24 June 2014

HEATING SYSTEM RETURN TEMPERATURE EFFECT ON HEAT PUMP PERFORMANCE


The revision of EPBD directive raises the role of increasing heating system
efficiency. Due to low primary energy consumption heat pumps will be one of the key solutions for residential sector where district heating network are far. Statistical data shows that heat pumps will replace fossil fuel boilers. The aim of the study was to quantify the return
temperature effect on heat pump performance. There are several studies for improving heat pump efficiency on component level, but analyzing whole annual heating system efficiency
with detailed dynamical heating system model is previously not analyzed enough deeply. Simulated results with IDA-ESBO heat pump model were compared to laboratory measurements of a heat pump performance at different testing points. Based on
measurements the correlation between heating system flow/return temperature and condensing temperature were derived. Results show that calculation with derived
condensing temperature correlation gave about 7% higher seasonal performance factor compared to IDA-ESBO simulation model stressing the effect of relatively low return
temperature in a radiator heating system.