A thermal management system for a fuel cell

Abstract

The present application relates to a set of heat management system, the system includes a primary heat dissipation cycle and secondary heat dissipation cycle, the primary heat dissipation cycle includes a double-layer structure with an inner circulating water tank, 1 inner circulating water pump and a plate heat exchanger, secondary heat dissipation system can be through water cooling or air cooling to the cold water end of the plate heat exchanger temperature control. The present application reduces the instability caused by thermostat and the singleness of temperature control on the one hand, and the cooling liquid after cooling by the plate heat exchanger flows into the inner circulating water tank, then flows into the outer circulating water tank through the water outlet of the inner circulating water tank, so that the cooling liquid temperature in the outer circulating water tank will not be too low, and due to the buffering effect of the inner circulating water tank, water splash or bubbles in the outer circulating water tank will not enter the circulating water pump with the cooling liquid, thereby improving the heat dissipation effect of the circulating water pump and the service life of the circulating water pump.

Description

Technical Field

[0001] This application belongs to the field of fuel cells, specifically relating to a thermal management system for fuel cells. Background Technology

[0002] A fuel cell is a power generation device that directly and efficiently converts the chemical energy in fuel and oxidant into electrical energy. Due to its significant advantages such as high energy conversion efficiency, environmental friendliness, fast start-up speed, and low environmental pollution, fuel cells are considered one of the preferred power sources for electric vehicles, stationary power stations, and various mobile power sources. During operation, fuel cells generate a large amount of heat internally. This excess waste heat needs to be dissipated promptly and effectively; otherwise, it will affect the lifespan of the fuel cell and may even pose a danger. However, to ensure the working performance and efficiency of the fuel cell, it is necessary to ensure that the internal temperature of the fuel cell does not drop too low.

[0003] Bipolar plates are crucial components in fuel cells, serving functions such as fluid distribution, conductivity, cooling, and separation of fuel and oxidant. Common bipolar plates have three chambers: a fuel chamber, an oxidant chamber, and a coolant chamber. The fuel cell connects to the thermal management system via the coolant chamber, enabling the removal of excess waste heat and control of the fuel cell's operating temperature. The thermal management system typically includes a primary and a secondary cooling cycle. In the primary cooling cycle, a thermostat is usually connected in series between the fuel cell's coolant outlet and the circulating water tank. The other outlet of the thermostat is connected to a plate heat exchanger. When the coolant outlet temperature is below the thermostat's opening temperature, coolant flows directly from the fuel cell coolant outlet back to the circulating water tank. When the coolant outlet temperature is above the thermostat's opening temperature, coolant flows from the fuel cell coolant outlet through the plate heat exchanger and then back to the circulating water tank. The secondary heat dissipation cycle controls the coolant temperature in the circulating water tank of the primary heat dissipation cycle (i.e., the inlet temperature of the fuel cell coolant chamber) by controlling the flow rate and temperature of the coolant in the cold water pipes flowing through the plate heat exchanger.

[0004] To control the internal temperature of a fuel cell (i.e., the coolant outlet temperature) at different levels, paraffin thermostats that open at different temperatures are often required. However, experiments frequently necessitate controlling the fuel cell's internal temperature (i.e., the coolant outlet temperature) at various levels, necessitating the shutdown of the experiment and replacement of the paraffin thermostat in the primary cooling cycle of the thermal management system. This process is cumbersome and time-consuming. If an electronic thermostat is used instead of a paraffin thermostat, its opening range depends entirely on the feedback value from the temperature sensor at the coolant outlet. Any abnormal temperature reading from the sensor or a malfunction in the electronic thermostat itself can directly cause abnormal internal temperatures, affecting experimental results and potentially posing a danger. Furthermore, when using a thermostat to control the temperature of the primary cooling cycle, since the thermostat is connected in series between the coolant outlet of the fuel cell stack and the water tank, the coolant flows directly back into the circulating water tank after passing through the fuel cell, regardless of whether the thermostat is open or not. The returning coolant will agitate a large number of water splashes and bubbles in the water tank. Due to the limited volume of the circulating water tank, the water splashes and bubbles generated have not had time to dissipate before being directly drawn into the fuel cell coolant chamber by the circulating water pump. This gas-liquid mixture directly affects the heat dissipation effect and working status of the circulating water pump, and will also seriously affect the service life of the circulating water pump. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings and deficiencies of the prior art and provides a fuel cell thermal management system, including: a circulating water tank, a plate heat exchanger, a circulating water pump, a controller, a first temperature sensor, and a second temperature sensor;

[0006] The circulating water tank includes an inner circulating water tank and an outer circulating water tank; the inner circulating water tank is located inside the outer circulating water tank;

[0007] The outer circulating water tank and the inner circulating water tank share the same return water inlet.

[0008] The bottom of the outer circulating water tank is provided with a second drain outlet;

[0009] A circulating water pump is provided at the second drain outlet, and the circulating water pump is connected to the coolant chamber inlet of the fuel cell;

[0010] The plate heat exchanger includes a first inlet and a first outlet.

[0011] The first water inlet is connected to the coolant chamber outlet of the fuel cell.

[0012] The first outlet and the return outlet are connected, and the above connection relationship constitutes a first-stage heat dissipation circulation process;

[0013] The plate heat exchanger also includes a second inlet and a second outlet. A cooling medium with an adjustable flow rate is introduced into the second inlet, which constitutes a two-stage heat dissipation cycle.

[0014] A flow valve is installed at the second water inlet;

[0015] A first temperature sensor is installed at the outlet of the fuel cell coolant chamber.

[0016] A second temperature sensor is installed at the inlet of the fuel cell coolant chamber.

[0017] The controller is connected to the first temperature sensor, the second temperature sensor, and the flow valve, and controls the temperature of the first-stage heat dissipation cycle by adjusting the flow rate of the cooling medium in the second-stage heat dissipation cycle.

[0018] Furthermore: the outer circulating water tank is an open water tank that is not enclosed, and the inner circulating water tank is an open water tank.

[0019] Furthermore: the inner circulating water tank is provided with a first drain outlet, which is located at 1 / 6 of the distance from the top of the inner circulating water tank. A right-angled pipe is provided at the first drain outlet and extends downward to 3-5 cm from the bottom of the outer circulating water tank.

[0020] Furthermore, the return water inlet is located 2-3 cm from the bottom of the inner circulating water tank.

[0021] Furthermore, the inner diameter of the first drain outlet of the inner circulating water tank is the same as that of the return outlet.

[0022] Furthermore, the inner circulating water tank is made of a metal material with thermal conductivity.

[0023] Furthermore, the plane where the first drain outlet is located is perpendicular to the plane where the outlet of the outer circulating water tank is located, and they maintain a certain distance from each other.

[0024] Furthermore, the coolant level in the outer circulating water tank is between 1 / 6 and 1 / 5 of the distance from the top of the inner circulating water tank.

[0025] Furthermore, the second drain outlet is located 2-3 cm from the bottom of the water tank.

[0026] This application discloses a thermal management system for fuel cells. In the primary cooling cycle of this system, a dual-layer inner circulating cooling water tank replaces the function of a traditional thermostat. The buffering effect of the inner circulating water tank ensures that the coolant temperature in the primary cooling cycle does not drop excessively. Simultaneously, in conjunction with the control of coolant flow and temperature in the secondary cooling cycle, the circulating water temperature in the tank can be accurately controlled, avoiding the single-layer temperature control and instability associated with thermostats. Furthermore, since the coolant flows directly back to the inner circulating water tank after passing through the plate heat exchanger from the battery coolant chamber outlet, and is then discharged to the outer circulating water tank through the drain outlet of the inner circulating water tank, the coolant has sufficient space and time in the inner circulating water tank to dissipate any splashes and bubbles agitated when returning to the outer circulating water tank. This ensures that no splashes or bubbles from the outer circulating water tank enter the circulating water pump along with the coolant, guaranteeing optimal pump operation and heat dissipation, while avoiding the instability and single-layer temperature control of thermostats.

[0027] To achieve the above objectives, the technical solution of the present invention is as follows: A thermal management system for a fuel cell, comprising a primary heat dissipation cycle and a secondary heat dissipation cycle. The primary heat dissipation cycle consists of a double-layered circulating water tank, a circulating water pump, and a plate heat exchanger. The outer layer of the double-layered circulating water tank is a normal circulating water tank, which is connected to the circulating water pump. The outlet of the circulating water pump is connected to the inlet of the fuel cell coolant chamber via a pipeline, and the outlet of the fuel cell coolant chamber is connected to the first inlet of the plate heat exchanger. Inside the double-layered circulating water tank is a non-enclosed, open inner circulating water tank. The first outlet of the plate heat exchanger is connected to the return outlet of the inner circulating water tank. The return outlet of the inner circulating water tank is located 2-3 cm from the bottom of the inner circulating water tank. A right-angled drain pipe is located at 1 / 6 to 1 / 5 of the distance from the top of the inner circulating water tank, extending to 2-3 cm from the bottom of the outer circulating water tank. In the primary cooling cycle, the coolant in the outer circulating water tank is pumped into the fuel cell by a circulating water pump. It flows out from the fuel cell coolant chamber outlet into the first inlet of the plate heat exchanger, and then flows back to the inner circulating water tank through the first outlet of the plate heat exchanger via the return port. Finally, it flows out from the inner circulating water tank's drain port back to the outer circulating water tank. In the secondary cooling cycle, the coolant temperature in the outer circulating water tank of the primary cooling cycle is controlled by regulating the flow rate and temperature of the coolant flowing through the second inlet of the plate heat exchanger.

[0028] Beneficial effects

[0029] (1) In the primary heat dissipation cycle of the thermal management system of this application, the use of a double-layer circulating water tank allows the coolant flowing from the outlet of the fuel cell coolant chamber through the plate heat exchanger and back into the circulating water tank to first enter the inner circulating water tank and then enter the outer circulating water tank through the drain outlet of the inner circulating water tank. The water splashes and bubbles agitated by the coolant flowing back into the inner circulating water tank have sufficient time and space to dissipate in the inner circulating water tank, so that the coolant will not be mixed with bubbles when it enters the circulating water pump, thus ensuring the heat dissipation effect and working condition of the circulating water pump and improving the service life of the circulating water pump.

[0030] (2) The thermal management system of this application includes a primary and a secondary thermal cycle. The use of a double-layer circulating water tank in the primary thermal cycle replaces the function of a traditional thermostat. During the experiment and testing of fuel cells, a thermostat needs to be selected to control the fuel cell at different temperatures. Paraffin thermostats have a limited control range, and the temperature control of electronic thermostats is entirely determined by the feedback value of the battery stack coolant chamber outlet temperature sensor. The temperature sensor and the electronic thermostat themselves are prone to failure. The double-layer circulating water tank in this application, due to the buffering effect of the inner circulating water tank, allows the coolant flowing back to the circulating water tank through the hot water pipe of the plate heat exchanger to first enter the inner circulating water tank for temperature neutralization. After mixing with the coolant in the inner circulating water tank, it flows into the outer circulating water tank through the drain pipe. This prevents the coolant temperature in the outer circulating water tank from dropping too low, reduces the temperature fluctuation range of the coolant in the outer circulating water tank, avoids the singleness and uncertainty of the temperature control range, and improves the reliability of the thermal management system. Attached Figure Description

[0031] Figure 1 Schematic diagram of thermal management system.

[0032] In the diagram: 1. Circulating water tank, 2. Inner circulating water tank, 3. Return water inlet, 4. First drain outlet, 5. Circulating water pump, 6. Coolant chamber inlet, 7. Coolant chamber outlet, 8. First water inlet, 9. First water outlet, 10. Second water inlet, 11. Second water outlet, 12. Primary heat dissipation circulation, 13. First temperature sensor, 14. Second temperature sensor. Detailed Implementation

[0033] To enable those skilled in the art to understand the purpose, features, and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] A thermal management system for a fuel cell includes a circulating water tank 1, a circulating water pump 5, a plate heat exchanger, a controller, a first temperature sensor 13, and a second temperature sensor 14.

[0035] The circulating water tank 1 adopts a double-layer structure, including an inner circulating water tank 2 and an outer circulating water tank, with the inner circulating water tank 1 located inside the outer circulating water tank.

[0036] The outer circulating water tank is an open water tank that is not sealed, and the inner circulating water tank 2 is an open water tank;

[0037] The outer circulating water tank and the inner circulating water tank 2 share the same return water inlet 3, which is located 3 cm away from the inner circulating water tank 2. It also serves as the inlet for both the outer circulating water tank and the inner circulating water tank 2. This return water inlet is connected to the first outlet 9 of the plate heat exchanger via a pipeline.

[0038] A first drain outlet 4 is provided at a distance of 1 / 6 from the top of the inner circulating water tank. A right-angled pipe is provided at the first drain outlet 4 and extends downward to a distance of 3-5cm from the bottom of the outer water tank.

[0039] The plane where the first drain outlet is located is perpendicular to the plane where the outlet of the outer circulating water tank is located, and they are kept at a certain distance. The outlet end of the extended part of the first drain outlet 4 needs to be as far away as possible from the inlet of the circulating water pump on the outer circulating water tank.

[0040] The inner diameter of the drain outlet 4 and the return outlet 3 of the inner circulating water tank are the same.

[0041] The inner circulating water tank 2 needs to be made of a metal material with good thermal conductivity so that the temperature of the coolant in the inner circulating water tank is basically the same as the temperature in the outer circulating water tank.

[0042] The coolant level in the outer circulating water tank is between 1 / 6 and 1 / 5 of the distance from the top of the inner circulating water tank 2.

[0043] A second outlet is provided 2-3 cm from the bottom of the outer circulating water tank, and a circulating water pump 5 is provided at the second outlet;

[0044] The circulating water pump 5 is connected to the coolant chamber inlet 6 of the fuel cell;

[0045] A first temperature sensor 13 is installed at the outlet 7 of the fuel cell coolant chamber to collect the internal temperature of the fuel cell.

[0046] A second temperature sensor 14 is installed at the inlet 6 of the fuel cell coolant chamber to collect the temperature of the circulating water in the circulating water tank.

[0047] The plate heat exchanger includes a first inlet 8 and a first outlet 9.

[0048] The first water inlet 8 is connected to the coolant chamber outlet 7 of the fuel cell.

[0049] The first outlet 9 is connected to the return outlet 3; the above connection relationship constitutes the first-stage heat dissipation cycle 12 of this application;

[0050] The plate heat exchanger also includes a second water inlet 10 and a second water outlet 11; the cold water inlet needs to be supplied with an adjustable flow rate cooling medium to form a two-stage heat dissipation circulation process; the cooling medium can be connected to tap water or a coolant.

[0051] A flow valve is provided at the cooling water inlet 10;

[0052] The controller is connected to the first temperature controller, the second temperature controller, and the flow valve; the temperature of the first-stage heat dissipation cycle is controlled by adjusting the flow rate of the coolant in the second-stage heat dissipation cycle.

[0053] Example

[0054] The goal is to control the fuel cell temperature at around 60°C using a new thermal management system.

[0055] First, the circulating water pump 5 in the primary heat dissipation circulation 12 of the thermal management system is connected to the fuel cell coolant chamber inlet 6 via a pipeline. Then, the fuel cell coolant chamber outlet 7 is connected to the first inlet 8 of the plate heat exchanger via a pipeline. The first outlet 9 of the plate heat exchanger is connected to the return outlet 3 of the inner circulating water tank via a pipeline. Deionized water is injected into the outer circulating water tank 1, which has a double-layer structure, until the maximum liquid level is not higher than the highest point of the inner circulating water tank. The internal temperature of the battery is monitored by the first temperature sensor 13 at the fuel cell coolant chamber outlet, and the circulating water temperature in the circulating water tank is monitored by the second temperature sensor 14 at the fuel cell coolant chamber inlet. After the fuel cell is started, the circulating water pump 5 starts to run, loading and discharging the fuel cell. As the fuel cell runs for a longer period of time, the temperatures measured by the first temperature sensor 13 and the second temperature sensor 14 at the fuel cell coolant chamber outlet and inlet gradually increase. Adjustable flow rate tap water is introduced into the second inlet 10 of the plate heat exchanger, and the tap water flows out from the second outlet 11 of the plate heat exchanger. When the temperature of the fuel cell coolant chamber outlet 7 is below 58°C, the tap water at the second inlet of the plate heat exchanger is shut off. When the temperature of the fuel cell coolant chamber outlet reaches 58°C, the flow rate of tap water is adjusted according to the temperature value fed back by the first temperature sensor 13 at the fuel cell coolant chamber outlet, so that the fuel cell outlet temperature is kept constant at 60±0.5°C. At this time, keeping the tap water flow rate of the secondary heat dissipation cycle constant can keep the fuel cell outlet temperature constant. At this time, the inlet temperature of the fuel cell is kept at 55~57°C.

[0056] When it is necessary to control the outlet temperature of the fuel cell coolant chamber at 50℃, continue to slowly increase the flow rate of tap water at the second inlet of the plate heat exchanger, while monitoring the temperature value fed back by the first temperature sensor 13 at the outlet of the fuel cell coolant chamber. When the fuel cell outlet temperature reaches 50±0.5℃ and remains constant, keep the tap water flow rate of the secondary heat dissipation cycle constant to maintain the fuel cell outlet temperature at around 50℃. At this time, the fuel cell inlet temperature is basically maintained at 45~47℃. During this period, if the working state of the fuel cell is adjusted due to load changes, adjust the tap water flow rate in the secondary heat dissipation cycle according to the fuel cell outlet water temperature until the temperature is stable.

Claims

1. A thermal management system for fuel cells, characterized in that, include: Circulating water tank, plate heat exchanger, circulating water pump, controller, first temperature sensor and second temperature sensor; The circulating water tank includes an inner circulating water tank and an outer circulating water tank; the inner circulating water tank is located inside the outer circulating water tank; The outer circulating water tank and the inner circulating water tank share the same return water inlet. The bottom of the outer circulating water tank is provided with a second drain outlet; A circulating water pump is provided at the second drain outlet, and the circulating water pump is connected to the coolant chamber inlet of the fuel cell; The plate heat exchanger includes a first inlet and a first outlet. The first water inlet is connected to the coolant chamber outlet of the fuel cell. The first outlet and the return outlet are connected, and the above connection relationship constitutes a first-stage heat dissipation circulation process; The plate heat exchanger also includes a second inlet and a second outlet. A cooling medium with an adjustable flow rate is introduced into the second inlet end, which constitutes a two-stage heat dissipation cycle. A flow valve is installed at the second water inlet; A first temperature sensor is installed at the outlet of the fuel cell coolant chamber. A second temperature sensor is installed at the inlet of the fuel cell coolant chamber. The controller is connected to the first temperature sensor, the second temperature sensor, and the flow valve, and controls the temperature of the first-stage heat dissipation cycle by adjusting the flow rate of the cooling medium in the second-stage heat dissipation cycle.

2. The thermal management system according to claim 1, characterized in that: The outer circulating water tank is an open tank that is not enclosed, and the inner circulating water tank is an open tank.

3. The thermal management system according to claim 1, characterized in that, The inner circulating water tank is provided with a first drain outlet, which is located at 1 / 6 of the distance from the top of the inner circulating water tank. A right-angled pipe is provided at the first drain outlet and extends downward to 3-5 cm from the bottom of the outer circulating water tank.

4. The thermal management system according to claim 1, characterized in that, The return water inlet is located 2-3 cm from the bottom of the inner circulating water tank.

5. The thermal management system according to claim 3, characterized in that, The inner diameter of the first drain outlet and the return outlet of the inner circulating water tank are the same.

6. The thermal management system according to claim 1, characterized in that, The inner circulating water tank is made of a metal material with thermal conductivity.

7. The thermal management system according to claim 3, characterized in that, The plane where the first drain outlet is located is perpendicular to the plane where the outlet of the outer circulating water tank is located, and they maintain a certain distance.

8. The thermal management system according to claim 1, characterized in that, The coolant level in the outer circulating water tank is between 1 / 6 and 1 / 5 of the distance from the top of the inner circulating water tank.

9. The thermal management system according to claim 1, characterized in that: The second drain outlet is located 2-3 cm from the bottom of the water tank.

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