18 May 2017

P.1.5.2 GreenHP – Air to Water Heat Pump Prototype for Retrofitting Buildings in Urban Areas


The Green Heat Pump project (www.greenhp.eu) aimed at developing a highly efficient heat pump concept for large renovated existing buildings in urban areas. Innovative approaches were pursued at component, unit and system level. The design of the GreenHP was strongly influenced by developments on the components level. The main factors determining the design were found in the areas of reducing refrigerant, using the natural refrigerant propane and optimizing the evaporator unit on the refrigerant and air side.
Based on a life cycle analysis, R290 emerged as the optimal refrigerant. To achieve high efficiency over the entire operating range and a limited refrigerant charge, the compressor included EVI and an optimized oil sump. Through the use of aluminum multi-port extrusion tubes in the condenser and evaporator the refrigerant charge was further minimized. An optimized design of the fan ensured a more efficient operation at icing conditions. On the refrigerant side, a newly developed bionic refrigerant distributor took care of the distribution of the refrigerant to the MPE tubes of the evaporator.
The newly developed components were assembled into a prototype heat pump and tested at AITs accredited testing facility according to international standards. The studies concentrated on the unit design and analysis of the performance and efficiency of the GreenHP prototype. The GreenHP reached a coefficient of performance (COP) of 3.0 at rating conditions A7/W55 and a seasonal coefficient performance (SCOP) for the average climate for high temperature applications of 3.3.