Performance Analysis of the Developed Air Source Heat Pump System at Low-to-Medium and High Supply Temperatures for Irish Housing Stock Heat Load Applications

Abstract

Decarbonization of the UK residential heating sector is crucial to cut the carbon emissions and meet the legal binding of the Climate Change Act, 2008. The current progress with residential building sector carbon neutrality is slow and, hence, acceleration in action is required. The heat pump (HP) technology was found to be a potential candidate for sustainable development instead of fossil fuel-based oil/gas boilers, but improvement in its coefficient of performance (COP) is essential to compete with the lower gas/oil unit energy cost. The number of studies found in the literature were very limited, with the customized prototype development in the context of Northern Ireland, but without considering the simultaneous impact of heat supply temperature and operating mode of control for performance improvement in different property types. It is evidenced in the literature that the variable speed capacity control approach could improve the annual performance, but the literature has not looked into the compressor efficiencies challenges. In this study, steady state testing with a range of fixed constant heat loads (3–18 KW), done by varying compressor speed and its impact on COP, compressor efficiencies, and inverter losses, was established. The HP performance was measured and evaluated at low (35 °C)-to-medium (45 °C) and high (55 °C) heat supply temperature levels under the controlled laboratory conditions over the experienced ambient temperature. According to the result the COP values varies according to heat supply temperature, ambient temperature conditions, and heating capacity. The HP annual performances with Irish housing stock were evaluated in two modes of control and three case studies (C1, C2, C3) based on the experimentally validated model. The heat load demand in five property types with four age periods were considered in the analysis. The system could meet the required heat load demand for all property types in VSM with different percentage improvements in performance in comparison to FSM depending on the considered case level of the heat supply temperature (C1, C2, C3).