WO2016087845A1 - Système de pile à combustible - Google Patents

Système de pile à combustible Download PDF

Info

Publication number
WO2016087845A1
WO2016087845A1 PCT/GB2015/053672 GB2015053672W WO2016087845A1 WO 2016087845 A1 WO2016087845 A1 WO 2016087845A1 GB 2015053672 W GB2015053672 W GB 2015053672W WO 2016087845 A1 WO2016087845 A1 WO 2016087845A1
Authority
WO
WIPO (PCT)
Prior art keywords
water
fuel cell
outlet
cell system
rate
Prior art date
Application number
PCT/GB2015/053672
Other languages
English (en)
Inventor
Pratap RAMA
Shahin MOGHIMI
Ben BURSLEM
Paul Adcock
Chris GURNEY
Original Assignee
Intelligent Energy Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Intelligent Energy Limited filed Critical Intelligent Energy Limited
Publication of WO2016087845A1 publication Critical patent/WO2016087845A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04828—Humidity; Water content
    • H01M8/04835—Humidity; Water content of fuel cell reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04768—Pressure; Flow of the coolant
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
    • H01M8/04059—Evaporative processes for the cooling of a fuel cell
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
    • H01M8/04126—Humidifying
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
    • H01M8/04126—Humidifying
    • H01M8/04134—Humidifying by coolants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
    • H01M8/04156—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying with product water removal
    • H01M8/04164—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying with product water removal by condensers, gas-liquid separators or filters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04291—Arrangements for managing water in solid electrolyte fuel cell systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/04492—Humidity; Ambient humidity; Water content
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04753—Pressure; Flow of fuel cell reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04761—Pressure; Flow of fuel cell exhausts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04858—Electric variables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04858—Electric variables
    • H01M8/04895—Current
    • H01M8/0491—Current of fuel cell stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2250/00—Fuel cells for particular applications; Specific features of fuel cell system
    • H01M2250/20—Fuel cells in motive systems, e.g. vehicle, ship, plane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/04537—Electric variables
    • H01M8/04574—Current
    • H01M8/04589—Current of fuel cell stacks
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the invention relates to the field of fuel cell systems, and in particular although not exclusively, to methods of operating evaporatively cooled fuel cell (ECFC) and liquid cooled fuel cell (LCFC) systems.
  • ECFC evaporatively cooled fuel cell
  • LCFC liquid cooled fuel cell
  • a LCFC system comprises a fuel cell stack with a cathode flow path and an anode flow path, each having an inlet and an outlet. Water is retrieved from the cathode outlet and fed back to the cathode inlet in order to provide hydration of the stack and so improve stack performance.
  • a separate water cooling loop is provided in order to cool the stack.
  • An ECFC system comprises a fuel cell stack with a cathode flow path and an anode flow path, each having an inlet and an outlet. Water is retrieved from the cathode outlet and fed back to the cathode inlet in order to provide cooling, as well as hydration. That is, the reactant flow path forms part of a water cooling circuit of the system and so a separate water cooling loop that is provided in addition to the cathode and anode fluid flow paths may therefore not be required.
  • a "water balance" is achieved when the rate of liquid water delivered to the fuel cell stack for evaporative cooling is equal to the amount of water retrieved from the cathode outlet through condensation and water separation.
  • Water recovery occurs when the rate of liquid water delivered to the fuel cell stack for evaporative cooling is less than the rate of water retrieval from the cathode outlet. Conversely, “water loss” occurs when the rate of liquid water delivered to the fuel cell stack for evaporative cooling is greater than the rate of water retrieval from the cathode outlet. If the system cannot maintain water balance or cannot recover from a water loss condition by means of water recovery then the fuel cell system can become dehydrated. Depending on operating conditions, loss of water in a fuel cell system may occur at a very low rate over time. Alternatively, temporary off-design peak power operation can result in rapid water loss in the system and a considerable amount of water can be lost in a short space of time. In both cases, loss of water, if not recovered, threatens the continued efficient operation of the fuel cell system.
  • a method of operating a fuel cell system comprising:
  • the method may ensure robustness and sustainability of operation of the fuel cell system under extreme operating conditions.
  • the parasitic losses afforded in regaining water balance using this method may be acceptable in many applications.
  • the operational parameters and input data used by the method may be available in some conventional fuel cell systems and so additional components, such as sensors and actuators, may not be necessary in order to implement the method in such systems.
  • the water circuit may be a stack water coolant circuit, in an evaporatively cooled fuel cell system for example.
  • the water circuit may be a humidification water circuit, in a liquid cooled fuel cell system for example.
  • the method may comprise controlling the one or more parameters in order to decrease a rate of water loss, or stop water loss, if the comparison indicates that the liquid level is decreasing at a rate that is greater than or equal to the threshold.
  • the method may comprise controlling the one or more parameters in order to increase the rate of water retrieval if the comparison indicates that the liquid level is decreasing at a rate that is greater than or equal to the threshold. Increasing the rate of water retrieval may have the effect of decreasing the rate of water loss.
  • the method may comprise controlling the one or more parameters in order to increase the rate of water retrieval if the comparison indicates that the liquid level is equal to or lower than the threshold.
  • the fuel cell system may comprise a first heat exchanger with a first side and a second side.
  • the water circuit may comprise the first side of the heat exchanger.
  • the first side of the heat exchanger may be in fluid communication with the outlet of the reactant flow path.
  • a coolant fluid in the second side of the first heat exchanger may be a liquid, such as a glycerol/water mixture, or a gas, such as air.
  • the one or more parameters may include one or more of:
  • a coolant flow rate such as the rate of coolant flow to, or through, the second side of the first heat exchanger
  • the threshold may be a lower threshold.
  • the method may comprise one or more of the sequential steps:
  • the threshold may be an upper threshold.
  • the method may comprise one or more of the sequential steps:
  • the method may comprise comparing the value related to the liquid level with both the lower and upper thresholds.
  • the method may comprise controlling the one or more parameters in accordance with both comparisons.
  • the method may comprise comparing the value related to the liquid level with the upper threshold after comparing the value related to the liquid level with the lower threshold.
  • Changing the value for example by increasing or decreasing it, may comprise changing the value by a pre-set percentage, such as 5 %, or by a pre-set absolute value.
  • a value may be changed from or to a normal level that is suitable for a normal state of operation.
  • the water circuit may comprise a water tank configured to receive water recovered from the outlet.
  • the liquid level may be determined using a liquid level sensor located associated with the water tank.
  • the liquid level sensor may be located within the water tank or outside the water tank.
  • the value related to the liquid level may be determined in accordance with an ambient temperature of the fuel cell system.
  • the water circuit may be a water cooling circuit.
  • the method may comprise directly injecting cooling water recovered from the outlet into the inlet such that evaporation of water in the reactant flow path is the principal source of cooling for the fuel cell stack.
  • a computer program configured to perform the method described above.
  • a fuel cell system comprising:
  • a stack water circuit configured to recover water from the outlet and directly inject water into the inlet
  • a controller configured to perform the method of any preceding claim.
  • a computer program configured to perform the method of any preceding claim.
  • Figure 1 illustrates a schematic of an evaporatively cooled fuel cell system
  • Figure 2a illustrates a method of operating a fuel cell system such as that described with reference to Figure 1 ;
  • Figure 2b illustrates another method of operating a fuel cell system such as that described with reference to Figure 1 ;
  • Figure 2c illustrates a further method of operating a fuel cell system such as that described with reference to Figure 1.
  • Examples in this disclosure relate to a method for maintaining water balance or providing water recovery in an evaporatively cooled fuel cell (ECFC) system, particularly during operation under hot ambient conditions when the temperature difference between the cooling fluid (atmospheric air) and the fuel cell cathode exit temperature is at its operational minimum.
  • the amount of latent heat extracted from the cathode exhaust flow may be increased by manipulating the system parameters.
  • the parameters used are primarily the coolant flow rate, cathode back pressure, air flow rate, and parameters associated with stack power management.
  • Figure 1 illustrates an evaporatively cooled fuel cell (ECFC) system 100 for use in a vehicle.
  • ECFC evaporatively cooled fuel cell
  • the fuel cell system 100 comprises a fuel cell stack 102, a fuel cell stack water circuit, an optional vehicle cooling circuit and a controller 104.
  • the configuration of the fuel cell system 100 is described below with reference to Figure 1 and the operation of the controller 104 is described further below in relation to Figures 2a to 2c.
  • the fuel cell stack 102 has a cathode flow path and an anode flow path, which are both examples of reactant flow paths within the fuel cell stack 102.
  • the anode flow path has an anode inlet 110 and an anode outlet 112. Hydrogen is provided from a hydrogen source 12 to the anode inlet during operation of the fuel cell stack 102.
  • the flow of exhaust hydrogen 16 from the stack is controlled by a valve 114 provided on an anode exhaust line 118.
  • the cathode flow path has a cathode inlet 106 and a cathode outlet 108.
  • Air is provided from an air blower 120 to the cathode inlet 106 via a cathode inlet line 122 during operation of the fuel cell stack 102.
  • a cathode inlet pressure sensor 124 and a cathode inlet temperature sensor 126 are provided on the cathode inlet line 122.
  • Cathode exhaust fluid from the cathode outlet 108 is provided to a first side (or "hot" side) of a first heat exchanger 128, which may be provided by a liquid/liquid condenser, via a cathode exhaust line 130.
  • a cathode oxygen level sensor 132, or lambda sensor, a cathode exhaust temperature sensor 134 and a cathode exhaust pressure sensor 136 are provided on the cathode exhaust line 130 for providing respective sensor signals.
  • a water separator 146 is configured to receive cooled cathode exhaust fluid from the first side of the first heat exchanger 128 and separate the fluid into liquid water and a gas/vapour. Preferably, the efficiency of the water separator is optimised.
  • the venting to atmosphere of the gas/vapour in the cathode exhaust fluid from the water separator 146 is controlled by a cathode exhaust value 148.
  • the liquid water from the water separator 146 is provided to a water tank 150.
  • the water tank 150 includes a number of optional sensors such as a temperature sensor 153, conductivity sensor 155 and a liquid level sensor 152.
  • the liquid level sensor 152 is configured to provide an indication of the liquid level in the water tank 150.
  • a delivery water pump 154 is provided on return water line 156 between the water tank 150 and the cathode inlet 106.
  • the water circuit for the fuel cell stack 102 is configured to recover and return water from the cathode outlet 108 of the fuel cell stack 102 and directly inject water into the cathode inlet 106 in order to cool the stack, as well as increase stack hydration.
  • the fluid flow rate at the inlet therefore comprise an oxidant flow rate in accordance with the air flow from the blower 120 and a coolant flow rate in accordance with a state of the delivery water pump 154.
  • the water circuit in this example comprises a closed loop of connected components in the sequence:
  • the water return line which provides the water to the cathode inlet 106.
  • the optional vehicle cooling circuit comprises a coolant pump 138 for pumping a mix of coolant, such as glycol/water solution, between a second heat exchanger 140, a second side (or "cold" side) of the first heat exchanger 128 and the rest of the vehicle system 142.
  • the second heat exchanger 140 is air cooled by a fan 144 in this example.
  • the heat transfer coefficient of the coolant and the log mean temperature difference both increase with increased coolant flow through the second side of the heat exchanger.
  • the first heat exchanger 128 may be provided as a thermal module, for example a thermal module of the vehicle.
  • the preferred the first heat exchanger 128 is configured to transfer heat form the cathode exhaust on its first side to the fluid on its second side without an intermediate loop.
  • the heat exchanger may be a single stage heat exchanger.
  • the controller 104 may be configured to receive information from one or more of the fuel cell stack 102, cathode inlet pressure sensor 124, cathode inlet temperature sensor 126, cathode oxidant level sensor 132, cathode exhaust temperature sensor 134, cathode exhaust pressure sensor 136 and, optionally, one or more of the liquid water level sensor 152, temperature sensor 153 and conductivity sensor 155.
  • the controller 104 may be configured to control operation of the air blower 120, cathode exhaust value 148, coolant pump 138, heat exchanger fan 144 and delivery water pump 154, the states of which are all examples of parameters of the fuel cell system 100.
  • the controller 104 can be configured to perform any method disclosed herein and may be implemented in hardware, software or a combination of hardware and software.
  • the loss of water balance may be caused by the inability of the first heat exchanger 128 to reject sufficient latent heat in order to recover sufficient liquid water from the cathode exhaust fluid.
  • This situation may be caused by, for example:
  • water loss may result from fuel cell system processes that are designed to maintain water purity (such as ionic purity or bacterial concentration) by jettisoning water from the water tank 150.
  • water purity such as ionic purity or bacterial concentration
  • LCFC liquid cooled fuel cell
  • water is retrieved from the cathode outlet and fed back to the cathode inlet by a stack rehydration loop in order to improve stack performance.
  • the stack rehydration loop may be similar to the water cooling loop described with reference to the ECFC embodiment illustrated with reference to figure 1. Such a loop may not require a water tank 150 in some examples.
  • the LCFC system comprises a separate water cooling loop in order to cool the stack.
  • Figure 2a illustrates a method 200 of controlling a fuel cell system such as that described with reference to figure 1.
  • the method 200 can be used to set the operating parameters of the system in response to the liquid level in the water circuit.
  • the method comprises the steps of:
  • An advantage of the method 200 is that it may be implemented in existing evaporatively cooled fuel cell stack systems.
  • the method can be applied equally to liquid/liquid or liquid/air condensing systems.
  • the rate of injection of the cooling water into the inlet may be controlled as a function of electrical current drawn from the fuel cell stack 102, which may be stored as a look-up table.
  • the one or more parameters of the system 100 may be controlled in order to increase the rate of water retrieval if the liquid level is decreasing at a rate that is greater than or equal to the liquid level threshold or if the liquid level is equal to or lower than the liquid level threshold.
  • the system may maintain water balance by monitoring the liquid level, by, for example, using the water level sensor 152.
  • the liquid level may be determined in accordance with one or more of an ambient temperature, a temperature at the cathode outlet 108 and a temperature of the first heat exchanger 128, such as an inlet or outlet temperature of the first side of the first heat exchanger 128, which are all examples of values related to the liquid level.
  • Parameters of the system for setting the rate of water retrieval include: (i) a coolant flow rate through the second side of the heat exchanger 128, ( ⁇ ) a pressure at the cathode outlet 108, which is also referred to as a back pressure;
  • Modifying parameter (i) above has the effect of changing a temperature of the cathode exhaust fluid at the first side of the heat exchanger 128.
  • Modifying parameters (ii) or (iii) above has the common effect of changing a temperature of the cathode exhaust fluid at the cathode outlet 108. Controlling the parameters (i) to (iii) to increase the temperature of the cathode exhaust fluid improves the performance of the first heat exchanger 128 and water separator 146.
  • the coolant flow rate may be measured using a flow sensor (not shown in figure 1) located at the inlet 106, the outlet 108 or within the stack 102.
  • the back pressure may be measured using the barometer, or pressure sensor 136, located at the outlet 108.
  • each of the parameters (i) to (iv) has a different effect on the fuel cell system and so it is preferable to alter parameters that are considered to have the least deleterious effect on performance of the system before altering parameters that have a more pronounced effect on system performance.
  • the system may sequentially: increase the coolant flow rate;
  • Some examples of the method may only move on to the next step in the sequence if the preceding step has not been sufficient to restore water balance or to provide sufficient water recovery.
  • the order in which parameters are varied may be chosen to optimise energy efficiency. In that case the order in which parameters are varied may be dependent on the hardware of the particular system, for example. Factors in the selection of the parameter order include the cell air sensitivity and compressor efficiency at different operating conditions, although cell degradation may also be considered.
  • the fuel cell system can be returned to a normal mode of operation, or a mode in which it was operating before water loss was detected.
  • This change in operating state can be achieved by reversing the changes to the operating parameters in first-in-last-out order.
  • the reversal of the sequence above comprises the sequential steps of:
  • Water may also be drained from the water tank 150 if the upper threshold is reached.
  • Figure 2b illustrates an example of the methods described above for operating a fuel cell system similar to that of figure 1.
  • a water level in the water tank 150 is measured 272 using the water level sensor 152. If the water level is determined 274 to be below a lower threshold, such as 40% of the tank being full, then the coolant flow rate through the second side of the first heat exchanger 128 is decreased, or minimised 276. If the water level is not below the threshold then the determination 274 of the water level is repeated until the water level falls below the threshold.
  • a lower threshold such as 40% of the tank being full
  • the cathode back pressure is increased, or maximised 278.
  • the air stoichiometry is decreased, or minimised 280.
  • the current/power available from the fuel cell stack is limited 282. In this example, the available power is limited to 30 kW.
  • Reversing the parameter settings comprises sequentially: removing the available current/power limit 286; increasing, or removing the minimum limit on, the air stoichiometry 288; decreasing, or removing the maximization of, the back pressure 290; and decreasing, or removing the maximization of, the coolant flow rate 292.
  • Figure 2c illustrates an example method 220 for controlling the operation of a fuel cell system such as that described with reference to Figure 1. The method also enables water balance to be maintained or recovered as described below. The method 220 of figure 2c can be considered to have six phases.
  • the fuel cell system 100 operates to a nominal cathode stoichiometry, and no or very low applied cathode back pressure (e.g. significantly less than 1000 mbar, such as 100 mbar or 200 mbar) is applied during the most of the time that the system 100 is in operation. Both of these conditions result in a low parasitic loss because the power demands on the air compressor, or air blower 120 are relatively low.
  • the coolant flow rate (either the flow rate of a water/glycol liquid coolant which runs across the cold side of a first heat exchanger 128 or air drawn through the cold side of the second heat exchanger 140) meets a nominal operating set point during normal system operation.
  • the method 220 commences by measuring 222 a liquid level in the water tank 150. If the water level is lower than a shutdown threshold 224, the system 100 goes into shutdown, or into an idle mode of operation 226, or even run the system without water injection or recovery in order to provide a reduced (or limited) output current/power.
  • Shutting down the system 100 may comprise operating 228 a number of the actuators described with reference to figure 1. For example, shutting down may comprise turning off or reducing the speed of the air blower 120 at the cathode inlet 106.
  • the current drawn from the stack 102 is set to a current at which the water retrieval rate from the cathode outlet is maximised, or at least at a high level compared to the water retrieval rate that corresponds to that in use in the system when the shutdown threshold 224 is reached.
  • the rate of change of the liquid level in the water tank is monitored 230. If it is detected that over a period of time, such as 5 minutes for example, the average rate of reduction in the liquid level in the water tank 150 with respect to time is greater than a pre-determined threshold then it is determined that water loss is occurring. Water loss occurs when the rate of liquid water fed to the inlet of the stack is greater than the rate of liquid water retrieved, or recovered, into the water tank 150 from the cathode outlet 108.
  • the detection of the water level, or the rate of change of the water level can be based on one or more sensor measurements and/or calculation techniques.
  • the water level sensor 152 deployed in the water tank 150 may provide sufficient resolution of the water level in many applications.
  • Water recovery is defined as being the opposite of water loss. Water recovery means that a higher rate of water from the cathode exhaust is condensated and retrieved than the rate of water injection to the cathode inlet 106 of the stack 102. Water recovery results in an increase in water level over time and can be allowed to happen under specific pre- determined conditions. Phases three to six relate to controlling parameters of the fuel cell system in order to provide water recovery. The parameters are set sequentially in accordance with the comparison between the rate of change in the liquid level with respect to time and the threshold. The result of the setting of the parameters is an increase in the rate of water retrieval from the cathode outlet and so phases three to six of the method 220 provide water recovery and regain water balance.
  • the rate of water retrieval from the cathode outlet 108 may be increased by increasing a coolant flow rate of the fuel cell system if the coolant value is not already saturated. It has been found that increasing the coolant flow rate tends to have a limited effect on the performance of the fuel cell stack and so it is advantageous to attempt to modify this operating parameter before modifying other operating parameters that may have a more substantial effect on stack performance.
  • the saturating effect is considered to be due to the limitation of the heat transfer coefficient of both the cathode exhaust fluid and the heat exchanger itself, which do not change with coolant flow rate through he second side of the heat exchanger.
  • the method 220 therefore further comprises the steps of checking if the coolant flow rate is saturated 232 and, if it is not saturated, increasing the coolant flow rate by a fixed amount or percentage, such as 5 % or 10 %.
  • the coolant flow rate can be increased by increasing a set point of the coolant pump 138 or by increasing a set point of the air fan 144 for the second heat exchanger 140.
  • the maximum coolant flow rate can be limited by the properties of the components of the system 100, such as the coolant pumps or air fans associated with the coolant circuits and heat exchangers, for example.
  • the hot side exit temperature of the first heat exchanger 128 can increase further if coolant does not reside in the cold side for long enough for heat transfer from the hot side to the cold side to occur. Where further increases in coolant flow rate do not lead to substantial additional heat transfer the coolant flow rate is said to be saturated. Therefore additional means of control are required in the case that the coolant flow rate is saturated. It has been found that coolant flow saturates at a lower flow rate at higher backpressures or at low air stoichiometry such that the stack temperature is higher. This is understood to be because heat transfer in the first heat exchanger 128 is made easier by providing these conditions.
  • Another method of increasing water recovery is by increasing a back pressure at the cathode outlet 108.
  • Increasing the back pressure also increases the temperature of the cathode exhaust fluid (due to application of the ideal gas law).
  • the temperature of the fluid entering the hot side of the first heat exchanger 128 is therefore higher if the back pressure is increased.
  • a larger temperature difference between the hot and cold side fluid entry temperatures of the first heat exchanger 128 results in an increase in the amount of heat that can be rejected by the cold side. As such, a greater amount of condensed liquid water which can be removed by the water separator 146.
  • the method 220 therefore further comprises the step of, in response to determining 232 that the coolant level is saturated, determining 234 whether the back pressure is saturated at the operating airflow rate.
  • the back pressure may be sensed using the pressure sensor 136 at the cathode outlet 108 of the fuel cell stack 102.
  • the air flow rate may be sensed using a flow meter 236 (not shown in figure 1 ) at the cathode inlet 106 or the cathode outlet 108. Alternatively, the airflow rate may be determined from the state of the air blower 120.
  • the method proceeds by determining 238 whether the cathode outlet temperature is equal to or greater than a maximum temperature threshold. If the cathode outlet temperature is within an operating range below the maximum operating temperature then the back pressure is increased 240 by a fixed amount or percentage, such as 5 % or 10 %. The back pressure may be increased by restricting fluid flow through an actuator, such as the cathode exhaust value 148. 5. System response: reduce cathode stoichiometry
  • the system can respond by reducing the cathode air stoichiometry.
  • the air flow stoichiometry relates to the oxidant level within the cathode flow path and more specifically to the ratio between reactant fed into the fuel cell stack and the reactant consumed within the fuel cell stack.
  • the air flow stoichiometry may be controlled by reducing air flow through the cathode flow path.
  • Oxygen-depleted air running through the cathode acts as a carrier for water vapour.
  • Limiting cathode stoichiometry reduces the air flow rate and so limits the amount of water vapour that can be carried away from the cathode. This means that the capacity for evaporative cooling within the fuel cell stack is reduced, resulting in a higher cathode exhaust temperature.
  • Increasing the cathode back pressure therefore also raises the temperature of the hot-side fluid entering the first heat exchanger 128. The amount of heat that can be rejected by the cold side of the first heat exchanger 128 is therefore increased and a greater amount of condensed liquid water can be recovered by the water separator 146 and delivered to the water tank 150, thereby raising the water level.
  • the method 220 therefore further comprises the step of, in response to determining 234 that the back pressure is saturated, determining 244 whether the air stoichiometry is saturated at a minimum current value determined using an ammeter 246 coupled to the power output of the fuel cell stack.
  • the air stoichiometry can be considered to be saturated if a reduction in the air stoichiometry does not result in a significant increase in water retrieval from the cathode outlet.
  • the air stoichiometry may be determined from a state of the air blower 120 or by the oxygen level measured using the oxygen level sensor 132, for example.
  • the method proceeds by determining 248 whether the cathode outlet temperature is equal to or greater than a maximum temperature threshold. If the cathode outlet temperature is within the operating range below the maximum operating temperature then the air stoichiometry is decreased 250, which may be by a fixed amount or percentage, such as 5 % or 10 %. The operation of the air blower 120 may be controlled in order to set the air stoichiometry.
  • controller 104 may attempt to increase water recovery by temporarily reducing the current available to be drawn from the fuel cell stack 102. Modifying the parameter of the current available to be drawn from the fuel cell stack affects the utility provided by the fuel cell system 100 and so in some examples is preferably only controlled after the parameters described in phases three to five have been exhausted.
  • the method 220 therefore further includes the step of determining 254 whether to reduce a load set point in accordance with (i) the lowest cell voltage dropping below a minimum cell voltage threshold, (ii) the rate of water loss and the absolute water level within the water tank.
  • the determination is trigger when one of the following conditions occur: the continuous voltage monitoring circuit 252 associated with the lowest voltage cell indicates that the cell voltage has fallen 250 to the minimum cell voltage threshold; during the fourth or fifth phase it was determined 238, 248 that the cathode outlet temperature is above the maximum temperature threshold. In these circumstances the available current from the stack is limited 256. Phases three to six above describe a method by which water loss in the tank can be minimised or eliminated.
  • the normal operation of the system can be restored by reversing the changes made to each of the parameters.
  • the parameters may therefore be controlled in reverse sequential order when the water level has increased to the threshold.
  • the available current will then be restored to normal operating conditions before the air stoichiometry.
  • the air stoichiometry will be restored to normal operating conditions before the back pressure.
  • the back pressure will be restored to normal operating conditions before the coolant flow rate.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Fuel Cell (AREA)

Abstract

L'invention se rapporte à un procédé permettant de faire fonctionner un système de pile à combustible, le système de pile à combustible comprenant un empilement de piles à combustible avec un chemin d'écoulement de réactif ayant un orifice d'entrée et un orifice de sortie, le chemin d'écoulement de réactif faisant partie d'un circuit d'eau du système de pile à combustible, le procédé consistant à : déterminer un niveau de liquide dans le circuit d'eau ; comparer une valeur en rapport avec le niveau de liquide avec un seuil ; commander un ou plusieurs paramètres du système de pile à combustible en fonction de la comparaison afin de régler une vitesse de récupération d'eau depuis l'orifice de sortie ; et injecter directement de l'eau dans l'orifice d'entrée.
PCT/GB2015/053672 2014-12-01 2015-12-01 Système de pile à combustible WO2016087845A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB1421283.1 2014-12-01
GB1421283.1A GB2533265B (en) 2014-12-01 2014-12-01 Fuel cell system

Publications (1)

Publication Number Publication Date
WO2016087845A1 true WO2016087845A1 (fr) 2016-06-09

Family

ID=52349716

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2015/053672 WO2016087845A1 (fr) 2014-12-01 2015-12-01 Système de pile à combustible

Country Status (2)

Country Link
GB (1) GB2533265B (fr)
WO (1) WO2016087845A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109469465A (zh) * 2018-11-14 2019-03-15 中国石油天然气股份有限公司大港油田分公司 注水井参数的处理方法、装置及存储介质
WO2021004714A1 (fr) * 2019-07-05 2021-01-14 Robert Bosch Gmbh Système de réservoir d'eau pour la fourniture d'eau pour un véhicule à piles à combustible

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013138249A2 (fr) * 2012-03-12 2013-09-19 Nuvera Fuel Cells, Inc. Système de refroidissement et procédé d'utilisation avec une pile à combustible
DE102019211493A1 (de) * 2019-08-01 2021-02-04 Audi Ag Verfahren zum Entlüften eines Kühlkreislaufs, Set einer Kühlmittelausgleichsanordnung und Kraftfahrzeug

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003086209A (ja) * 2001-09-06 2003-03-20 Equos Research Co Ltd 燃料電池装置
US20090214915A1 (en) * 2008-02-25 2009-08-27 Hyundai Motor Company Fuel cell system using evaporative cooling and method of cooling fuel cell system
WO2013081618A1 (fr) * 2011-12-01 2013-06-06 Utc Power Corporation Équilibrage de l'eau d'un système
DE102012024860A1 (de) * 2012-12-19 2014-06-26 Audi Ag Verfahren zum Betreiben eines Brennstoffzellensystems

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2409763B (en) * 2003-12-31 2007-01-17 Intelligent Energy Ltd Water management in fuel cells
GB2464946B (en) * 2008-10-30 2012-05-16 Intelligent Energy Ltd Fuel cell cooling
JP2010257644A (ja) * 2009-04-22 2010-11-11 Honda Motor Co Ltd 燃料電池システムの制御方法
JP6575867B2 (ja) * 2014-11-20 2019-09-18 パナソニックＩｐマネジメント株式会社 燃料電池システム

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003086209A (ja) * 2001-09-06 2003-03-20 Equos Research Co Ltd 燃料電池装置
US20090214915A1 (en) * 2008-02-25 2009-08-27 Hyundai Motor Company Fuel cell system using evaporative cooling and method of cooling fuel cell system
WO2013081618A1 (fr) * 2011-12-01 2013-06-06 Utc Power Corporation Équilibrage de l'eau d'un système
DE102012024860A1 (de) * 2012-12-19 2014-06-26 Audi Ag Verfahren zum Betreiben eines Brennstoffzellensystems

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109469465A (zh) * 2018-11-14 2019-03-15 中国石油天然气股份有限公司大港油田分公司 注水井参数的处理方法、装置及存储介质
WO2021004714A1 (fr) * 2019-07-05 2021-01-14 Robert Bosch Gmbh Système de réservoir d'eau pour la fourniture d'eau pour un véhicule à piles à combustible

Also Published As

Publication number Publication date
GB2533265B (en) 2021-09-15
GB2533265A (en) 2016-06-22
GB201421283D0 (en) 2015-01-14

Similar Documents

Publication Publication Date Title
CN111224131B (zh) 燃料电池系统及其低温吹扫方法
EP1803182B1 (fr) Systeme de piles a combustible
KR101592709B1 (ko) 차량의 연료전지시스템 및 그 제어방법
WO2016087845A1 (fr) Système de pile à combustible
CN109690851B (zh) 燃料电池系统及其控制方法
JP5324522B2 (ja) 燃料電池システム
JP6079227B2 (ja) 燃料電池システム
JP2002280046A (ja) 燃料電池システム
JP2004146240A (ja) 燃料電池システム
JP2003178778A (ja) 燃料電池システム
JP4744058B2 (ja) 燃料電池システム
JP5109284B2 (ja) 燃料電池システム
JP2005302489A (ja) 燃料電池システムの制御装置
JP2004039322A (ja) 燃料電池システム
CN110243115A (zh) 一种冷凝压力控制系统及方法
JP2007311087A (ja) 燃料電池システムと燃料電池システムにおける冷却系のイオン除去方法
JP5470815B2 (ja) 燃料電池システム
JP7137436B2 (ja) 燃料電池システム
JP7059879B2 (ja) 燃料電池システム
JP6094214B2 (ja) 燃料電池システム
JP2005050639A (ja) 燃料電池システム
JP2005235489A (ja) 燃料電池システム
JP5262520B2 (ja) 加熱制御装置
CN117174956B (zh) 燃料电池控制方法、装置、电子设备及燃料电池
JP2010049915A (ja) 燃料電池システムおよび燃料電池システムの掃気方法

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 15817501

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 15817501

Country of ref document: EP

Kind code of ref document: A1