الفهرس 
Chapter 1 : IntroductionOnly 14 pages are availabe for public view
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Abstract
Efficient and economical heat storage is the key to the effective and widespread utilization of solar energy for thermal applications.
Amongst the various heat storage techniques of interest, is latent heat storage using storage materials which, undergo a change in-phase and called phase change materials (PCMs). These materials have been viewed as being attractive for energy storage purposes.
Mixtures of different PCMs, in different ratios, are investigated for the object of determining that one which stores a higher amount of energy. The mixtures used are urea-sodium acetate, paraffin wax-stearic acid and sodium acetate-sodium thiosulphate mixture.
For its low melting point (30°C), the system urea-sodium acetate is not suitable as a storage medium in hot climates. So, the system is improved in this work by adding lead acetate in the ratio 16.6 % for the object of raising its melting point to a practical value through this additive A melting point of 44.5 °C is reached.
Different factors and parameters are studied (e.g., solar intensity, mass flow rate of HTF, effect of additives .... ).
Sodium acetate-sodium thiosulphate storage system and its container in the form of flat-plate collector were simulated experimentally in the laboratory.
Two computer programs have been developed and used to investigate the thermal performance of a flat-plate solar collector and the performance of the energy storage system.
The results showed that the systelCl composed of paraffin wax-stearic acid is the most efficient one amongst the system inve tigated. One kilogram of the storage mixture stored 318 kJ as thermal energy and its storage efticiency reached 46.46 %. The next system was urea-sodium acetate trihydrate-Iead acetate trihydrate, which stored 286 kJ/kg of storage mixture, and the last was sodium acetate trihydrate -sodium thiosulphatc pentahydrate sy tern, which stored 252 kJ/kg.