Circulation of biphase fuel cell coolant
View Patent ↗Coolant velocity greater than zero everywhere within the coolant channels ( 78, 85 ) of fuel cells ( 38 ) in a fuel cell stack ( 37 ) is assured by providing a flow of biphase fluid in the coolant channels, the flow being created by the outflow of a condenser ( 59 ). Positive pressure is applied to the coolant inlet ( 66 ) of the coolant channels. Biphase flow from an oxidant exhaust condenser, which may be a vehicle radiator ( 120 ), renders the coolant return flow more freeze tolerant. Using biphase flow within the coolant channels eliminates the need for a bubble-clearing liquid pump and reduces liquid inventory and other plumbing; this makes the fuel cell power plant more freeze tolerant.
1. A fuel cell power plant comprising:
a stack ( 37 ) of fuel cells ( 38 ), each fuel cell having coolant passageways ( 78 , 85 ) connected between a coolant inlet ( 66 ) and a coolant outlet ( 68 ), a fuel reactant gas flow field plate ( 75 ) connected between a fuel inlet ( 42 ) and a fuel outlet ( 47 ), an oxidant reactant gas flow field plate ( 81 ) connected between an air inlet ( 53 ) and an air outlet ( 57 ), at least one of said plates being porous and hydrophilic, and a membrane electrode assembly, including anode and cathode catalysts, disposed between said flow field plates; and
a controller ( 79 ;
characterized by:
a condenser ( 59 );
said coolant inlet ( 66 a ) includes a gas/liquid separator ( 107 / 108 ) having a gas exhaust outlet controlled by said controller; and
fluid communication between said air outlet ( 57 ), through said condenser, to said coolant inlet ( 66 a ).
2. A fuel cell power plant according to claim 1 further characterized by:
said condenser ( 59 ) is a radiator ( 59 a ) of a fuel cell-powered vehicle ( 120 ).
3. A fuel cell power plant characterized by:
a stack ( 37 ) of fuel cells ( 38 ), each fuel cell having coolant passageways ( 78 , 85 ) connected between a coolant inlet ( 66 ) and a coolant outlet ( 68 ), a fuel reactant gas flow field late 75 connected between a fuel inlet 42 and a fuel outlet 47 an oxidant reactant gas flow field late 81 connected between an air inlet 53 and an air outlet ( 57 ), at least one of said plates being porous and hydrophilic, and a membrane electrode assembly, including anode and cathode catalysts, disposed between said flow field plates; and
a controller ( 79 );
characterized by:
said coolant inlet ( 66 a ) includes a gas/liquid separator ( 107 / 108 ) having a gas exhaust outlet controlled by said controller; and
a condenser ( 59 ) between said air outlet and said coolant inlet; and
fluid communication of two-phase gas/liquid flow from said condenser to said coolant inlet.
4. A fuel cell power plant according to claim 3 further characterized by:
said condenser ( 59 ) is a radiator ( 59 a ) of a fuel cell-powered vehicle ( 120 ).