In this study, a general proton exchange membrane fuel cell (PEMFC) model has been developed in order to investigate the balance of plant of a fork-lift truck thermodynamically. The model takes into account the effects of pressure losses, water crossovers, humidity aspects, and voltage overpotentials in the cells. Moreover, it is zero-dimensional and is assumed to be steady state. The system includes a compressor, an air humidifier, a set of heat exchangers, and a stack that together build up the anode circuit, the cathode circuit, and the cooling loop. Several issues are discussed: water management, system sensitivity to coolant inlet temperature, air and fuel stoichiometry, anode inlet pressure, stack operating conditions, etc. System efficiency and electrical power at different operating conditions are also discussed. The results show that 12–30% of stack power is allocated for the auxilary components depending on the stack power or current. Further, at the higher current densities, heat losses and net power of the system increase, while system efficiency decreases. Furthermore, the system performance was not sensitive to the coolant temperature when water is used as the coolant.
International Journal of Green Energy, 2013, Vol 10
PEMFC; Fuel cell; System layout; Fork-lift; General model; Polarization curve