Thermal and hydraulic properties of sandy soils during drying and wetting cycles
Ali, Alexis Mohamed, Mostafa H.A. Aal, M. Schellart, A. Tait, Simon J.
Ali, Alexis
Mohamed, Mostafa H.A.
Aal, M.
Schellart, A.
Tait, Simon J.
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2014
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Abstract
There is an increasing interest in the use of Ground Source Heat Pumps (GSHPs) as a source of renewable energy in temperate countries. GSHPs coupled with buried heat collectors can harness the thermal energy from near-surface soils to provide the heating required for domestic properties. The performance of a GSHP system depends greatly on the thermal conductivity of the surrounding soils. Near-surface soils undergo cycles of drying and wetting due to, for example, the infiltration of rain water and/or fluctuations of the ground water table. Several parameters - including the properties of soil, suction head and saturation history - affect the thermal properties as well as the retention and flow of water. This paper presents results from a comprehensive laboratory investigation on sand samples with markedly different grain size distribution. Simultaneous measurements of thermal and hydraulic properties of the sands were taken under incremental increase/decrease in the suction head values to simulate cycles of drying and wetting. The results clearly suggest that the thermal conductivity is better expressed as a function of the matric suction head so as to reflect the saturation history. There has been almost five-fold increase in the measured value of thermal conductivity when the soil was wetted to a residual degree of saturation from being dry.
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Ali A, Mohamed MHA, Aal M et al (2014) Thermal and hydraulic properties of sandy soils during drying and wetting cycles. In: GeoShanghai International Conference: New Frontiers in GeoTechnical Engineering. 26-28 May 2014, Shanghai, China: 129-138.
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