الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
A concentration photovoltaic (CPV) unit was used in the current study, with an optimized microchannel heat sink to manage the thermal load of the CPV system and utilize the removed thermal energy as a heat source for the MD unit. This numerical study showed that, after optimizing the operating conditions, a coolant exits with a temperature of about 59 ºC, which is adequate for the MD unit. Moreover, integrating the CPV unit directly with the MD unit is also investigated to improve the thermal performance. This hybrid system showed high productivity of 23 kg/m2 .h at a concentration ratio (CR) of 200. A further modification in this unit was to increase the aspect ratio (i.e., the ratio of cell length to width) to utilize more thermal energy, which significantly enhanced the system’s productivity up to 33 kg/m2.h. Furthermore, enhancing the MD design was introduced numerically and experimentally. Improving the heat transfer coefficient within the flow channel was proposed to reduce the temperature polarization. The experimental and numerical results showed that decreasing the channel height from 2.5 mm to 1.5 mm (at 78 ◦C feed inlet temperature and 100 ml/min flow rate) increased the permeate flux by 21%. This accordingly improved the thermal efficiency and specific heat consumption considerably. In addition, a new composite membrane was successfully synthesized with superior hydrophobic characteristics. The synthesized nanofiller and composite membrane were characterized via SEM, XRD, FTIR, etc., to prove the successful preparation and impregnation of the nanofiller in the composite membrane. At 2wt% optimum filler load, the highest water contact angle was 160º. The experimental investigation on the direct contact membrane distillation (DCMD) unit showed permeate water productivity of 11 kg/m2 h at an operating bath temperature of 75 ºC and the average product water quality of 20 ppm. Finally, improving the performance of the air gap membrane distillation (AGMD) unit was also proposed by depositing a hydrophobic layer of reduced graphene oxide on the condensation plate using the electrophoretic technique. It was proposed to alter the condensation mechanism from film-wise to drop-wise condensation, which significantly reduces the thermal resistance and improves the system performance. The experimental results showed that using the modified condensation plate significantly increased the product water productivity relative to the conventional condensation plate. The percentage improvement increased with increasing the operating feed inlet temperature up to 28% at the highest feed temperature.