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,
Typically, the migration of multiple fluids in the subsurface is modeled as if it were independent of aqueous phase composition. However, solution conditions including pH, concentration of surface-active solutes, and ionic strength may impact the interfacial tension and the wettability of a system, which in turn may markedly affect subsurface transport. This study, presented in two parts, investigates the effects of solution chemistry upon surface tension, interfacial tension, wettability, and the subsurface transport property of capillary pressure versus saturation. In this part, the changes in air−water surface tension and o-xylene−water interfacial tension due to the presence of the surface-active solute octanoic acid were measured as a function of pH, concentration, and ionic strength. The interfacial tension depended only on the concentration and speciation of the octanoic acid and the aqueous phase, which displayed a strong dependence on pH. At the air−water interface, the neutral acid form, prevalent at low pH, was found to be more surface-active than the anionic form. However, in the two-liquid systems with fixed organic acid mass, the anionic form prevalent at high pH effected greater interfacial tension lowering because of the partitioning of the neutral form into the o-xylene.
Unwanted formation of air bubbles in the liquid water inside soil water tensiometers has always been a major nuisance afflicting this simple, fast, and accurate device. The stripper, a plastic wall (usually just a tubing wall) between the tensiometer water and a wet vacuum (containing some droplets of liquid water), strips any dissolved air out of this water. Bubbles cannot grow, they will shrink and disappear, unless the water pressure inside the tensiometer is less than the vapor pressure of water (at the ambient temperature). Choices of desirable plastic materials and other considerations are based on 7 yr of development and employment of this method.
In a boiling water reactor (BWR) and advanced boiling water reactor (ABWR) a main steam line pipe rupture in the main steam piping system, hereafter called main steam (MS) line, will create a decompression wave and a pressure disturbance that moves through the MS line toward the reactor pressure vessel (RPV). It expands into a large region transmitting a compression wave at acoustic speed and spreads as an acoustic wave over the adjacent dryer plate. The initial acoustic pressure force on the dryer is expected to spread from an origin at the steam line attachment. It reflects back toward the RPV wall and again to the dryer until it dissipates. This is expected in a space that is not of uniform spacing because the dryer surface is nearly flat and the vessel wall is a curved surface. The acoustic load region is bounded by the steam dryer outer surface and RPV inner wall surfaces. In this paper, simplified, conservative modeling is applied in this approach to obtain reasonable bounding loads. The method is compared against the result of a detailed fine-structure Computation Fluid Dynamic (CFD) analysis using the same input data. Therefore, the simplified method may be used to quickly estimate conservative decompression forces on a dryer surface.
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