الفهرس 
Chapter 1 : IntroductionOnly 14 pages are availabe for public view
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Abstract
According to the dangerous shortage in the non-renewable energies dll over the world and the pollution occures from their use, high attention is paid for utilizing of the solar energy as one of the most important renewable energies. Other types of the renewable energies, such as wind energy, hydroulic .. etc., are limited not only in Egypt but also allover the world. In addition, the extractions of energy in most of these cases are expensive. Due to these reasons, great effort has been done in Egypt and in other countries to study the possibility of using the solar energy specially in the sunny regions like Egypt.
The present research work deals wi th studying the effect of different painting mater ials that can be used on the performance of a flat-plate solar collector. This will lead to the selection of the most efficient ones regarding the improvement of the thermal character istics of the flat-platye collectors.
Accordingly, different painting materials found in the local Erket with relatively low costs have been chosen in addition to the choise of the available clays to be used in coating the absorption surfaces of the collector. In order to fulfil the main objecti ve of the present study, which is connected wi th the use of different painting and coating materials, primarily tests have been carried out for determining the characteristics of each ~terial. The most significant characteristics are related to the improvement of the selected materials in the rise of the temperatures more than those raised when using the ordinary black-paints.The influence of each painting and coating materials on the cooling rate of the collector has also been investigated as an essential primarily test. These tests represent the first step in this thesis. The secand part of the present work concerns the determination of the absorptivi ty factor for the painted and the coated surfaces wilh paints or local clays. It has been found that there are two types of mixLures giving approximately the same maximum improvement ralio for the collector temperatures.The use of clay has resulted in a siguificaut influence on preserving the absorbed energy for longer time than that absorbed with the normal black-paints. The third part of the study is connected with the investigation of the thermal characteristics for paints and clays in order to arrive at the optimum conditions. The thesis has also contained a critical comparison between the efficiencies of the chosen materials and those of the ordinary black-paints that used in majority of previous works particularly when changing the water flow rates.
Based on the acquired results through this work, it has been found that clay of EI-Minid site has approximately similar compositions as clays of other sites but giving a lower cooling rate than thos of other sites_ The use of the ordinary blackkpaint with the black-oxide (4: 5 by weight) has resulted.