Numerical simulation of heat and mass transfer in desiccant coated rotary dehumidifiers

A numerical model that predicts the heat and moisture transfer in a desiccant-coated, rotary dehumidifier was developed. The model is one-dimensional and transient, and includes all important parameters that affect the performance of desiccant wheels. The influential parameters include energy and mass storage in both the air and the matrix, convection, the axial thermal conduction through both the desiccant and the support material, the axial molecular diffusion within the desiccant coating, and the energy transfer between the air stream and the matrix. No existing models of desiccant coated rotary dehumidifiers include all the above-mentioned important parameters.; For validation of the numerical model, its predictions were compared with experimental data obtained with a test rig built in accordance with ASHRAE Standard. The accuracy of the numerical model has been confirmed by the good agreement with experimental data.; The effect of certain parameters on the predicted performance of a desiccant coated rotary dehumidifier was studied. The optimal rotation speed was then found. The variations in parameters of process and regeneration air with angular position and with depth into the tubes are simulated.; The numerical model was also applied to predict the performance of desiccant dehumidification and evaporative cooling (DDEC) systems. A two-stage DDEC system using low-temperature heat was proposed, and its performance was predicted. The required regeneration air inlet temperature of the two-stage DDEC system with intercooling was found to be 35.0°C lower than of the single-stage system. The lowered regeneration temperature will make it possible to utilize low-quality thermal energy such as solar energy and waste heat.; Direct evaporative air coolers are components of DDEC systems. The theoretical and experimental analysis of evaporative coolers filled with corrugated holed aluminum foil fillers (CHAF fillers) is detailed in this thesis. The experimental results show that CHAF filler is a good pad material.