A fuel cell double water pump heat dissipation system and control method

Abstract

The present invention relates to the technical field of fuel cells, and particularly to a fuel cell double-water pump heat dissipation system and a control method. The system includes a thermostat disposed between the outlet and the inlet of the fuel cell stack and having a first outlet and a second outlet; a main water pump disposed between the first outlet of the thermostat and the inlet of the fuel cell stack; a radiator disposed between the second outlet of the thermostat and the inlet of the main water pump; and a sub-water pump disposed between the outlet of the radiator and the inlet of the main water pump. By adding a sub-water pump, the present invention can solve the problem of insufficient heat dissipation capacity during high-power operation of the fuel cell; solve the problems of difficult water addition and exhaust and inability to meet the design values of flow rate and pressure when the large-circulation pressure loss is too large; when the flow resistance of the heat dissipation system is large, at the same rotation speed of the two water pumps, solve the problem of reducing the flow rate in order to ensure the pipeline pressure; the main water pump and the sub-water pump are connected in series, the pipeline pressure increases, and according to the water pump performance curve, at the same rotation speed, the flow rate will also increase.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly relates to a fuel cell double water pump heat dissipation system and a control method therefor. Background Art

[0002] The heat dissipation problem of fuel cell systems restricts the improvement of their performance. As the power of fuel cell systems continues to increase, the size of the matching radiator also continues to increase. Limited by the vehicle layout space, the radiator is generally arranged on the roof, resulting in complex or long heat dissipation system pipelines and increased flow resistance. This may lead to the inability of the water pump performance to cover the technical requirements of the head and flow rate under all working conditions, resulting in problems such as difficult water addition and exhaust, and too high water temperature of the fuel cell. In the lightest case, it affects the output performance of the fuel cell system, and in the worst case, it causes the fuel cell system to stop running, greatly shortening its lifespan.

[0003] The fuel cell heat dissipation systems of existing technical solutions generally only match one water pump for reference Figure 1 , to meet the flow rate and pressure requirements during the heat dissipation of the fuel cell stack. When the fuel cell operates at low power, the coolant is controlled to flow in a small cycle (adjust the thermostat so that the water circuit of the fuel cell heat dissipation system does not pass through the radiator) through the thermostat. As the power increases, the opening of the thermostat will gradually increase and finally fully open. At this time, the coolant flows in a large cycle (adjust the thermostat so that the water circuit of the fuel cell heat dissipation system passes through the radiator). From the moment the coolant enters the large cycle, the controller will adjust the fan duty ratio and the water pump speed according to the real-time water temperature and power of the fuel cell to keep the water temperature at the set value. When designing the system, the maximum pressure loss of the radiator and pipelines in the large cycle part will be proposed, and the water pump speed, thermostat opening, fan duty ratio and other parameters at each working condition point will be calculated based on this. If the pressure loss exceeds the required upper limit when installed on the vehicle, it may be difficult to add water and exhaust; in addition, if the previous calibration parameters are continued to be executed during the system operation, the pressure or flow rate in the system will be low, resulting in too high water temperature of the fuel cell.

[0004] In summary, the performance of the currently used single water pump cannot meet the heat dissipation requirements of high-power fuel cells; it cannot ensure that the flow meter pressure of the heat dissipation system can still reach the design value when the pressure loss in the large cycle is too large. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to provide a fuel cell double water pump heat dissipation system and a control method therefor that overcome the technical problems existing in the background art.

[0006] To solve the above technical problem, the technical solution adopted by the present invention is:

[0007] A fuel cell double water pump heat dissipation system includes

[0008] A thermostat is provided between the outlet and the inlet of the stack and has a first outlet and a second outlet;

[0009] A main water pump is provided between the first outlet of the thermostat and the inlet of the stack;

[0010] A radiator is provided between the second outlet of the thermostat and the inlet of the main water pump; and

[0011] A secondary water pump is provided between the outlet of the radiator and the inlet of the main water pump.

[0012] Preferably, an expansion tank is further included, and the expansion tank includes a water inlet and a water outlet;

[0013] The water inlet is respectively communicated with the second outlet of the thermostat and the inlet of the stack;

[0014] The water outlet is respectively communicated with the inlet of the main water pump and the inlet of the secondary water pump.

[0015] Preferably, a deionization device is further provided between the water inlet and the second outlet of the thermostat respectively.

[0016] Preferably, a heater is connected in parallel on the pipeline between the confluence of the first outlet of the thermostat and the outlet of the secondary water pump.

[0017] Preferably, a liquid level sensor is provided in the expansion tank.

[0018] Preferably, temperature sensors are respectively provided at the outlet of the stack, the inlet of the stack, the outlet of the radiator, and the inlet of the radiator.

[0019] To solve the above technical problems, another technical solution adopted by the present invention is:

[0020] A control method for a double water pump cooling system of a fuel cell, including

[0021] Step 1: During the operation mode of the stack, determine whether the actual output power P_st of the stack is less than or equal to the stack output power P_set in the mode of the main water pump working alone or the main and secondary water pumps working together; if so, the main water pump runs alone and step 2 is executed; if not, the main and secondary water pumps work together and determine whether the actual water flow Q_st in the main loop of the stack is less than the target water flow Q_tar in the main loop of the stack. If so, the thermostat is fully opened, and the main water pump is preferably used. If the main water pump speed cannot meet the flow requirement after being adjusted to the highest speed, the secondary water pump adjusts the speed according to the flow difference for supplementation and then step 2 is executed. If not, step 2 is executed;

[0022] Step 2: Determine whether the absolute value of the difference between the actual working temperature T_st of the stack and the target working temperature T_tar of the stack is less than or equal to 2. If so, return to step 1; if not, adjust the radiator power and then return to step 1.

[0023] Preferably, when the main water pump or the auxiliary water pump fails, the operating power of the fuel cell stack is reduced. When both the main water pump and the auxiliary water pump fail, the operation of the fuel cell stack is stopped.

[0024] Preferably, when the main water pump operates alone, the main water pump adjusts the rotational speed according to the demand of the fuel cell stack and simultaneously adjusts the opening degree of the thermostat.

[0025] Preferably, before performing the steps, the double-water-pump heat dissipation system of the fuel cell is debugged. The debugging includes:

[0026] Open the pressure cover of the expansion tank, control the opening degree of the thermostat to 100%, and add coolant to the double-water-pump heat dissipation system of the fuel cell until the coolant level scale in the expansion tank shows between the min-max marks and then stop;

[0027] Small cycle (adjust the thermostat so that the water circuit of the fuel cell heat dissipation system does not pass through the radiator) debugging:

[0028] Control the opening degree of the thermostat to 0, start the main water pump, perform air exhaust for the small cycle, and continuously increase the rotational speed of the main water pump. When the liquid level in the expansion tank drops, continue to add coolant to the expansion tank to keep the coolant level scale in the expansion tank between the min-max marks until the power at each working condition point of the main water pump and the performance curve differ by no more than ±50W;

[0029] Large cycle (adjust the thermostat so that the water circuit of the fuel cell heat dissipation system passes through the radiator) debugging:

[0030] Control the opening degree of the thermostat to increase from 0 to 100%, perform air exhaust for the large cycle; continuously increase the rotational speed of the main water pump. When the liquid level in the expansion tank starts to drop, continue to fill the expansion tank with coolant so that the liquid level in the expansion tank is maintained between min-max. After the power at each working condition point of the water pump and the performance curve differ by no more than ±50W, start the auxiliary water pump and continuously increase the rotational speed of the auxiliary water pump. When the liquid level starts to drop, continue to fill the expansion tank with coolant so that the liquid level in the expansion tank is maintained between min-max until the power at each working condition point of the auxiliary water pump and the performance curve differ by no more than ±50W;

[0031] When performing small cycle debugging and large cycle debugging and there is no gas visible to the naked eye discharged from the exhaust port of the expansion tank, it is regarded as the debugging being completed.

[0032] The beneficial effects of the present invention are as follows: By adding an auxiliary water pump, the problem of insufficient heat dissipation capacity during high-power operation of the fuel cell can be solved; the problems of difficult water addition and exhaust and inability to meet the design values of flow rate and pressure when the large-circulation pressure loss is too large can be solved; when the flow resistance of the heat dissipation system is large, at the same rotational speed of the two water pumps, the problem of reducing the flow rate to ensure the pipeline pressure can be solved; the main water pump and the auxiliary water pump are connected in series, and the pipeline pressure increases. According to the performance curve of the water pump, at the same rotational speed, the flow rate will also increase, and only the requirements of the fuel cell need to be met; after the flow rate increases to a certain extent, further increasing the flow rate has a very limited effect on improving the heat dissipation capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic framework diagram of the stack heat dissipation system in the prior art;

[0034] Figure 2 is a schematic framework diagram of a fuel cell dual-water pump heat dissipation system according to a specific embodiment of the present invention;

[0035] Figure 3 is a schematic flow diagram of a control method for a fuel cell dual-water pump heat dissipation system according to a specific embodiment of the present invention;

[0036] Reference numeral description: 1. Stack; 2. Heater; 3. Thermostat; 4. Radiator; 5. Auxiliary water pump; 6. Ion device; 7. Expansion tank; 8. Main water pump; 9. Stack outlet temperature sensor; 10. Radiator inlet temperature sensor; 11. Radiator outlet temperature sensor; 12. Liquid level sensor; 13. Stack inlet temperature sensor. SPECIFIC EMBODIMENTS

[0037] To describe in detail the technical content, achieved objectives and effects of the present invention, the following is described in conjunction with the embodiments and with reference to the accompanying drawings.

[0038] Embodiment 1

[0039] Refer to Figure 2 , a fuel cell dual-water pump heat dissipation system, including

[0040] a thermostat 3, arranged between the outlet and inlet of the stack 1 and having a first outlet and a second outlet;

[0041] a main water pump 8, arranged between the first outlet of the thermostat 3 and the inlet of the stack 1;

[0042] a radiator 4, arranged between the second outlet of the thermostat 3 and the inlet of the main water pump 8;

[0043] an auxiliary water pump 5, arranged between the outlet of the radiator 4 and the inlet of the main water pump 8.

[0044] Expansion tank 7, the expansion tank 7 includes an inlet and an outlet; the inlet is respectively communicated with the second outlet of the thermostat 3 and the inlet of the fuel cell stack 1; the outlet is respectively communicated with the inlet of the main water pump 8 and the inlet of the auxiliary water pump 5. A deionization device 6 is further provided between the inlet and the second outlet of the thermostat 3. A liquid level sensor 12 is provided in the expansion tank 7.

[0045] Heater 2, is provided in parallel between the confluence of the first outlet of the thermostat 3 and the outlet of the auxiliary water pump 5.

[0046] Wherein

[0047] Temperature sensors are respectively provided at the outlet of the fuel cell stack 1, the inlet of the fuel cell stack 1, the outlet of the radiator 4, and the inlet of the radiator 4, which are respectively the fuel cell stack outlet temperature sensor 9, the fuel cell stack inlet temperature sensor 13, the radiator outlet temperature sensor 11, and the radiator inlet temperature sensor 10.

[0048] Embodiment II

[0049] Refer to Figure 3 , a control method for a fuel cell double water pump cooling system of Embodiment I, includes

[0050] Pre - commissioning: Open the pressure cover of the expansion tank 7, control the opening of the thermostat 3 to 100%, add coolant to the fuel cell double water pump cooling system until the cooling liquid level scale in the expansion tank 7 shows between the min - max marks and then stop;

[0051] Small - cycle commissioning:

[0052] Control the opening of the thermostat 3 to 0, start the main water pump 8, conduct small - cycle exhaust, and continuously increase the speed of the main water pump 8. When the liquid level in the expansion tank 7 drops, continue to add coolant to the expansion tank 7 to keep the cooling liquid level scale in the expansion tank 7 between the min - max marks until the power and performance curves of the main water pump 8 at each working condition point differ by no more than ±50W;

[0053] Large - cycle commissioning:

[0054] Control the opening of the thermostat 3 to increase from 0 to 100% for large - cycle exhaust; continuously increase the speed of the main water pump 8. When the liquid level in the expansion tank 7 starts to drop, continue to fill the expansion tank 7 with coolant so that the liquid level in the expansion tank 7 is maintained between min - max. After that, start the auxiliary water pump 5 and continuously increase the speed of the auxiliary water pump 5. When the liquid level starts to drop, continue to fill the expansion tank 7 with coolant so that the liquid level in the expansion tank 7 is maintained between min - max until the power and performance curves of the auxiliary water pump 5 at each working condition point differ by no more than ±50W;

[0055] When performing small-loop debugging and large-loop debugging and there is no gas visible to the naked eye discharged from the exhaust port of the expansion tank 7, it is regarded as the debugging being completed.

[0056] Step 1: Under the operating mode of the fuel cell stack 1, determine whether the actual output power P_st of the fuel cell stack 1 is less than or equal to the output power P_set of the fuel cell stack 1 in the mode where the main water pump 8 operates alone or the main and auxiliary water pumps 5 work together; if so, the main water pump 8 operates alone, and the main water pump 8 adjusts the rotational speed according to the requirements of the fuel cell stack 1 and simultaneously adjusts the opening degree of the thermostat 3, and execute Step 2; if not, the main water pump 8 and the auxiliary water pump 5 work together and determine whether the actual water flow rate Q_st in the main circuit of the fuel cell stack 1 is less than the target water flow rate Q_tar in the main circuit of the fuel cell stack 1. If so, the thermostat 3 is fully opened, and the main water pump 8 is preferentially used. If the rotational speed of the main water pump 8 cannot meet the flow rate requirement after being adjusted to the highest speed, the auxiliary water pump 5 adjusts the rotational speed according to the flow rate difference for supplementation and then execute Step 2. If not, execute Step 2;

[0057] Step 2: Determine whether the absolute value of the difference between the actual working temperature T_st of the fuel cell stack 1 and the target working temperature T_tar of the fuel cell stack 1 is less than or equal to 2. If so, return to Step 1; if not, adjust the power of the radiator 4 and then return to Step 1.

[0058] If the main water pump 8 or the auxiliary water pump 5 fails, the operating power of the fuel cell stack 1 is reduced. If both the main water pump 8 and the auxiliary water pump 5 fail, the operation of the fuel cell stack 1 is stopped.

[0059] The above are only embodiments of the present invention, and thus do not limit the patent scope of the present invention. All equivalent transformations made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in related technical fields, are equally included in the patent protection scope of the present invention.

Claims

1. A control method for a heat dissipation system of a fuel cell double water pump, characterized in that, The fuel cell double-water pump cooling system includes a thermostat, which is arranged between the outlet and the inlet of the fuel cell stack and has a first outlet and a second outlet; a main water pump, which is arranged between the first outlet of the thermostat and the inlet of the fuel cell stack; a radiator, which is arranged between the second outlet of the thermostat and the inlet of the main water pump; and a sub-water pump, which is arranged between the outlet of the radiator and the inlet of the main water pump; The control method includes Step 1: In the fuel cell stack operation mode, determine whether the actual output power P_st of the fuel cell stack is less than or equal to the output power P_set of the fuel cell stack in the mode where the main water pump operates alone or the main and sub-water pumps work together; If so, the main water pump operates alone and Step 2 is executed; If not, the main and sub-water pumps work together and determine whether the actual water flow Q_st in the main loop of the fuel cell stack is less than the target water flow Q_tar in the main loop of the fuel cell stack. If so, the thermostat is fully opened, and the main water pump is preferentially used. If the flow requirement cannot be met after the main water pump speed is adjusted to the highest, the sub-water pump adjusts the speed according to the flow difference for supplementation and then Step 2 is executed. If not, Step 2 is executed; Step 2: Determine whether the absolute value of the difference between the actual working temperature T_st of the fuel cell stack and the target working temperature T_tar of the fuel cell stack is less than or equal to 2. If so, return to Step 1; If not, adjust the radiator power and then return to Step 1.

2. The control method of a fuel cell double water pump heat dissipation system according to claim 1, characterized in that It further includes an expansion tank, and the expansion tank includes a water inlet and a water outlet; The water inlet is respectively communicated with the second outlet of the thermostat and the inlet of the fuel cell stack; The water outlet is respectively communicated with the inlet of the main water pump and the inlet of the sub-water pump.

3. The control method of a fuel cell double water pump heat dissipation system according to claim 2, characterized in that, A deionization device is also arranged between the water inlet and the second outlet of the thermostat.

4. The control method of a fuel cell double water pump heat dissipation system according to claim 2, characterized in that, A heater is connected in parallel on the pipeline between the confluence of the first outlet of the thermostat and the outlet of the sub-water pump.

5. The control method of a fuel cell double water pump heat dissipation system according to claim 2, characterized in that, A liquid level sensor is arranged in the expansion tank.

6. The control method of a fuel cell double water pump heat dissipation system according to claim 1, characterized in that, Temperature sensors are respectively arranged at the outlet of the fuel cell stack, the inlet of the fuel cell stack, the outlet of the radiator, and the inlet of the radiator.

7. The control method of the fuel cell double water pump heat dissipation system according to claim 1, wherein, If the main water pump or the sub-water pump fails, the operation power of the fuel cell stack is reduced. If the main water pump and the sub-water pump both fail, the operation of the fuel cell stack is stopped.

8. The control method of the fuel cell double water pump heat dissipation system according to claim 7, characterized in that, When the main water pump operates alone, the main water pump adjusts the speed according to the fuel cell stack demand and simultaneously adjusts the opening degree of the thermostat.

9. The control method of the fuel cell double water pump heat dissipation system according to claim 8, characterized in that, Before executing the steps, the fuel cell double-water pump cooling system is debugged, and the debugging includes: Open the pressure cap of the expansion tank, control the opening degree of the thermostat to 100%, add coolant to the fuel cell double-water pump cooling system until the cooling liquid level scale in the expansion tank shows that it reaches between the min-max marks and then stop; Small cycle debugging: Control the opening degree of the thermostat to 0, start the main water pump, conduct small cycle exhaust, and continuously increase the speed of the main water pump. When the liquid level in the expansion tank drops, continue to add coolant to the expansion tank to keep the cooling liquid level scale in the expansion tank showing that it reaches between the min-max marks until the power of the main water pump at each working condition point and the performance curve differ by no more than ±50W; Large cycle debugging: Control the opening degree of the thermostat to increase from 0 to 100%, and conduct large cycle exhaust; Continuously increase the speed of the main water pump. If the liquid level in the expansion tank starts to drop, continue to add coolant to the expansion tank to keep the liquid level in the expansion tank between min and max until the power and performance curves of the water pump at each operating point differ by no more than ±50 W. Then start the auxiliary water pump and continuously increase its speed. If the liquid level starts to drop, continue to add coolant to the expansion tank to keep the liquid level in the expansion tank between min and max until the power and performance curves of the auxiliary water pump at each operating point differ by no more than ±50 W. When conducting small cycle debugging and large cycle debugging, and there is no gas visible to the naked eye discharged from the exhaust port of the expansion tank, it is regarded as the debugging being completed.

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