الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Air conditioning equipment became widely used during the last decades. The conventional air conditioning equipment consumes large amounts of electrical energy which causes a peak load on electrical networks, especially on hot summer days. Moreover, the moist air delivered by air handling units helps in growth and propagation of bacteria. Liquid desiccant air conditioning systems represent a promising option to decrease high summer energy demand caused by electrically driven vapor compression machines.
Liquid desiccant air conditioning system depends mainly on the dehumidifier and the regenerator. The system works on the principle that humidity is absorbed directly from the process air by direct contact with the desiccant. The desiccant is then regenerated, again in direct contact with an external air stream, by solar heat at relatively low temperature.
In the present work, high performance packing namely, slides gauze structured packing that combines good heat and mass transfer characteristics with low pressure drop, is proposed for dehumidification of air using liquid desiccant and for regeneration of weak liquid desiccant, and a LiCl aqueous solution was used as a liquid desiccant. The structured packing has a density (specific surface area per unit volume) of 400 m2/m3 and the distance among the slides is 5 mm.
The thesis presents theoretical and experimental analysis on mass transfer performance of cross flow liquid desiccant dehumidification and regeneration processes. The humidity reduction of dehumidifier and the humidity change of regenerator, as well as their effectiveness were assessed under the effects of some variables. The variables include; air and desiccant flow rates, air and desiccant temperature, air humidity ratio and desiccant concentration. The thesis also discusses the performance evaluation of an incorporation of a liquid desiccant system into an evaporative cooling-assisted 100% outdoor air system.
A mathematical model implying the equations governing the combined heat and mass transfer in dehumidifier and regenerator was proposed. The model was used to predict the variation in air temperature and humidity ratio along the dehumidifier and the regenerator during the dehumidification and regeneration processes. The predicted results were compared with the experimental data and the comparisons showed satisfactory agreements.
It is important to determine the optimum ratio between the liquid desiccant and air flow rate as it helps to reduce the power consumed by liquid pump and air fan during the dehumidification and regeneration processes. The optimum ratio was found to be 2.0 for the former and 4.0 for the latter. The results show that the variables that have the greatest impact on the dehumidification performance are the desiccant concentration, desiccant temperature and air humidity ratio while the desiccant flow rate, desiccant temperature, air flow rate and air humidity ratio have the greatest impact on the regeneration performance.
A simulation and analysis of an open-cycle dehumidifier air conditioning system has been studied. According to the results of calculations, it became possible to identify the characteristics of the air inlet to and outlet from the evaporative cooler, the dehumidifier and the regenerator. Also, the characteristics of liquid desiccant inlet to and outlet from the dehumidifier and the regenerator have been identified. An hourly variation of COP has been calculated and it ranges from 0.65 to 1.15.