土壤水力学特征对水平埋管换热能力的影响分析

INFLUENCE OF SOIL WATER RETENTION CHARACTERISTICS ON HEAT TRANSFER PERFORMANCE OF HORIZONTAL BURIED PIPES

以土壤毛管水力特征曲线为基础,通过数值模拟手段,计算分析地下水位线变化对水平换热埋管换热特性、土体热失衡风险和热泵机组技术经济特性的影响规律,并提出“单位热影响面积换热量”这一新的评价指标,讨论土壤水力学特征对水平埋管换热能力的影响规律。研究结果表明:随着地下水位线埋深变浅,埋管水平土壤含水饱和度从12%增加到100%时,在制冷工况下,水平管延米换热量增加了30%,出口水温降低了23%,单位热影响面积换热量提高了47%;制热工况下,水平管延米换热量增加了24%,出口水温升高了25%,单位热影响面积换热量提高了39%。地下水位线埋深和土壤中含水饱和度对水平埋管换热器地下换热效率影响显著。同时,不同水力特征曲线的蓄能土体热失衡风险具有差异性。

Based on the capillary water retention curve of the soil,this paper used the numerical modeling approach to investigate the influence of variation of water table on the heat exchange performance of horizontal pipes,heat imbalance risks of the energy storage soils and the techno-economic of heat pump.A new concept named“heat exchange per thermal impacted area”was proposed in this paper.The study results demonstrate that,as the water table depth reduces,and the soil water content increases from 12%to 100%,in the cooling mode,the heat transfer per meter of the horizontal pipe increases by 30%,the outlet water temperature decreases by 23%,and the heat exchange per thermal impacted area increased by 47%;in the heating mode,the heat transfer per meter of the horizontal pipe increases by 24%,the outlet water temperature ratio increases by 25%,and the heat exchange per thermal impacted area increases by 39%.The influence of variation in water table and water soil content is very obvious.Also,the difference of heat imbalance risk in soils under different water retention curves are discussed.