Comparison of a dynamic model and experimental results of a residential heat pump with vapor injection and variable speed scroll compressor

The first part of this paper presents a Modelica-based dynamic model of the system. Finite-volume models are used for the heat exchangers and the evaporator model takes into account frost formation. A thermodynamic model of the vapor injection scroll compressor is developed using empirical correlations for the volumetric efficiency, isentropic efficiency and the ratio between the injection and suction mass flow rate.
The second part presents experimental results of a vapor injection and variable speed scroll compressor air to water residential heat pump. The unit is a 10kW residential system working with R410a as working fluid and capable of providing floor heating and domestic hot water. It was tested in a controlled environment in order to achieve a wide range of outdoor, including frosting conditions, and indoor conditions. The model predictions and experimental results are compared in order to validate the component models in steady state.
The experimental investigations showed that there is room for improvement on the control side of the system and the developed model can be used in order to develop model based control of the injection and outdoor electronic expansion valves.