Waste heat recovery from a 1180 kW proton exchange membrane fuel cell (PEMFC) system by Recuperative organic Rankine cycle (RORC)

Nowadays due to the permanent increase in energy consumption and its high cost and also nonrenewable energies' destroying effects, clean technologies such as fuel cells should be supported and used. In present study, waste heat recovery of a low temperature proton exchange membrane fuel cell is surveyed using a recuperative organic Rankine cycle. The PEMFC system is equipped with a metal hydride storage. The key point of present study is that the heat absorbed from stack is utilized for other components in addition to RORC. Thus, different possible cycle configurations according to how cooling water circulates among RORC, pre-heater and metal hydride are thermodynamically analyzed. Furthermore, effects of RORC working fluid mass flow rate and pressure ratio are investigated. Moreover, three RORC working fluids are surveyed including: R-245fa, R-245ca and R-123. Results indicate thermal efficiency rise by increase in RORC working fluid mass flow rate with different gradients. Additionally, pressure ratio increase leads to rise in net output power and thermal efficiency. Models 8 has highest efficiency with 44.3% and R-123 is the best working fluid.