HEAT PUMP WITH HIGH OUTLET TEMPERATURES
For house heating applications heat-pumps have a lower primary energy demand than many other heating technologies like oil boilers. In several European countries the heat-pumps have a good market share in new buildings. But the big potential of the retrofit market in Europe was not accessible due to some restrictions: The older heating systems require an outlet temperature of 65°C to 70°C. The heat source for a retrofit HP should be ambient air. So the requirement is a high COP and a temperature lift from –15°C ambient air to 65°C outlet temperature. And the HP should be interesting from an economical point of view which excludes multistage HP and other solutions. Together with Copeland the German heating system manufacturer Viessmann developed a HP with an Economiser Cycle and hot gas injection in the compressor. The function of the cycle and measurement results from field tests and laboratory will be presented. The results show an interesting behaviour of the cycle for a COP and temperature optimisation.