Year: 2004
Type: conference-paper
Abstract: Electric heaters are used to defrost the tubes of cooling coils .They represent about 15% of the annual energy usage of residential refrigerators.This paper investigates a new methodology to minimize the heat used during the defrost process for a given evaporator-heater configuration by locating the heater appropriately.Two criteria are discussed and applied to determine the optimum heater(s) position, and their optimum share of the total power.The first criterion is maximizing the heat supplied to the tube that receives the minimum share of heat.The second criterion is minimizing the normalized standard deviation of the heat received by the tubes.Two cases are analyzed: one heater and two heaters sharing the same total power as the original.For the two heaters case, the two criteria agree on the optimal heaters locations and optimal power share of 80% to the lower heater and 20% to the higher one. 1-INTRODUCTIONIn the last 15 years domestic and commercial refrigerator manufacturers have faced different standards (DOE 1993 and DOE 2001) that have required design for lower energy consumption or environmental laws (phase out of CFCs and HCFCs) that have imposed energy penalties to existing products.While a refrigerator today consumes about one third of what it used to 15 years ago the pressure to get reductions is still present due to the increase in global competition and to some extent an increased awareness of consumers about energy use.Energy consumption reductions have been attained, not by means of few big changes, but rather a number of small cumulative improvements.Changes to attain the required levels include high efficiency compressors, heat exchangers redesign, new insulation technologies, better door gaskets, perfection of air distribution systems, innovative control strategies, etc. (Radermacher and Kim, 1996).
Authors: Ehab M. Mina, César Gutierrez
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1559689829