This work presents the impact of reactor design on the thermal performance and energy
storage during the dehydration of salt hydrate of thermochemical material; magnesium chloride
hexahydrate (MgCl2.6H2O). The dehydration process is performed by flowing hot air through the
material. A transient 2D axisymmetric mathematical model for an open thermochemical long-term
heat storage reactor by using COMSOL Multiphysics software is presented. Two configurations
of the reactor design are considered; cylinder and truncated cone having the same height and
volume of seven designs; cylindrical (base design), convergent truncated cones of inlet to outlet
area ratio (AR) 1.4, 4 and 5.8 and divergent truncated cones of AR 0.71, 0.25 and 0.17. Results
show that the reactor of lower AR has the lower charging time and higher pressure drop and
temperature difference. However, the reactor design hasn’t great impact on the maximum value of
water content concentration inside the thermochemical material. Maximum variation of the energy
storage of the thermochemical material is about 25.5% and the dehydration time more than three
times due to design reactor changing. Maximum stored energy is achieved for the reactor truncated
cone of AR 1.4 while the minimum desorption time is obtained for the cone of AR 0.17%.