MODELLING OF A THERMAL STORAGE REFRIGERATOR

The paper investigates the effect of adding a phase change material in thermal contact with the evaporator in a natural convection domestic refrigerator. The enthalpy method has been applied to investigate the heat release and storage rate of encapsulated ice. The effect of three parameters was investigated by the numerical method: PCM thickness, ambient temperature and evaporating temperature. The results showed that the melting and freezing time increased proportionally with PCM thickness. The refrigerator autonomy was reduced by 48% when the ambient temperature was increased from 20 degrees C to 43 degrees C and the freezing time increased by 27% when the evaporating temperature was reduced from -10 degrees C to -15 degrees C. A CFD simulation of the airflow and temperature distribution in the natural convection refrigerator was carried out to evaluate the most effective position to place the PCM (top or back wall). The predicted airflow patterns and temperature profiles were considerably different for the two PCM orientations. The predicted air temperature was above 5 degrees C, thus a eutectic PCM may be required to reduce the temperature in the refrigerator compartment.