间歇储热模式下低含水率土壤的增湿传热实验研究

在间歇储热模式下,本文对一维土柱传热实验台中热源附近的低含水率土壤分别进行加热初始时刻和恢复初始时刻的渗水增湿(50 ml、100 ml、150 ml),实验分析两时刻增湿量对土壤传热和温度恢复效果的影响。测试结果表明,在加热初始时刻增湿后,土壤的平均温度响应时间随增湿量的增加分别缩短28.7%、37.3%、43.2%,各温度测点峰值与土壤整体温度均有提升,且传热改善效果与增湿量呈正相关,同时在后续恢复阶段土壤温度恢复率随增湿量增加而增加,热源作用下的水分迁移有效增强了热扩散和温度恢复过程。恢复初始时刻增湿,土壤平均温度恢复率较未增湿工况增加13%-16%,热源处的热量扩散显著增强,恢复终温比未增湿工况分别低2.75℃、3.11℃、3.26℃,土壤整体温度出现先上升后下降趋势,越靠近热源处土壤温度恢复率增加越显著,但随增湿量的增加无明显差异,恢复阶段初始进行少量增湿即可增强低含水率土壤温度恢复,这与土壤的热湿特性有关。

Experimental Study on Heat Transfer of Soil with Low Moisture Content under Humidification Condition in Intermittent Heat Storage Mode

A one-dimensional soil column experimental platform is built to study the soil heat transfer and temperature recovery under the intermittent heat storage mode. The experiment is designed with the condition of humidification to the soil near the heat source. The soil near the heat source are humidified with 50 ml, 100 ml and 150 ml water respectively at the initial moment of heating and recovering. After the humidification at the initial moment of heating, the average speed of temperature response of soil shorten for 28.7%, 37.3% and 43.2% respectively, with the increase of the amount of water. At the same time, the peak temperature of each measuring point as well as the overall temperature of soil increases. The effect of heat transfer is positively correlated with humidification. Also, the soil temperature recovery rate increases with the increase of the amount of water injection during the subsequent recovery period. That is because the water migration under the thermal effect of the heat source enhances the thermal diffusion and temperature recovery in an effective way. After the humidification at the initial moment of recovery, the average temperature recovery rate of soil increased by 13%~16% compared with that of non-humidified condition. The heat diffusion of the soil at the heat source is significantly promoted. The final temperature is 2.75 ℃, 3.11 ℃ and 3.26 ℃ lower than that of the non-humidified condition. The temperature of other measurement points rises first and then decreases to a lower value. Besides, the soil temperature recovery rate increases with the shortening of the distance with heat source. However, there is no significant difference with the increase of the amount of water. Due to the heat and humidity characteristics of the soil, a slight amount of humidification in the initial moment of recovery can strengthen the recovery of soil temperature.