Performance Analysis of a Single-Stage Metal Hydride Hydrogen Compression System

In this study, a two-dimensional transient computational fluid dynamics (CFD) model is developed using ANSYS Fluent to investigate the performance of a single-stage metal hydride hydrogen compression (MHHC) system. The system integrates waste heat recovery from an electrolyzer with a pair of MH reactors charged with a TiFe-based alloy. The model is validated against experimental data from the literature, ensuring its accuracy in predicting key system performance metrics, including hydrogen sorption capacity, compression work, energy consumption, hydrogen productivity, and compression efficiency under varying operating conditions. Specifically, the effects of the high-temperature heat source (TH), varied between 70 °C and 80 °C, and the low-temperature heat sink (TL), ranging from 10 °C to 20 °C, are analyzed while maintaining constant hydrogen suction and discharge pressures at 5 and 15 bars, respectively. The results demonstrate that increasing TH and decreasing TL significantly enhance MHHC system performance. Under the studied conditions, a maximum compression efficiency of 8.861% is achieved at TH = 80 °C and TL = 10 °C. Additionally, the influence of MH alloy thermal conductivity is evaluated over the range of 1.6–4 W/(m∙K). Improvements in thermal conductivity are found to increase hydrogen sorption capacity, compression work, and compression efficiency by up to 21.1%, 21.4%, and 12.1%, respectively.