الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Desalination is characterized by rapidly evolving technologies. Many new desalination plants are tested and installed each year worldwide. The desalination technologies, which are divided mainly into thermal and membrane processes have reached both technical and economic maturity allowing them to have a more important role in the future in water supply. However, thermal processes have numerous limitations, which include intensive use of energy and problems related with corrosion of the equipment, while membrane processes suffer from membrane fouling, high membrane cost and smaller scale of production of fresh water. A most promising recent development in desalination is the use of humidification - dehumidification (H _ D) of air.
The H - D units are characterized by great functioning, simplicity and flexibility.
The principal innovation in the H - D process consists of maintaining a continuous humid airflow from an evaporator to a condenser. The vapor carrying capacity of air increases with temperature. When airflow is in contact with salt water, a certain quantity of vapor is extracted by air at the expense of the sensible heat of the salt water, which is therefore cooled. On the other hand, the distilled vapour is recovered by maintaining the humid air in contact with a cooling surface, causing condensation of part of the vapor that is mixed with air. Generally, condensation occurs in another exchanger in which salt water is preheated by latent heat recovery. The H - D process operates, as in any distillation process, with either once through flow or re-circulation of salt water.
In the present work, an innovated H-D unit which consists of two major parts namely a humidifier and a condenser, was devised and constructed, with its numerous accessories, with the aim of producing desalinated water from sea water, in a simple and cost-effective manner.
The experimental work was divided into two parts. The first dealt with humidification of ambient air in a specially devised innovated humidifier. The effect of important variables on the percent relative humidity of the humidified air, exiting air and water temperatures have been investigated, and these included water flow rate and its inlet temperature, flow rate and temperature of inlet air, type of packing material, presence of stages in the humidifier, number of stages, the mass of packing material required to fill the column and the mass of packing on each stage. Both natural draft and air-blown forced