Modelling of a water-to-air variable capacity ground-source heat pump

The present work aims at presenting the development of a performance-based model of a water-to-air variable capacity ground-source heat pump. The main challenge is to apply the recommended control strategy to vary the speed of the compressor for each mode of operation and to be able to switch from one mode to the other. A series of verification tests tend to confirm that the speed control strategy has been correctly implemented. The proposed model is used in annual simulations of a residential system equipped with a variable capacity ground-source heat pump. In this case, the seasonal performance factor (SPF = ratio of the annual energy requirement for heating, cooling and domestic hot water (DHW) over the annual total energy consumption) is 3.64. The corresponding value for a conventional system composed of a fixed capacity heat pump operating in on–off mode and a separate electric DHW tank is 2.60.