THEORETICAL INVESTIGATION OF INTEGRATED MANIFOLD SOLAR WATER HEATER

Abstract

A more elaborated mathematical model is developed in the current research to examine the thermal efficiency of a solar water heater with an evacuated tube collector (ETC). The configuration investigated is that of six copper tubes that are positioned evenly in a single evacuated tube whereby one tube is placed centrally and the other five positioned around the central tube in equal radial directions. This multi tube design aims at maximising the heat transfer and improving the effective heat-exchange surface area and improving an even temperature field in the collector. It derives energy balance equations of each tube considering conductive, convective and radiative heat transfer mechanisms and thermal interaction between neighbouring tubes. Correlations of heat-transfers are formulated and used to assess the temperature distributions and thermal characteristics of system on different operating conditions. The mathematical model developed is solved to give forecasts of outlet water temperature, useful heat gain as well as the overall thermal efficiency of the solar water-heating system. The measurements show that there is a great enhancement in thermal performance, when compared with traditional single-tube systems, and the overall system efficiency is seen to be improved by about 41 per cent. The suggested design and method of analysis offer invaluable information on the optimization of the evacuated tube solar water heaters and lead to the creation of solar thermal systems with high efficiency to be used both at home and at work