SIMULTANEOUS TRANSFER OF HEAT, WATER, AND SOLUTE IN POROUS-MEDIA .2. EXPERIMENT AND ANALYSIS

We conducted experimental and numerical studies of coupled heat and mass transport in dosed soil columns. Three soil textures were included. Initial solute concentrations were different among the soil textures. Low initial solute concentration (0.01-0.10 molal of KCl) was used with loam and silt loam soils and high initial solute concentration (0.50 molal) was used with the sandy loam soil. An explicit finite-difference numerical scheme was used to discretize coupled partial differential equations describing simultaneous heat, water, and solute transport in soil. Both observations and predictions showed accumulated water toward the low-temperature region and accumulated solute toward the high-temperature region. Predictions and observations were similar when relatively large initial soil water contents (0.134 m3 m-3 in loam soil and 0.166 m3 m-3 in Silt loam soils) and low initial solute concentration (<0.10 molal) were used. For small initial soil water content, the model underestimates soil water contents close to the low-temperature boundaries and overestimates near the high-temperature boundaries. For high initial solute concentration, the theory underestimates liquid transfer toward the hot boundary temperatures. A simplified version of the theory is useful for a range of conditions; however, osmotic effects on water flow are pronounced when high initial solute concentration occurs. When the osmotic effect was neglected, the theory predicted soil water content values similar to measured soil water content in solute-free soil (zero initial solute concentration). When the isothermal liquid diffusivity was multiplied by four, the predicted soil water content values are similar to the measured values 0.50 molal initial solute concentration).