Condensation-evaporation-phase change heat reservoir based on two-stage heat pump

Abstract

The invention provides a condensation-evaporation-phase change heat reservoir based on a two-stage heat pump, and relates to the technical field of heat storage and heat exchange design, the condensation-evaporation-phase change heat reservoir comprises a heat storage module, a pipeline module and a heat pump module, the pipeline module is connected with the heat storage module and the heat pump module, and the heat pump module is connected with the heat storage module. The condensation-evaporation-phase change heat storage device is coupled to the condensation side of the first-stage heat pump and the evaporation side of the second-stage heat pump and has the functions of condensation, evaporation and phase change heat storage / release, and in the heating-heat storage stage, the first-stage heat pump takes heat from a low-temperature heat source, condenses and releases heat in the condensation-evaporation-phase change heat storage device and stores heat at the same time; and in the heat release-heat supply stage, heat is released by the condensation-evaporation-phase change heat reservoir and is absorbed by the second-stage heat pump evaporator, and higher-temperature heat energy is prepared. The cascade phase change heat storage and heat pump two-stage compression are combined, the heat exchange efficiency is improved through cascade heat storage / release, and the cascade phase change heat storage heat pump has the characteristics of time-sharing operation, flexible heat supply and large temperature rise.

Description

Technical Field

[0001] The present invention relates to the technical field of heat storage and heat exchange design, and in particular to a condensation-evaporation-phase change heat storage device based on a two-stage heat pump. Background Art

[0002] Thermal energy, as one of the main forms of energy end-use, accounts for 51% of global final energy consumption. In the industrial sector, industrial boilers are a crucial source of thermal energy. However, traditional coal-fired industrial boilers are associated with high pollution and emissions. In recent years, to facilitate the achievement of China's dual carbon goals, various Chinese ministries and commissions have issued a series of policies related to industrial boilers, including the National Boiler Action Plan, to reduce energy use and control pollution from coal-fired industrial boilers. my country's industrial boilers are moving towards electrification and gasification, with the proportion of small boilers increasing annually, now exceeding 50% of total units. Heat pumps, as efficient and clean heating equipment, can improve both the quality and total amount of thermal energy using only a small amount of electrical energy. Therefore, replacing coal-fired boilers with heat pumps will become a key solution for thermal energy decarbonization.

[0003] The current demand for high-temperature thermal energy is increasing, and cascade heat pump technology is often used to achieve large temperature rises. However, cascade heat pumps are complex due to their multi-cycle coupling structure. Furthermore, the mismatch between heating costs and user demand for flexible heating under time-of-use electricity pricing limits their widespread application. Phase change thermal storage, a key branch of energy storage technology, focuses on efficient storage and management of thermal energy. This technology can effectively alleviate the intermittent and fluctuating nature of thermal energy supply, achieving temporal and spatial alignment between heat source, heat generation, and heat supply. Coupling phase change thermal storage technology with a heat pump to create a thermal storage-heat pump system is a key technical approach for achieving time-of-use heating and flexible heat supply. Conventional heat pumps and heat storage devices are coupled to the evaporator or condenser, but a single heat pump cannot achieve a large temperature rise. Therefore, a two-stage heat pump-based condensation-evaporation-phase change thermal storage system is designed by coupling the phase change thermal storage device to the evaporator and condenser of a single heat pump. This, combined with the high-efficiency heat exchange structure of cascaded phase change thermal storage, results in the design of a two-stage heat pump-based condensation-evaporation-phase change thermal storage system. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a condensation-evaporation-phase change heat storage device based on a two-stage heat pump.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a condensation-evaporation-phase change heat storage device based on a two-stage heat pump, comprising: a heat storage module, a pipeline module and a heat pump module, wherein the pipeline module connects the heat storage module and the heat pump module;

[0007] The heat pump module includes an evaporator, a condenser, a throttle valve and a compressor; the pipeline module includes a first centrifugal pump, a second centrifugal pump, a third centrifugal pump, a fourth centrifugal pump, a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve and a pipeline; the first end and the third end of the first valve are respectively connected to the first centrifugal pump and the second centrifugal pump; the first centrifugal pump is connected to the third end of the third valve; the second centrifugal pump is connected to the first end of the second valve; the third end of the second valve is connected to the throttle valve; and the throttle valve is connected to the first end of the third valve;

[0008] The first end of the fourth valve is connected to the fourth centrifugal pump, the third end of the fourth valve is connected to the third centrifugal pump, the fourth centrifugal pump is connected to the third end of the sixth valve, the fourth centrifugal pump is connected to the first end of the fifth valve, the third end of the fifth valve is connected to the compressor, and the compressor is connected to the first end of the sixth valve;

[0009] A plurality of the heat storage modules are connected in series between the second ends of the first valve and the fourth valve;

[0010] The condenser is connected between the second ends of the second valve and the fifth valve;

[0011] The evaporator is connected between the second ends of the third valve and the sixth valve.

[0012] Preferably, the number of the heat storage modules is 1-4, and each of the heat storage modules with different gradient phase change temperatures includes multiple U-shaped fin heat exchange tubes, a heat storage shell, an insulation layer, and a phase change material. Multiple layers of the U-shaped fin heat exchange tubes are arranged inside the heat storage shell. The interior of the U-shaped fin heat exchange tubes is a heat pump working fluid, the external space of the U-shaped fin heat exchange tubes is filled with phase change material, and the insulation layer is arranged on the outside of the heat storage shell; wherein, the difference between the phase change temperatures of the phase change materials in two adjacent heat storage modules is 2-10°C.

[0013] Preferably, 3-6 layers of U-shaped fin heat exchange tubes are arranged inside the heat storage module, corresponding to 3-6 inlets and outlets. The fluid inlets and outlets of the U-shaped fin heat exchange tubes are arranged in parallel and are connected to the main inlet and main outlet provided on the heat storage shell.

[0014] Preferably, the phase change material includes organic phase change materials and inorganic phase change materials, the organic phase change material includes at least one of paraffins, fatty acids, and higher aliphatic hydrocarbons, and the inorganic phase change material includes at least one of crystalline hydrated salts, molten salts, and metals.

[0015] Preferably, the heat pump working fluid includes one of R134a, R1234ze(E), R245fa, R1234yf, R1336mzz(Z), and R1233zd(E).

[0016] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0017] The present invention provides a condensation-evaporation-phase change heat storage device based on a two-stage heat pump. The condensation-evaporation-phase change heat storage device includes a heat storage module, a piping module, and a heat pump module. The piping module connects the heat storage module and the heat pump module. The present invention has the following advantages:

[0018] 1. Streamlining the heating module and improving heating efficiency. Traditional cascade heat pumps contain two compressor units. Excessive components lead to reduced heating efficiency, complex system piping structure and control procedures, and a large floor space. The condensation-evaporation-phase change heat storage device of the present invention can effectively streamline the heat pump heating module, reduce floor space, and improve heating efficiency.

[0019] 2. Smoothing out load fluctuations and reducing ineffective starts and stops, the integrated condensation-evaporation-phase change heat storage module can effectively utilize valley electricity to convert low-temperature heat into medium-temperature heat through the first-stage compression of the heat pump and store it in the condensation-evaporation-phase change heat storage. When the load side demands it, the stored heat is released through the second-stage compression of the heat pump to generate high-temperature heat and supply it to users. It can also operate normally when the heat source is unstable, and perform the second-stage compression when the load side demands it, thus reducing ineffective starts and stops of the heat pump and extending its service life.

[0020] 3. Optimize the heat exchange structure and improve the heat exchange efficiency. U-shaped finned heat exchange tubes are used in the condensation-evaporation-phase change heat storage device to optimize the internal structure of the tube and enhance the convective heat transfer coefficient during the heat storage and heat exchange process. The design of multiple heat storage units and multi-layer heat storage modules further improves the convective heat transfer coefficient, extends the heat storage-heat exchange time, and improves the heat storage power and density of the condensation-evaporation-phase change heat storage device.

[0021] 4. Reasonable use of electricity prices and efficient heating decarbonization. The integration of condensation-evaporation-phase change heat storage can achieve efficient utilization of valley electricity. Valley electricity is used to produce medium-temperature heat, and then high-temperature heat is produced through two-stage compression when the load side requires it. This increases the proportion of valley electricity used and reduces operating costs. Heat pumps and phase change heat storage are clean heating technologies with low carbon emissions during the heating process, which effectively achieves heating decarbonization.

[0022] 5. It has a wide range of application scenarios and is applicable to many fields. The output heat temperature can be reasonably adjusted according to the load side's demand for heat temperature. When the heat temperature cannot meet the requirements, the secondary compression heating mode can be turned on to produce high-temperature heat energy. It is applicable to residential, agricultural, industrial and other fields.

[0023] 6. The device has a simple structure and can be adjusted reasonably according to needs. The condensation-evaporation-phase change heat storage device is equipped with an opening, and the internal phase change material can be adjusted and replaced in real time according to needs. The pipelines can be disassembled and the refrigerant type can also be changed. The device is easy to clean and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 A schematic diagram of the structure of a condensation-evaporation-phase change heat storage device provided in an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the heating and heat storage operation of a condensation-evaporation-phase change heat storage device based on a two-stage heat pump provided by an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of heat release and heat supply operation of a condensation-evaporation-phase change heat storage device based on a two-stage heat pump provided by an embodiment of the present invention;

[0028] Figure 4 Schematic diagram of the heat storage module structure.

[0029] Figure numerals: 1. first valve; 2. second valve; 3. third valve; 4. fourth valve; 5. fifth valve; 6. sixth valve; 7. first centrifugal pump; 8. second centrifugal pump; 9. third centrifugal pump; 10. fourth centrifugal pump; 11. evaporator; 12. condenser; 13. throttle valve; 14. compressor; 15. pipeline; 16. heat storage shell; 17. insulation layer; 18. phase change material; 19. U-shaped fin heat exchange tube. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] The purpose of this invention is to provide a condensation-evaporation-phase change heat storage device based on a two-stage heat pump. Combined with a heat pump unit, this device achieves two-stage compression heating within the unit, achieving a large temperature rise while streamlining the heating module. Furthermore, the internal structure of the condensation-evaporation-phase change heat storage device is optimized to improve heat storage and release efficiency, providing a viable solution for high-temperature-rise heating and decarbonization.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Figure 1 A schematic diagram of the condensation-evaporation-phase change heat storage structure provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the present invention provides a condensation-evaporation-phase change heat storage device based on a two-stage heat pump, comprising:

[0034] A heat storage module, a pipeline module and a heat pump module, wherein the pipeline module connects the heat storage module and the heat pump module;

[0035] The heat pump module includes an evaporator, a condenser, a throttle valve and a compressor. The pipeline module includes a first centrifugal pump 7, a second centrifugal pump 8, a third centrifugal pump 9, a fourth centrifugal pump 10, a first valve 1, a second valve 2, a third valve 3, a fourth valve 4, a fifth valve 5, a sixth valve 6 and a pipeline 15. The first end and the third end of the first valve 1 are respectively connected to the first centrifugal pump 7 and the second centrifugal pump 8, the first centrifugal pump 7 is connected to the third end of the third valve 3, the second centrifugal pump 8 is connected to the first end of the second valve 2, the third end of the second valve 2 is connected to the throttle valve 13, and the throttle valve 13 is connected to the first end of the third valve 3;

[0036] A first end of the fourth valve 4 is connected to the fourth centrifugal pump 10, a third end of the fourth valve 4 is connected to the third centrifugal pump 9, the fourth centrifugal pump 10 is connected to a third end of the sixth valve 6, the fourth centrifugal pump 10 is connected to a first end of the fifth valve 5, a third end of the fifth valve 5 is connected to the compressor 14, and the compressor 14 is connected to a first end of the sixth valve 6;

[0037] A plurality of heat storage modules are connected in series between the second ends of the first valve 1 and the fourth valve 4;

[0038] The condenser 12 is connected between the second ends of the second valve 2 and the fifth valve 5;

[0039] The evaporator 11 is connected between the second ends of the third valve 3 and the sixth valve 6;

[0040] It should be noted that the above connections are all connected through pipelines 15.

[0041] The condensation-evaporation-phase change heat storage device based on the two-stage heat pump of the present invention is integrated with a heat storage module, a pipeline module and a heat pump module, coupled to the condensation side of the first-stage heat pump and the evaporation side of the second-stage heat pump, and has the functions of condensation, evaporation and phase change heat storage / release.

[0042] like Figure 4 As shown, the number of the heat storage modules is 1-4, that is, heat storage modules with different gradient phase change temperatures are used. Each of the heat storage modules includes multiple U-shaped fin heat exchange tubes 19, a heat storage shell 16, an insulation layer 17, and a phase change material 18. The interior of the heat storage shell 16 is provided with multiple layers of the U-shaped fin heat exchange tubes 19. The interior of the U-shaped fin heat exchange tubes 19 is filled with a heat pump working fluid. The external space of the U-shaped fin heat exchange tubes 19 is filled with the phase change material 18, and the insulation layer 17 is provided on the outside of the heat storage shell 16. The difference between the phase change temperatures of the phase change materials 18 in two adjacent heat storage modules is 2-10°C.

[0043] The overall heat storage module is composed of multiple heat storage modules with different gradient phase change temperatures connected in series;

[0044] The heat storage module is internally provided with 3-6 layers of U-shaped fin heat exchange tubes 19 corresponding to 3-6 inlets and outlets. The fluid inlets and outlets of the U-shaped fin heat exchange tubes 19 are arranged in parallel and are connected to the main inlet and main outlet provided on the heat storage shell 16.

[0045] The phase change material 18 includes organic phase change materials and inorganic phase change materials. The organic phase change material includes at least one of paraffin, fatty acid, and higher aliphatic hydrocarbon, and the inorganic phase change material includes at least one of crystalline hydrated salt, molten salt, and metal.

[0046] The evaporator 11 and condenser 12 of the heat pump module adopt a shell and tube heat exchange structure with fins installed inside. The heat pump working fluid adopts one of R134a, R1234ze(E), R245fa, R1234yf, R1336mzz(Z), and R1233zd(E);

[0047] The operation process of the condensation-evaporation-phase change heat storage device based on the two-stage heat pump is specifically as follows: the heat pump is in the first-stage compression mode, the condensation-evaporation-phase change heat storage device is connected to the heat pump condenser 12 through the first valve 1, the second valve 2, the fourth valve 4, the fifth valve 5, the second centrifugal pump 8, and the third centrifugal pump 9, the prepared medium-temperature heat transfer fluid enters the condensation-evaporation-phase change heat storage device through the pipeline 15 to exchange heat with the internal phase change material, and stores heat in the phase change material; the heat pump is in the second-stage compression mode, the condensation-evaporation-phase change heat storage device is connected to the heat pump evaporator 11 through the first valve 1, the third valve 3, the fourth valve 4, the sixth valve 6, the first centrifugal pump 7, and the fourth centrifugal pump 10 to release the stored heat;

[0048] In the heating-heat storage stage, the primary heat pump takes heat from a low-temperature heat source, condenses and releases heat in the condensation-evaporation-phase change heat storage device, and stores heat at the same time; in the heat release-heating stage, the condensation-evaporation-phase change heat storage device releases heat and acts as a secondary heat pump evaporator to absorb heat, producing higher temperature heat energy;

[0049] When the heat absorption of the secondary heat pump evaporator is insufficient, the primary heat pump and the secondary heat pump are started in parallel, so that the condensation-evaporation-phase change heat storage device can simultaneously perform the functions of condensation heat release and evaporation heat absorption;

[0050] The heat pump system adopts a one-stage compression mode to produce heat and store it in a phase-change heat exchanger. It also uses valley electricity at night to produce heat, which is highly economical. Specifically:

[0051] like Figure 2 As shown, the evaporator 11 absorbs heat from the heat source, raising the temperature of the refrigerant (heat pump working fluid). The high-temperature refrigerant that absorbs heat in the evaporator is compressed by the compressor to increase its pressure to form high-temperature and high-pressure refrigerant vapor, which is then sent to the condenser 12 side to condense and release heat. It then exchanges heat with the heat transfer fluid on the condenser side, transferring heat to the condenser 12 side. The condenser 12 then exchanges heat with the phase change material 18 in the heat storage heat exchanger through a pipeline, ultimately storing energy in the condensation-evaporation-phase change heat storage device.

[0052] Specifically, the refrigerant in the evaporator 11 absorbs heat from the heat source and enters the compressor 14 for compression through the sixth valve 6. The compressed high-pressure and high-temperature refrigerant enters the condenser 12 through the fifth valve 5, exchanges heat with the heat transfer fluid in the condenser 12, and transfers heat to the condenser 12 side. The low-temperature refrigerant on the condenser 12 side, which releases heat through condensation, enters the throttle valve 13 through the second valve 2 to reduce the pressure, and finally enters the evaporator 11 through the third valve 3 to complete the cycle; the condenser 12 exchanges heat with the condensation-evaporation-phase change heat storage through the second centrifugal pump 8, the third centrifugal pump 9, the first valve 1, the second valve 2, the fourth valve 4, and the fifth valve 5, and finally stores the heat in the condensation-evaporation-phase change heat storage;

[0053] The heat pump system adopts a two-stage compression mode to produce heat and supply it to users, which can obtain high-temperature heat to meet user needs. Specifically:

[0054] like Figure 3 As shown, the evaporator 11 absorbs heat from the condensation-evaporation-phase change heat storage device, further increasing the temperature of the refrigerant. The refrigerant is compressed by the compressor to form high-temperature and high-pressure refrigerant vapor, which is sent to the condenser 12 side. It exchanges heat with the heat transfer fluid on the condenser side and transfers heat to the condenser 12 side. The condenser supplies the generated high-temperature heat to the user.

[0055] Specifically, the refrigerant in the evaporator 11 absorbs the heat stored in the condensation-evaporation-phase change heat storage device, enters the compressor 14 for compression through the sixth valve 6, and the compressed high-pressure and high-temperature refrigerant enters the condenser 12 through the fifth valve 5, exchanges heat with the heat transfer fluid of the condenser 12, and transfers the heat to the condenser 12 side. The low-temperature refrigerant enters the throttle valve 13 through the second valve 2 to reduce the pressure, and finally enters the evaporator 11 through the third valve 3 to complete the cycle; the condenser supplies the produced high-temperature heat to the user.

[0056] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0057] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A condensation-evaporation-phase change heat storage device based on a two-stage heat pump, characterized in that: include: A heat storage module, a pipeline module and a heat pump module, wherein the pipeline module connects the heat storage module and the heat pump module; The heat pump module includes an evaporator, a condenser, a throttle valve and a compressor; the pipeline module includes a first centrifugal pump, a second centrifugal pump, a third centrifugal pump, a fourth centrifugal pump, a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve and a pipeline; the first end and the third end of the first valve are respectively connected to the first centrifugal pump and the second centrifugal pump; the first centrifugal pump is connected to the third end of the third valve; the second centrifugal pump is connected to the first end of the second valve; the third end of the second valve is connected to the throttle valve; and the throttle valve is connected to the first end of the third valve; The first end of the fourth valve is connected to the fourth centrifugal pump, the third end of the fourth valve is connected to the third centrifugal pump, the fourth centrifugal pump is connected to the third end of the sixth valve, the fourth centrifugal pump is connected to the first end of the fifth valve, the third end of the fifth valve is connected to the compressor, and the compressor is connected to the first end of the sixth valve; A plurality of the heat storage modules are connected in series between the second ends of the first valve and the fourth valve; The condenser is connected between the second ends of the second valve and the fifth valve; The evaporator is connected between the second ends of the third valve and the sixth valve.

2. The condensation-evaporation-phase change heat storage device according to claim 1, characterized in that: The number of heat storage modules with different gradient phase change temperatures is 1-4. Each heat storage module includes multiple U-shaped fin heat exchange tubes, a heat storage shell, an insulation layer, and a phase change material. Multiple layers of the U-shaped fin heat exchange tubes are arranged inside the heat storage shell. The heat pump working fluid is inside the U-shaped fin heat exchange tubes, and the external space of the U-shaped fin heat exchange tubes is filled with phase change material. The insulation layer is arranged on the outside of the heat storage shell. The difference between the phase change temperatures of the phase change materials in two adjacent heat storage modules is 2-10°C.

3. The condensation-evaporation-phase change heat storage device according to claim 2, characterized in that: The heat storage module is provided with 3-6 layers of U-shaped fin heat exchange tubes, corresponding to 3-6 inlets and outlets. The fluid inlets and outlets of the U-shaped fin heat exchange tubes are arranged in parallel and are connected to the main inlet and main outlet provided on the heat storage shell.

4. The condensation-evaporation-phase change heat storage device according to claim 2, characterized in that: The phase change material includes organic phase change materials and inorganic phase change materials. The organic phase change material includes at least one of paraffins, fatty acids, and higher aliphatic hydrocarbons. The inorganic phase change material includes at least one of crystalline hydrated salts, molten salts, and metals.

5. The condensation-evaporation-phase change heat storage device according to claim 2, characterized in that: The heat pump working fluid includes one of R134a, R1234ze(E), R245fa, R1234yf, R1336mzz(Z), and R1233zd(E).

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