On the basis of thermal conduction differential equations under microgravity condition

the enthalpy method was applied to establish calculation model for phase change heat storage unit in heat pipe receivers.Considering both the void cavity and phase change

numerical simulation was carried out.The effects of void cavity on temperature field and thermal performance of the phase change material(PCM)canister were investigated.The results show that

compared with the National Aeronautics and Space Administration(NASA)results

the established model is reasonable and accurate

which can well simulate the heat storage and release process of the PCM canister.The wall temperature of the heat pipe receiver is close to that of the PCM canister

implying the entire heat pipe containing PCM plays a role in heat load uniformity.The maximum melting rate of the PCM is 92%

indicating the utilization efficiency of the PCM is high.With an increase in void cavity

the unmelted PCM amount increases in the area close to the void during the last stage of solar radiation and the unconsolidated PCM amount increased during the last stage of shadow

indicating the PCM's utilization efficiency decreased and the PCM tank's heat storage capability reduced.Moreover

the temperature gradient in the PCM heat storage tank increased

which may cause over high thermal stress

leading to a decrease in the tank's service life.