Study On The Influence Of Loess Modification And Moisture And Heat Transfer On Its Thermal Conductivity

The problem of energy reuse in China is still one of the problems that need to be solved urgently.The ground source heat pump system has attracted more and more attention as a highefficiency renewable energy utilization method.China is the country with the widest loess distribution area.How to realize the applicability of the ground source heat pump system in the loess area is the current problem.Realizing the application of loess materials as backfill materials for ground source heat pumps and improving the thermal conductivity of modified loess materials are one of the key factors to solve this problem.In addition,China currently has the problems of large waste reserves and low utilization rate.It is feasible to modify loess with some materials with higher thermal conductivity.Based on this,this paper mainly studies the thermal conductivity of materials modified by loess tailings.The thermal conductivity of loess-modified materials under different dry density,moisture content,gradation,and saturation were measured by the steady-state protection hot plate method,and the influence of various factors on the thermal conductivity of the material was studied.The thermal conductivity of the modified material is positively correlated with the dry density,moisture content and saturation of the material.The improvement of the thermal conductivity of the graded modified material has a significant effect,and the thermal conductivity of the well-graded modified material is higher.The saturation degree and the thermal conductivity of the modified material can be fitted by empirical formulas,and the fitting degree is good.By comparing with the measured value of the same material transient method,it is found that the measured value of the transient method is greater than the measured value of the steady state method.This paper analyzes and summarizes the difference.Aiming at the influence of the water migration in the steady-state method,this paper tested the influence of different heat source temperature,material moisture content,dry density,and distance from the heat source on the temperature and humidity of the sand sample by establishing a one-dimensional soil column heat transfer model analysis.It is found that at higher water content,the water migration of the sand sample is more obvious.The process of water migration will produce heat transfer,which will affect the temperature field of the soil sample.