Study On The Regulation And Simulation Of Heat And Moisture Transfer In One-dimensional Unsaturated Soil

Water content and temperature are two key factors affecting the biological activity,seed germination and plant growth in the surface soil.As a typical porous medium,soil water migration and heat transfer are a complex coupling transfer process.It is important to study and master the law of soil heat and moisture transfer under non-Isothermal conditions for the efficient utilization of soil and water resources in arid areas.At present,most studies on heat and moisture transfer in unsaturated soils often ignore the effect of water vapor diffusion on water and heat transfer.In view of this,the heat and moisture transfer of different moisture content under the action of heat source was studied in this paper,and then the contribution of Hydrus-1D to water vapor in soil heat and moisture transport was explored.Two kinds of soils(sand and loam sand)were carried out respectively.Numerical simulation of soil moisture content and temperature affected by water vapor in 10 scenarios(30?and 40?)and 6 moisture content(0.8,0.11,0.13,0.15,0.15 and 0.30cm~3/cm~3).The main conclusions are as follows:(1)In the experiment of heat and moisture transfer of one-dimensional unsaturated soil column,the variation of soil temperature is as follows:at the beginning of heating,the soil temperature increases rapidly,but with the prolongation of heating time,the rising rate of soil temperature slows down gradually.And maintain stability after reaching the maximum value;The variation of water content is as follows:at the beginning of heating,the soil moisture accumulates rapidly near the heat source to reach a peak,and then the water moves away from the heat source,and the soil moisture content decreases continuously.(2)when the experiment was carried out by 1440min,the soil moisture content was still decreasing,and the temperature in the soil column was stable,which showed that the change of soil moisture field lagged behind the soil temperature field.The higher the heat source temperature is,the more intense the soil moisture transfer is,and the more obvious the peak water content is,and the clay is more likely to form the water content peak near the heat source than the medium sand.(3)the numerical simulation of the effect of water vapor on sand and loam sand shows that water vapor migration has an important effect on the water transport of the two soils,and has a greater effect on the water transport of loam sand.Water vapor transport has an effect on the temperature increase of different soil quality,and the degree of increase of loam sand is more obvious.(4)the lower the soil moisture content is,the greater the increase of water vapor transport on temperature is.With the increase of water content,the effect of water vapor migration on soil temperature decreases and disappears.The lower the initial moisture content,the greater the role of water vapor transport in the overall water transport.When the initial moisture content continues to increase to relative saturation(moisture content is greater than 0.20cm~3/cm~3),the effect of water vapor on the overall water transport can be ignored.Therefore,the effect of water vapor transport on water content and temperature should be considered in the study of soil heat and moisture transfer with low water content,and the effect of water vapor can be ignored at high water content.