Geometric Tweaks, Big Gains: Unlocking Heat Pump Efficiency Through Integrated Evaporator Design
Frost formation on air-source heat pump evaporators yields efficiency losses during their operation under certain temperature and humidity conditions. Today, frosting phenomena are often neglected during the evaporator design process, resulting in additional efficiency losses during operation. In the literature, integrating the (de)frosting process into the evaporator design enhances efficiency during operation. This paper investigates the influence of evaporator design on the operational performance of heat pumps, concerning frosting behavior in dynamic simulation studies. The underlying simulation model captures interactions between evaporator design (fin spacing, refrigerant-carrying tubes, and required installation space) and frosting behavior (influence on heat transfer and air-side pressure loss). Using a sensitivity analysis with respect to fin spacing, the model computes the energy efficiency in three different case studies (high humidity, average, and low humidity). The results demonstrate a potential for improvement of the cycle efficiency of up to 10 %, depending on operating conditions. In all, the findings highlight the importance of integrated design approaches considering geometric parameters in evaporator design and refrigerant cycle control to mitigate frosting and enhance energy efficiency. Therefore, considering the effects of frost formation in the design process contributes to increasing the efficiency of air-source heat pumps in the field.