30 May 2005

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).