Liquid cooling circulation switching system suitable for hydrogen fuel cell stack

Abstract

The utility model discloses a liquid cooling circulation switching system suitable for a hydrogen fuel cell stack. The liquid cooling circulation switching system comprises an environmental chamber, a liquid cooling machine, an internal circulation expansion water tank and an internal circulation variable frequency water pump, the liquid cooling machine is arranged outside the environmental chamber, the liquid cooling machine is communicated with the hydrogen fuel cell stack arranged in the environmental chamber through an input pipe and an output pipe respectively, and the liquid cooling machine, the input pipe, the hydrogen fuel cell stack and the output pipe are connected into a pipeline loop; a bypass pipe with the two ends connected with the input pipe and the output pipe respectively is further arranged between the input pipe and the output pipe, the bypass pipe is connected with the hydrogen fuel cell stack in parallel, an internal circulation variable frequency water pump is installed on the bypass pipe, and an internal circulation expansion water tank is installed on the portion, between the hydrogen fuel cell stack and the bypass pipe, of the output pipe. The system is reasonable in structural design, the bypass pipe is arranged in the system, internal circulation of the ethylene glycol solution is achieved through the internal circulation variable frequency water pump, the arranged internal circulation expansion water tank can adjust thermal expansion and cold contraction changes of the ethylene glycol solution, and the application prospect is good.

Description

Technical Field

[0001] The utility model relates to the technical field of hydrogen fuel cells, and in particular to a liquid cooling circulation switching system suitable for a hydrogen fuel cell stack, and in particular to a liquid cooling and heating circulation device specially designed for low-temperature cold start testing of a hydrogen fuel cell stack. Background Art

[0002] A hydrogen fuel cell is a power generation device that directly converts the chemical energy of hydrogen and oxygen into electrical energy. Its basic principle is the reverse reaction of water electrolysis, where hydrogen and oxygen are supplied to the anode and cathode respectively. After hydrogen diffuses outward through the anode and reacts with the electrolyte, it releases electrons and reaches the cathode through an external load. The hydrogen fuel engine system uses the electricity generated by the hydrogen fuel cell to power the engine system. The process does not involve combustion, has high energy conversion rate and low noise, and has safe, environmentally friendly and pollution-free emissions. It has received widespread attention and recognition from domestic and foreign automobile manufacturers and researchers. However, as the core component of hydrogen fuel new energy vehicles, the hydrogen fuel engine system must involve various environmental simulation tests to meet the reliability, stability, safety and other tests of hydrogen fuel engines under different environmental conditions. In the field of environmental simulation test equipment, various environmental simulation tests for hydrogen fuel engine systems at home and abroad are still in the research and development and exploration stage.

[0003] In the low-temperature cold start test of hydrogen fuel cells, it is necessary to switch between the small cycle and the inner cycle to complete the test of controlling temperature, pressure, and flow. However, it is extremely difficult to stabilize the temperature of the ethylene glycol solution at -40°C. The physical properties of ethylene glycol determine that its viscosity is relatively large at a low temperature of -40°C. Even if it reaches -40°C for a short time, the subsequent heat loss and the low return air pressure of the refrigeration compressor cannot be stable for a long time. In this state, it is necessary to switch to the inner cycle to heat up, and at the same time, the pressure and flow of the ethylene glycol solution need to be adjusted. There are too many uncertainties in the control and testing process in conjunction with the environmental chamber. Some tooling needs to be completed in the environmental chamber, and its operation is also extremely cumbersome.

[0004] Therefore, it is of great practical significance to develop a liquid cooling cycle switching system that is simple to operate and can solve the requirements of low temperature and heated ethylene glycol solution required in the low temperature cold start process. Utility Model Content

[0005] Due to the above-mentioned defects in the prior art, the utility model provides a liquid cooling cycle switching system that is easy to operate and can solve the requirements of low temperature and heated ethylene glycol solutions in the low temperature cold start process. The system is easy to operate and has a high degree of integration, so as to solve the problems in the current test process of low temperature cold start of hydrogen fuel cell stacks that the switching control of the liquid cooling small cycle and the internal cycle is difficult, and the temperature stability of the ethylene glycol solution is poor, the fluctuation is large, and the rapid change response is difficult to meet the use requirements during the low temperature cold start of the hydrogen fuel cell stack.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A liquid cooling circulation switching system suitable for a hydrogen fuel cell stack, comprising an environmental chamber, a liquid cooler, an internal circulation expansion water tank and an internal circulation variable frequency water pump;

[0008] The liquid cooler is arranged outside the environmental cabin, and is connected to the hydrogen fuel cell stack arranged in the environmental cabin through an input pipe and an output pipe respectively. The liquid cooler, the input pipe, the hydrogen fuel cell stack and the output pipe are connected to form a pipeline loop. A bypass pipe with two ends connected to the input pipe and the output pipe respectively is provided between the input pipe and the output pipe, and the bypass pipe is connected in parallel with the hydrogen fuel cell stack. An internal circulation variable frequency water pump is installed on the bypass pipe, and an internal circulation expansion water tank is installed on the output pipe between the hydrogen fuel cell stack and the bypass pipe. The bypass pipe, the internal circulation expansion water tank and the internal circulation variable frequency water pump are all arranged in the environmental cabin.

[0009] The utility model is suitable for the liquid cooling circulation switching system of the hydrogen fuel cell stack, has a reasonable structural design, and a bypass pipe is arranged in the system. The internal circulation of the ethylene glycol solution is realized by the internal circulation variable frequency water pump. At the same time, the internal circulation expansion water tank arranged at the same time can adjust the thermal expansion and contraction changes of the ethylene glycol solution in the process of the pipeline from low temperature to high temperature. The system has high overall safety, strong comprehensive performance, high automation integration and high reliability, and has good application prospects.

[0010] As the preferred technical solution:

[0011] As described above, a liquid cooling circulation switching system suitable for a hydrogen fuel cell stack is provided with a cooling water inlet and a cooling water outlet on the liquid cooler.

[0012] A liquid cooling cycle switching system suitable for a hydrogen fuel cell stack as described above, wherein the input pipe is provided with a large circulation inlet pipe connected to the input pipe, and the connection between the large circulation inlet pipe and the input pipe is closer to the liquid cooler than the connection between the bypass pipe and the input pipe;

[0013] The output pipe is provided with a large circulation outlet pipe connected with the output pipe, and the connection between the large circulation outlet pipe and the output pipe is closer to the liquid cooler than the connection between the bypass pipe and the output pipe.

[0014] A liquid cooling cycle switching system suitable for a hydrogen fuel cell stack as described above, wherein the large cycle inlet pipe is provided with a large cycle inlet switching valve; the large cycle outlet pipe is provided with a large cycle outlet switching valve;

[0015] The large circulation inlet switching valve and the large circulation outlet switching valve are both arranged outside the environmental chamber.

[0016] A liquid cooling cycle switching system suitable for a hydrogen fuel cell stack as described above, wherein the input pipe between the liquid cooler and the large cycle inlet pipe is sequentially provided with a liquid cooler outlet temperature sensor, a liquid cooler outlet pressure sensor and a liquid cooler outlet switching valve along the direction from the liquid cooler to the large cycle inlet pipe;

[0017] The output pipe between the liquid cooler and the large circulation outlet pipe is sequentially equipped with a liquid cooler inlet switching valve, a liquid cooler inlet pressure sensor and a liquid cooler inlet temperature sensor along the direction from the large circulation outlet pipe to the liquid cooler.

[0018] As described above, a liquid cooling circulation switching system suitable for a hydrogen fuel cell stack is provided, wherein an internal circulation inlet proportional valve is installed at the connection between the bypass pipe and the output pipe, an internal circulation outlet proportional valve is installed at the connection between the bypass pipe and the input pipe, and the bypass pipe is also provided with an internal circulation heater.

[0019] In the above-mentioned liquid cooling circulation switching system suitable for a hydrogen fuel cell stack, the input pipe between the bypass pipe and the hydrogen fuel cell stack is sequentially installed with a stack flow sensor, a stack pressure sensor, a stack temperature sensor and a stack manual valve along the direction from the bypass pipe to the hydrogen fuel cell stack;

[0020] A small circulation proportional valve is installed on the input pipe between the large circulation inlet pipe and the bypass pipe.

[0021] As described above, a liquid cooling circulation switching system suitable for a hydrogen fuel cell stack, an output pipe between the bypass pipe and the hydrogen fuel cell stack is sequentially installed with an output manual valve, an output pressure sensor, an internal circulation expansion water tank and an output temperature sensor along the direction from the hydrogen fuel cell stack to the bypass pipe.

[0022] The above-mentioned cooling water inlet and cooling water outlet provide cooling water of 8°C to 25°C for the liquid cooler; the above-mentioned liquid cooler outlet temperature sensor is used to monitor the outlet temperature of the liquid cooler; the liquid cooler outlet pressure sensor and the liquid cooler inlet pressure sensor are auxiliary cascade PID control. The temperature monitored by the liquid cooler inlet temperature sensor is within the set temperature range. At this time, the temperature setting of the environmental chamber is consistent with the temperature range set by the liquid cooler; the large cycle outlet switching valve and the large cycle inlet switching valve are the switching valves used to switch to the large cycle of the hydrogen fuel cell stack after the small cycle and internal cycle tests of the hydrogen fuel cell stack are completed; the stack flow sensor, stack pressure sensor, and stack temperature sensor The stack outlet temperature sensor is the feedback signal of the internal circulation control. It acts on the internal circulation outlet proportional valve, internal circulation inlet proportional valve, internal circulation heater, and internal circulation variable frequency water pump through multiple cascade PID controls to adjust the temperature, pressure, and flow entering the stack; the internal circulation expansion water tank is used to adjust the thermal expansion and contraction changes of the ethylene glycol solution in the process of low temperature to high temperature in the pipeline, and its design volume is 10% of the volume of the entire hydrogen fuel cell stack internal circulation pipeline; the manual valve for entering the stack and the manual valve for exiting the stack are designed to prevent a large amount of ethylene glycol solution from leaking when the hydrogen fuel cell stack is disassembled; the pipelines involved in the above systems are all made of 316L stainless steel pipes, which have good pressure resistance and corrosion resistance.

[0023] The present application only discloses a liquid cooling cycle switching system of the environmental chamber. The environmental chamber can also be cooled by cascade refrigeration, heated by thermal oil, and humidified by high-pressure steam.

[0024] The above system can use a central control unit to achieve linkage control. The central control unit consists of an electrical control cabinet, a touch screen and a PLC control system. The central control unit adopts a SIMATIC S-1200 series safety PLC. The project control system is developed based on the TIA portal V17 software platform. The central control unit is equipped with a local area network and a server at the remote end, which can realize wired signal transmission and wireless signal transmission, and realizes multi-platform operation of Android and window systems and long-term retention of historical experimental data. The central control unit reserves communication protocols such as CAN bus, modbus TCP, PROFINET, modbus RS-485, and realizes data docking and alarm linkage with the fuel cell stack test bench.

[0025] The above technical solution is only a feasible technical solution of the present utility model, and the protection scope of the present utility model is not limited thereto. Those skilled in the art can reasonably adjust the specific design according to actual needs.

[0026] Compared with the prior art, the above utility model has the following advantages or beneficial effects:

[0027] The utility model is suitable for a liquid cooling circulation switching system for a hydrogen fuel cell stack, and multiple valves are used to control the switching between the small circulation and the inner circulation. The flow and pressure stability of the small circulation and the inner circulation device are achieved through PID adjustment of the proportional valve and the variable frequency pump, and the flow and pressure regulation problem of the ethylene glycol in the small circulation of the fuel cell stack during the cooling precooling and heating preheating process. The viscosity of the ethylene glycol solution increases at -40°C, and the flow resistance of the entire circulation device increases. The utility model fully considers this problem when designing the overall pipeline, and minimizes the flow resistance of the low-temperature small circulation and the inner circulation of the hydrogen fuel cell stack, and keeps the three variables of temperature, flow and pressure of the ethylene glycol solution constant. The problem of excessive heat loss is solved through integration with the environmental chamber, and the test function of the small circulation and inner circulation switching of the low-temperature cold start test process of the hydrogen fuel cell stack is realized, which can improve the stability of the low-temperature cold start test of the 150KW hydrogen fuel cell stack and the reliability of its test results, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention and its features, appearance and advantages will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings. The same reference numerals indicate the same parts in all the drawings. The drawings are not drawn to scale, and the emphasis is on illustrating the subject matter of the present invention.

[0029] Figure 1 It is a structural schematic diagram of a liquid cooling cycle switching system applicable to a hydrogen fuel cell stack of the utility model;

[0030] Among them, 1-electrical control cabinet; 2-PLC control system; 3-touch screen; 4-environmental cabin; 5-cooling water inlet; 6-cooling water outlet; 7-liquid cooler; 8-liquid cooler outlet temperature sensor; 9-liquid cooler outlet pressure sensor; 10-liquid cooler outlet switching valve; 11-liquid cooler inlet temperature sensor; 12-liquid cooler inlet pressure sensor; 13-liquid cooler inlet switching valve; 14-large circulation inlet switching valve; 15-large circulation outlet switching valve; 16-small circulation proportional valve; 17-inlet flow sensor; 18-inlet pressure sensor; 19-inlet temperature sensor; 20-inlet manual valve; 21-internal circulation outlet proportional valve; 22-internal circulation inlet proportional valve; 23-internal circulation heater; 24-internal circulation variable frequency water pump; 25-outlet temperature sensor; 26-internal circulation expansion water tank; 27-outlet pressure sensor; 28-outlet manual valve. DETAILED DESCRIPTION

[0031] The structure of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but is not intended to limit the present invention.

[0032] Example 1

[0033] A liquid cooling cycle switching system suitable for a hydrogen fuel cell stack, such as Figure 1 As shown, it includes an environmental chamber 4, a liquid cooler 7, an internal circulation expansion water tank 26 and an internal circulation variable frequency water pump 24;

[0034] The liquid cooler 7 is arranged outside the environmental chamber 4. The liquid cooler 7 is connected to the hydrogen fuel cell stack arranged in the environmental chamber 4 through an input pipe and an output pipe respectively. The liquid cooler 7, the input pipe, the hydrogen fuel cell stack and the output pipe are connected to form a pipeline loop. The liquid cooler 7 is provided with a cooling water inlet 5 and a cooling water outlet 6 respectively. A bypass pipe with two ends connected to the input pipe and the output pipe respectively is provided between the input pipe and the output pipe, and the bypass pipe is connected in parallel with the hydrogen fuel cell stack. An internal circulation inlet proportional valve 22 is installed at the connection between the bypass pipe and the output pipe, and an internal circulation outlet proportional valve 21 is installed at the connection between the bypass pipe and the input pipe. The bypass pipe is also provided with an internal circulation heater 23 and an internal circulation variable frequency water pump 24. The bypass pipe is arranged in the environmental chamber 4;

[0035] The input pipe is provided with a large circulation inlet pipe connected with the input pipe, and the connection between the large circulation inlet pipe and the input pipe is closer to the liquid cooler 7 than the connection between the bypass pipe and the input pipe, and the large circulation inlet pipe is provided with a large circulation inlet switching valve 14; the output pipe is provided with a large circulation outlet pipe connected with the output pipe, and the connection between the large circulation outlet pipe and the output pipe is closer to the liquid cooler 7 than the connection between the bypass pipe and the output pipe, and the large circulation outlet switching valve 15 is provided on the large circulation outlet pipe, and both the large circulation inlet switching valve 14 and the large circulation outlet switching valve 15 are arranged outside the environmental chamber 4;

[0036] The input pipe between the liquid cooler 7 and the large circulation inlet pipe is sequentially provided with a liquid cooler outlet temperature sensor 8, a liquid cooler outlet pressure sensor 9 and a liquid cooler outlet switching valve 10 along the direction from the liquid cooler to the large circulation inlet pipe. The liquid cooler outlet temperature sensor 8, the liquid cooler outlet pressure sensor 9 and the liquid cooler outlet switching valve 10 are all arranged outside the environmental chamber 4;

[0037] The output pipe between the liquid cooler 7 and the large circulation outlet pipe is sequentially provided with a liquid cooler inlet switching valve 13, a liquid cooler inlet pressure sensor 12 and a liquid cooler inlet temperature sensor 11 along the direction from the large circulation outlet pipe to the liquid cooler. The liquid cooler inlet switching valve 13, the liquid cooler inlet pressure sensor 12 and the liquid cooler inlet temperature sensor 11 are all arranged outside the environmental chamber 4;

[0038] The input pipe between the bypass pipe and the hydrogen fuel cell stack is installed with a stack flow sensor 17, a stack pressure sensor 18, a stack temperature sensor 19 and a stack manual valve 20 in sequence along the direction from the bypass pipe to the hydrogen fuel cell stack, and a small circulation proportional valve 16 is installed on the input pipe between the large circulation inlet pipe and the bypass pipe;

[0039] The output pipe between the bypass pipe and the hydrogen fuel cell stack is sequentially installed with a stack outlet manual valve 28, a stack outlet pressure sensor 27, an internal circulation expansion water tank 26 and a stack outlet temperature sensor 25 along the direction from the hydrogen fuel cell stack to the bypass pipe;

[0040] The small circulation proportional valve 16, the inflow flow sensor 17, the inflow pressure sensor 18, the inflow temperature sensor 19, the inflow manual valve 20, the outflow manual valve 28, the outflow pressure sensor 27, the internal circulation expansion water tank 26 and the outflow temperature sensor 25 are all arranged in the environmental chamber 4;

[0041] It also includes a central control unit, which includes an electrical control cabinet 1 , in which a PLC control system 2 is installed, and a touch screen 3 is installed on the electrical control cabinet 1 .

[0042] In summary, the present application provides a liquid cooling circulation switching system suitable for a hydrogen fuel cell stack, which adopts multiple valves to control the switching between the small circulation and the inner circulation, and realizes the stability of the flow and pressure of the small circulation and the inner circulation device through PID adjustment of the proportional valve and the variable frequency pump, and solves the flow and pressure regulation problem of ethylene glycol in the small circulation process of the stack during cooling and precooling and heating and preheating. The viscosity of the ethylene glycol solution increases at -40°C, and the flow resistance of the entire circulation device increases. The utility model fully considers this problem in the overall pipeline design, minimizes the flow resistance of the low-temperature small circulation and the inner circulation of the hydrogen fuel cell stack, and keeps the temperature, flow and pressure of the ethylene glycol solution constant. The problem of excessive heat loss is solved by integration with the environmental chamber, and the test function of switching between the small circulation and the inner circulation in the low-temperature cold start test process of the hydrogen fuel cell stack is realized, which can improve the stability of the low-temperature cold start test of the 150KW hydrogen fuel cell stack and the reliability of its test results, and has good application prospects.

[0043] Those skilled in the art should understand that those skilled in the art can implement variations by combining the prior art and the above embodiments, which will not be described in detail here. Such variations do not affect the essential content of the present utility model, and will not be described in detail here.

[0044] The above describes the preferred embodiments of the utility model. It should be understood that the utility model is not limited to the above-mentioned specific implementation methods, and the devices and structures that are not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the utility model without departing from the scope of the technical solution of the utility model, or modify them into equivalent embodiments of equivalent changes, which does not affect the essential content of the utility model. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the utility model without departing from the content of the technical solution of the utility model still falls within the scope of protection of the technical solution of the utility model.

Claims

1. A liquid cooling cycle switching system suitable for a hydrogen fuel cell stack, characterized in that: It includes an environmental chamber, a liquid cooler, an internal circulation expansion water tank and an internal circulation variable frequency water pump; The liquid cooler is arranged outside the environmental cabin, and is connected to the hydrogen fuel cell stack arranged in the environmental cabin through an input pipe and an output pipe respectively. The liquid cooler, the input pipe, the hydrogen fuel cell stack and the output pipe are connected to form a pipeline loop. A bypass pipe with two ends connected to the input pipe and the output pipe respectively is provided between the input pipe and the output pipe, and the bypass pipe is connected in parallel with the hydrogen fuel cell stack. An internal circulation variable frequency water pump is installed on the bypass pipe, and an internal circulation expansion water tank is installed on the output pipe between the hydrogen fuel cell stack and the bypass pipe. The bypass pipe, the internal circulation expansion water tank and the internal circulation variable frequency water pump are all arranged in the environmental cabin.

2. A liquid cooling cycle switching system suitable for a hydrogen fuel cell stack according to claim 1, characterized in that: The liquid cooler is respectively provided with a cooling water inlet and a cooling water outlet.

3. A liquid cooling cycle switching system suitable for a hydrogen fuel cell stack according to claim 1, characterized in that: The input pipe is provided with a large circulation inlet pipe connected to the input pipe, and the connection between the large circulation inlet pipe and the input pipe is closer to the liquid cooler than the connection between the bypass pipe and the input pipe; The output pipe is provided with a large circulation outlet pipe connected with the output pipe, and the connection between the large circulation outlet pipe and the output pipe is closer to the liquid cooler than the connection between the bypass pipe and the output pipe.

4. A liquid cooling cycle switching system suitable for a hydrogen fuel cell stack according to claim 3, characterized in that: The large circulation inlet pipe is provided with a large circulation inlet switching valve; the large circulation outlet pipe is provided with a large circulation outlet switching valve; The large circulation inlet switching valve and the large circulation outlet switching valve are both arranged outside the environmental chamber.

5. The liquid cooling cycle switching system suitable for a hydrogen fuel cell stack according to claim 3, characterized in that: The input pipe between the liquid cooler and the large circulation inlet pipe is sequentially equipped with a liquid cooler outlet temperature sensor, a liquid cooler outlet pressure sensor and a liquid cooler outlet switching valve along the direction from the liquid cooler to the large circulation inlet pipe; The output pipe between the liquid cooler and the large circulation outlet pipe is sequentially equipped with a liquid cooler inlet switching valve, a liquid cooler inlet pressure sensor and a liquid cooler inlet temperature sensor along the direction from the large circulation outlet pipe to the liquid cooler.

6. A liquid cooling cycle switching system suitable for a hydrogen fuel cell stack according to claim 1, characterized in that: An internal circulation inlet proportional valve is installed at the connection between the bypass pipe and the output pipe, an internal circulation outlet proportional valve is installed at the connection between the bypass pipe and the input pipe, and the bypass pipe is also provided with an internal circulation heater.

7. A liquid cooling cycle switching system suitable for a hydrogen fuel cell stack according to claim 3, characterized in that: The input pipe between the bypass pipe and the hydrogen fuel cell stack is sequentially installed with a stack flow sensor, a stack pressure sensor, a stack temperature sensor and a stack manual valve along the direction from the bypass pipe to the hydrogen fuel cell stack; A small circulation proportional valve is installed on the input pipe between the large circulation inlet pipe and the bypass pipe.

8. The liquid cooling cycle switching system suitable for a hydrogen fuel cell stack according to claim 1, characterized in that: The output pipe between the bypass pipe and the hydrogen fuel cell stack is sequentially installed with a stack outlet manual valve, a stack outlet pressure sensor, an internal circulation expansion water tank and a stack outlet temperature sensor along the direction from the hydrogen fuel cell stack to the bypass pipe.

Images