Refrigerators and Freezers | Research & Encyclopedia Articles

Refrigerators and Freezers

With 120 million household refrigerators and freezers in operation in the United States, their consumption of electrical energy is of major concern not only to the consumer, but also to the power generating utilities that have to provide the power. The government, charged by Congress with guarding against air pollution, protecting the Earth's ozone layer, and fighting global warming, has a keen interest in refrigerator energy consumption.

Vapor compression, absorption refrigeration (instead of electric power, uses heat as the source of energy), and thermoelectric refrigeration (the direct conversion of electrical energy to cooling effect), are the principal means of refrigeration. Of the three methods, vapor compression, often referred to as mechanical refrigeration, is the most energy efficient, approximately two times more efficient than absorption refrigeration, and four times more efficient than thermoelectric refrigeration. Vapor compression is by far the most popular means for refrigerating household refrigerators and freezers, although the other two technologies have unique advantages in some specific applications.

Vapor Compression Basics

Figure 1 shows the four basic elements of the vapor compression system: (1) the evaporator, where the refrigerant vaporizes, and thus absorbs heat from the surroundings; (2) the compressor, where the refrigerant vapor is compressed (typically in the ratio of ten to one); (3) the condenser, where the refrigerant vapor of high pressure and high temperature is condensed by rejecting the heat absorbed by the evaporator, together with the heat of compression, to the atmosphere; and (4) the expansion device, be it an expansion valve or a capillary tube, that allows the liquid refrigerant arriving from the condenser at high pressure and at room temperature, to enter the evaporator, and repeat the refrigeration cycle.

Refrigerators and Freezers article

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