Profiles of hydrogen molar fraction and temperature in ZrV1.9Fe0.1 alloy bed for hydrogen absorption

Profiles of hydrogen molar fraction and temperature in a long ZrV1.9Fe0.1 alloy particle bed with a small diameter were determined experimentally and analytically as a basic study of chemical heat pumps operated at higher temperature. Since the alloy bed absorbed hydrogen even at 873 K and generated heat, the alloy was considered a suitable material for heat pump or hydrogen storage at higher temperature. Experimental profiles of both hydrogen molar fraction at the bed outlet and temperature inside the bed agreed with analytical solutions to heat and mass transfer equations. The analytical solutions were obtained under the conditions where constant-pattern approximation could be applied to the temperature and concentration profiles propagating in a bed with the same velocity. Properties relating with heat transfer such as a heat capacity, enthalpy change of hydrogen absorption and a heat-transfer coefficient between a wall and particles were correlated to two dimensionless parameters, α and β.