Calculating Energy Rating of Domestic Refrigerators Through Laboratory Heat Transfer Measurements and Computer Simulations

Most domestic refrigerators are supplied with an energy rating label which con-sumers can use to assess the quality of their appliance. This rating can be deter-mined by (a) testing the refrigerator under specified environmental conditions ac-cording to relevant standards and measuring its power consumption, or (b) analys-ing the refrigeration cycle thermodynamically, or (c) measuring the heat transfer through the walls of the refrigerator cabinet and its doors gaskets. While refrig-erator manufacturers use the first technique, most researchers take the second ap-proach. However, this paper is based on our laboratory experimentations and computer simulations following the third methodology. The premise for this in-vestigation is that under steady state conditions the power consumed by the com-pressor is equal to the rate of heat leakage through the refrigerator cabinets walls and doors gaskets as well as the heat input by auxiliary equipment such as light, fan, defroster, etc. This paper contains the details of this experimental study to-gether with a computer simulation which is designed to remove the need for such laboratory experimentations. After having validated the accuracy of the computer predictions by our own ex-perimental data and those obtained from refrigerator manufacturers, the computer software can now be used especially by manufacturers (a) to find the energy rat-ing of their refrigerators without performing laboratory experiments, and (b) to predict the energy rating of new types of refrigerators from their physical dimen-sions and characteristics, and environmental conditions before building a proto-type. Also, the computer code can be used as a flexible design tool (a) to investi-gate the effect of varying a single or a multitude of variables on the total energy consumption of the appliance, and (b) to test various refrigerators according to standards from different countries to facilitate the comparison of their energy rat-ing.