Exergetic and exergoeconomic evaluation of a trigeneration system based on natural gas-PEM fuel cell

In this study, the performance of a novel micro-combined heat and power generation system (mCHP) based on PEM fuel cell is analyzed from exergoeconomic aspect of view. The main components of the system are a 10 kW PEM fuel cell stack, a thermal energy storage tank based on phase change material, an absorption chiller, and a steam reformer that operates using natural gas. The main objective of this study is to perform an exergoeconomic evaluation on a PEM fuel cell system integrated with absorption chiller, which is designed to supply electrical energy, hot water and space cooling for a residential application. The effects of working temperature, pressure, current density, and heat source temperature of generator on the performance of the system are studied. The results reveal that besides operating pressure and temperature, fuel cell voltage can significantly affects the exergy cost of the system. It is concluded that by increasing the heat source temperature, the exergy cost of chilled water decreases and the COP of absorption chiller can be increased by more than 30%. Also, it is found that the PEM fuel cell, storage tank, and evaporator have the highest exergy destruction cost rates, respectively.