The effect of salts on thermal conductivity of Toyoura sand
1998
Mochizuki, H. (Tokyo Univ. (Japan)) | Miyazaki, T. | Nakano, M.
The objective of this study is to clarify the effects of salts on thermal conductivity of Toyoura sand (pd=1.60 g/cm3). In the first step, thermal conductivities of Toyoura sand without salts under several conditions were measured with the probe method. Then the effects of pressure, water content, and temperature were investigated. In the second step, depending on the relation between reciprocal pressure and the apparent thermal conductivities,the apparent thermal conductivities at latm, lambda, was separated into two components, the sensible heat transfer, lambdac, and the latent heat transfer due to the water vapor, lambdav. Finally, lambda, lambdae, and lambdav with salts, NaCl,CaCl2, and Na2SO4, were measured. The value of lambda was reduced about 10 % in maximum for the solution of 3 mol/l NaCl, about 10 % for that of 3 mol/l CaCl2, and about 15 % for that of 0.5 mol/l Na2SO4. The calculated values of lambda by using the equation of Noborio and Mclnnes (1993), which describes the effects of salts, agreed well with the measured value. The lambdav was remarkably reduced when the salt concentration was 0.5 mol/l, and was zero when that was 1.0 mol/l, but the lambdae was hardly affected with salts. In conclusion, the decrease of lambda was attributed to the decrease of lambdav, because salts reduce the relative humidity in soils
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