Fuel cell system without humidifier

Abstract

The utility model provides a fuel cell system without a humidifier. The fuel cell system comprises a galvanic pile, an air inlet pipeline for feeding air into the galvanic pile and a tail exhaust air pipeline for exhausting tail exhaust air from the galvanic pile. The air inlet pipeline is provided with an air compressor, the fuel cell system further comprises a humidifying branch, one end of the humidifying branch is communicated with the air inlet pipeline, the other end of the humidifying branch is communicated with the exhaust air pipeline, and the humidifying branch is further provided with a control mechanism for controlling the flow of exhaust air entering the air inlet pipeline. Part of tail exhaust air is introduced into an inlet of the air compressor again through the humidifying branch, and a large amount of water vapor and a small amount of liquid water contained in the tail exhaust air are used for humidifying reactor air.

Description

Technical Field

[0001] This utility model relates to the field of fuel cell technology, and in particular to a fuel cell system that eliminates the need for a humidifier. Background Technology

[0002] Proton exchange membrane fuel cells (PEM fuel cells) are energy devices that directly convert the chemical energy of the hydrogen-oxygen reaction into electrical energy. The reaction produces water, resulting in no pollutant emissions, and the fuel energy conversion efficiency is high, thus leading to their widespread application. Currently, PEM fuel cells are in the early stages of commercial application, with the main obstacles to commercialization being high cost, short lifespan, limited hydrogen refueling infrastructure, and high costs for hydrogen storage and transportation.

[0003] Proton exchange membranes (PEMs) require water as a medium to transport protons, and the membrane's water content must be maintained at a certain level; otherwise, the mass transfer resistance will significantly reduce performance. During the operation of a PEM fuel cell, the humidity of the air entering the stack has a significant impact on the proton water content. The air needs to be humidified before entering the stack to maintain its humidity within a reasonable range, thus maintaining the water balance within the stack and keeping the membrane water content within a suitable range. Currently, humidifiers are typically used in the fuel cell's air path. One side of the humidifier supplies dry air to the stack, while the other side supplies humid air to the stack. The humidifier transfers moisture from the humid air to the dry air, thereby increasing the humidity of the incoming dry air.

[0004] Patent application CN103137989A discloses a fuel cell system comprising a fuel cell stack containing a power generation component, an air supply unit supplying air to the cathode of the fuel cell, a humidifier humidifying exhaust air discharged from the cathode and supply air supplied from the air supply unit, a hydrogen supply unit supplying hydrogen to the anode of the fuel cell, and a water trap collecting and discharging condensate generated at the anode. The system can clean the fuel cell with hydrogen during startup, has a simple structure, and improves the humidity of the fuel cell during normal operation.

[0005] The humidifiers used in the above technical solutions are large and expensive, which will lead to a significant increase in system size and cost; the humidifier humidification efficiency will decrease with the increase of operating time, resulting in the need to adjust the operating conditions; the humidifier has pressure loss, which will increase the power consumption of the air compressor and thus reduce the system efficiency; the humidifier life is usually only 50% of the fuel cell system life, and it needs to be replaced regularly. Utility Model Content

[0006] To address the aforementioned technical problems in the existing technology, this utility model provides a fuel cell system that eliminates the need for a humidifier. By introducing a portion of the exhaust air back into the air compressor inlet through a humidification branch, the large amount of water vapor and a small amount of liquid water contained in the exhaust air are used to humidify the feed air.

[0007] The present invention provides a fuel cell system that eliminates the need for a humidifier, comprising: a fuel cell stack, an air inlet pipe for supplying air to the fuel cell stack, and an exhaust air pipe for discharging exhaust air from the fuel cell stack.

[0008] An air compressor is provided on the air intake pipe, and the fuel cell system also includes a humidification branch. One end of the humidification branch is connected to the air intake pipe, and the other end is connected to the exhaust air pipe. The humidification branch also has a control mechanism for controlling the flow rate of exhaust air entering the air intake pipe.

[0009] Furthermore, one end of the humidification branch is connected to the air intake pipeline located on the upstream side of the air compressor.

[0010] Furthermore, an air filter is also provided on the air intake pipe, the air filter is located upstream of the air compressor, and one end of the humidification branch is connected to a section of the air intake pipe located between the air filter and the air compressor.

[0011] Furthermore, an intercooler is also provided on the air intake pipe, located downstream of the air compressor. The function of the intercooler is to cool the air compressed by the air compressor, thereby improving the overall efficiency and performance of the fuel cell system.

[0012] Furthermore, a first back pressure valve is provided on the exhaust air duct, located on a section of the exhaust air duct between the humidification branch and the fuel cell stack; the control mechanism includes a second back pressure valve located on the humidification branch. The opening degree of the second back pressure valve can be calibrated according to system requirements, thereby reasonably controlling the flow rate of the air intake duct.

[0013] Furthermore, the control mechanism includes a three-way valve, the inlet of which and one of its outlets are connected to the exhaust air duct, and the other outlet of which is connected to the inlet of the humidification branch.

[0014] This invention provides a fuel cell system that eliminates the need for a humidifier. By introducing a portion of the humidified air exiting the stack into the air compressor inlet through a humidification branch, it mixes with fresh air to increase humidity. This eliminates the need for a humidifier while ensuring that the humidity entering the stack meets the stack requirements, thereby achieving the following beneficial effects:

[0015] a) It reduced the size of the fuel cell system and lowered the cost of the fuel cell system;

[0016] b) Reduced auxiliary consumption in the fuel cell system and improved the efficiency of the fuel cell system;

[0017] c) It avoids the short lifespan of humidifiers and improves the lifespan of fuel cell systems. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a fuel cell system without a humidifier, as provided in Example 1.

[0019] Figure 2 This is a schematic diagram of a fuel cell system without a humidifier, as provided in Example 2.

[0020] Figure reference numerals: 1. Fuel cell stack; 2. Air inlet pipe; 3. Exhaust air pipe; 4. Humidification branch; 5. Air compressor; 6. Air filter; 7. Intercooler; 8. First back pressure valve; 9. Second back pressure valve; 10. Three-way valve. Detailed Implementation

[0021] Example 1

[0022] like Figure 1 As shown, a fuel cell system without a humidifier includes: a fuel cell stack 1, an air inlet pipe 2 for supplying air to the fuel cell stack 1, an exhaust air pipe 3 for discharging exhaust air from the fuel cell stack 1, and a humidification branch 4.

[0023] An air compressor 5 is installed on the air intake line 2, and an air filter 6 is also installed on the air intake line 2, located upstream of the air compressor 5. An intercooler 7 is also installed on the air intake line 2, located downstream of the air compressor 5.

[0024] A first back pressure valve 8 is provided on the tail exhaust air duct 3. The first back pressure valve 8 is located on the tail exhaust air duct 3 on a section between the humidification branch 4 and the fuel cell stack 1.

[0025] Humidification branch 4 is connected at one end to the section of air intake pipe 2 located between air filter 6 and air compressor 5, and at the other end to exhaust air pipe 3.

[0026] The humidification branch 4 also has a control mechanism for controlling the flow rate of exhaust air into the air intake duct 2. The control mechanism includes a second back pressure valve 9 located on the humidification branch 4. The opening degree of the second back pressure valve 9 can be calibrated according to system requirements to reasonably control the flow rate of the air intake duct 2.

[0027] During operation, air first enters the air filter 6 to remove impurities, then is pressurized by the air compressor 5, and then enters the intercooler 7 to reduce its temperature caused by pressurization before entering the fuel cell stack 1. The exhaust air from the fuel cell stack 1 is partially discharged through the exhaust air line 3, and the rest enters the humidification branch line 4. The gas flow rate in the exhaust air line 3 can be adjusted by the first back pressure valve 8. The gas flow rate in the humidification branch line 4 can be adjusted by the second back pressure valve 9. The exhaust air entering the humidification branch line 4 and the air from the air filter 6 merge and enter the air compressor 5 together to complete a cycle.

[0028] In addition to the usual components of air, exhaust air typically contains a large amount of water vapor and even a small amount of liquid water. The moisture in the exhaust air mixes with the fresh air entering the fuel cell stack 1, increasing the humidity of the incoming air. The inlet pressure of air compressor 5 is negative, and the exhaust air pressure is significantly higher than atmospheric pressure. Under the influence of this pressure difference, it is beneficial for air compressor 5 to intake air, thereby reducing the power consumption of air compressor 5.

[0029] Example 2

[0030] like Figure 2 As shown, the difference between Embodiment 2 and Embodiment 1 is that Embodiment 2 does not contain the first back pressure valve 8 and the second back pressure valve 9, but instead has a three-way valve 10. The inlet and one of the outlets of the three-way valve 10 are connected to the exhaust air pipeline 3, and the other outlet of the three-way valve 10 is connected to the inlet end of the humidification branch 4.

[0031] During operation, air first enters the air filter 6 to remove impurities, then is pressurized by the air compressor 5, and then enters the intercooler 7 to reduce its temperature due to pressurization before entering the fuel cell stack 1. Part of the exhaust air from the fuel cell stack 1 is discharged through the three-way valve 10, while the other part enters the humidification branch 4. The three-way valve 10 can regulate the gas flow rate in both the exhaust air line 3 and the humidification branch 4. The exhaust air entering the humidification branch 4 and the air from the air filter 6 merge and enter the air compressor 5 together to complete a cycle.

Claims

1. A fuel cell system eliminating the need for a humidifier, comprising a fuel cell stack, an air inlet pipe for supplying air to the fuel cell stack, and an exhaust air pipe for discharging exhaust air from the fuel cell stack, wherein an air compressor is provided on the air inlet pipe, characterized in that, The fuel cell system also includes a humidification branch, one end of which is connected to the air intake pipe and the other end of which is connected to the exhaust air pipe. The humidification branch also has a control mechanism for controlling the flow rate of exhaust air into the air intake pipe.

2. The fuel cell system with humidifier elimination according to claim 1, characterized in that, One end of the humidification branch is connected to the air intake pipeline and is located on the upstream side of the air compressor.

3. The fuel cell system with humidifier elimination according to claim 2, characterized in that, An air filter is also provided on the air intake pipe. The air filter is located upstream of the air compressor. One end of the humidification branch is connected to a section of the air intake pipe located between the air filter and the air compressor.

4. The fuel cell system with humidifier elimination according to claim 2, characterized in that, An intercooler is also provided on the air intake pipeline, and the intercooler is located downstream of the air compressor.

5. The fuel cell system with humidifier elimination according to claim 1, characterized in that, The tail air duct is equipped with a first back pressure valve, which is located on a section of the tail air duct between the humidification branch and the fuel cell stack. The control mechanism includes a second back pressure valve located on the humidification branch.

6. The fuel cell system with humidifier elimination according to claim 1, characterized in that, The control mechanism includes a three-way valve, the inlet of which and one of its outlets are connected to the exhaust air pipeline, and the other outlet of which is connected to the inlet of the humidification branch.

Images