A passive fuel cell cooling system and implementation method thereof

Abstract

The present invention discloses a passive fuel cell cooling system and its implementation method. The entire cooling pipeline and the stack cooling channel are filled with coolant. As the stack works, the coolant in the stack is heated, the coolant density decreases and the volume increases. Due to the presence of a one-way valve at the inlet, the coolant will flow out from the outlet. As the stack works and heats, the coolant will form a pressure difference, thereby automatically circulating and performing heat exchange. The heater is prepared for cold start. The present invention can provide efficient heat dissipation capacity for low-power fuel cells and save the existing large amount of heat dissipation and the redundancy of water pumps as water circulation power sources.

Description

Technical Field

[0001] The present invention belongs to fuel cell heat dissipation technology, and in particular relates to a passive fuel cell cooling system and an implementation method thereof. Background Art

[0002] Fuel cells are generally hydrogen fuel cells, which are primarily composed of an anode plate, a cathode plate, and a proton exchange membrane. The cathode is supplied with air, while the anode is supplied with hydrogen, which is provided by a hydrogen storage bottle and a gas supply system. The gas enters the battery cell through a pipeline, undergoes a chemical reaction on the proton exchange membrane, and the connected circuit moves electrons, generating an electric current. During this process, the oxidation reaction generates heat, and heat dissipation is a critical issue for fuel cells.

[0003] Low-temperature PEM fuel cells operate at an efficiency of approximately 50-60%. While generating electricity, they also generate roughly the same amount of heat. This heat comes from four sources: entropic heat from the reaction, irreversible heat from the electrochemical reaction, heat generated by ohmic resistance, and heat from water vapor condensation. Low-power fuel cell stacks (less than 10kW) are currently mostly cooled with air, which results in low heat dissipation efficiency and excessively large radiators. This invention improves heat dissipation efficiency without changing the stack structure, simplifying the installation of the stack and system on transportation vehicles.

[0004] Most existing water-cooled heat dissipation systems utilize a radiator and water pump as a controller to provide the power source for water circulation. Air-cooled systems require a larger contact area and use a fan to provide airflow. Existing technology (CN115224303A) also employs a coolant reversing mechanism that adjusts the direction and flow rate of the coolant through reversing, reversible pumps, and variable flow mechanisms to improve heat dissipation. This mechanism primarily achieves uniform heat dissipation by eliminating temperature differences. It is generally used in high-power fuel cells. For low-power applications, its complex structure results in poor energy savings and is impractical. Summary of the Invention

[0005] Purpose of the invention: In view of the above-mentioned deficiencies in the prior art, the first purpose of the present invention is to provide a passive fuel cell cooling system. In view of the heat dissipation implementation method of the system, the present invention also provides a method for implementing a passive fuel cell cooling system.

[0006] Technical solution: A passive fuel cell cooling system includes a cooling pipe and a heater. The cooling pipe is connected to the cooling channel between the bipolar plates of the fuel cell stack and includes an inlet and an outlet. The coolant in the cooling channel flows out of the fuel cell stack through the outlet, passes through the heater and a one-way valve, and then flows into the cooling channel between the bipolar plates of the fuel cell stack, thereby realizing coolant circulation.

[0007] In the system, the cooling circuit outside the stack includes air cooling. A one-way valve is located in the cooling circuit from the heater to the stack, near the stack inlet. The cooling circuit includes heat dissipation fins on the outside.

[0008] Furthermore, the heater is a PTC heater equipped with a heating battery and a control switch, and the switch includes a setting for temperature-controlled start.

[0009] Furthermore, in the system, the coolant outlet in the stack bipolar plate cooling channel is lower than the inlet, and the stack external cooling pipes are arranged non-horizontally, promoting coolant circulation in the cooling pipes under gravity. A combination of cooling fins and a heat sink is used outside the cold zone pipes, with the heat sink supported by the fins.

[0010] In the system, the cooling pipeline located outside the fuel cell stack includes a coolant storage chamber, and the outside of the coolant storage chamber includes heat dissipation fins, heat dissipation plates or air cooling devices, and the air cooling device includes a fan to assist in heat dissipation.

[0011] Furthermore, the cooling pipeline is a hose.

[0012] The above-mentioned passive fuel cell cooling system is implemented in a method in which the entire cooling pipeline and the stack cooling channel are filled with coolant. The coolant in the stack is heated by the operation of the stack, the cooling density becomes smaller, and the volume becomes larger. The flow direction is controlled by a one-way valve, and the coolant flows out from the outlet. As the stack is heated, a pressure difference is formed in the coolant, thereby realizing automatic circulation of the coolant and heat exchange.

[0013] Beneficial Effects: Compared with existing technologies, the system described in this invention is suitable for low-power fuel cell stack cooling systems. It eliminates the radiator and replaces air cooling with liquid cooling, increasing heat dissipation efficiency. Furthermore, this invention fully utilizes the higher efficiency of liquid cooling compared to gas cooling. Furthermore, it uses passive cooling, eliminating the need for a cooling circulation pump. For low-power fuel cells, the main radiator and fan can be eliminated, reducing the complexity of fuel cell system integration in mobile vehicles, increasing system layout flexibility, and simplifying thermal management control strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of the system of the present invention;

[0015] Figure 2 is a schematic diagram of the battery stack structure of the present invention;

[0016] Figure 3 This is a schematic diagram of the passive cooling system of a hydrogen bicycle;

[0017] Figure 4This is a schematic diagram of the passive cooling system of the hydrogen express tricycle. DETAILED DESCRIPTION

[0018] To illustrate the technical solution disclosed in the present invention in detail, further description is given below in conjunction with the accompanying drawings.

[0019] This invention addresses the cooling issues faced by low-power fuel cell stacks, primarily those with a power output of less than 10kW. It employs passive cooling, whereby coolant fills the entire cooling circuit, utilizing heat energy for self-circulation, improving heat dissipation efficiency and eliminating the space required to install a primary radiator on a vehicle.

[0020] Specifically, combined with Figure 1 and Figure 2 First, for the battery stack structure, as shown in Figure 1 and Figure 2 As shown, the fuel cell stack consists of a single fuel cell package. The fuel cell includes an anode and a cathode. The anode is supplied with hydrogen, and the cathode is supplied with air. A proton exchange membrane is located between them. The membrane only allows the passage of water and protons. Ions bypass the membrane and move through the circuit, forming an electric current. Heat dissipation is a key issue in a fuel cell stack due to the oxidation reaction. In some fuel cell stack configurations, the stack consists of a cathode air supply module, an anode hydrogen supply module, a water management module, and a heat dissipation module. To dissipate heat, the heat dissipation module pumps coolant into the stack via a cooling pump (for air cooling, a fan drives air into the stack), dissipating waste heat from the stack. This control strategy effectively concentrates the thermal management burden on the main radiator and its fan configuration. Therefore, the main radiator is often configured based entirely on the stack's peak power. This approach actually overstates the actual heat dissipation requirements of mobile vehicles, as mobile vehicles, especially on-board fuel cells, rarely operate at peak power and typically operate near the high-efficiency cruising power point. Excessive heat dissipation redundancy increases the demand for mobile vehicle space and also increases the difficulty in system integration.

[0021] The system of the present invention eliminates the radiator in the cooling system of a small-power fuel cell stack, and changes the heat dissipation method from air cooling to coolant cooling, thereby increasing the heat dissipation efficiency. The entire cooling pipeline and the stack cooling channel are filled with coolant. As the stack heats the coolant in the stack during operation, the coolant density decreases and the volume increases. Due to the presence of a one-way valve at the inlet, the coolant will flow out from the outlet. As the stack heats up during operation, the coolant will form a pressure difference, thereby automatically circulating and performing heat exchange. Fins are added to the outer wall of the cooling channel outside the stack to increase the heat dissipation, thereby achieving the required cooling effect. For small-power fuel cell systems below 10 kW, because the amount of heat to be dissipated is limited, the heat dissipation function of the system can be completely undertaken by the passive cooling system, that is, the main radiator can be completely eliminated.

[0022] The passive fuel cell cooling system of the present invention includes a cooling pipe and a heater. The cooling pipe is connected to the cooling channel between the bipolar plates of the fuel cell stack and includes an inlet and an outlet. The coolant in the cooling channel flows out of the fuel cell stack through the outlet, passes through the heater and a one-way valve, and then flows into the cooling channel between the bipolar plates of the fuel cell stack, thereby realizing coolant circulation.

[0023] Figure 3 and Figure 4 The application structure of the system of the present invention on bicycles and express tricycles is illustrated.

[0024] The battery stack is located under the seat of a bicycle or tricycle. In order to fully utilize gravity, the coolant outlet should be lower than the inlet, and the outlet of the upper cooling pipe should be higher than the inlet. The cooling pipe is inside the bicycle structural beam and is connected to the structural beam through the heat dissipation fins on the cooling pipe, thereby increasing the heat dissipation area. The entire cooling pipe and battery stack cooling channel are filled with coolant. As the battery stack heats the coolant in the stack, the coolant density decreases and the volume increases. Due to the one-way valve at the inlet, the coolant will flow out of the outlet. As the battery stack heats up, the coolant will form a pressure difference, thereby automatically circulating and performing heat exchange. Considering the problem of low-temperature starting in winter, a PTC heater (equipped with a battery) can be added to the cooling pipe to heat the coolant and thus heat the battery stack for low-temperature starting.

[0025] Further explanation, compared with the prior art, the present invention does not require a water pump or the like as the power for circulation. It is self-circulating and does not require a reversing mechanism. In addition, a one-way valve is used for one-way circulation control. Small-power fuel cells such as hydrogen bicycles currently use air cooling to cool the fuel cell stack. There is a fan in the system for heat dissipation, or a windward cooling pipe for heat dissipation. For areas with higher temperatures, the heat dissipation effect is not good when just started. The present invention utilizes the preheating effect of the fuel cell stack and the volume change of the liquid after preheating to promote self-circulation. In order to increase the pressure difference drive brought by the temperature, a temperature-controlled heating heater is provided on the cooling pipe. The cooling pipe located outside the fuel cell stack can also be further provided with heat dissipation fins to support the heat dissipation plate to increase the heat dissipation effect. The packaging of the cooling pipe is also realized to ensure safety.

[0026] Furthermore, the cooling pipeline can also be set to be soft, which is more convenient for utilizing the gravity drive of the coolant to further promote self-circulation. In order to cool the cooling medium in the cooling pipeline, a storage cavity can be set, and then a fan can be used to assist in heat dissipation, or a water-cooled radiator can be set to improve the heat dissipation effect. The present invention realizes external circulation of the coolant in the cooling channel of the fuel cell stack, and expands the installation and arrangement of heat dissipation auxiliary equipment on the external circulation pipeline. Compared with the existing technology, the heat dissipation effect is poor and the structure is complex, which is concentrated in the fuel cell stack or limited space.

Claims

1. A passive fuel cell cooling system, comprising a cooling pipe and a heater, characterized in that: The cooling pipeline is connected to the cooling channel between the bipolar plates of the battery stack, and includes an inlet and an outlet. After the coolant in the cooling channel flows out of the battery stack from the outlet, it flows through the heater and the one-way valve and then flows into the cooling channel between the bipolar plates of the battery stack, thereby realizing the circulation of the coolant; In the system, the cooling pipeline located outside the stack includes air cooling and heat dissipation; In the system, the coolant outlet in the cooling channel of the stack bipolar plate is lower than the inlet, and the cooling pipeline outside the stack is arranged non-horizontally, so that the coolant in the cooling pipeline promotes circulation under gravity; In the system, a cooling pipeline located outside the fuel cell stack includes a coolant storage chamber, and the outside of the coolant storage chamber includes a heat dissipation fin, a heat dissipation plate or an air cooling device, and the air cooling device includes a fan to assist in heat dissipation; The system is filled with coolant in the entire cooling pipeline and the stack cooling channel. The coolant in the stack is heated by the operation of the stack, the cooling density becomes smaller, and the volume becomes larger. The flow direction is controlled by a one-way valve, and the coolant flows out from the outlet. As the stack is heated, a pressure difference is formed in the coolant, thereby realizing automatic circulation of the coolant and heat exchange.

2. The passive fuel cell cooling system according to claim 1, characterized in that: The one-way valve is located in the cooling pipeline from the heater to the fuel cell stack and is close to the inlet of the fuel cell stack.

3. The passive fuel cell cooling system according to claim 1, wherein: The outside of the cooling pipeline includes heat dissipation fins.

4. The passive fuel cell cooling system according to claim 1, wherein: The heater is a PTC heater equipped with a heating battery and a control switch, wherein the switch is set to start at a temperature control.

5. The passive fuel cell cooling system according to claim 1, characterized in that: A combination of heat dissipation fins and heat dissipation plates is used outside the cold zone pipeline, and the heat dissipation plates are supported by the heat dissipation fins.

6. The passive fuel cell cooling system according to claim 1, characterized in that: The cooling pipeline is a hose.

Images