Comparative Study of Natural and Forced Circulation of Solar Water Heater: A Review

Abstract

A comparative study between the natural and forced circulation for the thermal enhancement of solar water heater (SWH) has been presented in this article. SWH system convinces to be an efficient technology for converting solar radiation into heat energy. Hence the SWH plays an important role in domestic (flats, bungalows, and apartments) and industrial purposes (process industries, preheating boiler feed water etc.) due to its easy maintenance and simple operation. The huge amount of work is done on improving the thermal enhancement of SWH by using the different enhancing techniques such as natural and forced circulation with distinct types of hindrance promoters. The different hindrance promoter used by various researcher in SWH for its thermal enhancement are twisted tape, helical tape, triangular rod, ribs, coil-spring, helical coil-spring, ball turbulator and vortex generator. It is investigated that the twisted tape gives maximum  and in forced circulation process the enhancement devices used are coil-spring, helical coil-spring, ball turbulator and after investigation, it is found that the ball diametric ratio gives maximum enhancement.