开孔泡沫铝的低温热导率测量及其低温蓄冷应用研究

新型材料的应用对低温装置的发展起具有重大意义。为提高低温蓄冷装置的温度均衡性,一种孔隙率为63%的开孔泡沫铝材料最近在一种低温蓄冷装置中进行了实验研究。实验测试了样品从50 K到170 K的热导率,测试结果显示开孔泡沫铝在测试温度区间内热导率随温度降低而升高,其平均值为22W·(m·K)~(-1)。实验测试了开孔泡沫铝热导率对采用泡沫铝低温蓄冷装置的性能的影响。蓄冷装置中采用的相变材料为氮。实验中主要测试值为蓄冷装置在降温过程和融化过程中的温度值。实验结果显示,此装置上、下部分的最大温差小于0.5 K,远小于不采用开孔泡沫铝时的温差。随着低温蓄冷装置热导率的提高,蓄冷装置上、下部温差以及单个温度测定的温度波动均减小。

Thermal Conductivity of Open Cell Aluminum foam and Its Application as Advanced Thermal Storage Unit at Low Temperature

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