Chaichana, C, Wongsuwan, W, Lu Aye & Charters, WWS 2004 (accepted) 'An experimental study on natural working fluids in solar-boosted heat pump water heaters', 6th Gustav Lorentzen Natural Working Fluids Conference, Current Applications and Opportunities , Glasgow UK, 29 August - 1 September 2004, pp. 1-8.

Abstract

Solar-boosted heat pump water heaters (SBHPWH) are increasingly used in the domestic sector due to their ability to upgrade low temperature energy source to high temperature hot water at competitive price. However, SBHPWHs generally use R-22 as working fluid, which is one of the ozone depletion substances. The main aim of this study is to investigate experimentally the possibility of using propane and ammonia in the SBHPWHs. From the experiments conducted, it was found that propane could be substituted into existing SBHPWHs with only a minor change made to the thermostatic expansion valve. On the other hand, existing evaporator and condenser could be used with ammonia. The other parts need to be replaced with non-copper components. In terms of efficiency, the propane heat pump offers the highest COP among the three working fluids tested (R-22, propane, and ammonia).