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Corresponding Author

Elhefnawy, Mahmoud

Subject Area

Mechanical Power Engineering

Article Type

Original Study

Abstract

Align with shortage of fossil fuel reserves, as well as the bad effects of using it on climate, more attention must be paid to renewable energy sources which including solar energy. Egypt is one of the Sunbelt countries. The solar Atlas, which was issued in 1991, shows that the average direct normal solar radiation energy in Egypt is 2000-3200 kWh/m2/year. The sun shine duration ranges between 9-11 h/day with a few cloudy days [1]. One of the effective methods which are used to improve the performance of solar thermal energy conversion applications such as solar collectors is the design of the collector geometry. In the present work, the performance of a solar collector for water heating with spherical geometry design is investigated experimentally. The effects of incident solar radiation variation, ambient temperature changes and variation of water mass flow rate on the water outlet temperature and the performance of the collector were studied. The experiments were done at four different mass flow rates and non-flow rate. The results show that the average daily efficiency of the spherical solar collector with 1.1304 m2 surface area of absorber and 0.6 m diameter reaches its peak of 69%. The results also show that the collector efficiency factor was about 0.924 and the overall heat loss coefficient was 7.8 W/m2 °C.

Keywords

solar energy; Solar water heater; spherical solar collector and solar collector performance

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