水合物导热系数和热扩散率实验研究

基于Hot Disk热常数分析系统的单面测试功能，建立了一套新的天然气水合物热物性测试系统，并实验研究了I型水合物（甲烷）、H型水合物（甲烷和甲基环己烷）的导热系数和H型水合物的热扩散率。结果显示甲烷水合物样品导热系数随温度的变化非常小，平均导热系数约为0.53 W/(m•K)。结合文献报道和实验分析发现零孔隙率甲烷水合物的导热系数大约为0.7 W/(m•K)，水合物样品在压缩过程中虽然减少了孔隙，但是却引起晶体破碎，导致导热系数与理想值差距较大。水合物的导热系数与水合物的类型及客体分子有关，大体顺序为I型 > II型 > H型 > 半笼型水合物。甲烷−甲基环己烷生成的H型水合物热扩散率为0.205 ~ 0.26 mm2/s，和其他类型的水合物相当；水合物的热扩散率大约为水的两倍，而导热系数和水相近。

Experimental Study on Thermal Conductivities and Diffusivities of Gas Hydrate

By improving the Hot Disk thermal constant analysis system, a new thermal properties measurement method of natural gas hydrate was established. The thermal conductivities of structure I hydrate (methane), structure H hydrate (methane-methylcyclohexane) and the thermal diffusivities of structure H hydrate were studied. The results show that the thermal conductivities of methane hydrate sample were very small, and the average thermal conductivity was about 0.53 W/(m•K). By analysis of the experimental data and the literatures, the optimized thermal conductivity of the zero-porosity methane hydrate is about 0.7 W/(m•K). Moreover, the order of magnitude for the thermal conductivity were structure I > structure II > structure H > semi-clathrate hydrate. The thermal conductivity depended on not only the cage type but also the species of the guest molecules. The thermal diffusivity of the hydrate is about twice that of the water, while the thermal conductivity is similar to that of water.