Fully Immersed Self-Circulating Evaporative Cooling On-Vehicle Fuel Cell System and Working Method

Abstract

The present invention discloses a vehicle-mounted fuel cell system with fully immersed self-circulating evaporative cooling, which relates to the fields of clean energy application and transportation. It includes a metal sealed box, a fuel cell stack, a liquid level replenishment device, and a hydrogen storage tank; there is a wind deflector at the lower part of the metal sealed box, and the upper part and the top are heat dissipation structures; the liquid level replenishment device includes a medium expansion compensation tank and a first exhaust valve; the medium expansion compensation tank is connected to the metal sealed box, and the bottom of the medium expansion compensation tank is connected to the upper side of the metal sealed box. The liquid level replenishment device of the present invention can replenish the liquid level in the metal sealed box, ensure the fully immersed state in the metal sealed box, and at the same time absorb the expansion of the evaporative cooling medium when the fuel cell stack is in hot and cold states. The present invention also relates to a working method of such a vehicle-mounted fuel cell system with fully immersed self-circulating evaporative cooling.

Description

Technical Field

[0001] The present invention relates to the fields of clean energy application and transportation, and more specifically, it is an on-vehicle fuel cell system with fully immersed self-circulating evaporation cooling. The present invention also relates to a working method of such an on-vehicle fuel cell system. Background Art

[0002] Currently, most hydrogen fuel cell vehicles use 35Mpa or 70Mpa hydrogen storage tanks, with two or more (for heavy-duty trucks or large buses) connected in parallel and piped to the hydrogen input port of the fuel cell device; there is a possibility of hydrogen or oxygen leakage in the above-mentioned on-vehicle fuel cells; when hydrogen leaks, it can only be quickly discharged into the atmosphere, so there are very high requirements for the layout of fuel cells, anti-static and open flames, etc. The specific limitations are as follows:

[0003] 1) For on-vehicle fuel cells, the main dangerous characteristics are leaks in various sealing passages caused by reasons such as a decrease in the compression force of the stack or aging of the seals, resulting in a mixture of hydrogen and air and posing an explosion risk; therefore, from the perspective of the safety of fuel cells, overpressure relief devices, collision sensors, overcurrent and over-temperature protection, etc. must be installed to fully ensure the safety of the fuel cell stack.

[0004] 2) On-vehicle fuel cells need to be cooled during operation, should be arranged in a well-ventilated place or corresponding ventilation measures should be designed, and it should be ensured that hydrogen can quickly diffuse into the atmospheric environment in case of leakage. At the same time, when arranging the on-vehicle hydrogen system in the vehicle, a certain safety distance from the edge of the vehicle also needs to be considered for the fuel cell. The above characteristics all pose relatively high requirements for the storage of hydrogen fuel cell vehicles and the layout of in-vehicle hydrogen equipment.

[0005] 3) To ensure safety in case of hydrogen leakage, the conductive outer shell of the fuel cell vehicle also needs to be reliably connected to the ground to prevent static electricity from igniting hydrogen.

[0006] Therefore, it is necessary to develop a mobile on-vehicle fuel cell system with a fully immersed self-circulating evaporation cooling method. Summary of the Invention

[0007] The first object of the present invention is to overcome the deficiencies of the above background art and provide an on-vehicle fuel cell system with fully immersed self-circulating evaporation cooling.

[0008] The second object of the present invention is to overcome the deficiencies of the above background art and provide a working method of such an on-vehicle fuel cell system with fully immersed self-circulating evaporation cooling.

[0009] To achieve the above first object, the technical solution of the present invention is as follows: a fully immersed self-circulating evaporative cooling vehicle-mounted fuel cell system, characterized in that it includes a metal sealed box filled with an evaporative cooling medium, a fuel cell stack located inside the metal sealed box, a liquid level replenishing device connected to the top of the left side of the metal sealed box, and a hydrogen storage tank connected to the right side of the metal sealed box;

[0010] The lower part of the metal sealed box is provided with a wind deflector, and the upper part and the top are heat dissipation structures;

[0011] The liquid level replenishing device includes a medium expansion compensation tank and a first exhaust valve located at the top of the medium expansion compensation tank; the lower side of the medium expansion compensation tank is connected to the top of the metal sealed box, and the bottom of the medium expansion compensation tank is connected to the upper side of the metal sealed box;

[0012] It further includes a medium recovery device; the top of the medium recovery device is connected to the upper left side of the metal sealed box through a pressure relief valve, the side of the medium recovery device is connected to the lower left side of the metal sealed box through a medium release valve, and the bottom of the medium recovery device is connected to a second exhaust valve;

[0013] On the left side at the upper end inside the metal sealed box, there is a medium liquid level gauge; the bottom of the medium expansion compensation tank is connected to the medium liquid level gauge.

[0014] In the above technical solution, it further includes a leakage collection and storage room located at the top of the right side of the metal sealed box; there is a hydrogen and oxygen on-line monitoring device inside the leakage collection and storage room, and the top of the leakage collection and storage room is connected to a third exhaust valve.

[0015] In the above technical solution, the side of the leakage collection and storage room is provided with an observation window.

[0016] In the above technical solution, the hydrogen storage tank is connected to the fuel cell stack through a first valve; the right side of the fuel cell stack is connected to the outside through a second valve.

[0017] In the above technical solution, the heat dissipation structure is a structure with cooling fins or heat sinks.

[0018] In the above technical solution, the medium liquid level gauge is in the form of a liquid level flap gauge with a float valve.

[0019] To achieve the above second object, the technical solution of the present invention is as follows: a working method of a fully immersed self-circulating evaporative cooling vehicle-mounted fuel cell system, characterized by including the following steps:

[0020] Step 1: Fix the fuel cell stack in the metal sealed box 1. The metal sealed box uses an upper flange sealing cover. The vacuum pump extracts the air inside the metal sealed box, and then injects the evaporative cooling medium through the medium filling port until the liquid level reaches the position set by the medium expansion compensation tank connected to the metal sealed box, that is, the filling of the evaporative cooling medium is completed. The on-vehicle fuel cell system operates normally.

[0021] Step 2: When there is a trace amount of hydrogen leakage, due to the characteristics that hydrogen and oxygen are insoluble in the evaporative cooling medium, they will gather in the leakage collection and storage room. When the hydrogen and oxygen online monitoring device detects the leakage of hydrogen, oxygen or their mixed gas, an alarm is issued.

[0022] When there is continuous leakage of hydrogen and oxygen, or when the internal pressure of the metal sealed box rises due to the increase of the internal temperature and exceeds the limit value, the pressure relief valve opens to release the dangerous pressure, and automatically controls the closing of the hydrogen supply pipeline of the hydrogen storage tank to abort the reaction operation of the fuel cell stack.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1) During the vehicle operation, the air diversion and ventilation, and the air cooling are concentrated on the upper part and the top of the metal sealed box, forming a single-way air cooling channel, so that the upper structure of the metal sealed box has a condensation effect; in the external air cooling mode of the metal sealed box, the heat of the internal fuel cell stack causes the medium inside the metal sealed box to evaporate and form a gas state, which cools at the top inside the metal sealed box, thus forming a two-phase flow self-circulation and utilizing the naturally formed pressure difference for self-circulation evaporative cooling.

[0025] 2) The expansion liquid level replenishment device of the present invention can replenish the liquid level inside the metal sealed box, ensure the full immersion state inside the metal sealed box, and at the same time absorb the expansion of the evaporative cooling medium during the hot and cold states of the fuel cell stack.

[0026] 3) The fuel cell stack of the present invention is fully immersed and enclosed in the metal sealed box, effectively preventing the gas mixture when the unit cell leaks, and completely isolating the external air and harmful static electricity and open fire, thereby greatly improving the safety of the fuel cell vehicle.

[0027] 4) The safety of the present invention in terms of cooling, explosion prevention, leakage detection, and static electricity isolation is greatly improved, and the external cooling equipment can be cancelled, the cooling water or cooling medium is not passed into the fuel cell stack, the bipolar plate cooling channels and seals of each unit of the fuel cell stack are cancelled, the effective reaction area of the unit cell is increased, and the corresponding equipment and facilities are greatly simplified. Brief Description of the Drawings

[0028] Figure 1 It is a structural schematic diagram of the present invention. Detailed Embodiment

[0029] The implementation of the present invention will be described in detail below in conjunction with the accompanying drawings. However, they do not constitute a limitation to the present invention and are only for illustration purposes. At the same time, the advantages of the present invention will become clearer and easier to understand through the description.

[0030] Referring to the accompanying drawings, it can be seen that a fully immersed self-circulating evaporative cooling vehicle-mounted fuel cell system is characterized in that it includes a metal sealed box 1 filled with an evaporative cooling medium, a fuel cell stack 2 located inside the metal sealed box 1, a liquid level replenishing device 3 connected to the top left of the metal sealed box 1, and a hydrogen storage tank 4 connected to the right side of the metal sealed box 1;

[0031] The lower part of the metal sealed box 1 has a wind deflector 11, and the upper part and the top are heat dissipation structures 12;

[0032] The liquid level replenishing device 3 includes a medium expansion compensation tank 31 and a first exhaust valve 32 located at the top of the medium expansion compensation tank 31; the lower side of the medium expansion compensation tank 31 is connected to the top of the metal sealed box 1, and the bottom of the medium expansion compensation tank 31 is connected to the upper side of the metal sealed box 1;

[0033] It further includes a medium recovery device 6; the top of the medium recovery device 6 is connected to the upper left side of the metal sealed box 1 through a pressure relief valve 61, the side of the medium recovery device 6 is connected to the lower left side of the metal sealed box 1 through a medium release valve 62, and the bottom of the medium recovery device 6 is connected to a second exhaust valve 63.

[0034] On the left side of the upper end inside the metal sealed box 1, there is a medium liquid level gauge 13; the bottom of the medium expansion compensation tank 31 is connected to the medium liquid level gauge 13.

[0035] It further includes a leakage collection and storage room 7 located at the top right of the metal sealed box 1; inside the leakage collection and storage room 7, there is a hydrogen and oxygen on-line monitoring device 71, and the top of the leakage collection and storage room 7 is connected to a third exhaust valve 72.

[0036] There is an observation window 73 on the side of the leakage collection and storage room 7.

[0037] The water-sealed hydrogen transmission interface 41 of the hydrogen storage tank 4 is connected to the fuel cell stack 2 through a first valve 51; the right side of the fuel cell stack 2 is connected to the outside through a second valve 52.

[0038] The heat dissipation structure 12 is a structure with cooling fins or heat sinks.

[0039] The medium liquid level gauge 13 is a liquid level flap gauge with a float valve or other types of liquid level gauges.

[0040] In actual use, the fuel cell stack 2 is used for the reaction of hydrogen and oxygen to generate electricity and water;

[0041] The housing material of the metal sealed box 1 is a metal material with a high heat conduction system. The upper part and the top of the metal sealed box 1 are heat dissipation structures 12; the fuel cell stack 2 is fully immersed in the metal sealed box 1 filled with an evaporation cooling medium, and various pipelines are led out through flange interfaces.

[0042] The medium expansion compensation tank 31 can supplement the liquid level in the metal sealed box 1 to ensure the full immersion state in the metal sealed box 1, and at the same time absorb the expansion of the evaporation cooling medium when the fuel cell stack 2 is in hot and cold states.

[0043] The first valve 51 and the second valve 52 are used to release the medium pressure exceeding the safety or setting value, and the released medium is recovered by the medium recovery device 6.

[0044] The observation window 73 is used to observe the two-phase flow state of the medium in the housing of the metal sealed box 1.

[0045] The leakage collection and storage room 7 is used to store the leaked hydrogen for a short time;

[0046] The hydrogen and oxygen on-line monitoring device 71 is used to give an alarm when hydrogen, oxygen or their mixed gas leakage is detected.

[0047] The medium release valve 62 is arranged at the bottom of the housing and is used to release the medium in the housing of the metal sealed box 1, and the released medium is recovered by the medium recovery device 6.

[0048] The medium recovery device 6 recovers the medium released by the first valve 51, the second valve 52 and the medium release valve 62.

[0049] The medium liquid level gauge 13 is used to directly display the liquid level of the medium in the medium expansion compensation tank 31.

[0050] Leakage detection alarm devices are arranged at each valve to detect the medium leakage and hydrogen leakage at the housing interfaces, seals, etc.

[0051] The present invention adopts a fully immersed and self-circulating fuel cell cooling and isolation protection system: the fuel cell stack 2 and its connected hydrogen supply, oxygen supply, water supply pipelines, etc. are all immersed in a closed metal sealed box 1. The metal sealed box 1 is filled with an insulating, non-combustible and low-boiling-point evaporative cooling medium (such as HFC-4310). There are heat dissipation structures 12 on the upper part and the top of the metal sealed box 1. When the fuel cell stack 2 is working, the heat of the fuel cell stack 2 causes the medium to evaporate above the boiling point (such as 55 °C), absorb heat, and form a two-phase flow pressure head to carry out internal self-circulating cooling; in the present invention, the fuel cell stack 2 is fully immersed and enclosed in the metal sealed box 1, effectively preventing the gas mixture when the unit cell leaks, and completely isolating the external air and harmful static electricity and open flames, thereby greatly improving the safety of fuel cell vehicles; at the same time, the cooling of the hydrogen fuel cell does not require external devices or input of cooling medium, and is more energy-efficient, safe and reliable.

[0052] The working method of the present invention includes the following steps:

[0053] Step 1: Fix the fuel cell stack 2 in the metal sealed box 1. The metal sealed box 1 uses an upper flange sealing cover; the vacuum pump extracts the air in the metal sealed box 1, and then injects the evaporative cooling medium through the medium filling port until the liquid level reaches the position set by the medium expansion compensation tank 31 communicated with the metal sealed box 1, that is, the filling of the evaporative cooling medium is completed; when the evaporative cooling medium is filled, the on-vehicle fuel cell system can work stably under various working conditions of the vehicle operation.

[0054] Step 2: The on-vehicle fuel cell system is usually in a self-circulating and maintenance-free state. The evaporative cooling medium forms a two-phase flow and internal circulation through asymmetric ventilation cooling. The expansion compensation tank 31 absorbs thermal expansion and various vibrations, impacts and inertial forces during the vehicle operation.

[0055] When there is a small amount of leaked hydrogen, taking advantage of the characteristics that hydrogen and oxygen are insoluble in the evaporative cooling medium, it will concentrate in the leakage collection and storage room 7. When the hydrogen and oxygen online monitoring device 71 detects the leakage of hydrogen, oxygen or their mixed gas, an alarm is issued;

[0056] When there is continuous leakage of hydrogen and oxygen, or when the internal pressure of the metal sealed box 1 rises above the limit due to the increase in internal temperature, the pressure relief valve 61 opens to release the dangerous pressure, and can automatically control the closing of the hydrogen supply pipeline of the hydrogen storage tank 4 to stop the reaction work of the fuel cell stack 2.

[0057] The evaporative cooling medium can be recovered through the medium recovery device 6 and then injected into the metal sealed box 1 through the filling pump and valve.

[0058] In the present invention, since the in-vehicle fuel cell stack is fully immersed in an insulating, non-flammable evaporation medium with a low boiling point through a metal sealed box with a radiator, and hydrogen and oxygen are hardly soluble therein, static electricity and dangerous fire sources can be completely isolated, thus thoroughly solving the problem of static electricity protection of the fuel cell stack during vehicle operation. The present invention only takes fuel cell vehicles as an example. When the fuel cell stack is used for rail transit, the same principle and method of the present invention can be adopted.

[0059] Other parts not described belong to the prior art.

Claims

1. A vehicle-mounted fuel cell system with fully submerged self-circulating evaporation cooling, characterized in that: It comprises a metal sealed box (1) filled with an evaporative cooling medium, a fuel cell stack (2) located in the metal sealed box (1), a liquid level replenishing device (3) connected to the top of the left side of the metal sealed box (1), and a hydrogen storage tank (4) connected to the right side of the metal sealed box (1); The metal sealed box (1) has a windshield (11) at the bottom, and a heat dissipation structure (12) at the top and top. The liquid level replenishing device (3) comprises a medium expansion compensation box (31) and a first exhaust valve (32) located at the top of the medium expansion compensation box (31); the lower side surface of the medium expansion compensation box (31) is connected to the top of the metal sealing box (1), and the bottom of the medium expansion compensation box (31) is connected to the upper side surface of the metal sealing box (1); It also includes a medium recovery device (6); the top of the medium recovery device (6) is connected to the upper left side of the metal sealing box (1) through a pressure release valve (61), the side of the medium recovery device (6) is connected to the lower left side of the metal sealing box (1) through a medium release valve (62), and the bottom of the medium recovery device (6) is connected to a second exhaust valve (63); A medium level gauge (13) is provided on the left side of the upper end of the metal sealing box (1); the bottom of the medium expansion compensation box (31) is connected to the medium level gauge (13); It also includes a leakage collection storage room (7) located at the top right side of the metal sealed box (1); the leakage collection storage room (7) contains a hydrogen and oxygen online monitoring device (71), and the top of the leakage collection storage room (7) is connected to a third exhaust valve (72); The working method of the fully immersed self-circulating evaporative cooling vehicle-mounted fuel cell system is as follows: Step 1: The fuel cell stack (2) is fixed in the metal sealed box 1, and the metal sealed box (1) adopts an upper flange sealing cover; the vacuum pump extracts the air in the metal sealed box (1), and then injects the evaporative cooling medium through the medium filling port until the liquid level reaches the position set by the medium expansion compensation box (31) connected to the metal sealed box (1), and the filling of the evaporative cooling medium is completed; the vehicle-mounted fuel cell system works normally; Step 2: When a small amount of hydrogen leaks, hydrogen and oxygen are concentrated in the leakage collection and storage room (7) by taking advantage of the fact that they are insoluble in the evaporative cooling medium. When the hydrogen and oxygen online monitoring device (71) detects the leakage of hydrogen, oxygen or their mixed gases, an alarm is sounded; When hydrogen or oxygen continues to leak, or the internal pressure of the metal sealed box (1) rises to a value exceeding the limit due to the internal temperature rise, the pressure release valve (61) opens to release the dangerous pressure, and automatically controls the closure of the hydrogen storage tank (4) hydrogen delivery pipeline, thereby stopping the reaction of the fuel cell stack (2).

2. The fully-immersed self-circulating evaporative cooling vehicle-mounted fuel cell system according to claim 1, wherein: The leakage collection storage room (7) has an observation window (73) on the side.

3. The on-vehicle fuel cell system with fully-immersed self-circulating evaporation cooling according to claim 2, wherein: The hydrogen storage tank (4) is connected to the fuel cell stack (2) via a first valve (51); the right side of the fuel cell stack (2) is connected to the outside via a second valve (52).

4. The fully-immersed self-circulating evaporative cooling vehicle-mounted fuel cell system according to claim 3, wherein: The heat dissipation structure (12) is a structure with cooling fins or heat sinks.

5. The vehicle-mounted fuel cell system with fully immersed self-circulating evaporation cooling according to claim 4, characterized in that: The medium level meter (13) is a level flap meter type with a float valve.

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