الفهرس 
Introduction and literature reviewOnly 14 pages are availabe for public view
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Abstract
The latent heat thermal energy storage systems are widely used in several applications like solar energy systems to correct the mismatch between the available energy and demand. This study introduces a numerical study to optimize the orientation and eccentricity of the inner flat-tube placed in a double pipe storage unit. A 2-D transient numerical model was simulated using ANSYS 17.2. The model was validated by experimental data and the results indicated a good agreement with published work. The study investigated the effects of the inner flat-tube orientation and eccentricity of a double pipe storage unit on the melting characteristics of the phase change material. The studied cases of various aspect ratios of the inner flat-tube (0.9, 0.8, 0.7, 0.6, and 0.5) with different orientations of (ɵ = 0º, 30º, 60º, and 90º) were simulated .In addition, different eccentricities of (0, 0.25, 0.5, and 0.75) for aspect ratio of the inner flat-tube (1, 0.9, 0.8, 0.7, 0.6, and 0.5) were studied . In the study of orientations ,the results showed that the aspect ratio of 0.5 has the higher average PCM melting rate enchantment which is 97.88%, 69.56 %, and 24.92% for orientation of 90º, 60º, and 30º, respectively. In study of inner flattube eccentricity, the results revealed that; the higher average PCM melting rate enhancement is achieved for the circular inner tube which is 41%, 110.7%, and 218.5% for inner tube eccentricity of 0.25, 0.5, and 0.75, respectively, compared with the concentric case. Among all examined cases, the best melting performance was achieved for the circular tube with the highest eccentricity.