According to literature 6% of South Africa's primary energy consumption could be saved if heat pumps were used to their full technical potential. Although there is world-wide interest in the use of heat pumps and considerable effort has been expended on heat-pump research, heat pumps are not commonly used in South Africa. The objective of this paper is to determine the possibility of a combined evaporator or condenser with a normal pump. This will reduce cost and space of a normal heat pump and make heat pumps economically more competitive against resistance element geysers.
In order to investigate this combination research is done on semicircular heat exchangers, since this is the primary geometry of the heating channels in the condenser pump. Analyses is done experimentally on a standard 28.58 mm hard drawn copper tube, cut trough the middle, with a 1.6 mm copper plate in between to obtain a semicircular heat exchanger.
Turbulent flow is investigated with the flat side of the semicircular heat exchanger being horizontal or vertical and a spiraled semicircular heat exchanger. The heat exchanger is also tested with a s-shape configuration. In each case the heat transfer coefficient is determined with the use of the Wilson plot technique. Semicircular heat exchangers are found to have a significant increase in Nusselt number above a normal round tube of equal hydraulic diameter.