Influences of water and salt contents on the thermal conductivity of loess

In recent years, with the development of geothermal resources, the thermal conductivity of soil has become a research hotspot. In this study, the thermal conductivity measured by the transient plane heat source method was used to evaluate five common thermal conductivity models from the previous literature. The influences of water content and salt content on the internal heat transfer mode of this soil are explored. It was found that the presence of water in soil changes the conventional mode of point-to-point heat transfer between solid soil particles. With increases in water content, liquid bridges are formed between particles. During their formation, NaCl brine can transfer heat in a similar way to water. In this experiment, the model of Usowicz et al. (Intern J Heat Mass Transfer 57:536-571, 2006) was found to best describe the thermal conductivity of soil with salt contents of 0%, 2%, 4% and 6%. This study provides a valuable reference for the development of geothermal resources in the Guanzhong area and for engineering projects in loess areas.

Automated summary

This study used the transient plane heat source method to measure thermal conductivity and explored the effects of water and salt content on heat transfer within soil. The formation of liquid bridges and the heat transfer behavior of NaCl brine were observed, with the model by Usowicz et al. found to best describe soil thermal conductivity with salt contents ranging from 0% to 6%. The research provides valuable insights for geothermal resource development in the Guanzhong area and engineering projects in loess regions.