Experimental study of heat transfer and fluid flow in unsaturated porous media
A laboratory experiment was conducted to investigate thermal and fluid flow behavior in an unsaturated porous medium. The experiment consisted of a bed of homogeneous glass beads packed uniformly in a Lexan rectangular box. A cylindrical heat source was located horizontally in the middle region of the bed and the bed was heated to steady state conditions. Water was then introduced uniformly through square nozzles located over the fill material for short periods of time. The box was fitted with a screen at the bottom to keep the porous material intact while allowing the water to flow out. Below the box, an outflow system was located which consisted of a partitioned catch chamber for measuring the special variation of the water flowing out. Measurements in the bed were obtained using two types of devices that are placed in selected locations. These devices include capacitance elements for inferring moisture presence an thermocouples for measuring temperatures; The experimental results confirmed that the dominant mass and heat transfer mechanism were vaporization, condensation, conduction, and convection. The simulated medium was observed to develop a dry zone, a two-phase zone, and liquid zone. Moreover, placement of a heat source in an unsaturated porous medium causes a shifting of water around the heat source.