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Document Type |
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Thesis |
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Document Title |
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PARAMETRIC STUDY OF A SOLAR STILL ASSISTED WITH HEAT RECOVERY AND AIR CIRCULATION دراسة بارامترية لمقطر شمسي معزز باسترجاع الحرارة ودوران الهواء |
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Subject |
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PARAMETRIC STUDY OF A SOLAR STILL ASSISTED WITH HEAT RECOVERY AND AIR CIRCULATION |
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Document Language |
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Arabic |
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Abstract |
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The present work is an effort to study the parameters which affects the yield of the distillate water output from a solar still. The still incorporate a heat recovery subsystem and air mass circulation Humidification / Dehumidification (H/DH) subsystem inside the solar still. The study employed a solar still inclined southward against the sun by to horizontal and consists of two chambers, the upper chamber works as an evaporator (air humidification section) while the lower works as a heat recovery section where the recirculated humidified air mass is dehumidified.
The objective of the present work is to study the effects of various parameters on the overall system performance. These parameters include the still thermal capacity, feed water flow rate, feed water temperature and cooling water flow rates for the heat recovery subsystem. The output collected from the condensate or the glass cover (GC) is added to that collected from air dehumidification (DH) , summation represents the overall production. The overall productivity of the still increases as the thermal capacity decreases, In addition, the results showed that increasing of the feed and cooling water flow rates will increase the overall production rates and the still performance increases as well. At equal feed and cooling water flow rate of , the system output was about 1.74 L / m2.day, 2.06 L / m2.day and 2.76 L / m2.day when the thermal capacity of the still changes from , to respectively. The contribution of the (DH) to the distillate output varied from 50-55% for natural circulation with no heaters, to 60-65% for natural circulation with electric feed heaters and it reached 70% for forced circulation with electric feed heaters.
Two immersion electric heaters are used for feed preheating. The results showed that, as the feed water temperature increases, the overall output of distilled water increases and the performance ratio of the system increases as well. The experiments showed that, by using one electric heater (1200 W) to preheat the feed water the daily performance ratio of the solar still was about 0.28, 0.41 and 0.50 at thermostatic temperature setting of 40ºC, 60ºC and 80ºC respectively. Whereas, that the performance ratio ( Kg distillate per 2330 KJ input heat) of the solar still increased from 0.50, 0.62 and 0.74, by operating two electric heaters (2400 W).
Air circulating small fans are used to circulate the air in a closed circuit between the evaporation chamber and the condensation chamber (H/D). By employing the conditions for the best output from previous tested parameters, and , a comparison is made between natural and forced air circulation in the still. The results showed that the daily overall performance ratio of the still increased from 0.75 to about 0.90 and the overall distillate output was increased from L / m2.day to about L / m2.day as the number of used fans increased from one to four fans. The output of the still at natural convection (no fans) was about L / m2.day whereas, the overall output of the still at forced convection by using four fans was about 11.85 L / m2.day, which represent a rise of 18.5 %. In general, the present solar still can generate a distillate output which is about three times that sited in the literature of 4 L / m2.day, or 9.36 times that for the present still subsystem (GC) alone at similar conditions.
The distillate collected from the still subsystem glass cover, (GC) is compared with that of an available theoretical model by using “FORTRAN PROGRAM” as is[6] which is used to predict the hourly production rate of (GC) for for the three thermal capacities of the still : , and . The predicted results for the solar still matched reasonably with the collected results. |
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Supervisor |
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Dr. Ahmad Y. Bokhary |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1429 AH
2008 AD |
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Co-Supervisor |
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Professor Dr. Samir El Syed Aly |
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Added Date |
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Saturday, March 21, 2009 |
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