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The development and characterization of new materials is of extreme importance in the design of cryogenic apparatus. Recently a kind of open-cell aluminum foam was used for heat transfer enhancement at cryogenic temperature. Such aluminum foam was tested for cryogenic energy storage with a phase change material of nitrogen. The thermal conductivity of the open cell aluminum foam was studied. The thermal conductivities of the aluminum foam were measured between 50 K and 170 K. The results have shown that the thermal conductivity increases with the temperature decreases. Then the effects of thermal conductivity of open-cell aluminum foams on the performance of aluminum foam phase change material thermal storage unit were investigated. Nitrogen was selected as the phase change material. Temperature variations of the thermal storage unit during cooling and melting processes were tested. Test result has shown that the maximum temperature difference between the up and bottom of the thermal storage unit is less than 0.5 K, much lower than the case without aluminum foam. It was concluded that as the thermal conductivity of thermal storage unit increases, both the container temperature difference and temperature variation of the thermal storage unit decrease. #$NL