蓄/取热工况套管式地埋管换热器换热特性试验研究

Experimental Study on Heat Transfer Characteristics of Casing Type Buried Tube Heat Exchanger under Heat Storage/Extraction Condition

为研究竖直套管式地埋管的非稳态传热特性,通过搭建竖直套管式地埋管传热特性砂箱试验台,对竖直套管式地埋管进行了试验研究,分析了蓄热工况和取热工况下不同运行模式对竖直套管式地埋管以及其周围土壤传热特性的影响,获得了竖直套管式地埋管流体的进出口水温、周围土壤温度、单位井深换热量以及平均传热系数的变化规律。试验研究结果表明:蓄热工况下在间歇运行模式分别为1∶1与1∶2情况下,启停比越小,地埋管周围土壤温度波动范围越大;取热工况下,距离地埋管径向距离越远的土壤温度受启停比时间的影响较小;间歇运行模式下的单位井深换热量比连续运行模式下单位井深换热量高,运行72 h时启停比1∶1模式下单位井深换热量比连续模式下单位井深换热量高157.98 W/m。可见间歇运行模式有利于土壤恢复,实际工程中可根据建筑要求合理选择间歇运行。

In order to study the unsteady heat transfer characteristics of the vertical casing buried pipe,an experimental study on the vertical casing buried pipe was carried out by building the sand box test bench for heat transfer characteristics of the vertical casing buried pipe,the analysis of the working condition of heat storage and heat removal conditions different operation mode on the vertical pipe ground tube and the influence of the soil around heat transfer characteristics,the variation rules of inlet and outlet water temperature,surrounding soil temperature the average quantity of heat pet meter and the average heat transfer coefficient were obtained.The experimental results show that the smaller the start-stop ratio,the larger the fluctuation range of soil temperature around the buried pipe when the intermittent operation mode is 1∶1 and 1∶2 under heat storage condition.In the process of heat extraction,the soil temperature with the distance from the diameter of the buried pipe is less affected by the start-stop ratio time.The average quantity of heat pet meter in intermittent operation mode is higher than that in continuous operation mode.When running for 72 h,the average quantity of heat pet meter under start-stop ratio 1∶1 mode is 157.98 W/m higher than that under continuous mode.It is concluded that intermittent operation mode is beneficial to soil restoration,so the intermittent operation can be reasonably selected according to the building requirements in practical engineering.