Experimental study on the hydrogen charge and discharge rates of metal hydride tanks using heat pipes to enhance heat transfer

Heat transfer is a critical factor affecting the performance of metal hydrogen storage tanks. Many studies have proposed inner tubular heat exchangers for increasing the heat transfer rate between the metal powders and the exterior environment of the tanks. However, connecting cooling and heating fluid tubes to the storage tanks can be a tedious task, especially for large-scale hydrogen storage systems with a large array of tanks. This study presents a novel design for a metal hydride vessel equipped with heat pipes. These heat pipes enhance heat transfer for hydrogen charge and discharge without the need for tubing through the metal bed. This study experimentally demonstrates the effects of using heat pipes to enhance heat transfer in a hydrogen storage tank using LaNi5 as the storage media and comparing tanks with and without heat pipes. Results show that heat pipes can enhance the hydrogen storage rates in both absorption and desorption. The absorption time was reduced more than half with a 10 atm hydrogen supply pressure, and the desorption time for hydrogen discharge at 1 L/min was increased by 44%.