桩埋管与井埋管实验与数值模拟

Experiment and Numerical Simulation on U-Vertical Ground Coupled Heat Exchanger with Sandstone and Cement Backfills

建立了一套组合型地下埋管换热器地源热泵实验系统,针对该系统所采用的不同回填材料U型垂直埋管即沙石回填的U型井埋管和混凝土回填的U型桩埋管换热器,分别进行在不同进口温度和流量下的取热和排热实验,分析这两种埋管换热器的换热效果和性能.理论上,采用所建立的内热源埋地换热器理论模型和专业软件,对这两种埋管方式的周围土壤温度场进行数值模拟.经检验,理论计算与实验结果吻合较好.相同实验工况下,得到了U型桩埋管的换热效果和换热稳定性要优于U型井埋管.排热时,U型桩埋管比U型井埋管的单位井深换热量提高62.50/0,取热时,提高约160/0.

An experimental system of ground coupled heat pump （GCHP） was set up with two types of U-vertical ground coupled heat exchanger （UGCHE） , one of which was a UGCHE with sandstone backfills and the other was a UGCHE with cement backfills. Experiments were carried out on these two types of UGCHE at different inlet temperature and flow rate. The effect and performance of the two types of heat exchanger were analyzed. An inner heat source model and a professional computer software were adopted to conduct the numerical simulations in the temperature field of the soil around the underground heat exchanger. Simulation results coincided with the experimental results. Under the same experimental condition, the UGCHE with cement backfills had a better performance and stability than the one with sandstone backfills. In heat emission mode, the heat exchange rate per depth of the UGCHE with cement backfills was 62.5% higher than the UGCHE with sandstone backfills, and it was 16% higher for the heat extraction mode.