抄録
Latent heat transfer (LHT) with phase-change from liquid to gas occurs, when there is a temperature gradient in the porous media. LHT is a characteristic of porous media like soils, but there are few studies on the relationship between LHT and solutes. Although Philip and de Vries model was often used to analyze LHT, solutes have never been taken into consideration in the model. In this study, LHT was analyzed theoretically and experimentally with an assumption that the effects of temperature and salt concentration on thermal conductivity are caused by LHT. Thermal conductivities of Kaolin were measured under several conditions of water content, NaCl concentration and temperature. The LHT component of thermal conductivity was separated from the apparent one according to its temperature dependence, and analyzed by the extended method of Hiraiwa and Kasubuchi to estimate the phenomenological coefficient which contains tortuosity factor. As a result, the phenomenological coefficient never exceeded unity even at the maximum. The coefficient was expected to show a constant value under the fixed water content. However, it decreased with NaCl concentration. Further research is required on the tortuosity factor and modification of Philip and de Vries model, or introduction of other coefficients into the model to deal with solutes.
