Compression type high-temperature heat pump system with energy storage and enthalpy compensation functions

Abstract

The invention discloses a compression type high-temperature heat pump system with energy storage and enthalpy compensation functions. The system comprises a compressor, a condenser, an ejector, a gas-liquid separator, an expansion valve, an evaporator, an intermediate heat exchanger and a heat accumulator. The system can achieve switching of two operation modes, namely a supercooling energy storage mode and an energy releasing and enthalpy supplementing mode, the different operation modes are switched according to the operation working condition of the system and the energy storage condition of the heat accumulator, during energy storage, the supercooling energy storage mode is switched, and energy storage is conducted on the heat accumulator through the supercooling capacity of working fluid at an outlet of a condenser; and during energy release, an energy release and enthalpy compensation mode is switched, the mass flow of the steam injection branch is enhanced by utilizing heat in the heat accumulator, and the heat supply capacity and the operation performance of the system are enhanced.

Description

Technical Field

[0001] The present invention relates to the field of low-grade waste heat conversion, and in particular to a compression-type high-temperature heat pump system with energy storage and enthalpy replenishment, which can realize expansion work recovery and improve system heating efficiency through mode switching. By setting a heat accumulator and an ejector, effective recovery of expansion work is achieved, avoiding a large amount of irreversible thermodynamic energy loss generated in a traditional expansion valve. The heat pump system can realize two modes of supercooling energy storage and energy release and enthalpy replenishment through the switch control of a three-way valve. Both modes can effectively utilize the thermal energy and pressure energy of the working fluid at the outlet of the condenser to achieve thermal quality conversion of a large amount of low-grade waste heat. Background Art

[0002] In the industrial production process, a large amount of primary energy is used in the industrial production process system in the form of heat energy generated by fuel combustion. However, the existing industrial production process cannot completely convert the heat of combustion into the required energy, and most of the available heat is discharged into the environment in various forms, causing thermal pollution and energy waste. The energy utilization efficiency in the process production process can be effectively improved by recycling low-grade industrial waste heat. Common waste heat utilization methods include heat-to-work conversion, heat-to-cold conversion, and heat-to-grade conversion. Among them, heat-to-work conversion is difficult to effectively convert into electrical energy when using low-grade waste heat at 150°C, and the operating efficiency of heat-to-cold conversion driven by low-grade waste heat is not high. Therefore, using heat pump technology to improve the thermal grade of low-temperature waste heat is an effective way to efficiently utilize a large amount of industrial waste heat. Improve the energy efficiency of industrial processes by converting or upgrading heat energy that would otherwise be wasted. Compression heat pumps can be used to upgrade industrial waste heat at lower temperatures, and some electricity needs to be consumed to achieve the quality improvement of a large amount of waste heat. In order to minimize the consumption of high-grade electricity, the layout of heat pump systems with high operating performance needs to be further studied.

[0003] At lower waste heat temperatures, traditional single-stage compression systems have the disadvantages of high compression ratio, high exhaust temperature and large compression power. Therefore, many scholars have proposed many improved systems, including quasi-two-stage compression heat pump systems, multi-stage compression heat pump systems and cascade heat pump systems, based on the single-stage compression system. The optimization idea of ​​these systems is to reduce the compression ratio of a single compressor as much as possible and make the compression process approach constant temperature compression. Among them, compared with other systems, the air replenishment enthalpy increase system uses only one compressor to achieve a reduction in exhaust temperature and compression power consumption, and has a lower investment cost. In addition, the air replenishment of the compressor can increase the working fluid flow rate of the system to a certain extent, while increasing the heating capacity of the system; the adjustability of the air replenishment mass flow rate increases the flexibility of compressor control, making system adjustment more convenient.

[0004] Compared with the ideal reverse Carnot cycle, the traditional steam compression heat pump uses an expansion valve as an expansion device, resulting in a large amount of irreversible thermodynamic energy loss. Ordinary quasi-two-stage compression systems usually use flash tanks or subcoolers as key equipment to achieve air replenishment and enthalpy increase, but the air replenishment mass flow rate generated by this method is quite limited. Therefore, some scholars use exhaust gas with a higher waste heat temperature than the evaporator side to increase the mass flow rate of compressor air replenishment, which can significantly enhance the system performance. The thermodynamic principle of this performance enhancement method is to increase the average temperature of the system. However, in practical applications, additional waste heat input at different temperatures is usually difficult to meet. Therefore, how to greatly reduce high-grade compression work and improve the system's thermal grade conversion efficiency under the condition of a single waste heat source is an important problem to be solved.

[0005] China Invention Publication Patent CN118408296A discloses "a heat pump circulation system with an intermediate air injection ejector and a control method thereof. The technical solution uses a solar collector to collect solar heat, increases the mass flow of the air injection enthalpy increase branch, and enables more working fluids to avoid the process of expansion and then compression, and the system performance is effectively improved. In the process of industrial waste heat recovery, the actual process does not necessarily have two temperatures of waste heat sources, and the operation scenario of the dual-temperature waste heat source limits the application of the system.

[0006] China's invention patent CN109931721A discloses "a heat pump system based on solar thermal storage, defrosting, air replenishment and enthalpy increase". The system has two operating modes, namely thermal storage mode and defrost mode. In thermal storage mode, the heat energy of the solar sub-cycle and the working fluid at the condenser outlet is used to store solar energy and supercooled heat energy in the thermal storage device; in defrost mode, the heat in the thermal storage device is used for defrosting, ensuring the normal heating of the system. The system realizes thermal storage defrosting in low temperature scenarios, but the operating scenario of its dual-temperature waste heat source also limits the application of the system. Summary of the invention

[0007] The present invention introduces a heat accumulator into an injection-compression heat pump system, and constructs a compression-type high-temperature heat pump system with energy storage and enthalpy compensation through reasonable heat storage and heat release mode design. The system can effectively utilize the heat energy and pressure energy of the working fluid at the outlet of the condenser, and reduce the irreversible thermodynamic energy loss existing in the cyclic expansion process of the traditional heat pump. The system can operate in two modes, namely, a supercooling energy storage mode and an energy release and enthalpy compensation mode. In the supercooling energy storage mode, the system stores the supercooled heat released by the working fluid. The supercooled working fluid enters the evaporator side through the gas-liquid separator to absorb heat, thereby increasing the heating capacity of the system. In the energy release and enthalpy compensation mode, the working fluid at the outlet of the condenser first releases heat in the intermediate heat exchanger, and then absorbs the heat of the heat accumulator after the expansion valve reduces the pressure to become enthalpy compensation steam. In this mode, the exhaust temperature of the system compressor decreases and the compression power consumption decreases, and it has excellent heating performance. The system of the present invention can effectively solve the problem of excessive consumption of high-grade electric energy in the compression heat pump during the process of improving the quality of low-temperature waste heat. In the process of upgrading the quality of low-temperature industrial waste heat, the system has the characteristics of high economic effect and environmental friendliness.

[0008] In order to achieve the purpose of the present invention, the present invention provides a compression type high temperature heat pump system with energy storage and enthalpy compensation, comprising a compressor, a condenser, a three-way valve, an expansion valve, an ejector, a gas-liquid separator, an evaporator, a heat accumulator and an intermediate heat exchanger, wherein the system is switched between a supercooling energy storage mode and an energy release and enthalpy compensation mode by means of the three-way valve, wherein the three-way valve comprises a first three-way valve and a second three-way valve, and the expansion valve comprises a first expansion valve, a second expansion valve and a third expansion valve;

[0009] In the supercooling energy storage mode, the outlet of the compressor is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the first three-way valve, one of the outlets of the first three-way valve is connected to the ejector, and the other outlet is connected to the heat accumulator; the outlet of the heat accumulator is connected to the inlet of the first expansion valve, and the outlet of the first expansion valve is connected to the inlet of the gas-liquid separator; the outlet of the ejector is connected to the gas-liquid separator, the gas phase outlet of the gas-liquid separator is connected to the intermediate heat exchanger, the outlet of the intermediate heat exchanger is connected to the inlet of the compressor, the liquid phase outlet of the gas-liquid separator is connected to the second expansion valve, the outlet of the second expansion valve is connected to the evaporator, the outlet of the evaporator is connected to the inlet of the secondary nozzle of the ejector, and the working fluid at the outlet of the evaporator is ejected into the ejection chamber of the ejector by the fluid in the working nozzle of the ejector;

[0010] In the energy release and enthalpy compensation mode, the outlet of the compressor is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the first three-way valve, one of the outlets of the first three-way valve is connected to the ejector, and the other outlet is connected to the second three-way valve, the intermediate heat exchanger, the third expansion valve, and the heat accumulator in sequence, and the heat accumulator is connected to the air supply port of the compressor; the outlet of the ejector is connected to the gas-liquid separator, the gas phase outlet of the gas-liquid separator is connected to the inlet of the intermediate heat exchanger, the outlet of the intermediate heat exchanger is connected to the compressor, the working fluid enters the compressor after absorbing heat in the intermediate heat exchanger, the liquid phase outlet of the gas-liquid separator, the second expansion valve, the evaporator, and the ejector are connected in sequence, the working fluid enters the evaporator after being reduced in pressure by the second expansion valve, and the working fluid at the outlet of the evaporator is ejected by the fluid in the working nozzle of the ejector into the ejection chamber of the ejector.

[0011] Furthermore, the ejector can utilize the high-pressure fluid at the condenser outlet to eject the low-pressure fluid at the evaporator outlet, thereby increasing the pressure of the compressor inlet fluid and thereby reducing the compression ratio of the compressor.

[0012] Furthermore, the injector is an area-adjustable injector, and the injector throat area is adjusted according to the actual operating conditions of the system.

[0013] The three-way valve is an adjustable three-way valve, which can realize the free opening and closing of the valve.

[0014] Furthermore, when the system switches to the energy release and enthalpy compensation mode, the outlet fluid of the heat accumulator is used as the intermediate air supply of the compressor; when the system switches to the supercooling energy storage mode, part of the working fluid at the outlet of the condenser enters the heat accumulator for supercooling, and the released heat is stored in the heat accumulator.

[0015] Furthermore, the compressor is an air-supplementing compressor.

[0016] Furthermore, when the system is in the energy release and enthalpy compensation mode, the air supply channel of the compressor is opened, and the working fluid at the outlet of the heat accumulator serves as the intermediate air supply of the compressor; when the system is in the supercooling energy storage mode, the air supply port of the compressor is closed, and the supercooling heat of the condenser outlet fluid is stored in the heat accumulator.

[0017] Furthermore, in the supercooling energy storage mode, the outlet pressure of the ejector is the same as the pressure of the working fluid in the branch where the heat accumulator is located after expansion and pressure reduction.

[0018] Furthermore, in the energy release and enthalpy compensation mode, the outlet temperature of the accumulator is higher than the outlet temperature of the intermediate heat exchanger, but lower than the condensation temperature.

[0019] Furthermore, in the supercooling energy storage mode, the working fluid is pressurized by the compressor and then enters the condenser to release heat and condense. After the condensed working fluid in the condenser is diverted by the first three-way valve, one path enters the primary nozzle of the ejector to complete the pressure reduction and speed increase, and then the outlet fluid of the evaporator is injected into the ejector and mixed in the mixing chamber in the ejector. The mixed fluid is pressurized by the ejector and then enters the gas-liquid separator; the other path enters the heat accumulator to supercool and release heat, and the released heat is stored in the heat accumulator; the working fluid that is supercooled and releases heat in the heat accumulator enters the first expansion valve for expansion and pressure reduction, and the depressurized working fluid enters the gas-liquid separator to mix with the outlet fluid of the ejector; the gas phase fluid in the gas-liquid separator enters the intermediate heat exchanger to absorb heat and become superheated steam, and the superheated steam enters the compressor to complete the compression process; the liquid phase fluid enters the second expansion valve to expand and reduce pressure, and then enters the evaporator to absorb heat and evaporate, and finally is injected into the ejector by the primary flow of the ejector.

[0020] Furthermore, in the energy release and enthalpy compensation mode, the working fluid is mixed with the outlet fluid of the heat accumulator after being compressed and pressurized in the compressor, the mixed working fluid is compressed and pressurized in the high-pressure chamber of the compressor, the pressurized working fluid enters the condenser to release heat and condense, the condensed working fluid enters the first three-way valve and is divided into two streams, one of which becomes the ejector's induced fluid, the ejector fluid enters the ejector to reduce pressure and increase speed, the accelerated working fluid ejects the working fluid at the evaporator outlet and mixes in the ejector, the mixed fluid enters the ejector to increase pressure, and the pressurized working fluid enters One stream enters the gas-liquid separator; the other stream enters the intermediate heat exchanger to release heat. The working fluid after heat release enters the third expansion valve to expand and reduce pressure. The working fluid after pressure reduction absorbs the heat in the heat accumulator and enters the compressor to complete gas replenishment; the gaseous working fluid in the gas-liquid separator enters the intermediate heat exchanger to absorb heat and become superheated steam, and then enters the compressor for compression and pressure increase. The liquid working fluid in the gas-liquid separator enters the second expansion valve to expand and reduce pressure. The working fluid after pressure reduction enters the evaporator to absorb heat and evaporate. The outlet fluid of the evaporator is ejected by the working fluid in the ejector and enters the ejector.

[0021] In the supercooling energy storage mode, the heat accumulator can store the supercooled heat of the working fluid at the condenser outlet. The working fluid that has been cooled to a certain temperature enters the gas-liquid separator after being depressurized by the expansion valve. In the supercooling energy storage mode, the energy stored in the heat accumulator is part of the expansion work that would have been dissipated.

[0022] In the energy release and enthalpy compensation mode, the intermediate heat exchanger and the enthalpy compensation compressor recover the expansion work in the energy release and enthalpy compensation mode, while the heat accumulator uses the expansion work recovered in the subcooling heat storage mode to increase the mass flow rate of the replenishing air, thereby achieving an overall performance improvement of the system.

[0023] The compressor can increase the temperature and pressure of the working fluid by compressing it. This component can select compressors of different models and capacities according to the characteristics of the working fluid and the operating conditions of the system; the condenser can realize the heat exchange from the working fluid to the high-temperature carrier. This component can select condensers of different sizes and models according to the heat release temperature and heat release; the three-way valve can realize the flow path switching of the working fluid. This component can select three-way valves of different sizes and types according to the different control requirements of the system and the flow rate of the working fluid; the ejector can use the ejected fluid to increase the pressure of the ejected fluid to achieve the boosting effect of the ejected fluid. This component can select adjustable ejectors of different specifications according to the thermodynamic characteristics of the ejected fluid and the ejected fluid; the gas-liquid separator can separate the working fluids of different phases and has both storage Liquid action, this component can be replaced with different types of separation devices according to actual application requirements; the expansion valve can realize the pressure reduction of the working fluid in the system, and this component can be replaced with different types of expansion devices according to the mass flow rate of the working fluid and different application scenarios; the evaporator can absorb the heat exchange between the working fluid and the outside world, and input heat into the system. This component can select different types and sizes of evaporators according to the actual heat absorption and usage scenarios; the heat accumulator can store the heat released by the working fluid in the heat storage medium. This component can select different sizes and types of heat accumulators according to the difference in the heating capacity of the system; the intermediate heat exchanger allows two different fluids to exchange heat inside it. This component can select heat exchangers of different sizes and models according to the flow characteristics and flow rate of the heat exchange fluid.

[0024] Compared with the existing quasi-two-stage compression heat pump system, the present invention has the following advantages:

[0025] The system of the present invention can achieve the effect of mode switching, energy storage and enthalpy compensation efficiency enhancement, and can use the expansion work recovered in the supercooling energy storage mode to increase the air replenishment volume in the energy release and enthalpy compensation mode. In addition, the thermal energy and pressure energy of the working fluid at the condenser outlet in the energy release and enthalpy compensation mode can be utilized through the intermediate heat exchanger and the enthalpy compensation compressor. Compared with the traditional quasi-two-stage compression heat pump, the presence of the heat accumulator enhances the overall operating performance of the system. Under the condition of a single waste heat source, the performance enhancement effect of increasing the average heat absorption temperature of the system by using dual waste heat sources is achieved.

[0026] The system of the present invention utilizes the self-heat storage characteristics and uses the waste heat source as the low-temperature heat source, which has unique advantages in high-temperature heat pumps. For the energy storage enthalpy replenishment mode, sufficient waste heat can be stored through the heat accumulator to avoid waste of waste heat; for the energy release mode, it has good operating performance, that is, a higher COP. It can improve the system's utilization level of waste heat.

[0027] The system of the present invention can fully utilize the heat energy and pressure energy of the condenser outlet fluid through mode switching. Different operating modes are switched at different operating stages to improve the waste heat conversion efficiency of the heat pump system. Compared with the traditional quasi-two-stage compression heat pump, the system of the present invention has the characteristics of reasonable system layout, flexible operating mode, sufficient green energy saving and good stable heating.

[0028] The present invention uses the heat at the condenser outlet to improve the system enthalpy compensation performance in a self-enhanced manner. Compared with existing solutions, the system proposed in the present invention has a wider application scenario and is not limited by the number of waste heat sources in actual scenarios. At the same time, the system performance is improved without increasing the complexity of the system.

[0029] Using the ejector as an expansion device in the heat pump system can reduce the loss of expansion work and improve the heating efficiency of the system. As a static component, the ejector has the characteristics of simple structure, low cost, safety and reliability. The recovered expansion work can be used to increase the pressure of the compressor inlet fluid and reduce the power consumption of the compressor. Using the ejector in a quasi-two-stage compression heat pump system can minimize the high-grade compression work consumption. This combined method has significant advantages in improving the quality of low-temperature waste heat.

[0030] The present invention utilizes the heat storage device to recover the heat at the condenser outlet and utilizes the ejector to recover the expansion work of part of the working fluid, thereby further improving the performance. In addition, in the field of industrial heat recovery, the present invention utilizes the heat storage and air replenishment enthalpy increase technology to effectively overcome the problem of excessively high exhaust temperature of the compressor and overheating of the compressor.

[0031] The system of the present invention has a simpler system structure than the existing system, avoids the pressure fluctuation caused by the switching of the three-way valve, and improves the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Attached Figure 1 It is a schematic diagram of a compression-type high-temperature heat pump system with energy storage and enthalpy compensation according to an embodiment of the present invention.

[0033] Attached Figure 2 It is a schematic diagram of a supercooling energy storage mode of a compression high-temperature heat pump system with energy storage and enthalpy compensation according to an embodiment of the present invention.

[0034] Attached Figure 3 It is a schematic diagram of the energy release and enthalpy compensation mode of the compression high-temperature heat pump system with energy storage and enthalpy compensation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings.

[0036] See also Figure 1The present invention proposes a compression type high temperature heat pump system with energy storage and enthalpy compensation, including a compressor 1, a condenser 2, a three-way valve, an ejector 4, a gas-liquid separator 5, an expansion valve, an evaporator 7, a heat accumulator 9 and an intermediate heat exchanger 11, a total of 9 components, and each component works in coordination. By controlling the flow path switching by the three-way valve, two operating modes can be realized, namely, a supercooling energy storage mode and an energy release and enthalpy compensation mode. The corresponding mode can be switched according to the system operation stage.

[0037] In some embodiments of the present invention, the compressor 1 can increase the temperature and pressure of the working fluid by compressing the working fluid, wherein compressors of different models and capacities can be selected according to the characteristics of the working fluid and the operating conditions of the system; the condenser 2 can realize heat exchange from the working fluid to the high-temperature carrier, and condensers of different sizes and models can be selected according to the heat release temperature and the heat release amount; the three-way valve is used to realize the flow path switching of the working fluid, and three-way valves of different sizes and types can be selected according to different control requirements of the system and the flow rate of the working fluid, and the three-way valve includes a first three-way valve 3 and a second three-way valve 8; the ejector 4 can use the ejected fluid to increase the pressure of the ejected fluid to achieve the pressure-boosting effect of the ejected fluid, and adjustable ejectors of different specifications can be selected according to the thermodynamic characteristics of the ejected fluid and the ejected fluid; the gas-liquid separator 5 can separate different phases The working fluid also has the function of storing liquid, and can be replaced by different types of separation devices according to actual application requirements; the expansion valve can realize the pressure reduction of the working fluid in the system, and can be replaced by different types of expansion devices according to the mass flow rate of the working fluid and different application scenarios. The expansion valve includes a first expansion valve 10, a second expansion valve 6 and a third expansion valve 12; the evaporator 7 can absorb the heat exchange between the working fluid and the outside world, and input heat into the system. Different types and sizes of evaporators can be selected according to the actual heat absorption and usage scenarios; the heat accumulator 9 can store the heat released by the working fluid in the heat storage medium, and different sizes and types of heat accumulators can be selected according to the difference in the heating capacity of the system; the intermediate heat exchanger 11 allows two different fluids to exchange heat inside it, and heat exchangers of different sizes and models can be selected according to the flow characteristics and flow rate of the heat exchange fluid.

[0038] The three-way valve is an adjustable three-way valve, which can realize free opening and closing of the valve.

[0039] In some embodiments of the present invention, the injector 14 is an area-adjustable injector, and the throat area of ​​the injector 14 can be adjusted according to the actual operating conditions of the system to improve the injection capacity of the injector 14. The injector 14 can adapt to different operating conditions.

[0040] In some embodiments of the present invention, the ejector 14 is a two-phase ejector, which is a typical expansion work recovery device having the characteristics of simple structure and low cost.

[0041] In some embodiments of the present invention, the gas-liquid separator 5 has two inlets and two outlets, and the working fluid can be mixed at equal pressure inside the gas-liquid separator.

[0042] Figure 2 This is a schematic diagram of a supercooling energy storage mode of a compression high-temperature heat pump system with energy storage and enthalpy supplement proposed by the present invention. In the supercooling energy storage stage, the outlet of the compressor 1 is connected to the inlet of the condenser 2. The outlet fluid of the condenser 2 is divided into two paths after passing through the first three-way valve 3. One path enters the working nozzle of the ejector 4 to complete the pressure reduction and speed increase, and then injects the fluid at the outlet of the evaporator 7 into the ejector 4. The two are mixed in the mixing chamber of the ejector 4. The other path enters the heat accumulator 9 through the second three-way valve 8 for supercooling heat storage. The outlet of the heat accumulator 9 is connected to the inlet of the first expansion valve 10, and the outlet of the first expansion valve 10 is connected to one of the inlets of the gas-liquid separator 5. The outlet of the ejector 4 is connected to the other inlet of the gas-liquid separator 5; the gas phase outlet of the gas-liquid separator 5 is connected to the intermediate heat exchanger 11; the outlet of the intermediate heat exchanger 11 is connected to the inlet of the compressor 1. The liquid phase outlet of the gas-liquid separator 5 is connected to the second expansion valve 6, the second expansion valve 6 is connected to the evaporator 7, and the working fluid enters the evaporator 7 after being reduced in pressure by the second expansion valve 6; the outlet of the evaporator 7 is connected to the inlet of the secondary nozzle of the ejector 4, and the working fluid at the outlet of the evaporator 7 is ejected by the fluid in the working nozzle of the ejector 4 into the ejection chamber of the ejector 4.

[0043] In the supercooling energy storage stage of the heat accumulator, the working fluid is boosted by the compressor 1 and enters the condenser 2 to release heat and condense. After the condensed working fluid in the condenser 2 is split by the first three-way valve 3, one path enters the working nozzle (primary nozzle) of the ejector 4 to complete the pressure reduction and speed increase, and then the outlet fluid of the evaporator 7 is injected into the ejector 4. The two are mixed in the mixing chamber in the ejector 4. The mixed fluid is boosted by the diffuser section in the ejector 4 and enters the gas-liquid separator 5; the other path enters the heat accumulator 9 to supercool and release heat, and the released heat is stored in the heat accumulator 9. The working fluid that is supercooled and releases heat in the heat accumulator 9 enters the first expansion valve 10 to expand and reduce pressure, and the depressurized working fluid enters the gas-liquid separator 5 to mix with the outlet fluid of the ejector 4. The gas phase fluid in the gas-liquid separator 5 enters the intermediate heat exchanger 11 to absorb heat and become superheated steam, and the superheated steam enters the compressor 1 to complete the compression process; the liquid phase fluid enters the second expansion valve 6 to expand and reduce the pressure, and then enters the evaporator 7 to absorb heat and evaporate, and finally is ejected by the primary flow in the working nozzle of the ejector 4 into the ejection chamber of the ejector 4.

[0044] The heat accumulator 9 can store the supercooled heat of the working fluid at the outlet of the condenser 2, and the working fluid cooled to a certain temperature enters the gas-liquid separator 5 after being depressurized by the first expansion valve 10. In the supercooled energy storage mode, the energy stored in the heat accumulator 9 is part of the expansion work that would otherwise be dissipated.

[0045] The outlet pressure of the ejector 4 is the same as the pressure of the branch working fluid of the heat accumulator 9 after expansion and decompression.

[0046] Figure 3 This is a schematic diagram of the energy release and enthalpy compensation mode of a compression type high temperature heat pump system with energy storage and enthalpy compensation proposed by the present invention. In the stage of energy release and enthalpy compensation of the heat accumulator, the outlet of the compressor 1 is connected to the inlet of the condenser 2. After the heat release in the condenser 2, the working fluid enters the first three-way valve 3 and is divided into two streams, one of which becomes the injection fluid of the ejector 4, and the other enters the intermediate heat exchanger 11 through the second three-way valve 8 to release heat. The working fluid after heat release enters the third expansion valve 12 to reduce the pressure; the outlet of the third expansion valve 12 is connected to the inlet of the heat accumulator 9, and the outlet of the heat accumulator 9 is connected to the air supply port of the compressor 1. The working fluid absorbs the heat in the heat accumulator 9 and enters the air supply port of the compressor 1; the outlet of the ejector 4 is connected to the gas-liquid separator 5, and the gas phase outlet of the gas-liquid separator 5 is connected to the inlet of the intermediate heat exchanger 11. The working fluid absorbs heat in the intermediate heat exchanger 11 and enters the compressor 1. The liquid phase outlet of the gas-liquid separator 5 is connected to the inlet of the second expansion valve 6 , the outlet of the second expansion valve 6 is connected to the evaporator 7 , and the working fluid enters the evaporator 7 after being depressurized by the second expansion valve 6 ; the outlet of the evaporator 7 is connected to the secondary nozzle of the ejector 4 .

[0047] In the stage of releasing energy and replenishing enthalpy in the heat accumulator, the working fluid is compressed and pressurized in the low-pressure chamber of the compressor 1 and mixed with the outlet fluid of the heat accumulator 9. The mixed working fluid is compressed and pressurized in the high-pressure chamber of the compressor 1. The pressurized working fluid enters the condenser 2 to release heat and condense. The condensed working fluid enters the first three-way valve 3 and is divided into two streams. One stream becomes the ejection fluid of the ejector 4. The ejection fluid enters the working nozzle of the ejector 4 to reduce pressure and increase speed. The working fluid after speeding up ejects the working fluid at the outlet of the evaporator 7. The two are mixed in the mixing chamber in the ejector 4. The mixed fluid enters the diffuser section in the ejector 4 to complete the pressure increase. The pressurized working fluid enters the gas-liquid separator 5; the other stream enters the intermediate heat exchanger 11 to release heat. The working fluid after heat release enters the third expansion valve 12 to expand and reduce pressure. The depressurized working fluid absorbs the heat in the heat accumulator 9 and enters the compressor 1 to complete the gas replenishment, which effectively reduces the outlet temperature of the fluid in the compressor 1. The gaseous working medium in the gas-liquid separator 5 enters the intermediate heat exchanger 11 to absorb heat and become superheated steam, and then enters the compressor 1 for compression and pressure increase; the liquid working medium enters the second expansion valve 6 to expand and reduce the pressure, and the working fluid after pressure reduction enters the evaporator 7 to absorb heat and evaporate, and the outlet fluid of the evaporator 7 is ejected by the working fluid in the working nozzle of the ejector 4 and enters the ejection chamber of the ejector 4.

[0048] In some embodiments of the present invention, the heat storage medium in the heat accumulator 9 is a phase change material. In the energy storage enthalpy compensation mode, the outlet temperature (enthalpy compensation temperature / enthalpy compensation pressure) of the heat accumulator 9 is higher than the inlet temperature of the compressor 1 (the temperature of the superheated steam in the intermediate heat exchanger 11), but lower than the condensation temperature (condensation pressure).

[0049] The intermediate heat exchanger 11 and the reheat compensation compressor 1 recover the expansion work in the energy release and reheat compensation mode, while the heat accumulator 9 increases the mass flow rate of the replenishing gas by using the expansion work recovered in the supercooling heat storage mode, thereby improving the overall performance of the system.

[0050] The presence of the intermediate heat exchanger 11 allows partial diversion of the outlet of the condenser 2, that is, the diversion of the branch where the second three-way valve 8 is located, to achieve subcooling. Compared with the system without subcooling treatment, the expansion after subcooling To make it easier to understand, we can compare the ordinary steam compression heat pump and the steam compression heat pump with an intermediate heat exchanger. In terms of loss, overcooling causes the system to expand The loss has been reduced. The loss can be regarded as the expansion work loss. Therefore, the intermediate heat exchanger 11 realizes the subcooling of the fluid, that is, the recovery of the expansion work; the existence of the air replenishment enthalpy increase technology avoids the process of part of the working fluid undergoing expansion and then compression. Avoiding part of the expansion process, that is, avoiding part of the expansion Loss, expansion here The loss can be regarded as the lost expansion work. Therefore, the compressor 1 recovers the expansion work in this mode; the heat accumulator 9 increases the mass flow of the supplementary air, further increasing the recovered expansion work.

[0051] The compressor 1 is an air-supplementing compressor. When the system is in the energy-releasing and enthalpy-supplementing mode, the air-supplementing channel of the compressor 1 is opened, and the working fluid at the outlet of the heat accumulator 9 serves as the intermediate air-supplementing of the compressor 1; when the system is in the supercooling energy-supplementing mode, the air-supplementing port of the compressor 1 is closed, and the supercooling heat of the fluid at the outlet of the condenser 2 is stored in the heat accumulator 9.

[0052] When the system switches to the energy release and enthalpy compensation mode, the outlet fluid of the heat accumulator 9 can be used as the intermediate air supply of the compressor 1, which can effectively reduce the exhaust temperature of the compressor 1 and overcome the problem of excessively high exhaust temperature of the compression type high temperature heat pump. When the system switches to the supercooling energy storage mode, part of the working fluid at the outlet of the condenser 2 enters the heat accumulator 9 for supercooling, and the released heat can be stored in the heat accumulator 9.

[0053] A compression-type high-temperature heat pump system with energy storage and enthalpy supplement proposed in the present invention has ejector efficiency enhancement technology, air supplement enthalpy enhancement technology, energy storage efficiency enhancement technology and mode switching technology as core features, and organically integrates multiple technologies to construct a compression-type high-temperature heat pump system with energy storage and enthalpy supplement, which overcomes the problem of high-grade electric energy consumption in the process of low-temperature waste heat grade upgrading, and further improves the heat grade conversion efficiency of the heat pump for low-temperature waste heat recovery.

[0054] The present invention discloses a compression-type high-temperature heat pump system with energy storage and enthalpy supplementation, which solves the problems of industrial low-temperature waste heat dissipation, large compression ratio of single-stage compression high-temperature heat pumps and high compressor exhaust temperature. On the basis of the injection-compression high-temperature heat pump, a heat accumulator and an air supplement and enthalpy increase branch are added to achieve efficient recovery of low-grade waste heat and effective reduction of compressor exhaust temperature.

[0055] The working fluid at the outlet of condenser 2 is divided into two streams, one of which is used as the ejector fluid of ejector 4 to increase the inlet pressure of compressor 1; the other is used as the high-temperature medium of energy storage / enthalpy replenishment and intermediate heat exchanger to avoid liquid hammer. The two streams at the outlet of condenser 3 utilize two expansion work recovery methods, among which; the other fluid uses part of the expansion work for heat accumulator, intermediate heat exchanger, air replenishment and enthalpy replenishment, and intermediate heat exchanger during supercooling energy storage and energy release and enthalpy replenishment. The design of supercooling energy storage and energy release and enthalpy replenishment effectively reduces the exhaust temperature of the compressor and improves the heating efficiency of the system, with good economic benefits and environmental friendliness.

[0056] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A compression type high temperature heat pump system with energy storage and enthalpy supplementation, characterized in that: The system comprises a compressor (1), a condenser (2), a three-way valve, an expansion valve, an ejector (4), a gas-liquid separator (5), an evaporator (7), a heat accumulator (9) and an intermediate heat exchanger (11), wherein the system is switched between a supercooling energy storage mode and an energy release and enthalpy compensation mode by means of the three-way valve, wherein the three-way valve comprises a first three-way valve (3) and a second three-way valve (8), and the expansion valve comprises a first expansion valve (10), a second expansion valve (6) and a third expansion valve (12); In the supercooling energy storage mode, the outlet of the compressor (1) is connected to the inlet of the condenser (2), the outlet of the condenser (2) is connected to the inlet of the first three-way valve (3), one of the outlets of the first three-way valve (3) is connected to the ejector (4), and the other outlet is connected to the heat accumulator (9); the outlet of the heat accumulator (9) is connected to the inlet of the first expansion valve (10), and the outlet of the first expansion valve (10) is connected to the inlet of the gas-liquid separator (5); the outlet of the ejector (4) is connected to the gas-liquid separator (5), the gas phase outlet of the gas-liquid separator (5) is connected to the intermediate heat exchanger (11), the outlet of the intermediate heat exchanger (11) is connected to the inlet of the compressor (1), the liquid phase outlet of the gas-liquid separator (5) is connected to the second expansion valve (6), the outlet of the second expansion valve (6) is connected to the evaporator (7), and the outlet of the evaporator (7) is connected to the secondary nozzle inlet of the ejector (4); In the energy release and enthalpy compensation mode, the outlet of the compressor (1) is connected to the inlet of the condenser (2), the outlet of the condenser (2) is connected to the inlet of the first three-way valve (3), one of the outlets of the first three-way valve (3) is connected to the ejector (4), and the other outlet is connected to the second three-way valve (8), the intermediate heat exchanger (11), the third expansion valve (12), and the heat accumulator (9) in sequence, and the heat accumulator (9) is connected to the air supply port of the compressor (1); the outlet of the ejector (4) is connected to the gas-liquid separator (5), the gas phase outlet of the gas-liquid separator (5) is connected to the inlet of the intermediate heat exchanger (11), the outlet of the intermediate heat exchanger (11) is connected to the compressor (1), and the liquid phase outlet of the gas-liquid separator (5), the second expansion valve (6), the evaporator (7), and the ejector (4) are connected in sequence.

2. A compression type high temperature heat pump system with energy storage and enthalpy supplementation according to claim 1, characterized in that: The ejector (4) can utilize the high-pressure fluid at the outlet of the condenser (2) to eject the low-pressure fluid at the outlet of the evaporator (7), thereby increasing the pressure of the fluid at the inlet of the compressor (1) and thereby reducing the compression ratio of the compressor (1).

3. A compression type high temperature heat pump system with energy storage and enthalpy supplementation according to claim 1, characterized in that: The injector (14) is an area-adjustable injector, and the injector throat area is adjusted according to the actual operating conditions of the system.

4. A compression type high temperature heat pump system with energy storage and enthalpy supplementation according to claim 1, characterized in that: When the system is switched to the energy release and enthalpy compensation mode, the outlet fluid of the heat accumulator (9) is used as the intermediate air supply of the compressor (1); when the system is switched to the supercooling energy storage mode, part of the working fluid at the outlet of the condenser (2) enters the heat accumulator (9) for supercooling, and the released heat is stored in the heat accumulator (9).

5. A compression type high temperature heat pump system with energy storage and enthalpy supplementation according to claim 1, characterized in that: The compressor (1) is an air-supplementing compressor.

6. A compression type high temperature heat pump system with energy storage and enthalpy supplementation according to claim 5, characterized in that: When the system is in the energy release and enthalpy compensation mode, the air supply channel of the compressor (1) is opened, and the working fluid at the outlet of the heat accumulator (9) serves as the intermediate air supply of the compressor (1); when the system is in the supercooling energy storage mode, the air supply port of the compressor (1) is closed, and the supercooling heat of the fluid at the outlet of the condenser (2) is stored in the heat accumulator (9).

7. A compression type high temperature heat pump system with energy storage and enthalpy supplementation according to claim 1, characterized in that: In the supercooling energy storage mode, the outlet pressure of the ejector is the same as the pressure of the working fluid in the branch where the heat accumulator is located after expansion and pressure reduction.

8. A compression type high temperature heat pump system with energy storage and enthalpy supplementation according to claim 1, characterized in that: In the energy release and enthalpy compensation mode, the outlet temperature of the accumulator is higher than the outlet temperature of the intermediate heat exchanger, but lower than the condensing temperature.

9. A compression type high temperature heat pump system with energy storage and enthalpy supplement according to any one of claims 1 to 8, characterized in that: In the supercooling energy storage mode, the working fluid is pressurized by the compressor (1) and then enters the condenser (2) to release heat and condense. The condensed working fluid in the condenser (2) is diverted by the first three-way valve (3) and then enters the primary nozzle of the ejector (4) to reduce pressure and increase speed. Then, the outlet fluid of the evaporator (7) is injected into the ejector (4) and mixed in the mixing chamber of the ejector (4). The mixed fluid is pressurized by the ejector (4) and then enters the gas-liquid separator (5). The other fluid enters the heat accumulator (9) to release heat by supercooling, and the released heat is stored in the heat accumulator (9). The working fluid that has been supercooled and released heat in the heat accumulator (9) enters the first expansion valve (10) to expand and reduce pressure. The reduced-pressure working fluid enters the gas-liquid separator (5) and mixes with the outlet fluid of the ejector (4). The gas phase fluid in the gas-liquid separator (5) enters the intermediate heat exchanger (11) to absorb heat and become superheated steam. The superheated steam enters the compressor (1) to complete the compression process. The liquid phase fluid enters the second expansion valve (6) to expand and reduce pressure, then enters the evaporator (7) to absorb heat and evaporate, and finally is ejected into the ejector (4) by the primary flow of the ejector (4).

10. A compression type high temperature heat pump system with energy storage and enthalpy supplement according to any one of claims 1 to 8, characterized in that: In the energy release and enthalpy compensation mode, the working fluid is compressed and pressurized in the compressor (1) and then mixed with the outlet fluid of the heat accumulator (9). The mixed working fluid is compressed and pressurized in the high-pressure chamber of the compressor (1). The pressurized working fluid enters the condenser (2) to release heat and condense. The condensed working fluid enters the first three-way valve (3) and is divided into two streams. One stream becomes the ejection fluid of the ejector (4). The ejection fluid enters the ejector (4) to reduce pressure and increase speed. The working fluid after speeding up ejects the working fluid at the outlet of the evaporator (7) and is mixed in the ejector (4). The mixed fluid enters the ejector (4) to increase pressure. The pressurized working fluid enters the gas-liquid separator (5). ; the other stream enters the intermediate heat exchanger (11) to release heat, and the working fluid after releasing heat enters the third expansion valve (12) to expand and reduce pressure. The working fluid after reducing pressure absorbs the heat in the heat accumulator (9) and enters the compressor (1) to complete gas replenishment; the gaseous working fluid in the gas-liquid separator (5) enters the intermediate heat exchanger (11) to absorb heat and become superheated steam, and then enters the compressor (1) to be compressed and pressurized, and the liquid working fluid in the gas-liquid separator (5) enters the second expansion valve (6) to expand and reduce pressure. The working fluid after reducing pressure enters the evaporator (7) to absorb heat and evaporate, and the outlet fluid of the evaporator (7) is ejected by the working fluid in the ejector (4) and enters the ejector (4).

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