Self-produced water humidifying air-cooled fuel cell system and working method thereof

Abstract

The invention relates to a self-produced water humidifying air-cooled fuel cell system and a working method thereof. The system comprises a hydrogen path subsystem, an air path subsystem and an air-cooled galvanic pile, liquid hydrogen provided by a hydrogen source sequentially passes through the high-pressure valve assembly and the liquid hydrogen vaporizer and then enters from an anode inlet of the air-cooled galvanic pile to participate in a reaction; the fan is arranged outside an air inlet of the air-cooled electric pile and is used for feeding external air into the air-cooled electric pile, and the ultrasonic atomizer is used for humidifying air entering the pile; the liquid hydrogen vaporizer is arranged outside an air outlet of the air-cooled galvanic pile; the water storage tank is arranged below the liquid hydrogen vaporizer, and the water pump is used for pumping water out of the water storage tank and supplying the water to the ultrasonic atomizer. Liquid water in the stack air can be condensed by cold energy of the liquid hydrogen, and the liquid water is collected in the water storage device to serve as a water source of the ultrasonic atomizer, so that self-produced water humidification of the cathode of the air-cooled stack is realized on the premise of not adding a complex humidification system.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a self-produced water humidification air-cooled fuel cell system and a working method thereof. Background Art

[0002] In order to cope with the ever-increasing energy crisis and increasingly serious environmental pollution problems, the research and development of clean energy has become a top priority. Fuel cells, as an emerging clean energy technology, have received extensive attention and research. Among them, air-cooled fuel cells, as a type of fuel cell, have certain advantages due to their unique structure. The air sucked in by the fan can not only provide gas for the cathode of the fuel cell, but also be used to cool the stack, replacing the complex water-cooled cooling circuit system in traditional fuel cells. At the same time, it simplifies the air compressor, intercooler and other components in the air circuit system. Due to its simple structure, it has strong portability.

[0003] Existing air-cooled fuel cells still have some defects. If the cathode is not humidified, the membrane electrode is easily over-dried, resulting in a too low limiting current density. Due to the humidity limit of the membrane electrode, a higher gas stoichiometric ratio cannot be achieved, which limits the performance and service life of the air-cooled battery. Since the main advantages of air-cooled fuel cells are simple systems, low costs and high portability, in order to avoid the membrane electrode from being over-drying, a water storage tank is designed for the system to meet the humidification needs of the system, which is obviously contrary to the advantages of the simple and portable system. In addition, since the cathode of the air-cooled fuel cell is in an open state, the liquid water produced by the reaction in the stack is also difficult to collect, so the water produced in the stack is difficult to recycle. The main form of the anode gas source of the existing air-cooled fuel cell is a single large bottle of hydrogen. Once a gas source failure occurs, the stack will not work properly, and the gas cylinder can only be replaced as a whole, which increases gas waste and other problems.

[0004] Therefore, it is urgent to design a self-produced water humidification air-cooled fuel cell system and its working method to solve the problems existing in the above-mentioned prior art. Summary of the invention

[0005] In view of this, the present invention provides a self-produced water humidification air-cooled fuel cell system and its working method, with the aim of achieving self-produced water humidification of the cathode of the air-cooled fuel cell stack without adding a complex humidification system, thereby preventing the performance and life of the fuel cell from being reduced due to excessive drying of the membrane electrode.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A self-produced water humidification air-cooled fuel cell system, the system comprising a hydrogen path subsystem, an air path subsystem and an air-cooled fuel cell stack;

[0008] The hydrogen gas circuit subsystem includes a hydrogen source, a high-pressure valve assembly, a liquid hydrogen vaporizer and an anode tail exhaust valve. The liquid hydrogen provided by the hydrogen source passes through the high-pressure valve assembly and the liquid hydrogen vaporizer in sequence, and then enters the anode inlet of the air-cooled fuel cell to participate in the reaction. The anode tail exhaust valve is provided on the pipeline connected to the anode outlet of the air-cooled fuel cell.

[0009] The air path subsystem includes a fan, an ultrasonic atomizer, a water pump, and a water reservoir. The fan is arranged outside the air inlet of the air-cooled fuel cell stack and is used to send external air into the air-cooled fuel cell stack. The ultrasonic atomizer is arranged between the fan and the air inlet of the air-cooled fuel cell stack and is used to humidify the air entering the stack. The liquid hydrogen vaporizer is arranged outside the air outlet of the air-cooled fuel cell stack. The water reservoir is arranged below the liquid hydrogen vaporizer and the water pump is used to pump water out of the water reservoir and supply it to the ultrasonic atomizer.

[0010] Furthermore, the ultrasonic atomizer is provided with heat exchange fins, which are used to exchange heat between the high-temperature and high-humidity air leaving the stack and the hydrogen in the liquid hydrogen vaporizer; the pipeline connected to the anode outlet of the air-cooled fuel cell stack extends to the water reservoir.

[0011] Furthermore, the hydrogen source in the hydrogen circuit subsystem is configured as a mode in which multiple hydrogen cylinders are connected in series, and an electromagnetic valve is provided outside the outlet of each hydrogen cylinder, and the electromagnetic valve is used to control whether the corresponding hydrogen cylinder is connected to the hydrogen circuit subsystem; the self-produced water humidification air-cooled fuel cell system also includes a hydrogen cylinder cabinet, and a plurality of independent accommodating cavities are horizontally arranged in the hydrogen cylinder cabinet, and the accommodating cavities are matched with the shape of the hydrogen cylinders to facilitate the storage of hydrogen cylinders.

[0012] The present invention also provides a working method based on the above self-produced water humidification air-cooled fuel cell system, and the working method is as follows:

[0013] The fan delivers external air into the air-cooled fuel cell stack from the air inlet of the air-cooled fuel cell stack, and after the reaction occurs, the air is discharged from the air outlet of the air-cooled fuel cell stack;

[0014] At the same time, the liquid hydrogen provided by the hydrogen source enters the liquid hydrogen vaporizer after passing through the high-pressure valve assembly, and the liquid hydrogen vaporizes in the liquid hydrogen vaporizer, and then enters the air-cooled fuel cell from the anode inlet of the air-cooled fuel cell, and after the reaction occurs, it is discharged from the anode outlet of the air-cooled fuel cell;

[0015] The high-temperature and high-humidity air leaving the stack contacts the heat exchange fins of the liquid hydrogen vaporizer and exchanges heat with the hydrogen in the liquid hydrogen vaporizer. The temperature of the high-temperature and high-humidity air leaving the stack drops rapidly, and the gaseous water in the air condenses into liquid water. The condensed liquid water flows into the water reservoir under the action of gravity. At the same time, the hydrogen in the liquid hydrogen vaporizer absorbs a large amount of heat from the air leaving the air-cooled stack. The hydrogen temperature rises before entering the air-cooled stack, which prevents the hydrogen temperature from being too low and affecting the temperature distribution in the air-cooled stack.

[0016] The water pump pumps the water out of the reservoir and supplies it to the ultrasonic atomizer. The high-frequency vibration of the ceramic pieces in the ultrasonic atomizer breaks up the liquid water into water mist, which humidifies the air flow blown in by the fan before entering the air-cooled fuel cell stack.

[0017] Furthermore, the heat exchange fins of the liquid hydrogen vaporizer are selected according to the required heat exchange efficiency of the fins of the self-produced water humidification air-cooled fuel cell system. The specific calculation method of the required heat exchange efficiency η of the fins is as follows:

[0018] η=P_exc / (P_out+P_va)*2*100% (1);

[0019] Where, P_exc is the heat that the fin needs to exchange per unit time; P_out is the total heat of all substances in the battery stack per unit time; P_va is the hydrogen cooling power provided by liquid hydrogen;

[0020] The heat P_exc that the fin needs to exchange per unit time is calculated as follows:

[0021] P_exc = P_out - P_eve (2);

[0022] Where P_out is the total heat of all substances in the battery stack per unit time; P_eve is the heat discharged from the entire system per unit time;

[0023] The hydrogen cooling power P_va provided by liquid hydrogen is calculated as follows:

[0024] P_va=m_H 2 *k (3);

[0025] In the formula, m_H 2 is the actual hydrogen consumption mass flow rate; k is the cold energy of liquid hydrogen vaporization 4386.19 J / g;

[0026] The total heat P_out of all substances in the battery stack per unit time is calculated as follows:

[0027] P_out=m_O 2 _out*T_out*C_O 2 +m_N 2 _out*T_out*C_N 2 +m_W_out_g*

[0028] T_out*C_W_g+(m_W_out-m_W_out_g)*T_out*C_W_l(4);

[0029] Where, T_out is the temperature of the gas and liquid leaving the stack, which is usually a controlled parameter of the stack and a known quantity; m_O 2_out is the mass flow rate of oxygen out of the reactor; m_N 2 _out is the mass flow rate of nitrogen leaving the reactor; m_W_out is the mass flow rate of water leaving the reactor; m_W_out_g is the mass flow rate of water vapor leaving the reactor; C_O 2 is the specific heat capacity of oxygen; C_N 2 is the specific heat capacity of nitrogen; C_W_g is the specific heat capacity of water vapor, and C_W_l is the specific heat capacity of liquid water.

[0030] Furthermore, the mass flow rate m_W_out_g of the steam leaving the reactor is calculated as follows:

[0031] m_W_out_g=(m_ 2 _out+m_N 2 _out)*P_sat_out / (P_outlet-P_sat_out) (5);

[0032] Where P_outlet is the gas pressure out of the stack, which is usually a controlled parameter of the stack and a known quantity; P_sat_out is the saturated vapor pressure of the gas out of the stack, which is calculated as follows:

[0033] P_sat_out=exp(23.196-3816.44 / (T_out-46.13)) (6);

[0034] Where, T_out is the temperature of the gas and liquid out of the stack, which is usually a controlled parameter of the stack and a known quantity;

[0035] The heat P_eve discharged from the entire system per unit time is calculated as follows:

[0036] P_eve=m_O 2 _out*T_eve*C_O 2 +m_N 2 _out*T_eve*C_N 2 +m_W_eve_g*T_eve

[0037] *C_W_g+m_W_add*T_eve*C_W_l(7);

[0038] Where, T_eve is the temperature of the gas leaving the reactor after heat exchange; m_O 2 _out is the mass flow rate of oxygen out of the reactor; m_N 2 _out is the mass flow rate of nitrogen leaving the stack; m_W_eve_g is the permitted water escape amount; m_W_add is the mass flow rate of water added through the ultrasonic humidifier.

[0039] Furthermore, the mass flow rate of oxygen entering the reactor is m_O 2 _in is calculated as follows:

[0040] m_O 2 _in=m_Air*23 / 98; (8);

[0041] In the formula, m_Air is the actual air consumption mass flow rate, 23 / 98 is the ratio of oxygen mass in the air to air mass;

[0042] Nitrogen mass flow rate into the reactor m_N 2 _in is calculated as follows:

[0043] m_N 2 _in=m_Air*75 / 98; (9);

[0044] In the formula, 75 / 98 is the ratio of the mass of nitrogen in the air to the mass of air;

[0045] The mass flow rate of water in the air entering the reactor, m_W_in, is calculated as follows:

[0046] m_W_in=P_W*(m_ 2 _in+m_N 2 _in) / (P_atm-P_W) (10);

[0047] Where, P_atm is the standard atmospheric pressure; P_W is the partial pressure of water vapor in the air;

[0048] The mass flow rate of water added by the ultrasonic humidifier, m_W_add, is calculated as follows:

[0049] m_W_add=m_W_inall-m_W_in (11);

[0050] Where m_W_inall is the mass flow rate of water in the gas entering the reactor after humidification, which is calculated as follows:

[0051] m_W_inall=(P_inlet-P_sat_inlet*RH) / P_sat_inlet*RH*(m_O 2 _in+m_N 2 _in) (12);

[0053] Wherein, RH is the target humidity of the anode, which is 60%; P_inlet is the pressure of the gas entering the stack after humidification, which is usually a known quantity; P_sat_inlet is the saturated vapor pressure of the gas entering the stack; m_O2_in is the mass flow rate of oxygen entering the stack; m_N2_in is the mass flow rate of nitrogen entering the stack;

[0054] P_sat_inlet=exp(23.196-3816.44 / (T_inlet-46.13)) (13);

[0055] Where T_inlet is the inlet temperature, which is usually a controlled known quantity.

[0056] Furthermore, the mass flow rate of oxygen out of the reactor is m_O 2 _out is calculated as follows:

[0057] m_O 2 _out=m_O 2 _in-m_Air_th*21% (14);

[0058] In the formula, m_O 2 _in is the mass flow rate of oxygen entering the reactor; m_Air_th is the theoretical air consumption mass flow rate;

[0059] Nitrogen mass flow rate out of the reactor m_N 2 _out is calculated as follows:

[0060] m_N 2 _out=m_N 2 _in (15);

[0061] In the formula, m_N 2 _in is the mass flow rate of nitrogen entering the reactor;

[0062] The permissible water escape m_W_eve_g is calculated as follows:

[0063] m_W_eve_g=m_W_out-m_W_add=m_W_in+m_W (16);

[0064] Where, m_W_out is the mass flow rate of water leaving the reactor; m_W_req is the mass flow rate of liquid water required by the system; m_W is the mass flow rate of liquid water actually generated;

[0065] The mass flow rate of outflowing water m_W_out is calculated as follows:

[0066] m_W_out=m_W_in+m_W_add+m_W (17);

[0067] Where m_W_in is the mass flow rate of water in the air entering the reactor; m_W_add is the mass flow rate of water added by the ultrasonic humidifier; and m_W is the mass flow rate of water actually generated.

[0068] Furthermore, the mass flow rate m_W of the water actually generated is calculated as follows:

[0069] m_W=m_H2 _th / M_H 2 *M_W (18);

[0070] In the formula, M_H 2 is the molar mass of hydrogen; M_W is the molar mass of water;

[0071] The partial pressure of water vapor in air, P_W, is calculated as follows:

[0072] P_W=P_sat_anb*RH_anb (19);

[0073] In the formula, RH_anb is the ambient humidity, taking the local average humidity; P_sat_anb is the saturated vapor pressure of water vapor in the ambient air, calculated as follows:

[0074] P_sat_anb=exp(23.196-3816.44 / (T_anb-46.13)) (20);

[0075] In the formula, T_anb is the ambient temperature, taking the local average temperature;

[0076] If the system is to operate continuously and stably, the condensed water must meet the following conditions: the mass flow rate of liquid water m_W_req required by the system is equal to the mass flow rate of water added by the ultrasonic humidifier m_W_add, that is:

[0077] m_W_req=m_W_add (21).

[0078] Furthermore, the temperature T_eve of the gas leaving the reactor after heat exchange is calculated as follows:

[0079] T_eve=3816.44 / (23.196-ln(P_sat_eve_g))+46.13 (22);

[0080] Where P_sat_eve_g is the saturated vapor pressure of the gas that eventually leaves the system, calculated as follows:

[0081] P_sat_eve_g=P_atm*m_W_out_g / (m_O 2 _out+m_N 2 _out+m_W_out_g) (twenty three);

[0083] Where P_atm is the standard atmospheric pressure; m_W_out_g is the mass flow rate of water vapor leaving the reactor; m_O 2 _out is the mass flow rate of oxygen out of the reactor; m_N 2 _out is the mass flow rate of nitrogen out of the pile;

[0084] The actual air consumption mass flow m_Air is calculated as follows:

[0085] m_Air=m_Air_th*β (24);

[0086] Where β is the air metering ratio, usually 2; m_Air_th is the theoretical air consumption mass flow rate, calculated as follows:

[0087] m_Air_th=I*n*M_Air / f / a (25);

[0088] Where, I is the working current; n is the number of cells in the battery stack; f is the Faraday constant; M_Air is the molar mass of air; a is the charge number per unit oxygen molecule, a=4;

[0089] Actual hydrogen consumption mass flow m_H 2 The calculation is as follows:

[0090] m_H 2 =m_H 2 _th / α (26);

[0091] Where α is the fuel efficiency, which is usually taken as 0.96 based on experience; m_H 2 _th is the theoretical hydrogen consumption mass flow rate; it is calculated as follows:

[0092] m_H 2 _th = I*n / f (27);

[0093] Where I is the operating current, n is the number of cells in the battery stack, and f is the Faraday constant.

[0094] Compared with the prior art, the present invention has the following beneficial effects:

[0095] (1) Heat exchange fins are set on the liquid hydrogen vaporizer, and the high-temperature and high-humidity air leaving the stack is heat exchanged with the hydrogen in the liquid hydrogen vaporizer by using the heat exchange fins. The cold energy of the liquid hydrogen condenses the liquid water in the air leaving the stack, and the liquid water is collected in the water reservoir as the water source of the ultrasonic atomizer, so as to realize the cathode self-produced water humidification of the air-cooled stack without adding a complex humidification system; at the same time, the hydrogen in the liquid hydrogen vaporizer absorbs a large amount of heat from the air leaving the stack, and the hydrogen temperature rises before entering the air-cooled stack, so as to avoid the temperature distribution in the air-cooled stack being affected by the low hydrogen temperature. The required heat exchange efficiency of the fins is calculated by the calculation method, and the heat exchange fins suitable for the system are accurately selected according to the required heat exchange efficiency of the fins, so as to improve the heat exchange efficiency of the system and maximize energy utilization.

[0096] (2) By setting the hydrogen source to a mode in which multiple hydrogen cylinders are connected in series, and using a solenoid valve to control whether the corresponding hydrogen cylinders are connected to the hydrogen circuit system, the series gas supply mode increases the safety and stability of the hydrogen source. When hydrogen needs to be replenished, the solenoid valve corresponding to the used hydrogen cylinder can be closed and replaced with a new hydrogen cylinder without stopping the entire system. At the same time, the difficulty of replenishing gas and the waste of hydrogen caused by replacing the cylinder are reduced; the number of hydrogen cylinders installed in the hydrogen circuit system is determined according to the endurance requirements. While ensuring the mass power density of the system, the hydrogen in the cylinders is used in sequence, which is convenient for replacing the cylinders. There is no need to replace the cylinders when the total hydrogen is consumed, thereby speeding up the hydrogen replenishment efficiency. In addition, by designing a hydrogen cylinder cabinet, the method of horizontally and parallelly installing hydrogen cylinders reduces the difficulty of installing hydrogen cylinders.

[0097] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0099] Figure 1 A schematic diagram of the structure of a self-generated water humidification air-cooled fuel cell system according to an embodiment of the present invention is shown;

[0100] Figure 2 A three-dimensional schematic diagram of a hydrogen cylinder cabinet according to an embodiment of the present invention is shown.

[0101] In the figure: 1. Fan; 2. Ultrasonic atomizer; 3. Air-cooled fuel cell stack; 4. Anode tail exhaust valve; 5. Liquid hydrogen vaporizer; 6. High-pressure valve assembly; 7. Solenoid valve; 8. Hydrogen cylinder; 9. Hydrogen cylinder cabinet; 10. Water pump; 11. Water reservoir. DETAILED DESCRIPTION

[0102] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0103] The embodiment of the present invention provides a self-generated water humidification air-cooled fuel cell system, as shown in the attached Figure 1-2 As shown, the system includes a hydrogen path subsystem, an air path subsystem and an air-cooled fuel cell stack 3;

[0104] The hydrogen gas circuit subsystem includes a hydrogen source, a high-pressure valve assembly 6, a liquid hydrogen vaporizer 5 and an anode tail exhaust valve 4. The liquid hydrogen provided by the hydrogen source passes through the high-pressure valve assembly 6 and the liquid hydrogen vaporizer 5 in sequence, and then enters the anode inlet of the air-cooled fuel cell 3 to participate in the reaction. The anode tail exhaust valve 4 is provided on the pipeline connected to the anode outlet of the air-cooled fuel cell 3.

[0105] The air path subsystem includes a fan 1, an ultrasonic atomizer 2, a water pump 10, and a water reservoir 11. The fan 1 is arranged outside the air inlet of the air-cooled fuel cell stack 3, and is used to send external air into the air-cooled fuel cell stack 3. The ultrasonic atomizer 2 is arranged between the fan 1 and the air inlet of the air-cooled fuel cell stack 3, and the ultrasonic atomizer 2 is used to humidify the air entering the stack; the liquid hydrogen vaporizer 5 is arranged outside the air outlet of the air-cooled fuel cell stack 3; the water reservoir 11 is arranged below the liquid hydrogen vaporizer 5, and the water pump 10 is used to pump water out of the water reservoir 11 to supply the ultrasonic atomizer 2.

[0106] The ultrasonic atomizer 2 is provided with heat exchange fins, which are used to exchange heat between the high-temperature and high-humidity air leaving the stack and the hydrogen in the liquid hydrogen vaporizer 5. The temperature of the high-temperature and high-humidity air leaving the stack drops rapidly, and the gaseous water therein condenses into liquid water. The liquid water produced by the condensation flows into the water reservoir 11 under the action of gravity.

[0107] The pipe connected to the anode outlet of the air-cooled fuel cell stack 3 extends to the water reservoir 11, so that the water reservoir 11 can collect the liquid water regularly purged from the anode.

[0108] The hydrogen source in the hydrogen circuit system is set to a mode in which multiple hydrogen cylinders 8 are connected in series, and a solenoid valve 7 is set outside the outlet of each hydrogen cylinder 8, and the solenoid valve 7 is used to control whether the corresponding hydrogen cylinder 8 is connected to the hydrogen circuit system. The mode of multiple hydrogen cylinders 8 connected in series to supply gas increases the safety and stability of the hydrogen source. When hydrogen needs to be replenished, the solenoid valve 7 corresponding to the used hydrogen cylinder 8 can be closed and replaced with a new hydrogen cylinder 8 without stopping the entire system, while reducing the difficulty of replenishing gas and the waste of hydrogen caused by replacing the cylinder.

[0109] The number of hydrogen cylinders 8 installed in the hydrogen circuit subsystem is determined according to the endurance requirement. While ensuring the mass power density of the system, the hydrogen in the cylinders is used sequentially, which facilitates the replacement of cylinders. There is no need to replace the cylinders when the total hydrogen is consumed, thereby speeding up the hydrogen replenishment efficiency.

[0110] The self-produced water humidification air-cooled fuel cell system also includes a hydrogen cylinder cabinet 9, in which a plurality of independent accommodating cavities are horizontally arranged. The accommodating cavities match the shape of the hydrogen cylinders 8 to facilitate the storage of the hydrogen cylinders 8. The method of horizontally and parallelly installing the hydrogen cylinders 8 reduces the difficulty of installing the hydrogen cylinders 8.

[0111] The embodiment of the present invention further proposes a working method based on the above self-produced water humidification air-cooled fuel cell system, and the working method is as follows:

[0112] The fan 1 delivers external air into the air-cooled fuel cell stack 3 from the air inlet of the air-cooled fuel cell stack 3, and after reaction occurs, the external air is discharged from the air outlet of the air-cooled fuel cell stack 3;

[0113] At the same time, the liquid hydrogen provided by the hydrogen source enters the liquid hydrogen vaporizer 5 after passing through the high-pressure valve assembly 6, and the liquid hydrogen is vaporized in the liquid hydrogen vaporizer 5, and then enters the air-cooled fuel cell 3 from the anode inlet of the air-cooled fuel cell 3, and after the reaction occurs, is discharged from the anode outlet of the air-cooled fuel cell 3;

[0114] The high-temperature and high-humidity air leaving the stack contacts the heat exchange fins of the liquid hydrogen vaporizer 5, and exchanges heat with the hydrogen in the liquid hydrogen vaporizer 5. The temperature of the high-temperature and high-humidity air leaving the stack drops rapidly, and the gaseous water therein condenses into liquid water. The condensed liquid water flows into the water reservoir 11 under the action of gravity. At the same time, the hydrogen in the liquid hydrogen vaporizer 5 absorbs a large amount of heat in the air leaving the air-cooled stack 3, and the hydrogen temperature rises before entering the air-cooled stack 3, so as to avoid the hydrogen temperature being too low to affect the temperature distribution in the air-cooled stack 3.

[0115] The water pump 10 pumps water out of the water reservoir 11 and supplies it to the ultrasonic atomizer 2. The high-frequency vibration of the ceramic pieces in the ultrasonic atomizer 2 breaks up the liquid water into water mist, which humidifies the air flow blown in by the fan 1 before entering the air-cooled fuel cell stack 3.

[0116] The anode of the air-cooled fuel cell stack 3 adopts a closed-mouth periodic purge mode, which greatly increases the portability of the system and reduces the system cost. The liquid water periodically purged from the anode flows into the water reservoir 11 through a pipe connected to the anode outlet.

[0117] The heat exchange fins of the liquid hydrogen vaporizer 5 are selected according to the required heat exchange efficiency of the fins of the self-produced water humidification air-cooled fuel cell system. The specific calculation method of the required heat exchange efficiency η of the fins is as follows:

[0118] η=P_exc / (P_out+P_va)*2*100% (1);

[0119] Wherein, P_exc is the heat that the fin needs to exchange per unit time; P_out is the total heat of all substances in the battery stack per unit time; and P_va is the hydrogen cooling power provided by liquid hydrogen.

[0120] The heat P_exc that the fin needs to exchange per unit time is calculated as follows:

[0121] P_exc = P_out - P_eve (2);

[0122] Where P_out is the total heat of all substances in the battery stack per unit time; P_eve is the heat discharged from the entire system per unit time;

[0123] The hydrogen cooling power P_va provided by liquid hydrogen is calculated as follows:

[0124] P_va=m_H 2 *k (3);

[0125] In the formula, m_H 2 is the actual hydrogen consumption mass flow rate; k is the cold energy of liquid hydrogen vaporization 4386.19 J / g;

[0126] The total heat P_out of all substances in the battery stack per unit time is calculated as follows:

[0127] P_out=m_O 2 _out*T_out*C_O 2 +m_N 2 _out*T_out*C_N 2 +m_W_out_g*

[0128] T_out*C_W_g+(m_W_out-m_W_out_g)*T_out*C_W_l(4);

[0129] Where, T_out is the temperature of the gas and liquid leaving the stack, which is usually a controlled parameter of the stack and a known quantity; m_O 2 _out is the mass flow rate of oxygen out of the reactor; m_N 2 _out is the mass flow rate of nitrogen leaving the reactor; m_W_out is the mass flow rate of water leaving the reactor; m_W_out_g is the mass flow rate of water vapor leaving the reactor; C_O 2 is the specific heat capacity of oxygen; C_N 2 is the specific heat capacity of nitrogen; C_W_g is the specific heat capacity of water vapor, and C_W_l is the specific heat capacity of liquid water;

[0130] The mass flow rate of water vapor out of the reactor m_W_out_g is calculated as follows:

[0131] m_W_out_g=(m_ 2 _out+m_N 2 _out)*P_sat_out / (P_outlet-P_sat_out) (5);

[0132] Where P_outlet is the gas pressure out of the stack, which is usually a controlled parameter of the stack and a known quantity; P_sat_out is the saturated vapor pressure of the gas out of the stack, which is calculated as follows:

[0133] P_sat_out=exp(23.196-3816.44 / (T_out-46.13)) (6);

[0134] Where, T_out is the temperature of the gas and liquid out of the stack, which is usually a controlled parameter of the stack and a known quantity;

[0135] The heat P_eve discharged from the entire system per unit time is calculated as follows:

[0136] P_eve=m_O 2 _out*T_eve*C_O 2 +m_N 2 _out*T_eve*C_N 2 +m_W_eve_g*T_eve

[0137] *C_W_g+m_W_add*T_eve*C_W_l(7);

[0138] Where, T_eve is the temperature of the gas leaving the reactor after heat exchange; m_O 2 _out is the mass flow rate of oxygen out of the reactor; m_N 2 _out is the mass flow rate of nitrogen out of the stack; m_W_eve_g is the permissible amount of water escape; m_W_add is the mass flow rate of water added by the ultrasonic humidifier;

[0139] Oxygen mass flow rate into the reactor m_O 2 _in is calculated as follows:

[0140] m_O 2 _in=m_Air*23 / 98; (8);

[0141] In the formula, m_Air is the actual air consumption mass flow rate, 23 / 98 is the ratio of oxygen mass in the air to air mass;

[0142] Nitrogen mass flow rate into the reactor m_N 2 _in is calculated as follows:

[0143] m_N 2 _in=m_Air*75 / 98; (9);

[0144] In the formula, 75 / 98 is the ratio of the mass of nitrogen in the air to the mass of air;

[0145] The mass flow rate of water in the air entering the reactor, m_W_in, is calculated as follows:

[0146] m_W_in=P_W*(m_ 2 _in+m_N 2 _in) / (P_atm-P_W) (10);

[0147] Where, P_atm is the standard atmospheric pressure; P_W is the partial pressure of water vapor in the air;

[0148] The mass flow rate of water added by the ultrasonic humidifier, m_W_add, is calculated as follows:

[0149] m_W_add=m_W_inall-m_W_in (11);

[0150] Where m_W_inall is the mass flow rate of water in the gas entering the reactor after humidification, which is calculated as follows:

[0151] m_W_inall=(P_inlet-P_sat_inlet*RH) / P_sat_inlet*RH*(m_O 2 _in+m_N 2 _in) (12);

[0153] Wherein, RH is the target humidity of the anode, which is 60%; P_inlet is the pressure of the gas entering the stack after humidification, which is usually a known quantity; P_sat_inlet is the saturated vapor pressure of the gas entering the stack; m_O2_in is the mass flow rate of oxygen entering the stack; m_N2_in is the mass flow rate of nitrogen entering the stack;

[0154] P_sat_inlet=exp(23.196-3816.44 / (T_inlet-46.13)) (13);

[0155] Where T_inlet is the inlet temperature, which is usually a controlled known quantity.

[0156] Oxygen mass flow rate out of the reactor m_O 2 _out is calculated as follows:

[0157] m_O 2 _out=m_O 2 _in-m_Air_th*21% (14);

[0158] In the formula, m_O 2 _in is the mass flow rate of oxygen entering the reactor; m_Air_th is the theoretical air consumption mass flow rate;

[0159] Nitrogen mass flow rate out of the reactor m_N2 _out is calculated as follows:

[0160] m_N 2 _out=m_N 2 _in (15);

[0161] In the formula, m_N 2 _in is the mass flow rate of nitrogen entering the reactor;

[0162] The permissible water escape m_W_eve_g is calculated as follows:

[0163] m_W_eve_g=m_W_out-m_W_add=m_W_in+m_W (16);

[0164] Where, m_W_out is the mass flow rate of water leaving the reactor; m_W_req is the mass flow rate of liquid water required by the system; m_W is the mass flow rate of liquid water actually generated;

[0165] The mass flow rate of outflowing water m_W_out is calculated as follows:

[0166] m_W_out=m_W_in+m_W_add+m_W (17);

[0167] Where m_W_in is the mass flow rate of water in the air entering the reactor; m_W_add is the mass flow rate of water added by the ultrasonic humidifier; and m_W is the mass flow rate of water actually generated.

[0168] The actual mass flow rate of water generated, m_W, is calculated as follows:

[0169] m_W=m_H 2 _th / M_H 2 *M_W (18);

[0170] In the formula, M_H 2 is the molar mass of hydrogen; M_W is the molar mass of water;

[0171] The water vapor partial pressure P_W in air is calculated as follows:

[0172] P_W=P_sat_anb*RH_anb (19);

[0173] In the formula, RH_anb is the ambient humidity, taking the local average humidity; P_sat_anb is the saturated vapor pressure of water vapor in the ambient air, calculated as follows:

[0174] P_sat_anb=exp(23.196-3816.44 / (T_anb-46.13)) (20);

[0175] In the formula, T_anb is the ambient temperature, taking the local average temperature;

[0176] If the system is to operate continuously and stably, the condensed water must meet the following conditions: the mass flow rate of liquid water m_W_req required by the system is equal to the mass flow rate of water added by the ultrasonic humidifier m_W_add, that is:

[0177] m_W_req = m_W_add (21);

[0178] The temperature T_eve of the gas leaving the reactor after heat exchange is calculated as follows:

[0179] T_eve=3816.44 / (23.196-ln(P_sat_eve_g))+46.13 (22);

[0180] Where P_sat_eve_g is the saturated vapor pressure of the gas that eventually leaves the system, calculated as follows:

[0181] P_sat_eve_g=P_atm*m_W_out_g / (m_O 2 _out+m_N 2 _out+m_W_out_g) (twenty three);

[0183] Where P_atm is the standard atmospheric pressure; m_W_out_g is the mass flow rate of water vapor leaving the reactor; m_O 2 _out is the mass flow rate of oxygen out of the reactor; m_N 2 _out is the mass flow rate of nitrogen out of the pile;

[0184] The actual air consumption mass flow m_Air is calculated as follows:

[0185] m_Air=m_Air_th*β (24);

[0186] Where β is the air metering ratio, usually 2; m_Air_th is the theoretical air consumption mass flow rate, calculated as follows:

[0187] m_Air_th=I*n*M_Air / f / a (25);

[0188] Where, I is the working current; n is the number of cells in the battery stack; f is the Faraday constant; M_Air is the molar mass of air; a is the charge number per unit oxygen molecule, a=4;

[0189] Actual hydrogen consumption mass flow m_H 2 The calculation is as follows:

[0190] m_H 2=m_H 2 _th / α (26);

[0191] Where α is the fuel efficiency, which is usually taken as 0.96 based on experience; m_H 2 _th is the theoretical hydrogen consumption mass flow rate; it is calculated as follows:

[0192] m_H 2 _th = I*n / f (27);

[0193] Where I is the operating current, n is the number of cells in the battery stack, and f is the Faraday constant.

[0194] By setting heat exchange fins on the liquid hydrogen vaporizer, the heat exchange fins are used to exchange heat between the high-temperature and high-humidity air leaving the stack and the hydrogen in the liquid hydrogen vaporizer. The cold energy of the liquid hydrogen condenses the liquid water in the air leaving the stack, and the liquid water is collected in the water reservoir as the water source of the ultrasonic atomizer, so as to realize the cathode self-produced water humidification of the air-cooled stack without adding a complex humidification system; at the same time, the hydrogen in the liquid hydrogen vaporizer absorbs a large amount of heat from the air leaving the air-cooled stack, and the hydrogen temperature rises before entering the air-cooled stack, so as to avoid the temperature distribution in the air-cooled stack being affected by the low hydrogen temperature. The required heat exchange efficiency of the fins is calculated by calculation method, and the heat exchange fins suitable for the system are accurately selected according to the required heat exchange efficiency of the fins, so as to improve the heat exchange efficiency of the system and maximize energy utilization.

[0195] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-produced water humidification air-cooled fuel cell system, characterized in that: The system includes a hydrogen gas path subsystem, an air path subsystem and an air-cooled fuel cell stack; The hydrogen gas circuit subsystem includes a hydrogen source, a high-pressure valve assembly, a liquid hydrogen vaporizer and an anode tail exhaust valve. The liquid hydrogen provided by the hydrogen source passes through the high-pressure valve assembly and the liquid hydrogen vaporizer in sequence, and then enters the anode inlet of the air-cooled fuel cell to participate in the reaction. The anode tail exhaust valve is provided on the pipeline connected to the anode outlet of the air-cooled fuel cell. The air path subsystem includes a fan, an ultrasonic atomizer, a water pump, and a water reservoir. The fan is arranged outside the air inlet of the air-cooled fuel cell stack and is used to send external air into the air-cooled fuel cell stack. The ultrasonic atomizer is arranged between the fan and the air inlet of the air-cooled fuel cell stack and is used to humidify the air entering the stack. The liquid hydrogen vaporizer is arranged outside the air outlet of the air-cooled fuel cell stack. The water reservoir is arranged below the liquid hydrogen vaporizer and the water pump is used to pump water out of the water reservoir and supply it to the ultrasonic atomizer.

2. The self-produced water humidified air-cooled fuel cell system according to claim 1, characterized in that: The ultrasonic atomizer is provided with heat exchange fins, which are used to exchange heat between the high-temperature and high-humidity air leaving the stack and the hydrogen in the liquid hydrogen vaporizer; the pipeline connected to the anode outlet of the air-cooled fuel cell stack extends to the water reservoir.

3. The self-produced water humidified air-cooled fuel cell system according to claim 2, characterized in that: The hydrogen source in the hydrogen circuit subsystem is configured as a mode in which multiple hydrogen cylinders are connected in series, and a solenoid valve is provided outside the outlet of each hydrogen cylinder, and the solenoid valve is used to control whether the corresponding hydrogen cylinder is connected to the hydrogen circuit subsystem; the self-produced water humidification air-cooled fuel cell system also includes a hydrogen cylinder cabinet, and a plurality of independent accommodating cavities are horizontally arranged in the hydrogen cylinder cabinet, and the accommodating cavities are matched with the shape of the hydrogen cylinders to facilitate the storage of hydrogen cylinders.

4. A working method of a self-produced water humidified air-cooled fuel cell system based on any one of claims 1 to 3, characterized in that: The working method is as follows: The fan delivers external air into the air-cooled fuel cell stack from the air inlet of the air-cooled fuel cell stack, and after the reaction occurs, the air is discharged from the air outlet of the air-cooled fuel cell stack; At the same time, the liquid hydrogen provided by the hydrogen source enters the liquid hydrogen vaporizer after passing through the high-pressure valve assembly, and the liquid hydrogen vaporizes in the liquid hydrogen vaporizer, and then enters the air-cooled fuel cell from the anode inlet of the air-cooled fuel cell, and after the reaction occurs, it is discharged from the anode outlet of the air-cooled fuel cell; The high-temperature and high-humidity air leaving the stack contacts the heat exchange fins of the liquid hydrogen vaporizer and exchanges heat with the hydrogen in the liquid hydrogen vaporizer. The temperature of the high-temperature and high-humidity air leaving the stack drops rapidly, and the gaseous water in the air condenses into liquid water. The condensed liquid water flows into the water reservoir under the action of gravity. At the same time, the hydrogen in the liquid hydrogen vaporizer absorbs a large amount of heat from the air leaving the air-cooled stack. The hydrogen temperature rises before entering the air-cooled stack, which prevents the hydrogen temperature from being too low and affecting the temperature distribution in the air-cooled stack. The water pump pumps the water out of the reservoir and supplies it to the ultrasonic atomizer. The high-frequency vibration of the ceramic pieces in the ultrasonic atomizer breaks up the liquid water into water mist, which humidifies the air flow blown in by the fan before entering the air-cooled fuel cell stack.

5. The operating method of the self-produced water humidification air-cooled fuel cell system according to claim 4, characterized in that: The heat exchange fins of the liquid hydrogen vaporizer are selected according to the required heat exchange efficiency of the fins of the self-produced water humidification air-cooled fuel cell system. The specific calculation method of the required heat exchange efficiency η of the fins is as follows: η=P_exc / (P_out+P_va)*2*100% (1); Where, P_exc is the heat that the fin needs to exchange per unit time; P_out is the total heat of all substances in the battery stack per unit time; P_va is the hydrogen cooling power provided by liquid hydrogen; The heat P_exc that the fin needs to exchange per unit time is calculated as follows: P_exc = P_out - P_eve (2); Where P_out is the total heat of all substances in the battery stack per unit time; P_eve is the heat discharged from the entire system per unit time; The hydrogen cooling power P_va provided by liquid hydrogen is calculated as follows: P_va=m_H2*k (3); In the formula, m_H2 is the actual mass flow rate of hydrogen consumption; k is the cold energy of liquid hydrogen vaporization 4386.19 J / g; The total heat P_out of all substances in the battery stack per unit time is calculated as follows: P_out=m_O2_out*T_out*C_O2+m_N2_out*T_out*C_N2+m_W_out_g* T_out*C_W_g+(m_W_out-m_W_out_g)*T_out*C_W_l(4); In the formula, T_out is the temperature of the gas and liquid leaving the stack, which is usually a controlled parameter of the stack and a known quantity; m_O2_out is the mass flow rate of oxygen leaving the stack; m_N2_out is the mass flow rate of nitrogen leaving the stack; m_W_out is the mass flow rate of water leaving the stack; m_W_out_g is the mass flow rate of water vapor leaving the stack; C_O2 is the specific heat capacity of oxygen; C_N2 is the specific heat capacity of nitrogen; C_W_g is the specific heat capacity of water vapor, and C_W_l is the specific heat capacity of liquid water.

6. The operating method of the self-produced water humidification air-cooled fuel cell system according to claim 5, characterized in that: The mass flow rate of water vapor out of the reactor m_W_out_g is calculated as follows: m_W_out_g=(m_O2_out+m_N2_out)*P_sat_out / (P_outlet-P_sat_out) (5); Where P_outlet is the gas pressure out of the stack, which is usually a controlled parameter of the stack and a known quantity; P_sat_out is the saturated vapor pressure of the gas out of the stack, which is calculated as follows: P_sat_out=exp(23.196-3816.44 / (T_out-46.13)) (6); Where, T_out is the temperature of the gas and liquid out of the stack, which is usually a controlled parameter of the stack and a known quantity; The heat P_eve discharged from the entire system per unit time is calculated as follows: P_eve=m_O2_out*T_eve*C_O2+m_N2_out*T_eve*C_N2+m_W_eve_g*T_eve *C_W_g+m_W_add*T_eve*C_W_l(7); Wherein, T_eve is the temperature of the gas leaving the stack after heat exchange is completed; m_O2_out is the mass flow rate of oxygen leaving the stack; m_N2_out is the mass flow rate of nitrogen leaving the stack; m_W_eve_g is the allowed water escape amount; and m_W_add is the mass flow rate of water added through the ultrasonic humidifier.

7. The operating method of the self-produced water humidification air-cooled fuel cell system according to claim 6, characterized in that: The mass flow rate of oxygen entering the reactor m_O2_in is calculated as follows: m_O2_in=m_Air*23 / 98; (8); In the formula, m_Air is the actual air consumption mass flow rate, 23 / 98 is the ratio of oxygen mass in the air to air mass; The mass flow rate of nitrogen entering the reactor, m_N2_in, is calculated as follows: m_N2_in=m_Air*75 / 98; (9); In the formula, 75 / 98 is the ratio of the mass of nitrogen in the air to the mass of air; The mass flow rate of water in the air entering the reactor, m_W_in, is calculated as follows: m_W_in=P_W*(m_O2_in+m_N2_in) / (P_atm-P_W) (10); Where, P_atm is the standard atmospheric pressure; P_W is the partial pressure of water vapor in the air; The mass flow rate of water added by the ultrasonic humidifier, m_W_add, is calculated as follows: m_W_add=m_W_inall-m_W_in (11); Where m_W_inall is the mass flow rate of water in the gas entering the reactor after humidification, which is calculated as follows: m_W_inall=(P_inlet-P_sat_inlet*RH) / P_sat_inlet*RH*(m_O2_in+m_N2_in)(12); Wherein, RH is the target humidity of the anode, which is 60%; P_inlet is the pressure of the gas entering the stack after humidification, which is usually a known quantity; P_sat_inlet is the saturated vapor pressure of the gas entering the stack; m_O2_in is the mass flow rate of oxygen entering the stack; m_N2_in is the mass flow rate of nitrogen entering the stack; P_sat_inlet=exp(23.196-3816.44 / (T_inlet-46.13)) (13); Where T_inlet is the inlet temperature, which is usually a controlled known quantity.

8. The operating method of the self-produced water humidification air-cooled fuel cell system according to claim 7, characterized in that: The mass flow rate of oxygen out of the reactor m_O2_out is calculated as follows: m_O2_out=m_O2_in-m_Air_th*21% (14); Wherein, m_O2_in is the mass flow rate of oxygen entering the reactor; m_Air_th is the theoretical air consumption mass flow rate; The mass flow rate of nitrogen out of the reactor, m_N2_out, is calculated as follows: m_N2_out = m_N2_in (15); Where, m_N2_in is the mass flow rate of nitrogen entering the reactor; The permissible water escape m_W_eve_g is calculated as follows: m_W_eve_g=m_W_out-m_W_add=m_W_in+m_W (16); Where, m_W_out is the mass flow rate of water leaving the reactor; m_W_req is the mass flow rate of liquid water required by the system; m_W is the mass flow rate of liquid water actually generated; The mass flow rate of outflowing water m_W_out is calculated as follows: m_W_out=m_W_in+m_W_add+m_W (17); Where m_W_in is the mass flow rate of water in the air entering the reactor; m_W_add is the mass flow rate of water added by the ultrasonic humidifier; and m_W is the mass flow rate of water actually generated.

9. The operating method of the self-produced water humidification air-cooled fuel cell system according to claim 8, characterized in that: The actual mass flow rate of water generated, m_W, is calculated as follows: m_W=m_H2_th / M_H2*M_W (18); Where, M_H2 is the molar mass of hydrogen; M_W is the molar mass of water; The water vapor partial pressure P_W in air is calculated as follows: P_W=P_sat_anb*RH_anb (19); In the formula, RH_anb is the ambient humidity, taking the local average humidity; P_sat_anb is the saturated vapor pressure of water vapor in the ambient air, calculated as follows: P_sat_anb=exp(23.196-3816.44 / (T_anb-46.13)) (20); In the formula, T_anb is the ambient temperature, taking the local average temperature; If the system is to operate continuously and stably, the condensed water must meet the following conditions: the mass flow rate of liquid water m_W_req required by the system is equal to the mass flow rate of water added by the ultrasonic humidifier m_W_add, that is: m_W_req=m_W_add (21).

10. The operating method of the self-produced water humidification air-cooled fuel cell system according to claim 9, characterized in that: The temperature T_eve of the gas leaving the reactor after heat exchange is calculated as follows: T_eve=3816.44 / (23.196-ln(P_sat_eve_g))+46.13 (22); Where P_sat_eve_g is the saturated vapor pressure of the gas that eventually leaves the system, calculated as follows: P_sat_eve_g=P_atm*m_W_out_g / (m_O2_out+m_N2_out+m_W_out_g)(23); Wherein, P_atm is standard atmospheric pressure; m_W_out_g is the mass flow rate of water vapor out of the reactor; m_O2_out is the mass flow rate of oxygen out of the reactor; m_N2_out is the mass flow rate of nitrogen out of the reactor; The actual air consumption mass flow m_Air is calculated as follows: m_Air=m_Air_th*β (24); Where β is the air metering ratio, usually 2; m_Air_th is the theoretical air consumption mass flow rate, calculated as follows: m_Air_th=I*n*M_Air / f / a (25); Where, I is the working current; n is the number of cells in the battery stack; f is the Faraday constant; M_Air is the molar mass of air; a is the charge number per unit oxygen molecule, a=4; The actual hydrogen consumption mass flow m_H2 is calculated as follows: m_H2 = m_H2_th / α (26); Where α is the fuel efficiency, which is usually taken as 0.96 based on experience; m_H2_th is the theoretical hydrogen consumption mass flow rate; the calculation is as follows: m_H2_th=I*n / f (27); Where I is the operating current, n is the number of cells in the battery stack, and f is the Faraday constant.

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