INTERNAL STEAM GENERATION FOR FUEL CELL
A fuel cell system includes a fuel cell stack having an anode plate and a cathode plate arranged on opposing sides of a proton exchange membrane. Cooling channels are in thermal contact with at least one of the anode plate and the cathode plate and include an internal coolant passage. A pressure-drop device is provided in the coolant channels and is configured to provide a sub-atmospheric pressure within the coolant passage. In one example, the coolant within the coolant passage is at less than ambient pressure. A compression device fluidly interconnects to and is downstream from the internal coolant passage by a coolant system loop and configured to convey a sub-atmospheric pressure coolant steam. The compression device is configured to increase the pressure and a temperature of the sub-atmospheric coolant steam to a super-atmospheric pressure and maintain the coolant steam within a steam region of a pressure-enthalpy curve.
1 . A fuel cell system comprising:
a fuel cell stack including an anode plate and a cathode plate arranged on opposing sides of a proton exchange membrane, and coolant channels including an internal coolant passage in thermal contact with at least one of the cathode and anode plates;
a pressure drop device provided in the coolant channels and configured to provide a sub-atmospheric pressure within the coolant passage; and
a compression device fluidly interconnect to and downstream from the internal coolant passage by a coolant steam loop configured to convey a sub-atmospheric pressure coolant steam, the compression device configured to increase the pressure and a temperature of the sub-atmospheric coolant steam to a super-atmospheric pressure and maintain the coolant steam within a steam region of a pressure-enthalpy curve.
2 . The fuel cell system according to claim 1 , wherein the coolant channels are provided by a porous layer of at least one of the anode plate and the cathode plate.
3 . The fuel cell system according to claim 2 , wherein the porous layer provides the pressure drop device.
4 . The fuel cell system according to claim 3 , comprising a spray nozzle arranged in the coolant passage configured to provide spray water droplets into the coolant passage for conversion to the coolant steam.
5 . The fuel cell system according to claim 1 , wherein the coolant channels are provided by a solid non-porous plate provided by at least one of the anode plate and the cathode plate.
6 . The fuel cell system according to claim 5 , comprising a spray nozzle arranged in the coolant passage configured to provide spray water droplets into the coolant passage for conversion to the coolant steam.
7 . The fuel cell system according to claim 1 , wherein the compression device includes a scroll compressor.
8 . The fuel cell system according to claim 1 , comprising a fuel source in fluid communication with the coolant steam loop at a junction via a fuel supply line, the junction downstream from the compression device and configured to intermix a fuel and the super-atmospheric pressure coolant steam to provide a mixture.
9 . The fuel cell system according to claim 8 , comprising a fuel processing system in fluid communication with the junction and configured to receive the mixture, the fuel processing system fluidly interconnected to the anode plate via a reformate line and configured to provide a reformate thereto through the reformate line.
10 . The fuel cell system according to claim 1 , wherein the fuel cell stack is configured to operate at an equilibrium operating condition providing an internal cell stack coolant temperature of less than 100° C.
11 . The fuel cell system according to claim 1 , comprising a building fluid loop, and a heat exchanger including the building fluid loop and the coolant steam loop configured to transfer heat there between.
12 . The fuel cell system according to claim 1 , wherein the coolant steam is configured to undergo quasi-isentropic compression in the compression device in comparison to an entropy of the coolant steam within the fuel cell stack.
13 . A method of producing steam within a fuel cell system comprising:
creating a pressure drop within a fuel cell stack to lower the boiling point of coolant within the fuel cell stack;
boiling the coolant within the fuel cell stack to produce steam; and
supplying the steam to a component outside of the fuel cell stack via a coolant steam loop.
14 . The method according to claim 13 , wherein the creating step includes providing a coolant temperature within the stack of less than 100° C. and a pressure of less than atmospheric pressure.
15 . The method according to claim 13 , wherein the supplying step includes quasi-isentropically compressing the steam, in comparison to an entropy of the steam within the fuel cell stack, to a pressure greater than atmospheric pressure and maintaining the steam within a steam region of a pressure-enthalpy curve.