Design and optimization of a fan-shaped fluid channel reactor for magnesium hydride hydrogen storage: CFD simulation and response surface analysis

Magnesium hydride (MgH₂) has attracted much attention due to its high hydrogen storage density and excellent safety properties. However, heat removal from the MgH₂ bed during the hydrogen storage process is crucial. To increase the heat transfer area and further enhance hydrogen absorption performance, this study proposes a fan-shaped fluid channel reactor (FFCR). It simulates its hydrogen absorption process using COMSOL Multiphysics v6.1. The results show that increasing the number of fluid channels significantly improves heat transfer rate and reduces hydrogen storage time. Increasing the flow rate of the thermal fluid and the inlet hydrogen pressure also helps to shorten the hydrogen storage time. However, the hydrogen absorption rate slows down as the inlet temperature of the thermal fluid increases. A quadratic regression model of the operating parameters during hydrogen absorption in the FFCR is developed using response surface analysis. Considering both hydrogen absorption time and manufacturing constraints, a configuration with 5 channels ((Formula presented) ), a channel angle ((Formula presented) ) of 14.4°, and a height-to-diameter ratio ((Formula presented) )of 2 is ultimately recommended. Under optimal operating conditions, this newly designed FFCR, which exhibits excellent heat transfer and reaction performance, can achieve 90% hydrogen absorption saturation within 724 s. The FFCR demonstrated superior performance in the simulation, and this conceptual design provides theoretical basis and design guidance for the subsequent engineering development.