A Numerical and Experimental Study on Skin Condensers Applied to Household Refrigerators

The aim of this work is to numerically and experimentally investigate the performance characteristics of skin condensers applied to a specific household refrigerator model. To this end a mathematical model which takes into account both the heat transfer to the ambient and to the refrigerated compartments was developed. The model predicts the condenser performance from the internal and external air temperatures, geometry, mass flow rate, pressure and temperature at the heat exchanger inlet. Steady-state energy consumption tests – compressor running continuously with electric heaters being used to create artificial thermal load – were carried out in different operating conditions with the product maintained within a climate-controlled chamber. Tests were carried out at 25°C and 32°C ambient temperatures, 5°C to 10°C fresh-food compartment temperatures, -20°C to -15°C freezer compartment temperatures and compressor speeds of 3000 rpm and 4500 rpm. Thermo graphic images of the outer steel shell temperature fields were also recorded during the experiments. The model predictions were compared with the experimental database with the deviations falling inside a ±5% error band. It has been found that, independently of the operating conditions, 60% of the condenser heat released rate is transferred to the ambient while the remaining 40% is transferred to the refrigerated compartments. It has also been found that radiation plays an important role, being responsible by over 80% of the heat rejected to the ambient