A simplified method to evaluate the seasonal energy performance of water chillers

The calculation or certification of the energy consumption of buildings equipped with refrigerating or heating units operating on vapour compression cycles requires an accurate evaluation of their performance at full and part load under different operating conditions. Refrigeration systems simulation models are normally useless because of the large amount of input data required for a full characterization.A simplified numerical method for the performance prediction of vapour compression heat pumps and chillers is here presented, based only on performance data at the nominal rating conditions. The proposed procedure was validated against experimental data of different packaged air-cooled water chillers, operating on scroll compressors. In chillers full load conditions approximately 89.5% and 92.1% of the predicted EER and cooling capacity values respectively are consistent with the measured data within a relative deviation of ±10%. Simulation results are in good agreement with the experimental ones also if the experimental seasonal energy efficiency ratio, SEERon, described in the European standard draft prEN 14825, is considered. The deviations range from −3.2% to +5.1%. The proposed mathematical model appears to be a reliable tool to be implemented into dynamic building-plant energy simulation codes or into building energy certification tools.