Calculation of Temperature Effects on Wetting Coefficients of Porous Solids and Their Capillary Pressure Functions

Abstract

We explored the notion that changes in wetting coefficients of porous solids contributed to the temperature sensitivities of capillary pressure functions (CPFs). A chemical-thermodynamic explanation for these contributions was developed. If the temperature sensitivities of CPFs were due to capillarity (i.e., due to temperature-induced changes in liquid-gas interfacial tensions or wetting coefficients), then for a given degree of saturation the ratios of capillary pressures to their temperature derivatives should have been linear functions of thermodynamic temperature with slopes equal to 1. This indeed was the case for samples of both synthetic and natural porous media. Further, the estimated intercepts of these linear functions indicated that changes with temperature of these porous materials' wetting coefficients had pronounced effects on temperature sensitivities of their CPFs. A simple model for temperature effects on CPFs, which was derived from the linear relationship between temperature and the ratio of capillary pressure to its temperature derivative, could be fitted precisely by nonlinear regression to CPFs of two soils determined at four temperatures. GRANT AND SALEHZADEH: CALCULATIONOF TEMPERATURE EFFECTS 263 GRANT AND SALEHZADEH: CALCULATION OF TEMPERATURE EFFECTS Rowlinson, J. S., and B. Widom, Molecular Theory of Capillarity, Clarendon, Oxford, 1982. Salehzadeh, A., The temperature dependence of soil-moisture characteristics of agricultural soils, Ph.D. dissertation, Diss. Abstr. AAD91-01559, 191 pp., Univ. of Wis., Madison, 1990. Soll, W. E., M. A. Celia, and J. L. Wilson, Micromodel studies of three-fluid porous media systems: Pore-scale processes relating to capillary pressure-saturation relationships, Water Resour. Res., 29, 2963-2974, 1993. van Genuchten, M. T., A closed-form equation for predicting the hydraulic conductivity of unsaturated soils, Soil Sci. Soc. Am. J., 44, 892-898, 1980. Whalen, J. W., Thermodynamic properties of water adsorbed on quartz, J. Phys. Chem., 65, 1676-1681, 1961. S. A. Grant, Cold Regions Research and Engineering Laboratory, 72 Lyme Rd., Hanover, NH 03755-1290. (e-mail: sgrant@crrel. usace.army.mil) A. Salehzadeh,

Dynamic effects on capillary pressure–Saturation relationships for two‐phase porous flow: Implications of temperature

“…This is quite different with some other studies that have been suggested that the capillary pressure decreases with elevated temperature. 31,36 The reason for this difference may be due to the fact that we impose a lower pressure for water at the bottom of the domain for elevated temperatures. This may lead to higher capillary pressures at earlier time steps.…”

“…Grant 31 The model takes into account the interfacial tension as a function of temperature. It was determined that the two-parameter model is better than the one-parameter model for a system with a larger temperature range.…”

“…However, some authors report the effects of temperatures on the two-phase porous flow behavior. 5,[27][28][29][30][31][32][33][34][35][36][37][38][39][40] Sinnokrot et al 27 determined the effects of temperature on capillary pressure curves through measurement of drainage and imbibition capillary pressures for three consolidated sandstones and one limestone core. Lo and Mungan 41 proposed that oil recovery operations are more efficient at higher temperature.…”

Infiltration into soils: Conceptual approaches and solutions

“…In such case, expression of the infiltration process in terms of the diffusion equation (equation (7)) will not be appropriate since different points within the soil profile will follow different scanning curves, and there will be no unique relationship between gradients of and gradients of . Thermal effects will also induce significant changes in the estimated fluxes as temperature was found to affect soil hydraulic properties [Gardner, 1955;Philip and de Vries, 1957;Nimmo and Miller, 1986;Hopmans and Dane, 1986;Grant and Salehzadeh, 1996;Parlange et al, 1998;Grant and Bachman, 2002].…”

Drying Simulation of Ceramic Shell Build Up Process

“…In many soil transport and hygrothermal problems, this is expressed as the combination of temperature effect in reference [8,9].…”