Exergetic evaluation of a high-pressure hydrogen production system

Abstract

This study presents exergetic assessment of a high-pressure hydrogen production system (HPS). The system considered in this study includes a high-pressure proton exchange membrane (PEM) electrolyzer, two heat exchangers, a motor pump system, a circulation pump, and a hot water tank. In order to perform the main objective of this study, the following important parameters are taken into consideration: (1) the operating pressure (ranging from 1 to 200 bar), (2) the operating temperature (ranging from 70 to 80 °C), (3) dead-state temperature (assumed to be 25 °C), (4) the energy efficiency of the PEM electrolyzer (ranging from 0.5 to 1), (5) the pump efficiency (assumed to be 0.8), (6) mass flow rate of hydrogen from PEM electrolyzer (3 kg per hour), and (7) mass flow rate of pure water supplied to the PEM electrolysis (27 per hour). Considering all these parameters, exergy analysis is performed for the HPS. The results show that exergy efficiency of HPS increases with the rise of the operating pressure and temperature. It thus requires a higher amount of energy input. In this regard, there is a strong need to optimize the process.