Influence and reconciliation of seasonal fluctuations in soil temperature and thermal diffusivity jumps on the thermal discharge performance of borehole heat exchangers
Influence and reconciliation of seasonal fluctuations in soil temperature and thermal diffusivity jumps on the thermal discharge performance of borehole heat exchangers
To investigate the effects of different factors on the performance of a buried pipe group for heat extraction under stratified geological structures,a numerical heat transfer model was established to analyze the thermal performance of a pipe group under seasonal soil temperature fluctuations in this paper,accounting for factors such as soil thermal diffusivity,borehole spacing,backfill material thermal diffusivi-ty,and pipe group layout.The results showed that neglecting the seasonal fluctuation of soil temperature could lead to overestimation of the thermal efficiency of the pipe group and borehole unit heat exchange rate.The pipe group was situated in multi-layered soil,where the soil layer with higher thermal diffusivity would accumulate more coldness,resulting in more intense thermal interaction between boreholes.The central borehole in the pipe group was most affected by thermal interaction.For a rectangular array of bore-holes,increasing the borehole spacing from 3 m to 5 m resulted in 6.6％enhancement of the thermal effi-ciency of the pipe group.Increasing the borehole spacing or employing backfill material with high thermal diffusivity could increase the heat exchange capacity of individual boreholes.However,using excessively high thermal diffusivity backfill material for a given borehole spacing and pipe group configuration could decrease the overall heat efficiency of the pipe group.In addition,linear arrangement of pipe groups was found to be more suitable for short-term continuous operation scenarios.
关键词
竖直埋管换热器/季节性波动/热扩散率/回填材料/管群布局
Key words
Borehole heat exchanger/Seasonal fluctuations/Thermal diffusivity/Backfill material/Pipe group form
维普
万方数据