Thermal management system of hydrogen fuel cell stack

Abstract

The utility model relates to a thermal management system of a hydrogen fuel cell stack, and belongs to the technical field of thermal management of cell stacks. Comprising a refrigerant branch, the two ends of the refrigerant branch are connected with the B end and the D end of a four-way valve respectively, and a compressor is connected between the A end and the C end of the four-way valve in series; a water pump is connected in series in the water circulation main path, a galvanic pile radiator is connected in series between the water inlet side pipeline of the heater and the remaining end of the first three-way valve, and the remaining end of the second three-way valve is connected in series with the liquid cooling side of the air conditioner heat exchanger and then connected into the water inlet side pipeline of the galvanic pile heat exchanger. The switching function of the four-way valve is utilized to enable the compressor to be matched with the refrigerant branch to achieve switching between refrigerating circulation and heating circulation, then the compressor is matched with the first three-way valve to achieve switching between the branch where the heater is located and the branch where the galvanic pile radiator is located, switching between heating of the heater and heat dissipation of the radiator is achieved, and the heat dissipation and heating cost is effectively reduced.

Description

Technical Field

[0001] The utility model relates to a thermal management system for a hydrogen fuel cell stack, belonging to the technical field of fuel cell stack thermal management. Background Art

[0002] In recent years, the new energy industry has seen a wave of favorable conditions. New energy vehicles represented by pure electric vehicles and hydrogen fuel cell vehicles are replacing traditional internal combustion engine vehicles powered by fuel. Among them, hydrogen fuel cell vehicles have the advantages of high energy conversion efficiency, strong endurance, and fast energy replenishment, and are the preferred choice to replace internal combustion engine vehicles.

[0003] However, during driving, hydrogen fuel cell vehicles will generate a large amount of waste heat, and the emission of this waste heat brings many challenges and problems to the vehicle's thermal management system. Different from internal combustion engine vehicles that can take away part of the heat through vehicle exhaust, most of the waste heat of fuel cell vehicles must be taken to the front radiator by the coolant for heat dissipation; moreover, the normal operating temperature of the fuel cell is relatively low, and the available heat exchange temperature difference of the vehicle's thermal management system is small, resulting in a huge load on the front radiator and easily causing the hydrogen fuel cell stack to overheat, affecting the vehicle performance and safety. Since a large amount of waste heat needs to be released during the use of the hydrogen fuel cell stack to ensure that the stack operates within a certain temperature range, the actual use efficiency of the current hydrogen fuel cell stack is only 50%.

[0004] To ensure the normal discharge of waste heat and the maintenance of the stack temperature, a radiator is added to the hydrogen fuel cell stack system, and the antifreeze is passed into the stack for heat exchange and cooling. The heated antifreeze is forcibly discharged into the environment through the radiator in cooperation with the cooling fan. However, as the power of the hydrogen fuel cell stack increases, the volume of the radiator and the number of fans also increase, and the noise of the fan is very loud during use, seriously affecting the riding comfort and customer experience. The existing method of cooling the stack by using the antifreeze medium and forcibly cooling with a radiator maintains the internal temperature of the stack within a certain range, and the antifreeze inside the radiator is forcibly dissipated to the external environment through the cooling fan; however, a high-power stack needs to discharge more heat and the number of fans also increases, resulting in a large overall noise and volume.

[0005] In cold winter, the hydrogen fuel cell stack needs to be heated to a certain temperature before it can be used. To maintain the stack temperature, a water PTC (Positive Temperature Coefficient) heater is often used to heat the stack, which consumes a large amount of electricity and seriously affects the vehicle's endurance mileage.

[0006] In summary, the existing thermal management system for hydrogen fuel cell stacks has the following problems:

[0007] ① The existing heat dissipation of hydrogen fuel cell stacks is mainly forced heat dissipation, that is, air cooling is used to remove the heat of the hydrogen fuel cell stack through fan forced heat dissipation. When the heat dissipation of the hydrogen fuel cell stack is large, multiple high-power condensing fans are required to meet the heat dissipation requirements. The cost is high, the weight is heavy, the fan is noisy when running, the fan forced heat dissipation efficiency is low, and the heat dissipation capacity is limited; ② When the heat generated by the hydrogen fuel cell stack is large, the existing heat dissipation method cannot meet the cooling demand in time, which will affect the output of the stack power; ③ The heating of the existing hydrogen fuel cell stack adopts water-heating PTC. The water-heating PTC heater consumes a lot of power and has low conversion efficiency. When running in cold weather in winter, it has a great impact on the cruising range of the whole vehicle. Utility Model Content

[0008] The utility model aims to provide a hydrogen fuel cell stack thermal management system to solve the problem of relatively high heat dissipation and heating costs of existing hydrogen fuel cell stack thermal management systems.

[0009] To achieve the above purpose, the solution of the utility model includes:

[0010] The utility model discloses a thermal management system for a hydrogen fuel cell stack, comprising an off-vehicle heat exchanger for heat exchange with an off-vehicle environment, an expansion valve, and a refrigerant side of an air-conditioning heat exchanger for heat exchange between a refrigerant side and a liquid-cooled side, which are sequentially connected in series to form a refrigerant branch, the two ends of the refrigerant branch are respectively connected to the B end and the D end of the four-way valve, a branch where a compressor is located is connected in series between the A end and the C end of the four-way valve, and the switching of the two ends AB of the four-way valve with the two ends DC respectively and the two ends AD of the four-way valve with the two ends BC respectively realizes the switching of the refrigeration cycle and the heating cycle; it also comprises a water circulation main circuit, the water circulation main circuit comprises a stack heat exchanger, a heater, a first three-way valve and a second three-way valve which are sequentially connected in series, a water pump is also connected in series in the water circulation main circuit, a stack radiator is connected in series between the water inlet side pipeline of the heater and the remaining end of the first three-way valve, and the remaining end of the second three-way valve is connected in series to the liquid-cooled side of the air-conditioning heat exchanger and then connected to the water inlet side pipeline of the stack heat exchanger.

[0011] Furthermore, a main radiator for exchanging heat with the environment is connected in series between the remaining end of the second three-way valve and the liquid-cooled side of the air-conditioning heat exchanger.

[0012] Furthermore, the off-vehicle heat exchanger and the main radiator are arranged in an air flow channel formed by the same fan.

[0013] Furthermore, the water outlet side of the heater is connected to the liquid cooling side of the air-conditioning heat exchanger in series through a pipeline and then connected to the water inlet side pipeline of the fuel cell stack heat exchanger.

[0014] Furthermore, the water inlet side of the water pump is connected to the water outlet side of the stack heat exchanger, and the water outlet side of the water pump is respectively connected to the water inlet side of the heater and the water inlet side of the stack radiator.

[0015] Further, the branch where the compressor is located further includes a gas-liquid separator connected in series on the input side of the compressor.

[0016] Further, the second three-way valve is a three-way flow regulating valve.

[0017] Further, it further includes a deionizer disposed on the water inlet side of the stack radiator for removing conductive ions.

[0018] Further, it further includes an expansion tank connected to the main water circulation path. The expansion tank is used to maintain the liquid volume in the main water circulation path; the water outlet side of the expansion tank is connected to the input end of the deionizer.

[0019] Further, it further includes a conductivity meter disposed on the water outlet side of the stack radiator for detecting the conductivity value.

[0020] Advantages of the present utility model:

[0021] The present utility model is an improved invention. It provides a heat management system for a hydrogen fuel cell stack. By utilizing the switching function of the four-way valve, the compressor cooperates with the refrigerant branch to achieve the switching between the refrigeration cycle and the heating cycle. Then, in cooperation with the first three-way valve, the switching between the branch where the heater is located and the branch where the stack radiator is located is achieved to realize the switching between the heater heating and the radiator cooling. Through the heating cycle in cooperation with the heater heating or through the refrigeration cycle in cooperation with the radiator cooling, the heat dissipation and heating requirements of the hydrogen fuel cell stack are met, and the heat dissipation and heating costs are effectively reduced. Specifically, it includes a refrigerant branch formed by sequentially connecting in series an external vehicle heat exchanger for heat exchange with the external environment of the vehicle, an expansion valve, and the refrigerant side of an air-conditioning heat exchanger for heat exchange between the refrigerant side and the liquid-cooled side. The two ends of the refrigerant branch are respectively connected to the B end and the D end of the four-way valve. A branch where the compressor is located is connected in series between the A end and the C end of the four-way valve. The switching between the refrigeration cycle and the heating cycle is achieved by the connection and disconnection between the AB ends and the DC ends of the four-way valve and the connection and disconnection between the AD ends and the BC ends of the four-way valve; it further includes a main water circulation path, which includes a stack heat exchanger, a heater, a first three-way valve, and a second three-way valve connected in series in sequence. A water pump is also connected in series in the main water circulation path. A stack radiator is connected in series between the water inlet side pipeline of the heater and the remaining end of the first three-way valve. The remaining end of the second three-way valve is connected to the liquid-cooled side of the air-conditioning heat exchanger and then connected to the water inlet side pipeline of the stack heat exchanger. Description of the Drawings

[0022] Figure 1 It is the working principle diagram of the heat management system for a hydrogen fuel cell stack according to an embodiment of the present utility model.

[0023] Description of the Reference Numerals:

[0024] 1. Stack heat exchanger; 2. Expansion tank; 3. Water pump; 4. Heater; 5. Deionizer; 6. Stack radiator; 7. Conductivity meter; 8. First three-way valve; 9. Second three-way valve; 10. Main radiator; 11. Fan; 12. Out-of-vehicle heat exchanger; 13. Expansion valve; 14. Air-conditioning heat exchanger; 15. Gas-liquid separator; 16. Compressor; 17. Four-way valve. Detailed implementation mode

[0025] To solve the problems in the background technology, the present utility model provides a heat management system for a hydrogen fuel cell stack. By using the switching function of the four-way valve, the compressor cooperates with the refrigerant branch to realize the switching between the refrigeration cycle and the heating cycle. Then, in cooperation with the first three-way valve, the switching between the branch where the heater is located and the branch where the stack radiator is located is realized, so as to realize the switching between the heater heating and the radiator heat dissipation. Through the heating cycle in cooperation with the heater heating or through the refrigeration cycle in cooperation with the radiator cooling, the heat dissipation and heating requirements of the hydrogen fuel cell stack are met, and the heat dissipation and heating costs are effectively reduced. The present utility model uses the air-conditioning heat exchanger to assist the radiator in refrigeration or assist the heater in heating, so as to meet the heat dissipation and heating requirements of the hydrogen fuel cell stack and reduce the heat dissipation and heating costs.

[0026] To make the purpose, technical solution and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] An embodiment of a heat management system for a hydrogen fuel cell stack:

[0028] A heat management system for a hydrogen fuel cell stack, referring to Figure 1 , includes an out-of-vehicle heat exchanger 12, an expansion valve 13 and an air-conditioning heat exchanger 14. The refrigerant sides of the out-of-vehicle heat exchanger 12, the expansion valve 13 and the air-conditioning heat exchanger 14 are connected in series in sequence to form a refrigerant branch. The two ends of the refrigerant branch are respectively connected to the B end and the D end of the four-way valve 17. A branch where the compressor 16 is located is connected in series between the A end and the C end of the four-way valve 17. The switching between the communication of the AB ends and the DC ends of the four-way valve 17 (i.e., the communication mode 1 where the AB ends are connected and the DC ends are connected) and the communication of the AD ends and the BC ends of the four-way valve 17 (i.e., the communication mode 2 where the AD ends are connected and the BC ends are connected) realizes the switching between the refrigeration cycle and the heating cycle. That is, the four-way valve 17 realizes the switching between the refrigeration cycle and the heating cycle through the switching of the communication mode 1 (the AB ends are connected) and the communication mode 2 (the AD ends are connected). When the AB ends of the four-way valve 17 are connected, the DC ends of the four-way valve 17 are connected. When the AD ends of the four-way valve 17 are connected, the BC ends of the four-way valve 17 are connected; among them, the refrigerant side of the air-conditioning heat exchanger 14 exchanges heat with the liquid-cooled side, and the air-conditioning heat exchanger 14 has the function of an evaporator; the out-of-vehicle heat exchanger 12 is used for heat exchange with the out-of-vehicle environment, and the out-of-vehicle heat exchanger 12 has the function of a condenser.

[0029] It also includes a main water circulation path, which includes a stack heat exchanger 1, a heater 4, a first three-way valve 8, and a second three-way valve 9 connected in series in sequence. A water pump 3 is also connected in series in the main water circulation path. A stack radiator 6 is connected in series between the water inlet side pipeline of the heater 4 and the remaining end of the first three-way valve 8. The remaining end of the second three-way valve 9 is connected to the liquid cooling side of the air conditioner heat exchanger 14 and then accesses the water inlet side pipeline of the stack heat exchanger 1.

[0030] Specifically, a main radiator 10 for heat exchange with the environment is also connected in series between the remaining end of the second three-way valve 9 and the liquid cooling side of the air conditioner heat exchanger 14, which can preliminarily cool the hot water entering the air conditioner heat exchanger through the main radiator to prevent the compressor from malfunctioning due to too high evaporation temperature.

[0031] Specifically, the outside vehicle heat exchanger 12 and the main radiator 10 are arranged in the air flow channel formed by the same fan 11. The fan 11 serves as a cooling fan. By sharing the cooling fan for the outside vehicle heat exchanger and the main radiator, the volume of the hydrogen fuel cell stack thermal management system is reduced.

[0032] Specifically, the water outlet side of the heater 4 is also connected to the liquid cooling side of the air conditioner heat exchanger 14 through a pipeline and then accesses the water inlet side pipeline of the stack heat exchanger 1.

[0033] Specifically, the water inlet side of the water pump 3 is connected to the water outlet side of the stack heat exchanger 1, and the water outlet side of the water pump 3 is respectively connected to the water inlet side of the heater 4 and the water inlet side of the stack radiator 6.

[0034] Specifically, the branch where the compressor 16 is located also includes a gas-liquid separator 15 connected in series on the input side of the compressor 16.

[0035] Specifically, the second three-way valve 9 is a three-way flow regulating valve, which is used to regulate the flow rate.

[0036] Specifically, it also includes a deionizer 5 arranged on the water inlet side of the stack radiator 6 for removing conductive ions.

[0037] Specifically, it also includes an expansion tank 2 connected to the main water circulation path. The expansion tank 2 is used to maintain the liquid volume in the main water circulation path.

[0038] Specifically, the input end of the deionizer 5 is connected to the water outlet side of the expansion tank 2.

[0039] Specifically, it also includes a conductivity meter 7 arranged on the water outlet side of the stack radiator 6 for detecting the conductivity value. The conductivity meter 7 (conductivity acquisition instrument) monitors the conductivity of the stack circulating antifreeze all the time, and cooperates with the deionizer 5 to ensure that its conductivity does not exceed the standard.

[0040] The working principle of the hydrogen fuel cell stack thermal management is as follows Figure 1As shown, it includes a refrigerant system cycle and a water circuit system cycle.

[0041] Among them, the working principle of the refrigerant system is as follows:

[0042] 1) Refrigeration cycle: The high-temperature and high-pressure refrigerant coming out of the compressor 16 passes through the A-B of the four-way valve 17 (the AB ends connected by the four-way valve 17), and then after being cooled by the external heat exchanger 12 of the vehicle, it flows into the refrigerant side of the air-conditioning heat exchanger 14 through the expansion valve 13, absorbs heat and evaporates, and then returns to the compressor 16 through the D-C flow path of the four-way valve 17 and then through the gas-liquid separator 15 to complete the cycle.

[0043] 2) Heating cycle: The high-temperature and high-pressure refrigerant coming out of the compressor 16 passes through the A-D of the four-way valve 17, and then after being cooled by the air-conditioning heat exchanger 14, it flows into the external heat exchanger 12 of the vehicle through the expansion valve 13, absorbs heat and evaporates, and then returns to the compressor 16 through the B-C flow path of the four-way valve 17 and then through the gas-liquid separator 15 to complete the cycle.

[0044] The working principle of the water circuit system is as follows:

[0045] 1) Stack cooling: The high-temperature hot water (liquid) coming out of the stack heat exchanger 1 enters the stack radiator 6 (stack radiator assembly) through the water pump 3 for heat dissipation, and then enters the second three-way valve 9 through the first three-way valve 8. Part of it is cooled again by the main radiator 10 and then enters the air-conditioning heat exchanger 14 for further cooling, and then mixes with the other part of the water in the second three-way valve 9 and returns to the stack heat exchanger 1 for stack cooling; the conductivity meter 7 set at the output of the stack radiator 6 is used to detect the conductivity value in the water circulation system at all times to ensure the normal circulation of the system.

[0046] 2) Stack heating (heat pump heating): The low-temperature cold water coming out of the stack heat exchanger 1 passes through the water pump 3 and the heater 4 which is a water PTC, and then enters the second three-way valve 9 through the first three-way valve 8. Part of it enters the air-conditioning heat exchanger 14 after passing through the radiator 10 for temperature increase again, and the heated hot water returns to the stack heat exchanger 1 for heating and temperature increase, and the other part directly returns to the stack heat exchanger 1.

[0047] 3) Stack heating (water PTC heating): The low-temperature cold water coming out of the stack heat exchanger 1 is heated and increased in temperature by the water pump 3 and the heater 4, and then returns to the stack heat exchanger 1 through the first three-way valve 8 and the second three-way valve 9 to heat and increase the temperature of the stack.

[0048] Among them, the air-conditioning heat exchanger 14 can be a plate heat exchanger. The expansion tank 2 is used to maintain the balance of the water volume in the stack system (water circuit system) when the ambient temperature changes. The heater adopts a positive temperature coefficient water heater.

[0049] Among them, the deionizer 5 is used to remove the conductive ions in the water circulation system, ensure that the conductive ions entering the stack are controlled within a certain range, and prevent the stack from giving false alarms.

[0050] Among them, the conductivity meter 7 is used to detect the conductivity value in the water circulation system at all times for the normal circulation of the system.

[0051] Among them, the first three-way valve 8 has a non-adjustable flow rate and is mainly used for switching the water circuits for hydrogen stack cooling and heating.

[0052] Among them, the second three-way valve 9 is a three-way flow regulating valve with adjustable flow rate, which is mainly used to adjust the flow rate of the refrigerant circulating water to ensure that the compressor operates within a reasonable temperature range.

[0053] The utility model cools and heats the hydrogen fuel cell stack by means of heat exchange between the refrigerant and the antifreeze, keeping the hydrogen stack within a reasonable temperature range so that it can output power and the vehicle can operate normally.

[0054] The utility model replenishes heat and cold in the stack thermal management system through refrigerant circulation for rapid cooling and heating of the stack. This solution can reduce the heat dissipation requirement for the stack radiator. The whole system can reduce weight, decrease volume, and reduce the noise of the condenser fan (the fan of the external heat exchanger of the vehicle), enabling the stack power to be further increased and the vehicle's endurance to be improved again.

[0055] The utility model maintains the stack within a reasonable temperature range through cooling or heating of the stack; the utility model adopts a refrigeration cycle to cool the stack and improve the stack heat dissipation efficiency; the hot water entering the air-conditioning heat exchanger is first preliminarily cooled by the main radiator to prevent the compressor from failing to operate due to too high evaporation temperature, and the external heat exchanger and the main radiator share a cooling fan to reduce volume; the utility model adopts a four-way reversing valve so that when the winter temperature drops, the stack is heated by means of a heat pump cycle; the utility model realizes rapid warming in winter by adding a water heating PTC for auxiliary heating in the system; the utility model adds a second three-way valve and a first three-way valve in the system to effectively combine and autonomously switch between the heat pump and water PTC modes; compared with the air-cooled heat dissipation and water PTC heating methods, the utility model can reduce the product volume, improve the cooling energy efficiency and the stack temperature difference, heat the stack in the form of a heat pump, reduce the volume of the radiator and the number of cooling fans, thereby reducing the overall noise, reducing the system energy consumption, making the stack temperature more stable, improving the stack use efficiency, and extending the vehicle endurance mileage.

[0056] Among them, the number of radiators and the number of fans can both be adjusted as needed; the positions of the conductivity meter, the deionizer, and the circulation water pump can all be adjusted as needed; the utility model can also use different refrigerants as needed.

Claims

1. A hydrogen fuel cell stack thermal management system, characterized in that: It includes an external heat exchanger for heat exchange with the external environment, an expansion valve, and a refrigerant side of an air-conditioning heat exchanger for heat exchange between the refrigerant side and the liquid-cooled side, which are connected in series in sequence to form a refrigerant branch, the two ends of the refrigerant branch are respectively connected to the B end and the D end of the four-way valve, and a branch where a compressor is located is connected in series between the A end and the C end of the four-way valve, and the switching of the two ends AB of the four-way valve with the two ends DC and the two ends AD of the four-way valve with the two ends BC can realize the switching of the refrigeration cycle and the heating cycle; it also includes a water circulation main circuit, which includes a battery stack heat exchanger, a heater, a first three-way valve and a second three-way valve connected in series in sequence, and a water pump is also connected in series in the water circulation main circuit, a battery stack radiator is connected in series between the water inlet side pipeline of the heater and the remaining end of the first three-way valve, and the remaining end of the second three-way valve is connected in series with the liquid-cooled side of the air-conditioning heat exchanger and then connected to the water inlet side pipeline of the battery stack heat exchanger.

2. The hydrogen fuel cell stack thermal management system according to claim 1, characterized in that: A main radiator for exchanging heat with the environment is also connected in series between the remaining end of the second three-way valve and the liquid-cooled side of the air-conditioning heat exchanger.

3. The hydrogen fuel cell stack thermal management system according to claim 2, characterized in that: The off-board heat exchanger and the main radiator are arranged in an air flow channel formed by the same fan.

4. The hydrogen fuel cell stack thermal management system according to claim 1, characterized in that: The water outlet side of the heater is also connected to the water inlet side pipeline of the fuel cell heat exchanger after being connected in series with the liquid cooling side of the air-conditioning heat exchanger through a pipeline.

5. The hydrogen fuel cell stack thermal management system according to claim 1, characterized in that: The water inlet side of the water pump is connected to the water outlet side of the stack heat exchanger, and the water outlet side of the water pump is respectively connected to the water inlet side of the heater and the water inlet side of the stack radiator.

6. The hydrogen fuel cell stack thermal management system according to claim 1, characterized in that: The branch where the compressor is located also includes a gas-liquid separator connected in series on the input side of the compressor.

7. The hydrogen fuel cell stack thermal management system according to claim 1, characterized in that: The second three-way valve is a three-way flow regulating valve.

8. The hydrogen fuel cell stack thermal management system according to claim 1, characterized in that: It also includes a deionizer arranged on the water inlet side of the stack radiator for removing conductive ions.

9. The hydrogen fuel cell stack thermal management system according to claim 8, characterized in that: It also includes an expansion water tank connected to the main water circulation path, and the expansion water tank is used to maintain the amount of liquid in the main water circulation path; the water outlet side of the expansion water tank is connected to the input end of the deionizer.

10. The hydrogen fuel cell stack thermal management system according to claim 8 or 9, characterized in that: It also includes a conductivity meter arranged on the water outlet side of the stack radiator for detecting the conductivity value.

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