Enhancement of soil thermal conductivity in dry condition

摘要

The efficiency and performance of an underground power cable is strongly influenced by thermalrnconductivity of soil in which it is placed. Most soils have extremely low thermal conductivity in dry state asrncompared to that in saturated condition. It is essential to improve the thermal conductivity in dry state for thernoptimum performance and safe operation of the cable, as backfill soils dry due to continuous heat generatedrnfrom the cable. This paper presents extensive laboratory study to develop backfill soils with higher dry thermalrnconductivity by modifying grain size distribution into fuller curve gradation. Experimental results clearly showrna significant improvement of the thermal conductivity of modified soils. The improvement is attributed to fullerrncurve gradation which contributes to obtain lower porosities and improve interparticle contacts. A result ofrnthermal simulation run for single cable clearly shows large improvement in heat dissipation for modified soil asrncompared to unmodified soil.