Meanwhile, the water vapor in stack anode exhaust could also be recycled, which contributes to the overall water utilization. For air intake, a filter is necessary to wipe out the poisonous impurities [12]. An air compressor or blower is necessary for increasing the reactant gas pressure. Besides, a radiator or an intercooler is usually placed after the compressor since the air temperature rises significantly after compression. The humidification of air is achieved by the membrane humidifier. Although there are researcheswhich utilizes liquid water to humidify the inlet gases [13], it significantly increases the system complexity compared with utilizing stack cathode exhaust for humidification. A water knockout is placed before the purge valve in order to separate the product water. In reality, the cathode operating pressure of stack is guaranteed by the cooperation of air compressor and purge valve. The heat management subsystem not only maintains the appropriatestack operating temperature but also reduces the temperature difference among each individual cell