Comparison of different types air source heat pumps water heaters in South Africa

Abstract

To mitigate global warming and energy crisis as well as to achieve energy efficiency, it is of paramount importance to use renewable energy technologies that can provide optimum and cost-effective energy savings. The research focused on the identification of critical parameters (volume of hot water drew off, ambient temperature, relative humidity, refrigerant temperatures at the inlet and outlet of the compressor and condenser) and deterministic quantities (time used, power consumption and coefficient of performance (COP)) as indicators to benchmark the performance of both the split and integrated types air source heat pump (ASHP) water heaters. The analysis was performed based on two predominant scenarios (first-hour heating rating and the heating cycle due to controlled volume of hot water drew off) wherein both the integrated and split types ASHP water heaters were undergoing vapour compression refrigeration cycles (VCRC). A data acquisition system (DAS) was constructed and implemented to monitor the performance of both systems. The results obtained during the summer season showed that under the scenario of 150 L hot water withdrawal, the average COP of the two systems was 3.18 and 2.85 for the split and integrated types, in March 2016. The average power consumed was 1.29 kW and 0.85 kW, for the split and integrated types systems while the time of operation was 84 minutes and 138 minutes, respectively.