Hydro-thermal performance of multilayer capillary barriers in arid lands |
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| Authors: | A M O Mohamed I Shooshpasha |
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| Institution: | (1) Civil and Environmental Engineering Department, UAE University, P.O. Box 17555, Al Ain, United Arab Emirates;(2) Civil and Environmental Engineering Department, UAE University, P.O. Box 17555, Al Ain, United Arab Emirates;(3) Department of Civil Engineering, Mazandaran University, Iran |
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| Abstract: | In this study, a capillary barrier system was designed and tested for an arid land environment. To simulate arid land conditions
of high temperature and sub-irrigation systems, the barrier was subjected to thermal and hydraulic gradients in opposite directions;
to test the barrier system under these severe conditions, an experimental apparatus was designed and fabricated. The multilayer
capillary barrier consisted of three layers made of silica sand, a mixture of sand and bentonite in equal portions, and a
mixture of clay (25%) and aggregate (75%). Several one dimensional coupled heat and moisture tests were performed. Temperature
variations along the thickness of the barrier were recorded as a function of time, and at the end of each test, the barrier
was sliced into small sections, for the determination of volumetric water content as a function of distance from the heat
source. The experimental results were discussed in view of the barrier's intended purpose of its ability to store moisture
for long time durations.
Coupled heat and moisture flow equations were developed and solved numerically via a finite difference method. Diffusivity
parameters were calculated by using experimental results, a numerical model, and Powell's conjugate directions method of nonlinear
optimization. The model was calibrated and the results were discussed. Good agreement between calculated and experimental
results was obtained.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | coupled processes heat and moisture flow numerical analysis open system optimization soil water potential swelling soil transport parameters |
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