Research On The Law Of Heat Transfer In Forest Soil Facing Thermoelectric Power Generation

The forest soil thermoelectric power generation system uses geothermal energy to generate electricity and has a wide range of application prospects in the future.At present,thermoelectric conversion efficiency of soil thermoelectric power generation system is low,so it is necessary to obtain the temperature gradient of the forest soil in the depth direction,and optimize the thermoelectric power generation system.This paper takes the heat transfer of forest soil as the research object.Through studying the heat transfer properties of soil,a material model for calculating soil heat transfer was established.Based on this material model,a steady-state and unsteady-state heat transfer model of soil was established.The soil heat transfer model was verified by the soil heat source distribution test.Hot Disk analyzer was used to measure the thermal properties of soils with different water contents and densities.The formulas for soil thermal properties were determined.Combined with the three-phase characteristics of soil,the reconstruction model to predicted soil thermal properties was established and the prediction was compared with the experiment data.The average deviation between the predicted and measured values was 3.05%,which proved the model was feasible.Based on soil thermophysical properties and soil reconstruction models,two different material models for studying soil heat transfer were established,and they were used as boundary conditions.The steady-state and unsteady-state mathematical models were established,and combined with the above boundary conditions,the steady-state and unsteady-state heat-transfer differential equations were solved.Indoor and outdoor forest soil heat source distribution experiments were conducted to obtain temperature data of soils at different depths within one day or one year.Test data was used to verify the soil heat transfer model of this paper:compared with the prediction and measurement values of steady-state heat transfer mathematical model,the average deviation between them was 3.92%.The average deviation between the predicted and measured values of the unsteady-state heat transfer mathematical model was 4.21%.Combined with previous experimental data,the average deviation between predicted and measured values of soil heat transfer model in this paper was 12.16%,which proves the feasibility of the soil heat transfer model in this paper.