Determining the potential impact of a micro heat pump for domestic water heating

Abstract

Hot water used in the South African domestic sector is mostly heated by in-tank electrical resistance heaters. These so-called "geysers" are the major contributors to the undesirable high morning and afternoon peaks imposed on the national electricity supply grid. These peak demands continue to be of concern to Eskom. The "reduced capacity in-line water heating system design methodology" was developed to address this problem. A parallel inline heat pump water heater further reduces the electrical energy required. This paper employs a detailed statistical thermo-fluid simulation model to investigate the potential impact on the national peak electrical demand if this methodology is extensively applied in the domestic sector. The results will show that in certain areas of South Africa employing a micro heat pump for domestic hot water is a viable economic proposition. The coastal regions with the higher wet bulb temperatures and mild winter temperature fall in this category. The inland regions with their prolonged subzero temperatures requires a different approach to the standard way of using heat pumps. Implementing heat pumps for domestic use will also reduce the peak demand on the supply grid. Though the supplier of electricity will be selling less energy to customers, huge expenses in additional power stations to meet the peak demand, will be prevented.