Thermal separation of soil particles from thermal conductivity measurement under various air pressures

作   者：陆森，任图生，卢奕丽，孟平，张劲松
期刊名称：Scientific Reports
影响因子：4.259
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论文摘要：
The thermal conductivity of dry soils is related closely to air pressure and the contact areas between solid particles. In this study, the thermal conductivity of two-phase soil systems was determined under reduced and increased air pressures. The thermal separation of soil particles, i.e., the characteristic dimension of the pore space (d), was then estimated based on the relationship between soil thermal conductivity and air pressure. Results showed that under both reduced and increased air pressures, destimations were significantly larger than the geometrical mean separation of solid particles (D), which suggested that conductive heat transfer through solid particles dominated heat transfer in dry soils.
The increased air pressure approach gave d values lower than that of the reduced air pressure method.
With increasing air pressure, more collisions between gas molecules and solid surface occurred in micropores and intra-aggregate pores due to the reduction of mean free path of air molecules. Compared to the reduced air pressure approach, the increased air pressure approach expressed more micropore structure attributes in heat transfer. We concluded that measuring thermal conductivity under increased air pressure procedures gave better-quality d values, and improved soil micro-pore structure estimation.