CN201440432U - External air humidifying device for fuel cell - Google Patents

Abstract

The utility model discloses a fuel cell's gaseous humidification device of outside is through the produced high temperature used heat by recycle fuel cell to shift this used heat recovery for reactant gas (hydrogen or air), again via gaseous humidification device's processing, can make its temperature of the effectual promotion of reactant gas and moisture content in the short time, in the reactant gas after being heated and the humidification gets into fuel cell, can make the polymer film obtain good humidification effect, through this generating efficiency and the life who promotes fuel cell.

Description

External gas humidification device for fuel cells

technical field

The utility model relates to a gas humidifying device, which is applied to a proton exchange membrane fuel cell, in particular to a kind of recycling and utilization of high-temperature waste heat generated by the fuel cell, and then through the treatment by the gas humidifying device, the reaction gas can be processed in a short time A humidification device for the external gas inside the fuel cell to elevate its temperature and moisture content.

Background technique

Proton Exchange Membrane Fuel Cells (PEMFCs) is a device that directly utilizes hydrogen (H ₂ ) and oxygen (O ₂ ) to generate electricity through electrochemical reactions. Due to its low operating temperature, fast start-up, High energy density, low pollution, and a wide range of applications, it has become a technology that has been developed and promoted by countries all over the world.

The main components of a typical proton exchange membrane fuel cell (PEMFC) include a proton exchange membrane (Proton Exchange Membrane, referred to as PEM), a catalyst layer (Catalyst Layer), a gas diffusion layer (Gas Diffusion Layer, referred to as GDL) and a bipolar plate (Bipolar Plate) and so on. Proton membrane exchange membrane (PEM) is a solid polymer film (such as DuPont's Nafion membrane, Asahi Chemical's Aciplex membrane, Ballard's BAM membrane and Gore's Gore Select membrane), and its main function in PEMFC cells is to isolate The cathode and the anode are two kinds of reactive gas molecules, which also isolate electrons. It only allows water molecules (H ₂ O) and hydrogen ions (H ⁺ ) to conduct, so this polymer film is an airtight film that can only conduct Hydrogen ions (H ⁺ ) but do not conduct electrons. When hydrogen ions (H ⁺ ) conduct in this polymer film, it must be carried by water molecules, so the higher the moisture content of the polymer film, the higher the conductivity of hydrogen ions (H ⁺ ). good. Therefore, how to increase the moisture content of the polymer film to obtain better hydrogen ion conduction efficiency is a necessary condition for maintaining good performance of the proton exchange membrane fuel cell (PEMFC).

Fuel cell humidification methods and designs for reaction gases can generally be divided into two types: internal humidification and external humidification, each with its own advantages and disadvantages. In terms of external humidification, it needs to add a humidifier outside the fuel cell. In addition to occupying space, this method also requires additional power to supply the heater in the humidifier to increase the temperature and humidity of the reaction gas. , which is the main disadvantage of this technique. But it also has many advantages: (1) It can provide stable humidification; (2) It can control and adjust the humidification; (3) It can handle a large amount of gas humidification; (4) It is easy to repair and maintain. As for the internal humidification method, it is mainly to design some humidification mechanisms inside the fuel cell. The main advantages of this method are: (1) small size and no space occupation; (2) no additional humidifier and heater are needed, so it can save (3) The waste heat or water generated by the fuel cell itself can be directly recycled. But it also has many disadvantages: (1) The pipeline design of the humidifying mechanism and the connection with the battery are quite complicated; (2) The humidification amount is not easy to control and adjust; (3) When the load is large, the gas humidification is often difficult to reach a saturated state; ( 4) It is not easy to carry out repair and maintenance work.

Patents related to the humidification design of the reaction gas of the fuel cell system have also been proposed and improved in recent years. The previous cases, such as the US Patent No. 5,482,680 and No. 5,527,363, mainly add a special fuel cell stack (Cell Stack) The disadvantage of the humidification section is that the volume and weight of the battery stack are greatly increased. In addition, the design of the fuel, oxidant and water flow channels inside the battery stack is quite complicated. U.S. Patent No. 6,406,807 is to design water spray holes at the ribs (Rid, Land) between the gas channels on the carbon plate, which can directly add water to the PEM membrane; U.S. Patent No. 6,403,249 is to add water to the battery pack. The last film type humidification section can directly humidify the reaction gas. US Patent No. 6,207,312 is a self-wetting design that uses a closed flow channel (Interdigitated flow field) and a carbon plate to design a thin-film humidification zone. US Patent No. 6,066,408 is to add a water-absorbing core (Wick) in the gas flow channel, and design a water-filling hole to supplement the water content of the water-absorbing core. US Patent No. 5,998,054 is a design for spraying water to humidify the front end of each gas channel on a carbon plate. US Patent No. 5,952,119 is to sew hydrophilic thin threads at fixed intervals on the gas diffusion layer (carbon cloth), and supplementary water passes through the fine threads to distribute water on the PEM membrane. In US Patent No. 5,965,288, an external permeable membrane humidifier is used to humidify the reaction gas.

Utility model content

The main purpose of this utility model is to propose an external gas humidification device for fuel cells, which can increase the temperature and moisture content of the reaction gas in a short time, and make the polymer film obtain a good humidification effect, through which the fuel cell can be improved. (PEMFC) power generation efficiency and service life.

According to the external air humidification device of the fuel cell disclosed by the utility model, it includes a cylinder body, a preheating coil, and a gas diffuser, and the coil section of the coil is preheated by separating the liquid stored in the cylinder by the gas diffuser It is immersed in the liquid, and the outlet end is located in the gas chamber separated by the gas diffuser, so that the reaction gas enters the preheating coil, and exchanges heat with the liquid through the coil section, and passes through the gas diffuser from the gas chamber. The state of tiny bubbles enters the liquid, increasing the temperature and humidity of the reaction gas. At the same time, in conjunction with recycling the high-temperature waste heat generated by the fuel cell, the waste heat is transferred to the reaction gas through the liquid in the cylinder, saving the energy loss required for heating the liquid, and the reaction gas produces a large number of tiny bubbles, which can greatly increase the reaction rate. The contact area between gas and water, in addition, in the liquid of the cylinder and above the coil section of the preheating coil, the liquid baffle designed with fins is used to block the reaction gas, which can greatly increase the residence time of the reaction gas in contact with the liquid Time (Retention Time), which can improve the heating and humidification effect of the reaction gas.

On the other hand, a gas baffle designed with fins can be used before the outlet of the cylinder, which can reduce the dew point temperature of the gas (Dew point), so that the supersaturated water vapor molecules can gather and condense, which can prevent the fuel cell from generating Flooding.

The beneficial effects of the utility model are: the temperature and moisture content of the reaction gas can be increased in a short time, and the polymer film can obtain a good humidification effect, thereby improving the power generation efficiency and service life of the fuel cell (PEMFC).

Description of drawings

For detailed content and technology of the present utility model, please cooperate with accompanying drawing to explain as follows, wherein:

FIG. 1 is a schematic diagram of an external air humidifying device for a fuel cell of the present invention.

Detailed ways

According to the humidification device for the external air of the fuel cell disclosed in the present utility model, please refer to FIG. 1, it is applied to the humidification of the reaction gas of the fuel cell (not shown in the figure), and the reaction gas can be hydrogen (H ₂ ) or air ( air) and other gas heating and humidification. The main components of a fuel cell include a proton exchange membrane (PEM), a catalyst layer (CatalystLayer), a gas diffusion layer (GDL) and a bipolar plate (BipolarPlate). When the PEMFC battery is in operation, the oxidation reaction of hydrogen (H ₂ ) is carried out at the anode (Anode), and the reduction reaction of oxygen (O ₂ ) is carried out at the cathode (Cathode). First, the reaction gas is catalyzed by the catalyst to decompose hydrogen (H ₂ ) into hydrogen ions (H ⁺ ) and electrons (e ^- ) (H ₂ → 2H ⁺ +2e ^- ), and electrons (e ^- ) flow out from the anode to The external circuit of the battery flows into the cathode after the load (Load) does work. At the same time, hydrogen ions (H ⁺ ) also pass through the proton exchange membrane (PEM) from the anode to the cathode, and combine oxygen molecules (O ₂ ) and electrons (e ^- ) to generate water (H ₂ O) and heat (Heat) (1 /2O ₂ +2H ⁺ +2e ^- →H ₂ O+Heat). When hydrogen ions (H ⁺ ) are generated at the anode, due to the potential drop inside the battery, the hydrogen ions will continue to move to the cathode through conduction. When hydrogen ion (H ⁺ ) moves due to conduction, it must be accompanied by several water molecules to conduct conduction (that is, move in the form of hydrated ion H+(H ₂ O)n). Therefore, when the battery is running, the water molecules will continue to move to the cathode. At this time, if the water cannot be replenished in time, the PEM membrane will be over-dried and the conductivity of hydrogen ions (H ⁺ ) will be reduced, which will affect the power generation performance of the PEMFC battery. dramatically drop.

As shown in FIG. 1 , the external air humidifier 1 includes a cylinder 10 , a preheating coil 20 , a gas diffuser 30 , a heat exchanger 40 , an electric heater 44 , a liquid baffle 52 and a gas baffle 50 . As shown in the figure, the cylinder body 10 is a vertical tubular water tank structure, and has an accommodating space 11 inside for storing the liquid 12 for humidification. The outer side of the accommodating space 11 can be provided with a layer of heat insulating layer to prevent The temperature of the liquid 12 leaks out, of course, the liquid level controller 70 and the thermocouple thermometers 61 and 62 can also be connected. Among them, the liquid level controller 70 is mainly used to control and adjust the capacity of the liquid 12, so that the water level of the liquid 12 is maintained at a certain height (in principle, it is better to cover the liquid baffle plate 52), and the thermocouple thermometers 61, 62 are mainly Used to control and indicate the temperature of the liquid 12 , the top has an outlet 112 and a liquid water source inlet 111 , and the liquid 12 can be supplemented by the liquid water source inlet 111 .

The preheating coil 20 has an inlet port 21, an outlet port 22, and a coil segment 23 located in the middle. Through the coiled design of the coil segment 23, it is immersed in the liquid 12, thereby increasing the contact area with the liquid 12, thereby increasing The effect of heat exchange. The gas disperser 30 is disposed near the bottom of the cylinder body 10 to separate the liquid 12 in the accommodation space 11 to form a gas chamber 31 , and the outlet end 22 of the preheating coil 20 is in the gas chamber 31 . The gas diffuser 30 is a planar porous material structure with a very small pore diameter below 0.1 mm, and can be made of foamed metal, porous metal oxide, porous carbon, and the like. The liquid baffle plate 52 and the gas baffle plate 50 are composed of at least one plate body with a plurality of fins 51 and 53 respectively, and have a downwardly inclined angle.

First, when the reaction gas (hydrogen (H ₂ ) or air (air)) enters the external gas humidifier 1 through the inlet port 21, and passes through the coil section 23 of the preheating coil 20, at this time, due to the coil section 23 of the preheating coil 20 It is completely submerged in the liquid 12 , so the reaction gas will exchange heat with the liquid 12 through the coil section 23 to increase the temperature of the reaction gas. And the heat source of liquid 12 can be provided by the high-heat exhaust gas produced after the reaction of the fuel cell, enters the heat exchanger 40 by the exhaust gas inlet 41, and enters the heat exchange tube 43 of the heat exchanger 40, and heats up with the liquid 12 Exchange, increase the temperature of the liquid 12, and then leave through the exhaust gas outlet 42, the heat exchange tube 43 can be in any shape such as a plate shape or a coiled tube. In addition, the heat source of the liquid 12 can also be provided by the electric heater 44 arranged on the gas disperser 30 .

Next, the reaction gas enters the gas chamber 31 (GasChamber) from the outlet port 22 through the coiled pipe section 23. Because the gas disperser is a porous material structure, a large number of tiny bubbles 13 can be generated when the reaction gas passes through and enter the liquid 12. When this micro-bubble 13 contacts with liquid 12, it can greatly increase the contact area of reaction gas and liquid 12, and this micro-bubble 13 can rise upwards because of buoyancy, when leaving liquid 12, can pass through the stop of liquid baffle plate 52, Because there are many fins 53 on the surface of the liquid baffle plate 52, these fins 53 can greatly increase the residence time (Retention Time) of the reaction gas in the liquid 12, so that the reaction gas can be fully and effectively heated and humidified. It is easy to make the reaction gas fully saturated. When the reaction gas is fully heated and humidified by water, before leaving the cylinder 10 through the outlet 112, it will pass through the barrier of the gas baffle 50, because there are many fins 51 on the surface of the gas baffle 50, and these fins 51 are mainly used To reduce the dew point temperature (Dew Point) of the reaction gas, and make the water vapor molecules in the reaction gas gather and condense, so as to prevent the supersaturated reaction gas from entering the fuel cell, because the supersaturated gas is easy to condense into liquid water , so that the fuel cell will be flooded, which will greatly reduce the power generation efficiency of the fuel cell. Through this, the reaction gas can effectively increase its moisture content and temperature to enter the fuel cell in a short time.

Although the present invention is disclosed above with the aforementioned preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications and changes without departing from the spirit and scope of the present invention. modification, so the scope of protection of the present utility model should be defined by the scope of claims.

Claims (10)

1. An external air humidifying device for a fuel cell, the fuel cell feeds a reaction gas to react to generate electricity, and discharges high-heat waste gas, it is characterized in that the external air humidifying device includes: A cylinder with a liquid in it and an outlet on the top surface; A preheating coil, installed in the barrel, has an outlet end, an inlet port for the reaction gas to enter, and a coil segment, and the coil segment is immersed in the liquid; a liquid baffle, arranged in the liquid in the cylinder, and located above the coil section of the preheating coil; and A gas disperser is arranged at the bottom of the cylinder to separate the liquid to form a gas chamber, and the outlet end of the preheating coil is arranged in the gas chamber. 2 . The external air humidifying device of the fuel cell according to claim 1 , further comprising a heat exchanger installed on the barrel. 3 . 3 . The external air humidifying device of the fuel cell according to claim 1 , further comprising a thermocouple thermometer installed on the barrel and inserted into the liquid. 4 . 4 . The external air humidifying device for a fuel cell according to claim 1 , wherein the liquid baffle further includes a plurality of fins. 5. The external air humidifying device for a fuel cell as claimed in claim 1, wherein the liquid baffle has a downward inclination angle. 6 . The external air humidifier of the fuel cell according to claim 1 , wherein the gas diffuser is made of a porous material. 6 . 7 . The external air humidifier of a fuel cell according to claim 6 , wherein the porous material is selected from the group consisting of foamed metal, porous metal oxide and porous carbon material. 7 . 8 . The external air humidification device for a fuel cell according to claim 1 , further comprising a gas baffle disposed in front of the outlet of the cylinder. 9 . 9 . The external air humidifier of the fuel cell according to claim 8 , wherein the gas baffle further includes a plurality of fins. 10 . The external air humidifier for fuel cells as claimed in claim 8 , wherein the gas baffle has a downward inclination angle. 11 .

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