Adaptive Purging For A Fuel Cell System

Abstract

An adaptive purge technique is used for purging fuel cells 102, which adjusts the purge technique between subsequent purges based in part on one or more parameters of the fuel cells. A difference betw

Description

14 02 25 TECHNICAL FIELD

[0001] This application is directed to fuel cell systems, and more particularly, to adaptively managing a control valve for purging one or more fuel cells of a fuel cell system. BACKGROUND

[0002] Conventional electrochemical fuel cells convert fuel and oxidant into electrical energy and a reaction product. A common type of electrochemical fuel cell includes a membrane electrode assembly (MEA), which includes a polymeric ion (proton) transfer membrane between an anode and a cathode flow paths or gas diffusion structures. The fuel, such as hydrogen, and the oxidant, such as oxygen from air, are passed over respective sides of the MEA to generate electrical energy and water as the reaction product. A stack may be formed including a number of such fuel cells arranged with separate anode and cathode fluid flow paths. Such a stack is typically in the form of a block including numerous individual fuel cell plates held together by end plates at either end of the stack.

[0003] It is important that the polymeric ion transfer membrane remains hydrated for efficient operation. It is also important that the temperature of the stack is controlled. Thus, coolant may be supplied to the stack for cooling and / or hydration. It may be necessary at particular times or periodically to purge the flow paths or gas diffusion structures of the fuel cell of coolant, contaminants, or reaction by-products using a purge gas.

[0004] Periodically, purging (i.e., removing) the water and other gases from the fuel cells should be performed. The removal gas, which may include the fuel (hydrogen for example) flows through the anode flow path to remove the water and gases from the fuel cell. Conventional fuel cells are set to provide this removal process at a specified time regardless of whether the removal is necessary at that particular time. This can result in inefficient use of gases used to remove the water, particularly when the gas is also used to generate electrical energy. DISCLOSURE 14 02 25

[0005] According to a first aspect of the present disclosure there is provided a fuel cell system, comprising: a fuel cell assembly comprising an anode exhaust and a fuel cell; a valve configured to exhaust a purge gas from the anode exhaust; and a valve controller configured to: prior to a first purge of the fuel cell with the purge gas, obtain a first parameter measurement of altitude or humidity of the fuel cell; subsequent to the first purge, obtain a second parameter measurement of altitude of humidity of the fuel cell; obtain a difference between the first parameter measurement of altitude and the second parameter measurement of altitude; or obtain a difference between the first parameter of humidity and the second parameter of humidity; and, determine, based on the difference between the first and second parameter measurements of altitude or humidity, a time delay for a second purge subsequent to the first purge.

[0006] According to a second aspect of the present disclosure there is provided a method for adaptively pursing purging a fuel cell, the method comprising: prior to performing a first purge of the fuel cell to exhaust a purge gas from an anode exhaust of a fuel cell assembly, the fuel cell assembly comprising the anode exhaust and the fuel cell, obtaining a first parameter measurement of altitude or humidity of the fuel cell; subsequent to the first purge, obtaining a second parameter measurement of altitude or humidity of the fuel cell; obtaining a difference between the first parameter measurement of altitude and the second parameter measurement of altitude or obtaining a difference between the first parameter measurement of humidity and the second parameter measurement of humidity; and determining, based on the difference between the first and second parameter measurements of altitude or humidity, a time delay for a second purge subsequent to the first purge. DESCRIPTION OF THE DRAWINGS 14 02 25

[0007] Certain features of the subject technology are set forth in the appended claims. However, for purpose of explanation, several exemplars of the subject technology are set forth in the following figures.

[0008] FIG. 1 illustrates a schematic diagram of a fuel cell system including a fuel cell assembly, exhaust assembly and a control valve, in accordance with aspects of the present disclosure.

[0009] FIGS. 2A and 2B illustrate an example valve that can be actuated in two operating positions, in accordance with aspects of the present disclosure.

[0010] FIG. 3 illustrates a schematic diagram of a fuel cell assembly, in accordance with aspects of the present disclosure.

[0011] FIG. 4 illustrates a schematic diagram of an alternate fuel cell system, in accordance with aspects of the present disclosure.

[0012] FIG. 5 illustrates a schematic diagram of an alternate fuel cell system with multiple valves, in accordance with aspects of the present disclosure.

[0013] FIG. 6 illustrates a method for adaptively purging a fuel cell, in accordance with aspects of the present disclosure.

[0014] FIG. 7 illustrates an alternate method for adaptively purging a fuel cell, in accordance with aspects of the present disclosure. FURTHER DISCLOSURE

[0015] The disclosure set forth below is intended as a description of various configurations of the subject technology and is not intended to represent the only configurations in which the subject technology may be practiced. The appended drawings are incorporated herein and 14 02 25 constitute a part of the detailed description. The disclosure includes specific details for the purpose of providing a thorough understanding of the subject technology. However, it will be clear and apparent to those skilled in the art that the subject technology is not limited to the specific details set forth herein and may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring the concepts of the subject technology.

[0016] The subject technology is directed to adaptively purging fuel cells based on various selected parameters of the fuel cells. For example, a time delay, or purge time delay, between actuation (e.g., opening) of a valve can vary based in part upon a difference between two measured parameters. In particular, the degree of difference (e.g., greater difference or lesser difference) between the two measured parameters is used by a valve controller to determine when to actuate the valve for a subsequent purge event. The “difference” described herein may include an absolute value of the difference. Beneficially, actuation of the valve occurs when needed to purge the fuel cel 1 (s), rather than at predetermined time intervals when purging may not be necessary.

[0017] Several parameters can be selected to determine an adaptive purge. As non-limiting examples, the parameters may include voltage, temperature, electrical current, altitude, humidity (of incoming air), gas quality, and hydration. In one exemplary implementation, the voltage output of a fuel cell is measured prior to opening a valve to purge the fuel cell. The voltage output of the fuel cell is again measured after opening the valve. The delta, or difference, between the two measured voltages can be used to determine the time delay used for a subsequent valve opening (including the next valve opening) to purge the fuel cell. In this regard, when the measured voltage output difference is relatively high (e.g., 20 millivolts (mV)), the time delay may be relatively short (e.g., 30 seconds (s)). Conversely, when the measured voltage output difference is relatively low (e.g., 5 mV), the time delay may be comparatively long (e.g., 120 s). Accordingly, the time delay can be inversely proportional with respect to the difference between the measured parameters. 14 02 25

[0018] In addition to the adaptive purge time delay between valve actuation events for purging, an additional time parameter may be integrated. For example, the time the valve is open (e.g., time between opening and closing), representing a purge duration, can vary based in part upon the aforementioned parameters. As a result, a fuel cell system can adaptively actuate a valve in a manner that not only to adjust the time between subsequent valve openings, but can also adjust the time the valve remains open.

[0019] In yet another example, an adaptive purge technique may include a cluster, or series, of purge events in which a valve is opened and closed repeatedly. A purge cluster event may cause a series of pressure increases within a fuel cell (or cells), thus causing water molecules to exit the fuel cell(s). The purge cluster event occur in response to a measured different between parameters, such as an output voltage difference.

[0020] The adaptive purge techniques described herein may occur separately or in combination. Put another way, any one or more adaptive purge techniques can be implemented together. As a non-limiting example, in response to one or more measured parameters, a purge time delay between an initial purge and a purge cluster event may occur, followed by a change in the duration of the opening of a valve.

[0021] The fuel cell systems described herein with adaptive purging capabilities provides several advantages. For example, when the gas used to purge the fuel cell is also used to generate electrical energy, the gas is conserved as adaptive purging is a predictive technique as opposed to traditional technique of predetermined time intervals between purging events.

[0022] According to aspects of some exemplars, for example as shown in FIG. 1, a fuel cell system 100 comprising a fuel cell assembly 102 and a control valve 104, or simply valve, for controlling the exhaust flow of a purge gas. Thus, the control valve 104 may be referred to as a purge control valve that forms part of an exhaust assembly configured to receive fluids leaving an anode flow path through the fuel cell assembly 102 and a cathode flow path though the fuel cell assembly 102. During a purge operation, a gas, such as a fuel (e.g. hydrogen) flows through the anode flow path to purge the anode flow path of coolant, hydration fluid, contaminants, inert 14 02 25 substances (such as nitrogen), and / or reaction by-products. The control valve 104 is configured to control the purge gas exhaust flow that exhausts from the fuel cell assembly 102.

[0023] The fuel cell assembly 102 in this example includes a fuel cell stack including multiple proton exchange membrane fuel cells stacked together. The fuel cell assembly 102 is configured to receive a flow of fuel, such as hydrogen, through an anode inlet 106 and a flow of oxidant, such as air, through a cathode inlet 108. An anode exhaust 110 is provided to allow for through flow of any unused fuel and any purge gas. A cathode exhaust outlet 112 is provided to allow for through flow of the oxidant. The control valve 104 is connected to the anode exhaust 110 and includes a two port, two position valve. A schematic diagram of the control valve 104 is shown in FIG. 1 and example valve positions are shown in FIGS. 2A and 2B.

[0024] Referring to FIGS. 2A and 2B, the control valve 104 includes a valve body 116 containing a valve member 118. The valve member 118 may be slidably mounted in the valve body 116 moveable between a first position (FIG. 2A) and a second position (FIG. 2B). The valve body 116 includes an inlet port 120 for receiving the purge gas exhausted from the fuel cell assembly 102 (shown in FIG. 1) and an outlet port 122 for providing an outlet for the purge gas.

[0025] In the first position (FIG. 2A), the valve member 118 acts to prevent exhausted purge gas (represented by a dotted line) from flowing between the inlet port 120 and the outlet port 122. In the second position (FIG. 2B), the valve member 118 allows the flow of purge gas between the inlet port 120 and the outlet port 122. Thus, the valve member 118 is configured to close the inlet port 120 in its first position and open the inlet port 120 in its second position. In particular, the inlet port 120 includes a valve seat 124 against which a sealing surface 126 of the valve member 118 seals in the first position. When the sealing surface 126 valve member 118 is not engaged with the valve seat 124 (as shown in FIG. 2B), the purge gas is permitted to flow through the control valve 104.

[0026] The valve member 118 is biased to the first position by a biasing means, which may include a spring as a non-limiting example. The control valve 104 may include a solenoid valve and thus the valve member 118 may be movable between its first and second position by 14 02 25 actuation of a solenoid (not shown) which is configured to move the valve member 118 to the second position against the force of the biasing means.

[0027] With reference to FIG. 1, during a purge operation, fuel may flow through the anode flow path of the fuel cell assembly 102. The control valve 104 may be actuated, by way of the solenoid, to move the valve member 118 from the first position to the second position, which may allow the purge gas to flow through the fuel cell assembly 102.

[0028] Referring to FIG. 3, a fuel cell assembly 202 includes n fuel cells, with a fuel cell 230a, a fuel cell 230b, a fuel cell 230c, and a fuel cell 230n. In this regard, the fuel cell assembly 202 may include a fuel cell stack composed of fuel cells 230a through 230n. Additionally, the fuel cells 230a and 230n may be referred to as end cells, as the fuel cells 230a and 230n represent the two outermost fuel cells.

[0029] Additionally, the fuel cell assembly 202 includes one or more sensors 232 designed to monitor at least one of the fuel cells 230a through 23 On. In some exemplars, the one or more sensors 232 includes a voltmeter(s) designed to determine an output voltage of at least one of the fuel cells 230a through 230n. Further, in some exemplars, the one or more sensors 232 includes a temperature sensor(s) designed to measure a temperature of at least one of the fuel cells 230a through 230n. Still further, in some exemplars, the one or more sensors 232 includes a barometric sensor(s) designed to measure a pressure (e.g., ambient pressure) least one of the fuel cells 230a through 230n. In this regard, the one or more sensors 232 can determine an elevation (i.e., relative to sea level) of the fuel cell assembly 202 based on the measure pressure. Alternative to the barometric sensor, the one or more sensors 232 may include an altimeter used to determine the altitude. Additionally, in some exemplars, the one or more sensors 232 includes a humidity sensor(s) designed to measure relative humidity of air entering at least one of the fuel cells 230a through 230n. Also, in some exemplars, the one or more sensors 232 includes a gas analyzer(s) designed to measure gas composition, which can be used to determine purity / quality of gas in at least one of the fuel cells 230a through 23 On. Also, in some exemplars, the one or more sensors 232 includes a hydration sensor designed to measure an amount of liquid in at least one of the fuel cells 230a through 23 On. 14 02 25

[0030] Referring to FIG. 4, a fuel cell system 300 includes a fuel cell assembly 302 and a control valve 304 that is actuated by a controller 334. The fuel cell assembly 302 includes a fuel cell 330 and one or more sensors 332 that monitor the fuel cell 330. The one or more sensors 332 may include any of the aforementioned sensors described herein. Also, as shown, the one or more sensors 332 is / are integrated with the fuel cell assembly 302. However, it should be noted that the one or more sensors 332 can be separate from the fuel cell assembly 302 while still monitoring the fuel cell 330 and in communication with the controller 334.

[0031] The controller 334 includes a memory 336 representing one or more memory circuits that store(s) executable code or executable instructions. The controller 334 further includes a processor 338 representing processing circuitry in the form of a central processing unit, a programmable logic circuit, and / or an application-specific integrated circuit. The processor 338 is designed to execute the instruct!ons / code stored on the memory 336. For example, the processor 338 can use instructions stored on the memory 336 to actuate (i.e., open and close) to control valve 304. When the controller 334 opens the control valve 304, a gas 340 passes through the fuel cell assembly 302 to purge the fuel cell 330. The gas 340 may include hydrogen, as a non-limiting example.

[0032] Additionally, the processor 338 can be used to send instructions stored on the memory 336 to obtain data (e.g., a numeric value(s)) from the one or more sensors 332. In this regard, the controller 334 can receive the data from the one or more sensors 332 by requesting the data periodically (e.g., on the order of milliseconds or seconds) or continuously receive updated data from the one or more sensors 332. In some exemplars, the controller 334 obtains the data from the one or more sensors 332 before and after actuation of the control valve 304. For example, prior to the controller 334 opening the control valve 304, the controller 334 can obtain data from the one or more sensors 332. Further, after the controller 334 closes the control valve 304, the controller 334 can obtain data (i.e., updated data) from the one or more sensors 332.

[0033] In an exemplary exemplar, the one or more sensors 332 includes at least one voltmeter designed to monitor and determine an output voltage of the fuel cell 330. Prior to the 14 02 25 controller 334 opening the control valve 304, the controller 334 can obtain an output voltage from the one or more sensors 332. Further, after the controller 334 closes the control valve 304, the controller 334 can output a voltage from the one or more sensors 332. The opening and closing of the control valve 304 represents a purge event.

[0034] Using the memory 336 and the processor 338, the controller 334 can determine a difference between the two output voltages, and determine a time delay to provide instructions to the control valve 304 for a subsequent purge event. Put another way, the controller 334 uses the output voltage difference to determine when to initiate the next purge event. The time delay between consecutive purge events may be inversely proportional. For example, the time delay is relatively longer when the output voltage difference is relatively smaller, and conversely, the time delay is relatively shorter when the output voltage difference is relatively greater. This process may include an iterative process that compares the difference between consecutive output voltages at a purge event, and adjusts the time delay for the next purge event. Beneficially, the fuel cell system 300 includes an adaptive purge technique that predicts subsequent purges, which may reduce the number of purge events to conserve the gas 340, or alternatively, increase the number of purge events to more efficiently operate the fuel cell assembly 302 (particularly, the fuel cell 330) to promote increased energy output and / or to limit or prevent damage to the fuel cell assembly 302.

[0035] Also, in some exemplars, when then the difference between the two parameters (e.g., difference between two measured output voltages) is below a threshold difference, the controller 334 does not adaptively adjust the time delay. Put another way, the change in time delay is zero seconds for a subsequent purge and the prior time delay is used.

[0036] Generally, the foregoing example may be implemented in a similar manner with different sensors. For example, when the one or more sensors 332 includes at least one temperature sensor that monitors and determines a temperature of the fuel cell 330, the controller 334 can obtain a voltage from the one or more sensors 332 both before opening the control valve 304 and after the control valve 304 closes, determine a temperature difference between the two obtained temperatures, and determine a time delay based upon the temperature difference. 14 02 25 Alternatively, the measured temperatures may be compared against an ideal set of temperatures on a curve (e.g., bell curve), and the time delay is based upon deviation from the curve.

[0037] In another example, when the one or more sensors 332 includes a current meter, the measured current may be compared against a range (e.g., optimal range), and the time delay is based upon deviation from the range.

[0038] Other examples of the one or more sensors 332 include a barometric pressure sensor, an altimeter, a humidity sensor, a gas analyzer, and / or a hydration sensor. In a similar manner, the controller 334 can obtain respective data from the alternative examples of the one or more sensors 332 before opening the control valve 304 and after closing the control valve 304, determine a difference between the two obtained data, and determine a time delay based upon the determined difference. The time delay can again be inversely proportional to the determined difference. For example, the time delay between consecutive purge events may decrease when the altitude difference (determined by a barometric sensor or an altimeter) is relatively larger. Similarly, the time delay between consecutive purge events may decrease when the humidity difference (determined by a humidity sensor) is relatively larger.

[0039] Alternative to, or in combination with, the time delay between consecutive purge events, the duration of a purge event can be adaptively adjusted. The duration of the purge event may refer to the time between (and including) the opening and subsequent closing of the control valve 304. For example, the controller 334 may use the output voltage difference to determine the duration of the purge event for a subsequent purge event (or events), including the next purge event. By further adaptively controlling the control valve 304 to decrease the purge duration, the gas 340 may be conserved. Alternatively, by further adaptively controlling the control valve 304 to increase the purge duration, the fuel cell assembly 302 (particularly, the fuel cell 330) is operated more efficiently to promote increased energy output, and / or is prevented from damage. In addition to voltmeters, it should be noted that purge duration may be associated with any implementation of the examples of the one or more sensors 332.

[0040] Alternative to, or in combination with, the time delay between consecutive purge events and or the duration of a purge event, additional adaptive purge techniques may be used. 14 02 25 For example, a purge cluster, in which the control valve 304 is repeatedly opened and closed a number of times, may occur. A purge cluster may cause water molecules to be pushed out of the fuel cell assembly 302 without the water molecules beading or otherwise joining together. Beneficially, the water molecules, by not beading, do not increase in weight, thus requiring less pressure to move the water molecules. The controller 334 may receive one or more parameters to determine whether to implement a purge cluster. As a non-limitmg example, the controller 334 may use an output voltage difference from a prior purge event, and use a purge cluster for the next purge event. Alternatively, the controller 334 may obtain an output voltage, perform a purge cluster and obtain a subsequent output voltage after the purge cluster, and use the difference to adjust the number in the series of a subsequent purge cluster event. In this regard, the number of repeated purges may vary based on the parameters. For example, one purge cluster includes 5 purge events, while another purge cluster includes 10 purge events. The aforementioned number of purge events in a purge cluster are intended to be exemplary, and the number of individual purge events in a cluster may vary.

[0041] It should be noted that the controller 334 may use any combination of adaptive purge techniques. For example, the controller 334 can cause the control valve 304 to perform a purge event, initiate a purge delay based on a comparison between received parameters, adjust the duration of the opening of the control valve 304 for a subsequent purge, and later perform a purge cluster by causing the control valve 304 to repeatedly open and close for a predetermined number of times.

[0042] The controller 334 may use one or mor parameters to select an adaptive purge technique (or techniques). For example, based on the altitude of the fuel cell system 300, the controller 334 may selected the purge cluster. Other parameters mentioned in this detailed description can be used by the controller 334 to select an appropriate adaptive purge technique(s). Alternatively, or in combination, other factors of the fuel cell assembly 302, such as pore size and pressure (internal or ambient), may be used by the controller 334 to select the adaptive purge technique(s). 14 02 25

[0043] Referring to FIG. 5, a fuel cell system 400 includes multiple fuel cell assemblies. As shown, the fuel cell system 400 includes n fuel cell assemblies and n control valves. A fuel cell assembly 402a, a fuel cell assembly 402b, and a fuel cell assembly 402n are shown. The fuel cell assembly 402a includes a fuel cell 430a and one or more sensors 432a. The fuel cell assembly 402b includes a fuel cell 430b and one or more sensors 432b. The fuel cell assembly 402n includes a fuel cell 430n and one or more sensors 432n. The one or more sensors 432a, 432b, and 432n may include any of the aforementioned sensors described herein.

[0044] Also, a control valve 404a, control valve 404b, and control valve 404n are used to permit a gas 440 to purge the fuel cell 430a, the fuel cell 430b, and the fuel cell 43 On, respectively. The fuel cell system 400 further includes a controller 434 used to actuate each of the control valves 404a, 404b, and 404n to purge the fuel cells 430a, 430b, and 43 On, respectively. Also, as shown, the one or more sensors 432a, 432b, and 432n are integrated with the fuel cell assemblies 402a, 402b, and 402n, respectively. However, it should be noted that the one or more sensors 432a, 432b, and 432n can be separate from the fuel cell assemblies 402a, 402b, and 402n, respectively, while still monitoring the fuel cells 430a, 430b, and 430n, respectively, and still in communication with the controller 434.

[0045] The controller 434 includes a memory 436 representing one or more memory circuits that store(s) executable code or executable instructions. The controller 434 further includes a processor 438 representing processing circuitry in the form of a central processing unit, a programmable logic control circuit, and / or an application-specific integrated circuit. The processor 438 is designed to execute the instructions / code stored on the memory 436. For example, the processor 438 can use instructions stored on the memory 436 to actuate (i.e., open and close) the control valves 404a, 404b, and 404n. When the controller 434 opens the control valves 404a, 404b, and 404n, the gas 440 passes through the fuel cell assemblies 402a, 402b, and 402n, respectively, to purge the fuel cells 430a, 430b, and 43On. The gas 440 may include hydrogen, as a non-limiting example. Further, the controller 434 is designed to independently actuate the control valves 404a, 404b, and 404n. In this manner, the fuel cells 430a, 430b, and 43 On can be independently purged. 14 02 25

[0046] Additionally, the processor 438 can be used to send instructions stored on the memory 436 to obtain data from the one or more sensors 432a, 432b, and 432n in a manner previously described. Accordingly, the controller 434 can adaptively purge each of the fuel cells 430a, 430b, and 43 On in an independent manner. For example, the time delay between consecutive purge events for each of the fuel cells 430a, 430b, and 43 On can be different from each other, or two or more of the fuel cells 430a, 430b, and 43 On may include the same time delay between consecutive purge events based on data form the one or more sensors 432a, 432b, and 432n. Beneficially, the fuel cell assemblies 402a, 402b, and 402n can be independently managed, which may increase efficiency of the hardware of the controller 434 (i.e., the processor 438) and / or conserve the gas 440.

[0047] Alternative to, or in combination with, the time delay between consecutive purge events, the duration of a purge event can be adaptively adjusted. For example, the controller 434 use data from the one or more sensors 432a, 432b, and 432n to determine the duration of the purge event for a subsequent purge event for the fuel cells 430a, 430b, and 430n, respectively. By further adaptively controlling the control valves 404a 404b, and 404n to decrease the purge duration, the gas 440 may be conserved. Alternatively, by further adaptively controlling the control valves 404a 404b, and 404n to increase the purge duration, the fuel cell assemblies 402a, 402b, and 402n are operated more efficiently to promote increased energy output and / or are prevented from damage.

[0048] Referring to FIG. 6, a method 500 for adaptively purging a fuel cell is shown. The various steps of the method 500 may be carried out by a controller of a fuel system shown and described herein.

[0049] At step 502, prior to performing a first purge, a first parameter of the fuel cell is obtained. A “purge” represents an event in which gas (e.g., purge gas) is permitted to enter and remove unwanted liquid (e.g., water) and gas (e.g., nitrogen). The first parameter of the fuel cell may be measured / monitored by a sensor. As non-limiting examples, the sensor may include a voltmeter, a temperature sensor, a barometric sensor, an altimeter, a humidity sensor, a gas 14 02 25 analyzer, or a hydration sensor. The controller can obtain, from the sensor, data related to the first parameter.

[0050] At step 504, subsequent to performing the first purge, a second parameter of the fuel cell is obtained. Similar to the first parameter, the controller can obtain, from the sensor, data related to the second parameter. Also, the same sensor used to measure / monitor the first parameter can be used to measure / monitor the second parameter.

[0051] At step 506, a difference between the first parameter and the second parameter is obtained. The difference may include a subtraction of a first parameter value of the first parameter from a second parameter value of the second parameter. Alternatively, the difference may include a deviation from an ideal parameter (or ideal range of parameters) as determined form a curve / plot.

[0052] At step 508, a purge technique is determined, based on the difference, for a second purge subsequent to the first purge. The purge technique may include a time delay, representing the time subsequent to the first purge when the controller will initiate the second, or next, purge to be performed. Alternatively, the purge technique may include a purge duration, representing the time (subsequent to the first purge) when the controller maintains the valve in an open position during a purge event. Alternatively, the purge technique may include a purge cluster, representing a series of openings and subsequent closings of the valve for a predetermined number of times. In some embodiments, two or more purge techniques may be used.

[0053] Referring to FIG. 7, a method 600 for adaptively purging a fuel cell is shown. The various steps of the method 600 may be carried out by a controller of a fuel system shown and described herein.

[0054] At step 602, prior to a first purge, a first parameter of one or more fuel cells is obtained. A “purge” represents an event in which gas (e.g., purge gas) is permitted to enter and remove unwanted liquid (e.g., water) and gas (e.g., nitrogen). When at least two fuel cells are present, the fuel cells represents a fuel stack. In this regard, one or more sensors can be used to 14 02 25 monitor selected fuel cells or all of the fuel cells. In some exemplars, the end cells of the fuel stacks are monitored by the one or more sensors.

[0055] At step 604, subsequent to the first purge, a second parameter of one or more fuel cells is obtained. Similar to the first parameter, the controller can obtain, from the sensor, data related to the second parameter. Also, the same sensor used to measure / monitor the first parameter can be used to measure / monitor the second parameter.

[0056] At step 606, a difference between the first parameter and the second parameter is obtained. When at least two fuel cells are present, a difference between the first and second parameters for each of the fuel cells.

[0057] At step 608, a determination is made whether the one or more differences is greater than a threshold difference (or set of threshold differences). When at least two fuel cells are present, a determination is made whether each difference is above or below a predetermined threshold difference. When the difference is below the predetermined threshold difference, the method 600 returns to step 602 and a new first parameter is determined prior to a purge. Further, the controller may not implement a new time delay for a subsequent purge of the fuel cell when the predetermined threshold difference is not exceeded. When the difference is above the predetermined threshold difference, the method 600 proceeds to step 610. When at least two fuel cells are present, the controller can independently manage each fuel cell such that each fuel cell can be evaluated and independently advanced in the method 600.

[0058] At step 610, a purge technique for a second purge is determined based on the difference(s). The purge technique may include a time delay, representing the time subsequent to the first purge when the controller will initiate the second, or next, purge to be performed. When at least two fuel cells are present, a time delay can be independently determined for each fuel cell based upon evaluation of the respective first and second parameters. Alternatively, the purge technique may include a purge duration, representing the time (subsequent to the first purge) when the controller maintains the valve in an open position during a purge event. Alternatively, the purge technique may include a purge cluster, representing a series of openings 14 02 25 and subsequent closings of the valve for a predetermined number of times. In some embodiments, two or more purge techniques may be used.

[0059] As used herein, the phrase “at least one of’ preceding a series of items, with the term “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list (i.e., each item). The phrase “at least one of’ does not require selection of at least one of each item listed; rather, the phrase allows a meaning that includes at least one of any one of the items, and / or at least one of any combination of the items, and / or at least one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and / or at least one of each of A, B, and C.

[0060] The predicate words “configured to”, “operable to”, and “programmed to” do not imply any particular tangible or intangible modification of a subject, but, rather, are intended to be used interchangeably. In one or more implementations, a processor configured to monitor and control an operation or a component may also mean the processor being programmed to monitor and control the operation or the processor being operable to monitor and control the operation. Likewise, a processor configured to execute code can be construed as a processor programmed to execute code or operable to execute code.

[0061] Phrases such as an aspect, the aspect, another aspect, some aspects, one or more aspects, an implementation, the implementation, another implementation, some implementations, one or more implementations, an exemplar, the exemplar, another exemplar, some exemplars, one or more exemplars, a configuration, the configuration, another configuration, some configurations, one or more configurations, the subject technology, the disclosure, the present disclosure, other variations thereof and alike are for convenience and do not imply that a disclosure relating to such phrase(s) is essential to the subject technology or that such disclosure applies to all configurations of the subject technology. A disclosure relating to such phrase(s) may apply to all configurations, or one or more configurations. A disclosure relating to such phrase(s) may provide one or more examples. A phrase such as an aspect or some aspects may refer to one or more aspects and vice versa, and this applies similarly to other foregoing phrases.

[0062] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any exemplar described herein as “exemplary” or as an “example” is not necessarily to be construed as preferred or advantageous over other exemplars. Furthermore, to the extent that the term “include”, “have”, or the like is used in the disclosure or the claims, such term is intended to be inclusive in a manner similar to the term “comprise” as “comprise” is interpreted when employed as a transitional word in a claim. 14 02 25

Claims

14 02 251. A fuel cell system, comprising:a fuel cell assembly comprising an anode exhaust and a fuel cell;a valve configured to exhaust a purge gas from the anode exhaust; anda valve controller configured to:prior to a first purge of the fuel cell with the purge gas, obtain a first parameter measurement of altitude or humidity of the fuel cell;subsequent to the first purge, obtain a second parameter measurement of altitude or humidity of the fuel cell;obtain a difference between the first parameter measurement of altitude and the second parameter measurement of altitude; orobtain a difference between the first parameter of humidity and the second parameter of humidity; and,determine, based on the difference between the first and second parameter measurements of altitude or humidity, a time delay for a second purge subsequent to the first purge.

2. The fuel cell system of claim 1, comprising one or more sensors including an altimeter configured to measure an altitude of the fuel cell.

3. The fuel cell system of claim 1 or claim 2, comprising one or more sensors including a humidity sensor configured to measure a relative humidity of air entering the fuel cell.

4. The fuel cell system of claim 2 or claim 3, wherein the one or more sensors is integrated with the fuel cell assembly.

5. The fuel cell system of claim 2 or claim 3, wherein the one or more sensors is separate from the fuel cell assembly, configured to monitor the fuel cell, and in communication with the valve controller.14 02 256. The fuel cell system of any of claims 1 to 5, wherein when the difference between the first and second parameter measurements is below a threshold difference, the valve controller is configured to determine a time delay for a subsequent purge to be equal to the time delay between the first and second purge.

7. The fuel cell system of any of claims 1 to 5, wherein the time delay is inversely proportional to the difference between the first and second parameter measurements.

8. The fuel cell system of any preceding claim, wherein the first and second parameter measurements are used to determine a duration in which the valve is actuated to remain open during the second purge.

9. The fuel cell system of any of claims 1 to 8, wherein the valve controller is configured to implement a purge cluster, in which the valve is repeatedly opened and closed a number of times.

10. The fuel cell system of claim 9, wherein the valve controller is configured to implement the purge cluster in dependence on the difference between the first and second parameter measurements of altitude or humidity.

11. A method for adaptively purging a fuel cell, the method comprising:prior to performing a first purge of the fuel cell to exhaust a purge gas from an anode exhaust of a fuel cell assembly, the fuel cell assembly comprising the anode exhaust and the fuel cell, obtaining a first parameter measurement of altitude or humidity of the fuel cell;subsequent to the first purge, obtaining a second parameter measurement of altitude or humidity of the fuel cell;obtaining a difference between the first parameter measurement of altitude and the second parameter measurement of altitude or obtaining a difference between the first parameter measurement of humidity and the second parameter measurement of humidity; and14 02 25determining, based on the difference between the first and second parameter measurements of altitude or humidity, a time delay for a second purge subsequent to the first purge.

12. The method of claim 11, further comprising measuring, using an altimeter, the altitude of the fuel cell.

13. The method of claim 11, further comprising measuring, using a humidity sensor, a relative humidity of air entering the fuel cell.

14. The method of any of claims 11 to 13, wherein when the difference between the two parameter measurements is below a threshold difference, determining a time delay for a subsequent purge to be equal to the time delay between the first and second purge.

15. The method of any of claims 11 to 13, wherein the time delay is inversely proportional to the difference between the first and second parameter measurements.

16. The method of any of claims 11 to 15, further comprising determining a duration in which the valve is actuated to remain open during the second purge.

17. The method of any of claims 11 to 16, further comprising implementing a purge cluster, in which the valve is repeatedly opened and closed a number of times.

18. The method of claim 17, comprising implementing the purge cluster in dependence onthe difference between the first and second parameter measurements of altitude or humidity.

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