Fuel Cell Energy Recovery

The mission of GVE with this research grant is to develop high power density, high-efficiency energy recovery system for fuel cell system. Utilization of its patented Jirnov Vortex Turbine (JVT) bottoming cycle engine will increase the overall efficiency of fuel cell. The robust design of the JVT allows using a fuel cell raffinate stream for the bottoming cycle. The fuel cell stream consists of high enthalpy gases such as 0.065 H2, 0.41 H2O, 0.019 CO, 0.20 CO2, 0.016 CH4, 0.29 N2, and H2S. The stream temperature is 400C (673.1K), pressure is 7 Bars (709275 Pa) and flow rate is 900 Kg/hr (0.250 Kg/s). The stream is not combustible, but presents the highly corrosion mixture. Available fuel cell stream waste energy is 100kW. Energy recovered with the General Vortex Energy Inc., Positive Displacement Rotary Expander (PDRE) is about 60 kW. The conventional energy recovery technologies require further separation of hydrogen, water and H2S and then using the stream in the waste energy recovery system (heat exchanger), piston expander or turbine. First, the bottoming cycle based on the piston expander and turbine is not as efficient as the JVT cycle. Second, the separation devices will increase the volume and mass of the bottoming cycle device and reduce the power density. Another conventional method of energy recovery is using the heat exchanger to transfer the energy of fuel cell stream to some closed bottoming cycle. In this case efficiency is reduced by the heat exchanger and complicated by closed cycle device. Thus the power density and overall efficiency will suffer again.