الفهرس 
arabic summaryOnly 14 pages are availabe for public view
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Abstract
Heat and mass transfers in soil are important for many engineering applications. In this study a coplete theoretical model was presented depending on a new boundary conditions and the model of Philip and De Vries which describes the heat and mass transfer in porous media. In this study, an accurate manipulation of the boundary conditions for bare and mulched soil with polyethylene films was made. This manipulation is depending on the knowledge of the soil monochromatic directional reflectance of the soil and the monochromatic directional transmittance of the polyethylene film and the spectral distributions of the solar and the sky radiations. A new factor named matching factor was made for accurate prediction of the diffuse solar radiation. Also, a complete computer program was made to solve the problem of heat and mass transfers for bare, partially mulched and fully mulched soil with the polyethylene mulches. The alternative directional implicit (ADI) finite difference method was used to solve the two dimensional problem while the implicit finite difference method was used to solve the one dimensional problem. The needed input data are the hourly weather data, monochromatic directional soil reflectance, monochromatic directional transmittance of the polyethylene film and the Van Genuchen’s parameters n and . The computer program calculates the required soil thermal, hydraulic and optical properties and the polyethylene optical properties. To verify the predivted results, an experimentsal set-up soil bin designed, constructed and assembled on the roof of the heat laboratory. Four experiments had been made for bare and partially covered sand soil. Good agreement has been achieved between the measured and the predicted data which tested the ability of the theoretical model and its computer program to predict the temperatures and water contents for such problems. Also, simulsation runs were made to study the effect if changing of the mulch width on the results for time ranging between 300 and 600 hours at different summer and weinter meteorological conditions. Also, 300 hours duration simulation runs were made to study the effect of wind speed on the temperature and water content distributions. The results show that the computer program has the flexibility to be used under different weather and operating conditions.