不同运行模式下土壤-空气换热器热性能研究

基于多孔介质传热传质理论,建立了二维非饱和土壤耦合热湿迁移的数学模型。基于有限体积法,利用FORTRAN语言开发了二维椭圆型传热传湿计算程序。利用自编程序对不同运行模式下的土壤-空气换热器系统进行了全面的数值研究。连续模式下系统连续运行24 h;间歇模式1下系统运行60 min,然后停止运行30 min;间歇模式2下系统运行60 min,然后停止运行60 min.结果表明,在连续模式下较高含湿量的土壤比较低含湿量的土壤的系统热性能提升20.13%,含湿量较低的土壤在间歇模式下运行系统热性能较连续模式提升12.7%。

Investigation on Thermal Performance of Earth-to-Air Heat Exchanger Under Different Operation Strategies

Based on the theory of the heat and mass transfer of the porous media,a bi-dimensional mathematical model coupled the heat and moisture transfer in unsaturated soil is established.Furthermore,a bi-dimensional elliptical heat and mass transfer calculation program is developed for this mathematical model by using FORTRAN language with the finite volume method.A comprehensive numerical study on the earth-to-air heat exchanger(EAHE)system is conducted by a self-complied program.In continuous mode,EAHE system works continuously for 24 h;in intermittent mode 1,it works for 60 min and then it is off for 30 min;in intermittent mode 2,it runs for 60 min and remains off for 60 min.The result show that in continuous mode,higher moisture content soil improves the system thermal performance by 20.13%as compared to least moisture content soil and soil with lower moisture content shows system thermal performance improvement of 12.7%when operated in intermittent mode as compared to continuous mode.