A numerical analysis was performed to study PEMFC performance characteristics depending on the flow direction of cathode reactant gas, cathode relative humidity, and porosity of gas diffusion layer. As cathode relative humidity decreases and porosity increases, current density increases due to better diffusion of reactant gas to cathode surface. As current density increases, power density increases initially and then decreases with its maximum located around current density value of 2.2 Amperes per square centimeter. From the analysis of current density distribution inside membrane, the counter-flow cases show more uniform profile across the membrane than the co-flow cases due to more uniform reactant gas supply.

A three dimensional numerical analysis was performed to study the cooling performance of xEV battery module depending on cooling fluid inlet position. Depending on the inlet position from the top, case 1 (top inlet), case 2 (middle inlet), and case 3 (bottom inlet) are selected. For the case 1, the temperature of the battery near inlet was higher than that of the battery near outlet. For the case 2 and 3 the temperature of the battery near inlet was lower than that of the battery near outlet. From the analysis result, the cooling performance is higher in the order of case 2, case 3, and case 1.

The temperature distribution of a generic battery module was analyzed for different flow rates of cooling fluid. For the given battery module design, the temperature of battery cell near the inlet is higher than that of battery cell near the outlet. Because the inlet is located at the higher elevation than the top of battery electrodes, most of the incoming cooling fluid flows directly towards the battery housing wall above the outlet. For the inlet velocities of 1, 3, 5 m/s, the maximum temperature differences are 28, 19, 15 degrees Celcius respectively.

A numerical analysis was performed to study PEMFC characteristics depending on the flow direction of reactant gas in cathode gas channel using the Fluent. As cathode relative humidity increases, water mass fraction increases due to back diffusion from cathode. For the both of co-flow and counter-flow cases, water mass fraction is higher near the hydrogen inlet region where the chemical reaction rate is high. In overall, counter-flow case gives higher current density compared to co-flow case for the same operating conditions. However, the difference in the current density is not high. The temperature is also higher near the hydrogen inlet region due to the chemical reaction rate for the both of co-flow and counter-flow cases.

A numerical analysis was performed to study PEMFC characteristics depending on GDL porosity and the inlet direction in cathode gas channel using the FLUENT. As GDL porosity increases, temperature increases. For the both of co-flow and counter-flow cases, temperature is higher near the hydrogen inlet region where the chemical reaction rate is high. As GDL porosity increases, current density increases. In overall, counter-flow case gives higher current density compared to co-flow case for the same operating conditions. However, the difference in the current density is not high. The water mass fraction is also higher near the hydrogen inlet region due to the chemical reaction rate for the both of co-flow and counter-flow cases.

The EnergyPlus is used for the analysis of energy demand at two rural house models. Photovoltaic (PV) system is installed to reduce the energy demand of annual building. The energy economic analysis is performed to provide quantitative data at choosing a suitable house model. Two types of PV system installations are considered as each building type. Among 4 different cases analyzed through this study, the best setup is provided for 12.3 years at recovering PV system installation cost.