Effect of solid–fluid thermal expansion on thermo-osmotic tests: An experimental and analytical study

Abstract

Abstract The effect of solid–fluid thermal expansion on thermo-osmotic tests is investigated using novel thermo-osmosis analytical solutions. A series of thermo-osmotic experiments are carried out on three clay-free sandstone samples with different physical properties such as permeability, porosity and thermal diffusivity. The results from the sandstone experiments are then compared with the derived thermo-osmosis analytical solutions with and without considering the effect of solid–fluid thermal expansion. When the analytical solution including the effect of solid–fluid thermal expansion is used, no thermal osmosis was needed to fit the experimental data for the sandstone samples. Ignoring the effect of solid–fluid thermal expansion in fitting the data, however, leads to relatively high, and incorrect, values for the thermal osmotic coefficients. Bearing in mind that the sandstone samples have no thermal osmotic behaviour, it is emphasised that ignoring the solid–fluid thermal expansion is likely to cause an incorrect interpretation of the experimental data. The solid–fluid thermal expansion should therefore be implemented as a standard in analytical/numerical solutions used to analyse the results of thermo-osmotic tests in natural aggregate systems.