ICHMT DIGITAL LIBRARY ONLINE
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ARTICLE:
A. Nasr Graham L. Morrison Masud Behnia ABSTRACT To avoid problems of freezing in solar collectors and blockage of the tubes by calcium deposits in hard water areas, various indirect techniques have been devised to connect the collector and the hot water storage tank. One of the most common heat exchanger-based thermosyphon systems utilises a concentric heat exchanger around the hot water storage tank. Due to the simultaneous occurrence of both cooling and heating processes, the performance of concentric heat exchanger in conjunction with solar storage tanks is quite complex and different from that of traditional heat exchangers. The flow features and heat transfer characteristics in the annulus are numerically investigated and the calculations are validated against experimental data. A new heat exchanger deficiency coefficient is used to quantify the degradation of temperature stratification in the inner storage tank caused by the flow in the annulus. |
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