Abstract: Methods and systems are provided for cold-start of fuel cell stack in fuel cell vehicles. In one example, a method may include in response to cold-start of fuel cell vehicle, limiting the load drawn from the fuel cell stack. In addition, a coolant pump may be operated at a higher rate through a bypass loop to get heat quickly to the fuel cell stack to increase the solubility of water in the fuel cell stack to prevent ice formation. The net effect is that the fuel cell stack is then operated within the ice capacity of the membrane, and start-up at lower temperatures is possible without experiencing an intermittent performance drop due to active area freezing. Once the fuel cell stack is sufficiently warmed up, the coolant pump rate and fuel cell stack may be adjusted according to the demand.

Abstract: A method for starting operation of a solid polymer fuel cell from a temperature below 0° C. is disclosed that prevents certain problems with ice formation as the fuel cell thaws. During startup, the method involves providing the volumetric oxidant flow at a rate less than two thirds of its maximum when the coolant temperature is near 0° C.

Abstract: Methods and systems are provided for cold-start of fuel cell stack in fuel cell vehicles. In one example, a method may include in response to cold-start of fuel cell vehicle, limiting the load drawn from the fuel cell stack. In addition, a coolant pump may be operated at a higher rate through a bypass loop to get heat quickly to the fuel cell stack to increase the solubility of water in the fuel cell stack to prevent ice formation. The net effect is that the fuel cell stack is then operated within the ice capacity of the membrane, and start-up at lower temperatures is possible without experiencing an intermittent performance drop due to active area freezing. Once the fuel cell stack is sufficiently warmed up, the coolant pump rate and fuel cell stack may be adjusted according to the demand.

Abstract: A method for starting operation of a solid polymer fuel cell from a temperature below 0° C. is disclosed that prevents certain problems with ice formation as the fuel cell thaws. During startup, the method involves providing the volumetric oxidant flow at a rate less than two thirds of its maximum when the coolant temperature is near 0° C.

Abstract: A fuel cell system comprising a fuel cell stack, a fuel recirculation line provided with a jet pump and a valve controlled by a control unit based on the anode-cathode pressure differential such that the valve is closed to reduce or stop fuel supply when the anode-cathode pressure differential reaches a predetermined value, and opened again to circulate more fuel through the jet pump when the pressure differential is below a predetermined value, to create a pulsed fuel supply that improves the fuel recirculation at low loads and ensures adequate water removal from the anode flow field channels.

Abstract: Start up systems and methods for a fuel cell system are disclosed. The start up systems and methods include supplying a hydrogen containing fluid to both the cathode electrode and the anode electrode of the fuel cell at substantially the same time during a first stage in the start up, ceasing the supply of the hydrogen containing fluid to the cathode electrode during a second stage of the start up, and supplying an oxidant to the cathode electrode at a third stage in the start up of the fuel cell.

Abstract: Methods and systems for reducing irregularities in temperature distribution in the operation of a fuel cell stack during a load transient based on the actual stack outlet temperature. In representative embodiments, the coolant flow rate and/or the oxidant stoichiometry is adjusted during a load transient based on a determined value for the same in view on the actual stack outlet temperature. As a result, the fuel cell reaches steady state conditions more quickly, thus reducing periods of non-steady state fuel cell operation.

Abstract: A fuel cell stack is provided having a plurality of fuel cells, each including a membrane electrode assembly interposed between anode and cathode flow field plates that form anode and cathode channels, respectively. An accumulating device is positioned downstream of the fuel cell stack. A purge control device is positioned downstream of the accumulating device operable in a first state to allow fluid communication between the anode and cathode channels, and in a second state to isolate an oxidant outlet from the accumulating device. Some embodiments include a purge control device between the anode channels and the accumulating device. A method of operation of the fuel cell stack includes selectively purging fluids from the fuel cell stack into the accumulating device at a first time and selectively purging fluids from the accumulating device at a second time, subsequent to the first time.