الفهرس 
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Abstract
.1.
This thesis describes the work carried out towords the devee... opment of the agricultural wastes, tOJ be used as insulators in the solar energy heaters. The principle aim is to produce an efficient solar water heater with minimum cost.
Several agricultural wastes such as cotton seed hulls, wheat straw, Bean straw, pea-nut hulls, crina and sawdust have been tested and have also been compared with the conventional innsulating materials such as glasa wool and Foam •
Tests were carried out at different climatic and surrounding temperature conditions as weel as different tank volume, tank geometry and insulating thickness. These test were performed over 24 hours.
The thermal conductivity of these materials in the form of solid plates has been measured qy using urea Formaldehyde Reisn as a binding media •
The results obtained from this investigation indicate that, all materials under consideration except sawdust have lower thermal conductivity than that of the conventional insulatting materials such as glass wool and Foam.
During the summer time the stored water temperature DROPped b.1 about 35 ~ whereas, in winter time it DROPped qy about
43 fo wi thin 24 hrs • At surrounding temperature of 8°0 ” the stored water temperature was DROPped b,y about 47 fo within the same period. The rate of decrease of the stored water temperature is about 10 C/hour for cotton seed hulls and whheat straw, 1.2° C/hou for glass wool and Foam.
.2.
Regarding heat transfer, and as expected, cylindrical tanks proved to be more efficient than rectangular ones due to the relatively lower surface area to volume ratio.
The optimum and economical insulating thickness is found to be about 50 mm. The optimum tank proportions i.e, height to diameter HID is 1.00 •
In general, it could be concluded that, the agricultural waastes such as cotton seed hulls, wheat straw, Bean straw, pea nut hulls and crina in their natural form provide relatively better insulating capacity when compared with conventional insulators such as glass wool and Foam •