is to divide the high-pressure liquid refrigerant from the condenser into two parts. One part is further cooled by heat expansion through throttling to reduce the temperature of the other part, making it supercooled. The stabilized supercooled liquid enters the evaporator for refrigeration. The other part of the uncooled gaseous refrigerant passes through the connecting pipe between the economizer and the compressor, re-enters the compressor for further compression, and enters the cycle. The economizer stabilizes the liquid refrigerant medium through expansion refrigeration to improve the system capacity and efficiency.

[0054] The first filter 1-11, the second filter 1-12 and the third filter 3-6 are components for filtering impurities in the system. They are installed mainly on the front and rear sides of the electronic expansion valve or capillary tube of the unit to prevent impurities in the system from clogging the electronic expansion valve and causing failure of the electronic expansion valve.

[0055] The dry filters 1-8 are used to absorb moisture in the system, filter out impurities in the system, and prevent ice blockage and dirt blockage in the system pipeline. Since the parts of the system that are most likely to be blocked are the electronic expansion valve and capillary tube, the dry filter is usually installed between the condenser and the throttling device.

[0056] In order to realize automatic control, the first valve 1, the second valve 2, the third valve 3 and the fourth valve 4 are all electric valves.

[0057] Furthermore, the third pipeline 7 , the fifth pipeline 9 , the eleventh pipeline 15 and the twelfth pipeline 16 are provided with check valves 21 .

[0058] Furthermore, an electric heater is provided in the buffer water tank 2-1, and a drain valve 22 is provided at the bottom of the buffer water tank.

[0059] Furthermore, a water replenishing device is connected to the lower part of the domestic hot water storage tank 4-2 for replenishing water in the domestic hot water storage tank.

[0060] The working mode of the utility model is as follows:

[0061] See also Figure 1 and Figure 2 , Single-stage heating / cooling mode: start the second circulation pump 19, stop the operation of the first circulation pump 18 and the third circulation pump 20; start the first heat pump; stop the second heat pump. Open the fourth valve 4, close the first valve 1, the second valve 2, and the third valve 3.

[0062] When the system operates in single-stage heating mode in winter, the low-temperature hot water in the buffer water tank 2-1 enters the primary condensation end of the first-stage condenser 1-5 through the first pipe 5 and is heated to the required temperature. Under the action of the second circulation pump 19, it enters the user terminal 4-3 through the twelfth pipe 16 and the sixth pipe 10 in turn for heating, and then returns to the buffer water tank 2-1 through the seventh pipe 11, the eighth pipe 12, the fifteenth pipe 24, the fourth valve 4 and the thirteenth pipe 17 to complete the cycle.

[0063] In summer, when the system is in single-stage cooling operation, the primary heat pump performs a refrigeration cycle, and the primary condenser 1-5 acts as an evaporator. The low-temperature water in the buffer water tank 2-1 enters the primary side of the primary condenser 1-5 through the first pipe 5 to be cooled, and enters the user terminal 4-3 through the twelfth pipe 16 and the sixth pipe 10 in sequence under the action of the second circulation pump 19 for cooling, and then returns to the buffer water tank 2-1 through the seventh pipe 11, the eighth pipe 12, the fifteenth pipe 24, the fourth valve 4 and the thirteenth pipe 17 to complete the cycle.

[0064] See also Figure 1 and Figure 3 , two-stage heating and hot water mode: start the first circulation pump 18 and close the fourth valve 4; on this basis, if the first valve 1, the second circulation pump 19, and the third valve 3 are opened, the heating cycle is connected; if the second valve 2, the third circulation pump 20 are opened, and the third valve 3 is closed, the hot water cycle is connected; the heating cycle and the hot water cycle do not run at the same time.

[0065] When the system is in two-stage heating operation in winter, the high-temperature hot water at the condensation end of the secondary side of the secondary condenser 3-4 can, under the action of the second circulation pump 19, enter the user terminal 4-3 from the other side outlet of the secondary condenser 3-4 through the fifth pipeline 9, the first valve 1, and the sixth pipeline 10 for heating, and then return to the inlet of the secondary condenser 3-4 through the seventh pipeline 11, the second circulation pump 19, the eighth pipeline 12, the third valve 3, and the ninth pipeline 13 to complete the circulation; or under the action of the third circulation pump 20, enter the heat exchanger 4-1 from the other side outlet of the secondary condenser 3-4 through the fifth pipeline 9, the fourteenth pipeline 23, the second valve 2, and the tenth pipeline 14 to preheat the domestic hot water, and then enter the eleventh pipeline 15 and the ninth pipeline 13 through the outlet of the heat exchanger 4-1 to return to the other side inlet of the secondary condenser 3-4.

[0066] See also Figure 1 and Figure 4 , Refrigeration and hot water mode: start the first circulation pump 18, the second circulation pump 19 and the third circulation pump 20; start the first heat pump refrigeration cycle, start the second heat pump. Open the second valve 2 and the fourth valve 4, and close the first valve 1 and the third valve 3.

[0067] When the system is in double-stage operation in summer, the primary side is a refrigeration cycle, and the water in the buffer water tank 2-1 enters the primary condenser 1-5 (the evaporation end at this time) through the first pipe 5 to cool down. Under the action of the second circulation pump 19, the water enters the user terminal 4-3 from the other side outlet of the primary condenser 1-5 through the second pipe 6, the twelfth pipe 16 and the sixth pipe 10 in sequence; the return water after absorbing heat comes out of the user terminal 4-3 and returns to the inlet of the buffer water tank 2-1 through the seventh pipe 11, the second circulation pump 19, the eighth pipe 12, the fifteenth pipe 24, the fourth valve 4 and the thirteenth pipe 17 in sequence. The secondary side is a heating cycle. The low-temperature water in the buffer water tank 2-1 enters the secondary side evaporator through the first circulation pump 18, and returns to the buffer water tank through the fourth pipe 8 after absorbing heat. The hot water at the outlet of the secondary condenser 3-4, under the action of the third circulation pump 20, enters the heat exchanger 4-1 from the other side outlet of the secondary condenser 3-4 through the fifth pipe 9, the fourteenth pipe 23, the second valve 2, the third circulation pump 20 and the tenth pipe 14 to exchange heat with the domestic hot water tank 4-2. The return water after releasing heat returns to the secondary condenser 3-4 through the eleventh pipe 15 and the ninth pipe 13 to complete the cycle.

[0068] See also Figure 1 and Figure 5, Defrosting mode: Start the first circulation pump 18, the primary heat pump starts the defrosting working mode, the heat stored in the buffer water tank 2-1 is provided to the primary heat pump through the first pipe 5 as a defrosting heat source, and under the action of the first circulation pump 18, the heat is returned to the inlet of the buffer water tank 2-1 from the outlet of the buffer water tank 2-1 through the second pipe 6, the secondary evaporator 3-1, and the fourth pipe 8 in sequence. When the heat of the buffer water tank 2-1 is insufficient, the electric heater in the buffer water tank 2-1 starts to supplement part of the heat to ensure the heat required for defrosting by the primary heat pump. In this mode, the second circulation pump 19 and the third circulation pump 20 stop, the secondary heat pump stops, and the system stops supplying heat to the outside.

[0069] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A two-stage heat pump trigeneration system, characterized in that: It includes a primary heat pump, a buffer water tank energy storage system, a secondary heat pump, a two-stage operation heating circuit, a two-stage operation hot water preheating circuit, a primary operation heating circuit, a primary operation cooling circuit and a secondary hot water supply circuit; The primary heat pump comprises a primary compressor, the outlet of the primary compressor is connected to one side inlet of the primary condenser through a four-way reversing valve, one side outlet of the primary condenser is connected to the primary evaporator through a primary main electronic expansion valve, and the primary evaporator is connected to the inlet of the primary compressor through the four-way reversing valve to form a first circulation loop; The buffer water tank energy storage system comprises a buffer water tank, the outlet of the buffer water tank is connected to the other side inlet of the primary condenser through a first pipe, the other side outlet of the primary condenser is connected to a second pipe, the second pipe is connected to a third pipe through a first circulation pump, the third pipe is connected to one side inlet of the secondary evaporator, and one side outlet of the secondary evaporator is connected to the inlet of the buffer water tank through a fourth pipe, forming a second circulation loop; The secondary heat pump comprises a secondary evaporator, the other side outlet of the secondary evaporator is connected to a secondary compressor, the secondary compressor is connected to one side inlet of a secondary condenser, and one side outlet of the secondary condenser is connected to the other side inlet of the secondary evaporator through a secondary electronic expansion valve to form a third circulation loop; The two-stage operation heating circuit includes a secondary condenser, the other side outlet of the secondary condenser is connected to the first valve through a fifth pipeline, the first valve is connected to the inlet of the user end through a sixth pipeline, the outlet of the user end is connected to a seventh pipeline, the seventh pipeline is connected to a second circulation pump, the second circulation pump is connected to a third valve through an eighth pipeline, the third valve is connected to the other side inlet of the secondary condenser through a ninth pipeline, forming a fourth circulation circuit; The two-stage operation hot water preheating loop includes a secondary condenser, and the other side outlet of the secondary condenser is sequentially connected to the fifth pipeline, the thirteenth pipeline, the second valve, the third circulation pump, the tenth pipeline, one side inlet of the heat exchanger, one side of the heat exchanger, one side outlet of the heat exchanger, the eleventh pipeline, the ninth pipeline and the other side inlet of the secondary condenser to form a fifth circulation loop; The primary operation heating circuit includes a primary condenser, and the other side outlet of the primary condenser is sequentially connected to the second pipeline, the twelfth pipeline, the sixth pipeline, the user terminal, the seventh pipeline, the second circulation pump, the eighth pipeline, the fifteenth pipeline, the fourth valve, the thirteenth pipeline, the buffer water tank, the first pipeline and the other side inlet of the primary condenser to form a sixth circulation loop; The primary operation cooling circuit is the same as the primary operation heating circuit, and the primary condenser is used as an evaporator to form a seventh circulation circuit; The secondary hot water supply loop includes a secondary condenser, and the other side outlet of the secondary condenser is sequentially connected to the fifth pipeline, the thirteenth pipeline, the second valve, the third circulation pump, the tenth pipeline, the heat exchanger, the eleventh pipeline, the ninth pipeline and the other side inlet of the secondary condenser to form an eighth circulation loop; The outlet on the other side of the heat exchanger is connected to the inlet of the domestic hot water storage tank, and the outlet of the domestic hot water storage tank is connected to the inlet on the other side of the heat exchanger.

2. The two-stage heat pump trigeneration system according to claim 1, characterized in that: The four-way reversing valve is connected to the inlet of the first-stage compressor through the first-stage gas-liquid separator; the pipeline connecting one side outlet of the first-stage condenser and the first-stage main electronic expansion valve is connected with a first-stage liquid reservoir, one side inlet of the economizer, one side outlet of the economizer, a drying filter and the sixteenth pipeline in sequence; one outlet on the other side of the economizer is connected to the first-stage compressor, and the other outlet on the other side of the economizer is connected to the first filter through the auxiliary electronic expansion valve, the first filter is connected to the sixteenth pipeline, and a second filter is provided on the pipeline connecting the main electronic expansion valve and the inlet of the first-stage evaporator.

3. The two-stage heat pump trigeneration system according to claim 2, characterized in that: The other side outlet of the secondary evaporator is connected to the secondary compressor through a secondary gas-liquid separator, and the pipeline connecting the one side outlet of the secondary condenser and the secondary electronic expansion valve is sequentially connected to a secondary liquid reservoir and a third filter.

4. The two-stage heat pump trigeneration system according to any one of claims 1 to 3, characterized in that: The first valve, the second valve, the third valve and the fourth valve are all electric valves.

5. The two-stage heat pump trigeneration system according to claim 4, characterized in that: The third pipeline, the fifth pipeline, the eleventh pipeline and the twelfth pipeline are provided with check valves.

6. The two-stage heat pump trigeneration system according to claim 5, characterized in that: An electric heater is arranged in the buffer water tank, and a drain valve is arranged at the bottom of the buffer water tank.

7. The two-stage heat pump trigeneration system according to claim 6, characterized in that: The lower part of the domestic hot water storage tank is connected with a water replenishing device.

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