Proton exchange membrane fuel cell coupled high temperature heat pump system and capacity design method

Abstract

The application discloses a kind of proton exchange membrane fuel cell coupling high temperature heat pump system, including hydrogen pressure reducing valve, ejector, proton exchange membrane fuel cell, hydrogen water segregator, air filter, air compressor, intercooler, humidifier, first evaporator, air water segregator, cooling water tank, cooling water pump, cooling water heat exchanger, air cooler, second evaporator, heat pump compressor, heat pump condenser, heat pump throttle valve, first water supplement pump, water collector, heat storage tank, second water supplement pump, three-way valve, third water supplement pump, flash decompression valve, flash tank and steam compressor.The application can fully recover the latent heat of proton exchange membrane fuel cell cathode exhaust, effectively improve the efficiency of proton exchange membrane fuel cell, realize efficient recovery and cascade utilization of fuel cell waste heat, meet the industrial steam and power load demand.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fuel cell cogeneration, and particularly relates to a proton exchange membrane fuel cell coupled high-temperature heat pump system and a capacity design method. BACKGROUND

[0002] The proton exchange membrane fuel cell cogeneration system is one of the key research directions of distributed energy supply, and can realize energy cascade utilization due to its high efficiency and greenness. The proton exchange membrane fuel cell cogeneration system supplies domestic hot water and heating to users by recovering the waste heat of the fuel cell on the basis of the traditional proton exchange membrane fuel cell system.

[0003] The proton exchange membrane fuel cell cogeneration system is a kind of fuel cell waste heat recovery technology, and its working principle is as follows: hydrogen at the anode of the fuel cell and oxygen in the air at the cathode undergo an electrochemical reaction at the cathode side to generate electricity and heat. Part of the heat generated by the fuel cell is taken out by the gas at the anode and the cathode, and the remaining part is absorbed by the fuel cell cooling system. The proton exchange membrane fuel cell cogeneration system supplies users with the heat generated by the fuel cell reaction through the waste heat recovery technology, thereby realizing the combined supply of electricity and heat. At present, the proton exchange membrane fuel cell cogeneration system only considers the waste heat recovery of the fuel cell cooling system. The cathode exhaust gas temperature of the proton exchange membrane fuel cell is 60-80℃, and the water vapor in the exhaust gas is usually saturated or supersaturated. The latent heat of the high-temperature, high-humidity and high-flow exhaust gas of the high-power proton exchange membrane fuel cell is high, and direct discharge causes waste of heat. The proton exchange membrane fuel cell cogeneration system mainly faces household or community applications, and can only supply low-grade heat products. The proton exchange membrane fuel cell cogeneration system currently cannot meet the demand for industrial steam. SUMMARY

[0004] The purpose of the present application is to provide a proton exchange membrane fuel cell coupled high-temperature heat pump system and a capacity design method. The system can effectively recover the waste heat of the proton exchange membrane fuel cell cooling system and the latent heat of the exhaust gas, meet the demand for steam and electricity in the industrial field, realize the supply of high-grade heat products, and broaden the application field of fuel cells.

[0005] The proton exchange membrane fuel cell coupled high-temperature heat pump system of the present application comprises a hydrogen pressure reducing valve, an ejector, a proton exchange membrane fuel cell, a hydrogen water separator, an air filter, an air compressor, a middle cooler, a humidifier, a first evaporator, an air water separator, a cooling water tank, a cooling water pump, a cooling water heat exchanger, an air cooler, a second evaporator, a heat pump compressor, a heat pump condenser, a heat pump throttling valve, a first water supplement pump, a water collector, a heat storage tank, a second water supplement pump, a three-way valve, a third water supplement pump, a flash decompression valve, a flash tank and a steam compressor.

[0006] The ejector, hydrogen water separator, first evaporator, air water separator, cooling water heat exchanger, second evaporator, heat pump condenser, water collector, heat storage tank, three-way valve and flash tank all contain two channels; the proton exchange membrane fuel cell contains three channels;

[0007] The hydrogen pressure reducing valve, the first channel of the ejector, the first channel of the proton exchange membrane fuel cell, the first channel of the hydrogen water separator and the second channel of the ejector are sequentially connected by a hydrogen pipeline to form a hydrogen circulation loop.

[0008] The air filter, air compressor, intercooler, humidifier, second channel of the proton exchange membrane fuel cell, first channel of the first evaporator, first channel of the air water separator are sequentially connected by an air pipeline to form an air loop.

[0009] The third channel of the proton exchange membrane fuel cell, cooling water tank, cooling water pump, first channel of the cooling water heat exchanger, air cooler are sequentially connected by a cooling water pipeline to form a cooling water circulation loop.

[0010] The second channel of the first evaporator, second channel of the second evaporator, heat pump compressor, second channel of the heat pump condenser, heat pump throttling valve are sequentially connected by a heat pump working medium pipeline to form a heat pump circulation loop.

[0011] The first water supplement pump, second channel of the cooling water heat exchanger, first channel of the heat storage tank, second water supplement pump, first channel of the three-way valve, third water supplement pump, first channel of the heat pump condenser, flash decompression valve, first channel of the flash tank, steam compressor are sequentially connected by a water-steam pipeline to form a water-steam loop.

[0012] The second channel of the hydrogen water separator, first channel of the water collector, second channel of the heat storage tank are sequentially connected by a water-steam pipeline to form a water-steam loop, the second channel of the air water separator, second channel of the water collector, second channel of the heat storage tank are sequentially connected by a water-steam pipeline to form a water-steam loop, the second channel of the flash tank, second channel of the three-way valve are sequentially connected by a water-steam pipeline to form a water-steam loop.

[0013] Further, the heat pump throttling valve is an expansion valve; the intercooler is an air cooler, which uses air convection for heat conduction; the humidifier is an external film humidifier, which is humidified by the gas discharged by the first evaporator; the air cooler is an active air cooler, which adjusts the fan speed to regulate the real-time temperature of the cooling water; the water collector is an anode and cathode water collection device; the heat required by the second evaporator is provided by an external heat source, which can be provided by industrial waste heat or photovoltaic-photothermal; the first evaporator is a double-sided phase change heat transfer enhancer; the steam compressor is an internal main machine liquid jet cooling.

[0014] The application also discloses a capacity design method of a proton exchange membrane fuel cell coupled high-temperature heat pump system.

[0015] Step 1, setting system constraints, including hydrogen supply boundary conditions and target power and steam product demand conditions, environmental working condition conditions, fuel cell coupled high-temperature heat pump flash evaporation system configuration;

[0016] Step 2, setting the proton exchange membrane fuel cell capacity, fuel cell operating temperature, inlet humidity, heat pump supercooling degree, hydrogen and oxygen excess coefficient, evaporator outlet refrigerant temperature, superheat degree, compressor isentropic efficiency and mechanical efficiency; setting the fuel cell electric efficiency, heat pump COP, system thermal efficiency;

[0017] Step 3, based on the set conditions, sequentially calculating the hydrogen supply amount, oxygen supply amount, water supply amount, cooling system heat load, evaporator heat load, condenser heat load, cathode and anode water recovery amount, heat storage tank inlet flow, air compressor power consumption, pump power consumption, heat pump compressor power consumption, steam compressor power consumption, system net output electric power, steam production rate, fuel cell electric efficiency, heat pump COP, system thermal efficiency;

[0018] Step 4, judging whether the hydrogen supply meets the hydrogen demand, if not, adjusting the rated capacity of the fuel cell, starting from the current value and reducing a step size, and continuing to operate; if the hydrogen supply meets the demand, assuming the second evaporator capacity, calculating the air consumption and cooling system heat load, and calculating the heat pump, flash evaporation and heat storage tank capacity; thereby obtaining the heat storage tank hot water flow, system net output electric power, steam production rate, fuel cell electric efficiency, heat pump COP and system thermal efficiency;

[0019] Step 5, judging whether the steam production rate meets the steam load demand, if not, adjusting the second evaporator assumed capacity and recalculating, if the steam load demand is met, judging whether the system net output electric power meets the electric load demand, if not, adjusting the fuel cell capacity and continuing to calculate, if the electric load demand is met, judging whether the fuel cell electric efficiency is greater than a preset value, if not, adjusting the fuel cell capacity and continuing to calculate, if the preset value is met, judging whether the heat pump COP is greater than a preset value, if not, adjusting the second evaporator capacity and continuing to calculate, if the preset value is met, judging whether the system thermal efficiency is greater than a preset value, if not, adjusting the entire fuel cell capacity and continuing to calculate, if the preset value is met, ending the entire operation; and finally outputting the results of the corresponding system optimal operating state of all iterative operation steps.

[0020] Furthermore, in step 1, the hydrogen supply boundary condition is the maximum hydrogen input flow rate, and the target electricity and steam product demand conditions include the system net electrical output power, steam flow rate, steam temperature, and steam pressure; the environmental operating conditions include ambient temperature and ambient humidity; and the fuel cell coupled high-temperature heat pump flash system configuration includes the layout position and form of the heat pump evaporator.

[0021] Furthermore, in step 1, the system constraints include:

[0022] P i,min ≤P i,t ≤P i,max

[0023] n H2,min ≤n H2,t ≤n H2,max

[0024] T PEM,min ≤T PEM,t ≤T PEM,max

[0025] η PEM,min ≤η PEM,t ≤η PEM,max

[0026] Where, P i,min and P i,max are the minimum and maximum output power of each component, i is proton exchange membrane fuel cell, heat pump, flash tank, steam compressor, P i,t is the current power of each device, n H2,min and n H2,max are the minimum and maximum supply volumes of hydrogen, n H2,t is the actual supply of hydrogen, T PEM,min and T PEM,max are the lowest and highest operating temperatures of proton exchange membrane fuel cells, T PEM,t is the current operating temperature of the proton exchange membrane fuel cell, η PEM,min and η PEM,max are the lowest and highest electrical power of proton exchange membrane fuel cells, η PEM,t is the current electrical power of the proton exchange membrane fuel cell.

[0027] Furthermore, in step 4, the hydrogen demand is the hydrogen flow rate of the system's proton exchange membrane fuel cell anode.

[0028] Further, in step 5, the steam load demand is a user steam load demand, the electric load demand is a user electric load demand; the fuel cell electric efficiency comprises a fuel cell electric efficiency lower limit and a fuel cell electric efficiency upper limit; the heat pump COP comprises a heat pump COP lower limit and a heat pump COP upper limit; and the system thermal efficiency comprises a system thermal efficiency lower limit and a system thermal efficiency upper limit.

[0029] Advantages: Compared with the prior art, the present application has the following remarkable advantages:

[0030] (1) The proton exchange membrane fuel cell coupled high-temperature heat pump steam-electric cogeneration system according to the present application recovers waste heat of a proton exchange membrane fuel cell cooling system through a water vapor loop, realizes efficient heat storage, recovers latent heat of cathode exhaust of the proton exchange membrane fuel cell cooling system through a heat pump circulation loop, further heats hot water in a heat storage tank, realizes high-grade heat supply, recovers and utilizes water resources through a hydrogen water separator, an air water separator and a water collector, preheats heat pump working medium through a first evaporator, fully recovers latent heat of the cathode exhaust, supplies heat required for evaporation of the heat pump working medium through a second evaporator, improves adaptability of the heat pump, realizes efficient regulation and control of electric power and steam, and realizes efficient and green production of high-temperature water vapor through a flash cycle and steam compression.

[0031] (2) The present application can fully recover latent heat of cathode exhaust of a proton exchange membrane fuel cell, effectively improve efficiency of the proton exchange membrane fuel cell, realize efficient recovery and cascade utilization of waste heat of the fuel cell, and meet industrial steam and electric load demand. The method of the present application can complete capacity configuration and operation regulation and control of each device of a proton exchange membrane fuel cell coupled high-temperature heat pump steam-electric cogeneration system under conditions of a determined hydrogen supply boundary, target electric power and steam demand, environmental conditions and structural characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Fig. 1 is a structural schematic diagram of a fuel cell coupled high-temperature heat pump steam-electric cogeneration system according to an embodiment of the present application.

[0033] In the figure, the hydrogen pressure reducing valve 1, the ejector 2, the proton exchange membrane fuel cell 3, the hydrogen water separator 4, the air filter 5, the air compressor 6, the intercooler 7, the humidifier 8, the first evaporator 9, the air water separator 10, the cooling water tank 11, the cooling water pump 12, the cooling water heat exchanger 13, the air cooler 14, the second evaporator 15, the heat pump compressor 16, the heat pump condenser 17, the heat pump throttle valve 18, the first water supplement pump 19, the water collector 20, the heat storage tank 21, the second water supplement pump 22, the three-way valve 23, the third water supplement pump 24, the flash decompression valve 25, the flash tank 26 and the steam compressor 27.

[0034] Figure 2Flow chart of capacity configuration method of the present application;

[0035] Figure 3 Flow chart of operation method of the fuel cell coupled high-temperature heat pump steam power cogeneration system under the conditions of system capacity and user power, steam demand, environment and structure characteristics of the present application;

[0036] Figure 4 Figure of variation of net power output and steam production rate with fuel cell operation DETAILED DESCRIPTION

[0037] The technical solutions of the present application are further described below in combination with the drawings.

[0038] As shown in Figure 1 the fuel cell coupled high-temperature heat pump steam power cogeneration system of the embodiment of the present application comprises a hydrogen pressure reducing valve 1, an ejector 2, a proton exchange membrane fuel cell 3, a hydrogen water separator 4, an air filter 5, an air compressor 6, an intercooler 7, a humidifier 8, a first evaporator 9, an air water separator 10, a cooling water tank 11, a cooling water pump 12, a cooling water heat exchanger 13, an air cooler 14, a second evaporator 15, a heat pump compressor 16, a heat pump condenser 17, a heat pump throttling valve 18, a first water supplement pump 19, a water collector 20, a heat storage tank 21, a second water supplement pump 22, a three-way valve 23, a third water supplement pump 24, a flash pressure reducing valve 25, a flash tank 26, and a steam compressor 27.

[0039] The ejector 2, hydrogen water separator 3, first evaporator 9, air water separator 10, cooling water heat exchanger 13, second evaporator 15, heat pump condenser 17, water collector 20, heat storage tank 21, three-way valve 23 and flash tank 26 each include two channels, and the proton exchange membrane fuel cell 3 includes three channels. Among them, the hydrogen pressure reducing valve 1, the first channel 2 of the ejector, the first channel of the proton exchange membrane fuel cell 3, the first channel of the hydrogen water separator 4 and the second channel of the ejector 2 are connected in sequence through a hydrogen pipeline to form a hydrogen circulation loop; the air filter 5, the air compressor 6, the intercooler 7, the humidifier 8, the second channel of the proton exchange membrane fuel cell 3, the first channel of the first evaporator 9, and the first channel of the air water separator 10 are connected in sequence through an air pipeline to form an air circuit; the third channel of the proton exchange membrane fuel cell 3, the cooling water tank 11, the cooling water pump 12, the first channel of the cooling water heat exchanger 13, and the air cooler 14 are connected in sequence through a cooling water pipeline to form a cooling water circulation loop; the second channel of the first evaporator 9, the second channel of the second evaporator 15, the heat pump compressor 16, the second channel of the heat pump condenser 17, the heat pump throttle Valve 18 is connected sequentially through the heat pump working fluid pipeline to form a heat pump circulation loop. The first feed water pump 19, the second channel of the cooling water heat exchanger 13, the first channel of the thermal storage tank 21, the second feed water pump 22, the first channel of the three-way valve 23, the third feed water pump 24, the first channel of the heat pump condenser 17, the flash pressure reducing valve 25, the first channel of the flash tank 26, and the steam compressor 27 are connected sequentially through the water vapor pipeline to form a water vapor circuit. The second channel of the hydrogen water separator 4, the first channel of the water collector 20, and the second channel of the thermal storage tank 21 are connected sequentially through the water vapor pipeline to form a water vapor circuit. The second channel of the air water separator 10, the second channel of the water collector 20, and the second channel of the thermal storage tank 21 are connected sequentially through the water vapor pipeline to form a water vapor circuit. The second channel of the flash tank 26 and the second channel of the three-way valve 23 are connected sequentially through the water vapor pipeline to form a water vapor circuit. The lines in the figure represent the following: solid lines represent various fluid pipelines, and dashed lines represent electricity.

[0040] In one embodiment of the present invention, the throttling device 3 may be an expansion valve. The expansion valve can not only realize the throttling function, but also throttle the high-temperature and high-pressure liquid refrigerant into a low-temperature and low-pressure mist-like hydraulic refrigerant, creating conditions for the evaporation of the refrigerant.

[0041] The following combination Figure 1 The illustrated embodiment illustrates the operating principle of a fuel cell coupled high-temperature heat pump steam and power cogeneration system.

[0042] like Figure 1As shown, in the hydrogen circulation loop, the outlet of the hydrogen pressure reducing valve 1 is connected to the inlet of the first channel of the ejector 2 through a hydrogen pipeline, the inlet of the first channel of the proton exchange membrane fuel cell 3 is connected to the outlet of the first channel of the ejector 2, the inlet of the first channel of the hydrogen water separator 4 is connected to the outlet of the first channel of the proton exchange membrane fuel cell 3, and the outlet of the first channel of the hydrogen water separator 4 is connected to the inlet of the second channel of the ejector 2.

[0043] In the air circulation loop, the outlet of the air filter 5 is connected to the inlet of the air compressor 6, the inlet of the intercooler 7 is connected to the outlet of the air compressor 6, the inlet of the humidifier 8 is connected to the outlet of the intercooler 7, the inlet of the second channel of the proton exchange membrane fuel cell 3 is connected to the outlet of the humidifier 8, the inlet of the first channel of the first evaporator 9 is connected to the outlet of the second channel of the proton exchange membrane fuel cell 3, the inlet of the first channel of the air water separator 10 is connected to the outlet of the first channel of the first evaporator 9, and the outlet of the first channel of the air water separator 10 is discharged to the environment through an air pipeline.

[0044] In the heat pump circulation loop, the outlet of the second channel of the first evaporator 9 is connected to the inlet of the second channel of the second evaporator 15, the outlet of the second channel of the second evaporator 15 is connected to the inlet of the heat pump compressor 16, the outlet of the heat pump compressor 16 is connected to the inlet of the second channel of the heat pump condenser 17, the outlet of the second channel of the heat pump condenser 17 is connected to the inlet of the heat pump throttle valve 18, and the outlet of the heat pump throttle valve 18 is connected to the inlet of the second channel of the first evaporator 9.

[0045] In the water vapor loop, the outlet of the first water supplement pump 19 is connected to the inlet of the second channel of the cooling water heat exchanger 13, the outlet of the second channel of the cooling water heat exchanger 13 is connected to the inlet of the first channel of the heat storage tank 21, the outlet of the first channel of the heat storage tank 21 is connected to the inlet of the second water supplement pump 22, the outlet of the second water supplement pump 22 is connected to the inlet of the first channel of the three-way valve 23, the outlet of the first channel of the three-way valve 23 is connected to the inlet of the third water supplement pump 24, the outlet of the third water supplement pump 24 is connected to the inlet of the first channel of the heat pump condenser 17, the outlet of the first channel of the heat pump condenser 17 is connected to the inlet of the flash pressure reducing valve 25, the outlet of the flash pressure reducing valve 25 is connected to the inlet of the first channel of the flash tank 26, the outlet of the first channel of the flash tank 26 is connected to the inlet of the steam compressor 27, the outlet of the steam compressor 27 is connected to an external steam source; the outlet of the second channel of the hydrogen water separator 4 is connected to the inlet of the first channel of the water collector 20, and the outlet of the first channel is connected to the inlet of the second channel of the heat storage tank 21; the outlet of the second channel of the air water separator 10 is connected to the inlet of the second channel of the water collector 20, and the outlet of the second channel of the water collector 20 is connected to the inlet of the second channel of the heat storage tank 21; the outlet of the second channel of the flash tank 26 is connected to the inlet of the second channel of the three-way valve 23.

[0046] The fuel cell coupled high-temperature heat pump steam power cogeneration system works as follows: hydrogen flows in the hydrogen circulation system, as shown in FIG. 1, and air flows in the air circulation system, as shown in FIG. 2. Figure 1As shown, the hydrogen output by the pressure reducing valve 1 enters the ejector 2 and mixes with the unreacted hydrogen to enter the proton exchange membrane fuel cell 3 for electrochemical reaction. The unreacted hydrogen enters the hydrogen water separator 4 for gas-water separation, and the unconsumed hydrogen enters the ejector 4 to continue the reaction, and the separated water enters the water collector 20.

[0047] When the fuel cell coupled high temperature heat pump steam power cogeneration system is working, the air flows in the air circuit, such as Figure 1 As shown, the air output from the air filter 5 is compressed by the air compressor 6, enters the intercooler 7 and the humidifier 8 for cooling and humidification, and then enters the proton exchange membrane fuel cell 3 to participate in the electrochemical reaction. The high-temperature and high-humidity gas after the reaction enters the first evaporator 9 to provide heat for the heat pump. The cooled air is separated into gas and liquid by the air water separator 10, and the air is discharged into the environment. The condensed water discharged from the gas water separator 10 enters the water collector 20.

[0048] When the fuel cell is coupled with a high-temperature heat pump steam power cogeneration system, the refrigerant circulates in the refrigerant circulation loop. Figure 1 As shown, the high-temperature, superheated gaseous refrigerant compressed in the heat pump compressor 16 enters the heat pump condenser 17 through the refrigerant pipeline for condensation and liquefaction. The cooled high-pressure, medium-temperature liquid refrigerant enters the throttling device 18 through the refrigerant pipeline for further cooling and decompression until the refrigerant temperature reaches the desired evaporation temperature. The low-pressure, low-temperature refrigerant reaching the desired evaporation temperature enters the first evaporator 9 through the refrigerant pipeline, where it absorbs heat from the humid air at the outlet of the proton exchange membrane fuel cell 3. The heated refrigerant enters the second evaporator 15 through the refrigerant pipeline, where its temperature is further increased. The gaseous refrigerant enters the compressor 16 again through the refrigerant pipeline for pressurization and temperature increase, thereby achieving the circulation of the refrigerant in the refrigerant circulation loop.

[0049] When the fuel cell coupled high temperature heat pump steam power cogeneration system is working, water flows in the water-steam loop, such as Figure 1 As shown, the make-up water output by the first make-up water pump 19 enters the cooling water heat exchanger 13 to absorb heat and is then stored in the heat storage tank; the condensed water from the hydrogen water separator 4 and the air water separator 10 enters the heat storage tank through the water collector 20; the hot water in the heat storage tank is pressurized by the second make-up water pump 22 and mixed with the flash liquid water through the three-way valve 23 to enter the heat pump condenser 17 to be heated into high-temperature hot water, and the high-temperature hot water is reduced in pressure by the flash pressure reducing valve 25 and enters the flash tank 26 for vaporization, and the water vapor enters the steam compressor 27 for pressurization and temperature increase and is then provided to users; the flash liquid water enters the three-way valve 23 and is mixed with the make-up water for cyclic use.

[0050] See also Figure 2 The present invention provides a method for designing the capacity configuration of each device in a power and steam cogeneration system under a determined hydrogen supply boundary and target power and steam demand conditions, environmental conditions, and structural characteristics, comprising the following steps:

[0051] The initial stage obtains the boundary conditions of hydrogen supply (maximum hydrogen input flow rate), target power (net system electric output power), and steam demand (steam flow rate, steam temperature, steam pressure), environmental conditions (ambient temperature and ambient humidity), fuel cell coupled high-temperature heat pump flash evaporation system configuration (heat pump evaporator arrangement position and form), and the like.

[0052] First, the proton exchange membrane fuel cell capacity, fuel cell operating temperature, inlet humidity, heat pump subcooling degree, hydrogen and oxygen excess coefficients, evaporator outlet refrigerant temperature, superheat degree, compressor isentropic efficiency, and mechanical efficiency are input. Second, the fuel cell electric efficiency (fuel cell electric efficiency lower limit, fuel cell electric efficiency upper limit), heat pump COP (heat pump COP lower limit, heat pump COP upper limit), and system thermal efficiency (system thermal efficiency lower limit, system thermal efficiency upper limit) are input. Based on the set conditions, the hydrogen supply, oxygen supply, water supply, cooling system heat load, evaporator heat load, condenser heat load, cathode and anode water recovery, heat storage tank inlet flow rate, air compressor power consumption, pump power consumption, heat pump compressor power consumption, steam compressor power consumption, net system output electric power, steam production rate, fuel cell electric efficiency, heat pump COP, and system thermal efficiency are sequentially calculated.

[0053] It is determined whether the hydrogen supply meets the hydrogen demand (proton exchange membrane fuel cell anode hydrogen flow rate). If not, the fuel cell rated capacity is adjusted by decreasing the current value by one step, and the calculation is continued. If the hydrogen supply meets the demand, the second evaporator capacity is assumed, the air consumption and cooling system heat load are calculated, and the heat pump, flash evaporation, and heat storage tank capacity are calculated. The heat storage tank hot water flow rate, net system output electric power, steam production rate, fuel cell electric efficiency, heat pump COP, and system thermal efficiency are obtained. It is determined whether the steam production rate meets the steam load demand (user steam load demand). If not, the second evaporator assumed capacity is adjusted, and the calculation is recalculated. If the steam load demand is met, it is determined whether the net system output electric power meets the electric load demand (user electric power load demand). If not, the fuel cell capacity is adjusted, and the calculation is continued. If the electric load demand is met, it is determined whether the fuel cell electric efficiency is greater than a preset value. If not, the fuel cell capacity is adjusted, and the calculation is continued. If the preset value is met, it is determined whether the heat pump COP is greater than a preset value. If not, the second evaporator capacity is adjusted, and the calculation is continued. If the preset value is met, it is determined whether the system thermal efficiency is greater than a preset value. If not, the entire fuel cell capacity is adjusted, and the calculation is continued. If the preset value is met, the entire calculation is ended. The final output result is the device capacity corresponding to the optimal system operating state in all iteration calculation steps.

[0054] In the embodiment of the present application, the system net electric output power and steam production quantity and other parameters are calculated through a proton exchange membrane fuel cell model, a heat pump model and a flash steam model, and then the system capacity configuration optimization is realized by adjusting the fuel cell and the second evaporator capacity. The device models include a proton exchange membrane fuel cell model, a compressor model, a pump model, a condenser model, an expansion valve model, an evaporator model, a flash model, a humidifier model and a heat exchanger model.

[0055] Referring to Figure 3 The present application provides a fuel cell coupled high-temperature heat pump steam electric power co-production system operation method under the conditions of determined system capacity and user electric power and steam demand, environmental working conditions and structural characteristics, which comprises the following steps:

[0056] Firstly, the electric power and steam demand (user electric power load demand and steam load demand) are input, the system constraint conditions (the highest and lowest power constraints of the fuel cell, the heat pump and the flash tank device, the highest and lowest input quantity constraints of hydrogen, the highest and lowest temperature constraints of the fuel cell operation, the highest and lowest electric efficiency constraints of the fuel cell) and the load balance conditions (system electric power balance and heat balance) are set, the system operation parameter package environmental temperature and environmental humidity, fuel cell operation temperature, pressure, humidity, hydrogen and oxygen excess coefficient, heat pump evaporation temperature and condensation temperature, heat pump compressor operation pressure, throttling pressure, steam compressor operation pressure, cooling water circulation temperature, compressor isentropic efficiency and mechanical efficiency and the like are set; the fuel cell output electric power and system pump and compressor power consumption are calculated to obtain the fuel cell heat production; the second evaporator heat load is given, and the system steam production quantity is calculated. It is judged whether the steam production rate meets the steam load demand. If not, the second evaporator hypothetical capacity is adjusted, and the calculation is re-performed. If the steam load demand is met, the whole operation is ended. The final output result is the system operation condition meeting the user electric power and steam load demand.

[0057] In the embodiment of the present application, the proton exchange membrane fuel cell output power is determined by the user electric power load demand, the fuel cell heat production condition is calculated, the system net electric output power and heat pump first evaporator heat load and other parameters are obtained, and then the system steam production quantity is matched with the user steam load demand by adjusting the second evaporator heat load. The device models include a proton exchange membrane fuel cell model, a compressor model, a pump model, a condenser model, an expansion valve model, an evaporator model, a flash model, a humidifier model and a heat exchanger model.

[0058] The system constraints are:

[0059]

[0060] In the formula, P i,min and P i,maxare the minimum and maximum output power of each component, i is proton exchange membrane fuel cell, heat pump, flash tank, steam compressor, P i,t is the current power of each device. H2,min and n H2,max are the minimum and maximum supply volumes of hydrogen, n H2,t is the actual supply of hydrogen, T PEM,min and T PEM,max are the lowest and highest operating temperatures of proton exchange membrane fuel cells, T PEM,t is the current operating temperature of the proton exchange membrane fuel cell, η PEM,min and η PEM,max are the lowest and highest electrical power of proton exchange membrane fuel cells, η PEM,t is the current electrical power of the proton exchange membrane fuel cell.

[0061] The electrical load balance condition is:

[0062]

[0063] Where, P PEM,t is the electrical output power of the proton exchange membrane fuel cell, kW; is the total pump power consumption of the system, kW, is the total compressor power consumption of the system, P load,t Indicates the user's power load demand.

[0064] The heat load balance condition is:

[0065] Q PEM,t =Q PEM,cooling,t +Q PEM,gas,t (3)

[0066] Where Q PEM,t is the total heat generated by the proton exchange membrane fuel cell, Q PEM,cooling,t Q is the heat absorbed by the cooling system of the proton exchange membrane fuel cell. PEM,gas,t The heat absorbed by the proton exchange membrane fuel cell gas.

[0067] Q steam,t =Q load,t (4)

[0068] Where Q steam,t is the total heat of steam product, Q load,t The steam load demand of the user.

[0069] The purpose of arranging the second evaporator 15 between the first evaporator 9 and the heat pump compressor 16 is that the proton exchange membrane fuel cell 3 can adjust the electric output power in real time considering the change of the user electric load, and therefore the heat generated by the proton exchange membrane fuel cell 3 changes in real time. The heat load of the first evaporator 9 changes in real time with the electric load, and the heat pump operation is greatly affected by evaporation. In particular, when the proton exchange membrane fuel cell 3 operates in a low load condition, the first evaporator 9 can not meet the requirement of minimum input heat, and the steam production is greatly affected by the change of the electric load. By increasing the second evaporator 15, the heat pump operation can be adjusted in real time. On the one hand, when the proton exchange membrane fuel cell 3 operates in a low load condition, the heat required for evaporation of the working medium can be effectively supplemented to ensure the stable operation of the heat pump. On the other hand, the arrangement of the second evaporator 15 can maximize the recovery of the latent heat of the gas of the proton exchange membrane fuel cell 3, and realize the decoupling of the energy of the heat pump operation and the fuel cell operation.

[0070] Under the determined hydrogen supply boundary and target electric power, steam demand conditions, environmental conditions and structural characteristics, a capacity configuration calculation example is carried out. The input conditions are shown in Table 1.

[0071] Based on the above input parameters, the structure of the proton exchange membrane fuel cell coupled high-temperature heat pump steam electric power cogeneration system as shown in Figure 1 and the capacity configuration method as shown in Figure 2 are adopted, and the system capacity configuration is carried out according to the user electric power and steam load data of different scenes. In order to have higher economy while meeting the requirements of capacity configuration, a design margin ε is introduced in this embodiment to ensure that the configuration result will not exceed the scene demand too much. Under the premise that the calculation result meets the load and performance parameter requirements, the proportion of the calculation result to the set value is calculated, and the calculation formula is as follows:

[0072]

[0073] wherein Y i,cal represents the calculation result, i represents the steam load, the electric load, the fuel cell electric efficiency, the heat pump COP and the system thermal efficiency, and Y i,set represents the set value. If the calculation design margin ε is less than the set design margin ε0, it indicates that the configuration result meets the demand while there is no capacity remaining. The different scene parameter settings are shown in Table 2.

[0074] The configuration result is shown in Table 3. The steam load has a greater influence on the overall configuration result of the system. When the electric load is unchanged, the increase of the steam load will still lead to the increase of the fuel cell capacity, which is mainly caused by the increase of the system parasitic loss due to the increase of the steam production, so that the fuel cell configuration capacity increases.

[0075] Table 1 Input conditions

[0076]

[0077] Table 2 Parameter settings for different scenarios

[0078]

[0079] Table 3 Configuration results

[0080]

[0081] Under the condition that the ambient temperature and relative humidity are 25℃ and 50% respectively, the present invention carries out a system operation control calculation example. The operating temperature of the proton exchange membrane fuel cell is 75℃, the operating humidity is 70%, and the rated power is 127kW. Figure 1 The proton exchange membrane fuel cell coupled with a high-temperature heat pump steam power cogeneration system shown in the figure is calculated as follows: Figure 4 The net electrical output power and steam production rate are shown as they vary with fuel cell operation. Figure 4 It can be clearly seen that the PEMFC current density is 1.0A / cm 2 The proton exchange membrane fuel cell-coupled high-temperature heat pump steam and power cogeneration system achieves a maximum net power output of 90kW. Steam production increases with current density, reaching a maximum steam production rate of 63kg / h at the system's highest net power output. This steam production is the steam production without the second evaporator. According to the capacity configuration and operating method of the present invention, adding the second evaporator maintains the system's maximum steam production rate of 80kg / h, unaffected by fuel cell operation.

[0082] According to the proton exchange membrane fuel cell coupled high-temperature heat pump steam power cogeneration system of the present invention, heat gradient recovery and joint supply of electricity and steam are achieved by constructing a heat pump circulation loop and a water vapor loop; the utilization rate of hydrogen chemical energy can be improved by setting a first evaporator 9 to recover the cathode exhaust latent heat of the proton exchange membrane fuel cell 3; the heat pump circulation loop realizes the decoupling of waste heat recovery of the proton exchange membrane fuel cell 3 and heat pump circulation energy by adding a second evaporator 15, which can meet the subsequent efficient and stable supply of steam and real-time regulation needs; the water vapor loop is heated in stages through the cooling water heat exchanger 13 and the heat pump condenser 17, fully recovering different forms of waste heat of the proton exchange membrane fuel cell 3 and realizing high-temperature hot water supply; high-temperature steam is produced by flash compression, which can reduce carbon emissions in the steam production process and realize green and efficient supply of high-temperature steam.

[0083] The embodiment of the present application provides a method for configuring the capacity of each device of a combined power and steam supply system under the conditions of a determined hydrogen supply boundary and target power and steam demand, environment working condition and structural feature, and based on the result of the configuration, a method for operating a fuel cell coupled high-temperature heat pump combined power and steam supply system is provided.

[0084] In the present application, unless specifically defined and limited otherwise, the terms "mounting", "connection", "linking", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0085] In the present application, unless specifically defined and limited otherwise, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature can be directly above or obliquely above the second feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature can be directly below or obliquely below the second feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0086] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples, without contradiction.

[0087] It should be understood that parts of the present application can be realized by hardware, software, firmware or a combination thereof. In the above-described embodiments, a plurality of steps or methods can be realized by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if realized by hardware, and as in another embodiment, it can be realized by any one or a combination of the following technologies known in the art: discrete logic circuit with logic gate circuit for implementing logic functions on data signals, application specific integrated circuit with suitable combination logic gate circuit, programmable gate array (PGA), field programmable gate array (FPGA) and the like.

[0088] Those skilled in the art of the present technology can understand that all or part of the steps carried out by the above-mentioned embodiment method can be completed by a program instructing the relevant hardware, and the program can be stored in a computer readable storage medium. The program, when executed, includes one of the steps of the method embodiment or a combination thereof.

[0089] In addition, each functional unit in each embodiment of the present application can be integrated into one processing module, or each unit can exist physically, or two or more units can be integrated into one module. The above integrated module can be realized in the form of hardware or in the form of software functional module. The integrated module, if realized in the form of software functional module and sold or used as an independent product, can also be stored in a computer readable storage medium.

[0090] Although the embodiments of the present application have been shown and described above, it should be understood that the above-described embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A proton exchange membrane fuel cell coupled with a high-temperature heat pump system, characterized in that: It includes a hydrogen pressure reducing valve, an ejector, a proton exchange membrane fuel cell, a hydrogen water separator, an air filter, an air compressor, an intercooler, a humidifier, a first evaporator, an air water separator, a cooling water tank, a cooling water pump, a cooling water heat exchanger, an air cooler, a second evaporator, a heat pump compressor, a heat pump condenser, a heat pump throttle valve, a first feed water pump, a water collector, a heat storage tank, a second feed water pump, a three-way valve, a third feed water pump, a flash pressure reducing valve, a flash tank and a steam compressor; The ejector, hydrogen water separator, first evaporator, air water separator, cooling water heat exchanger, second evaporator, heat pump condenser, water collector, heat storage tank, three-way valve and flash tank each contain two channels; the proton exchange membrane fuel cell contains three channels; The hydrogen pressure reducing valve, the first channel of the ejector, the first channel of the proton exchange membrane fuel cell, the first channel of the hydrogen water separator and the second channel of the ejector are sequentially connected through a hydrogen pipeline to form a hydrogen circulation loop; The air filter, the air compressor, the intercooler, the humidifier, the second channel of the proton exchange membrane fuel cell, the first channel of the first evaporator, and the first channel of the air water separator are sequentially connected through an air pipeline to form an air circuit; The third channel of the proton exchange membrane fuel cell, the cooling water tank, the cooling water pump, the first channel of the cooling water heat exchanger, and the air cooler are sequentially connected through a cooling water pipeline to form a cooling water circulation loop; The second channel of the first evaporator, the second channel of the second evaporator, the heat pump compressor, the second channel of the heat pump condenser, and the heat pump throttle valve are sequentially connected through a heat pump working medium pipeline to form a heat pump circulation loop; The first make-up water pump, the second channel of the cooling water heat exchanger, the first channel of the heat storage tank, the second make-up water pump, the first channel of the three-way valve, the third make-up water pump, the first channel of the heat pump condenser, the flash pressure reducing valve, the first channel of the flash tank, and the steam compressor are sequentially connected through a water vapor pipeline to form a water vapor circuit; The second channel of the hydrogen water separator, the first channel of the water collector, and the second channel of the heat storage tank are connected in sequence through a water vapor pipeline to form a water vapor circuit. The second channel of the air water separator, the second channel of the water collector, and the second channel of the heat storage tank are connected in sequence through a water vapor pipeline to form a water vapor circuit. The second channel of the flash tank and the second channel of the three-way valve are connected in sequence through a water vapor pipeline to form a water vapor circuit.

2. A proton exchange membrane fuel cell coupled high-temperature heat pump system according to claim 1, characterized in that: The heat pump throttle valve is an expansion valve; the intercooler is an air cooler that uses air convection for heat conduction; the humidifier is an external film humidifier that humidifies the gas discharged from the first evaporator; the air cooler is an active air cooler that controls the temperature of the cooling water in real time by adjusting the fan speed; the water collector is an anode and cathode water collection device; the heat required for the second evaporator is provided by an external heat source, which can be provided by industrial waste heat or photovoltaic thermal energy; the first evaporator is a double-sided phase change, enhanced heat transfer type heat exchanger; the steam compressor is internal host liquid spray cooling.

3. A capacity design method for a proton exchange membrane fuel cell coupled high-temperature heat pump system according to claim 1, characterized in that: The steps include: Step 1: Set system constraints, including hydrogen supply boundary conditions, target electricity and steam product requirements, environmental operating conditions, and the configuration of the fuel cell-coupled high-temperature heat pump flash evaporation system. Step 2: Set the proton exchange membrane fuel cell capacity, fuel cell operating temperature, inlet humidity, heat pump subcooling, hydrogen and oxygen excess coefficients, evaporator outlet refrigerant temperature, superheat, compressor isentropic efficiency and mechanical efficiency; set the fuel cell electrical efficiency, heat pump COP, and system thermal efficiency; Step 3: Based on the set conditions, the hydrogen supply volume, oxygen supply volume, water supply volume, cooling system heat load, evaporator heat load, condenser heat load, cathode and anode water recovery volume, thermal storage tank inlet flow, air compressor power consumption, pump power consumption, heat pump compressor power consumption, steam compressor power consumption, system net output power, steam production rate, fuel cell electrical efficiency, heat pump COP, and system thermal efficiency are calculated in sequence; Step 4: Determine whether the hydrogen supply meets the hydrogen demand. If not, adjust the fuel cell rated capacity based on feedback, reducing it by one step from the current value, and continue the calculation. If the hydrogen supply meets the demand, assume the capacity of the second evaporator, calculate the air consumption and the heat load of the cooling system, and use this to calculate the capacity of the heat pump, flash evaporation, and thermal storage tank. The hot water flow rate of the thermal storage tank, the net output power of the system, the steam production rate, the fuel cell electrical efficiency, the heat pump COP, and the system thermal efficiency are thus obtained. Step 5. Determine whether the steam production rate meets the steam load requirement. If not, adjust the assumed capacity of the second evaporator and recalculate. If the steam load requirement is met, determine whether the system net output electric power meets the electric load requirement. If not, adjust the fuel cell capacity and continue the calculation. If the electric load requirement is met, determine whether the fuel cell electric efficiency is greater than a preset value. If not, adjust the fuel cell capacity and continue the calculation. If the preset value is met, determine whether the heat pump COP is greater than a preset value. If not, adjust the second evaporator capacity and continue the calculation. If the preset value is met, determine whether the system thermal efficiency is greater than the preset value. If not, adjust the entire fuel cell capacity and continue the calculation. If the preset value is met, end the entire calculation. The final output result is the capacity of each device in the optimal operating state of the system corresponding to all iterative calculation steps.

4. The capacity design method according to claim 3, characterized in that: In step 1, the hydrogen supply boundary condition is the maximum hydrogen input flow rate, and the target power and steam product demand conditions include the system net electrical output power, steam flow rate, steam temperature, and steam pressure; the environmental operating conditions include ambient temperature and ambient humidity; and the fuel cell coupled high-temperature heat pump flash system configuration includes the layout position and form of the heat pump evaporator.

5. The capacity design method according to claim 3, characterized in that: In step 1, the system constraints include: P i,min ≤P i,t ≤P i,max T PEM,min ≤T PEM,t ≤T PEM,max or PEM,min ≤η PEM,t ≤η PEM,max Where, P i,min and P i,max are the minimum and maximum output power of each component, i is proton exchange membrane fuel cell, heat pump, flash tank, steam compressor, P i,t is the current power of each device, n H2,min and n H2,max are the minimum and maximum supply volumes of hydrogen, n H2,t is the actual supply of hydrogen, T PEM,min and T PEM,max are the lowest and highest operating temperatures of proton exchange membrane fuel cells, T PEM,t is the current operating temperature of the proton exchange membrane fuel cell, η PEM,min and η PEM,max are the lowest and highest electrical power of proton exchange membrane fuel cells, η PEM,t is the current electrical power of the proton exchange membrane fuel cell.

6. The capacity design method according to claim 3, characterized in that: In step 4, the hydrogen demand is the hydrogen flow rate of the system's proton exchange membrane fuel cell anode.

7. The capacity design method according to claim 3, characterized in that: In step 5, the steam load demand is the user's steam load demand, the electric load demand is the user's electric load demand; the fuel cell electrical efficiency includes a fuel cell electrical efficiency lower limit and a fuel cell electrical efficiency upper limit; the heat pump COP includes a heat pump COP lower limit and a heat pump COP upper limit; The system thermal efficiency includes a system thermal efficiency lower limit and a system thermal efficiency upper limit.

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