An application of a homogenization method to the estimation of effective thermal conductivity of a hydrogen storage alloy bed considering variation of contact conditions between alloy particles

A homogenization method is applied to the estimation of effective thermal conductivity of a hydrogen storage alloy bed. By including the contact conditions between the alloy particles, the effect of contact conditions on the thermal conductivity is investigated. When the pressure is lower than 1 bar, the effective thermal conductivity increases with an increase in the mean gap distance and the contact ratio of point contact. On the other hand, when the pressure is higher than 1 bar, the effective thermal conductivity increases with an increase in the contact ratio of plane contact and the Biot number. In addition, in the comparison of the parameters before and after charge and discharge cycles, it is shown that the mean gap, the contact ratio of plane contact and Biot number are involved in a decrease in effective thermal conductivity of the pulverized alloy particle bed.