EFFECT OF CLIMATIC CONDITIONS ON THE PERFORMANCE OF AN AIR-TO-WATER REVERSIBLE HEAT PUMP USING R290 AS REFRIGERANT: SEASONAL SYSTEM PERFORMANCES EVALUATION BY MEANS OF EXPERIMENTS AND MODELING
Domestic heating and cooling is responsible for a fair percentage of world energy consumption. Heat pumps offer the most energy efficiency way to provide heating and cooling in many applications. They can use alternative refrigerants, such as hydrocarbons, e.g. propane (R290) as one of natural refrigerants is already being used specifically in western and northern Europe, predominantly in small capacity equipment. This paper presents a wide analysis of the influence of Mediterranean climatic conditions (of great importance for Cooling), on the performance of a specifically modified 20kW air-to-water reversible heat pump unit using propane (R290) as working fluid in both modes of operation: heating and cooling. The characterization points were selected according to the EN 255-1 and EN-12055 Standards European Normative. Experimental results are compared with model predictions (ART Model). Using the ART model, the performance of the heat pump for different geometries of a finned tube heat exchanger (number of circuits and the tube diameter) and air temperate conditions are calculated. The performance analysis of the heat pump system was made taking into account the COP and the Seasonal System Performance Factors (SPF) in both modes of operation: heating and cooling. For this purpose, an extensive study of relevant climatological parameters of Valencia-Spain was made. These results were transformed in bin-hour data which are used for calculating the heating seasonal performance factor (HSPF) and cooling seasonal performance factor CSPF according to the ANSI/ASHRAE 116-1995 and ARI Standard 210/240-2003. As a result, it was concluded that climatic conditions has a strongly effects on the seasonal system performance in both modes of operation. In the heating mode the HSPF varies between 3.1 and 3.3; whereas the CSPF varies between 3.1 and 3.4 for the three years studied (2000, 2001 & 2002).