Performance characterisation of a small milk cooling system with ice storage for PV applications

The presented work proposes a calculation method to estimate the transient performance of a small on-farm milk cooling system for PV applications. The system employs 3 kg ice for fast cooling of 17 L milk in conventional 20-L-milk-cans. Two units of a commercial DC refrigerator operate at -10 degrees C and at 4 degrees C for ice production and milk preservation respectively. The development of milk temperature and energy consumption during a cooling event was studied experimentally at different ambient temperatures of 20 degrees C, 30 degrees C and 40 degrees C. A computational model was developed and validated where thermal resistances and COP were adjusted with experimental data. The results between 20 degrees C and 40 degrees C ambient temperature show a COP reduction of around 30% and a total daily energy consumption increase of around 100%. The specific total energy consumption of the system per litre milk was between 30 Wh/L and 58 Wh/L for the studied ambient temperature range. The suggested model can be used for the optimisation of photovoltaic stand-alone systems at specific locations. (C) 2015 Elsevier Ltd and International Institute of Refrigeration. All rights reserved.