How2Day: The Electrical Requirements for Refrigerators

Refrigerators keep fruits and vegetables fresh Buena Vista Images/Stockbyte/Getty Images
In the U.S., most electrical appliances, particularly domestic, work on the standard grid voltage supply of 120 V, with minor variations, since most electrical power systems are prone to slight variations in voltage due to demand or other factors. The refrigerator utilizes electric components to keep its inside cool. Food can be stored for long periods if kept cold, generally at 3-5° C. At such low temperatures, bacteria that would otherwise spoil the food cannot survive.

A refrigerator consists of a set of leak-proof containers, an electric compressor, heat-dissipation tubes in a protective grill, a commercial coolant like R134A, condenser and thermostats. The compressor compresses the coolant. The Joule-Thomson effect raises the temperature of the coolant, which then goes through the heat-dissipation tubes located behind or on the sides of the refrigerator. This condenses the gaseous coolant into liquid at high pressure. This liquid flows through an aperture into the area of low pressure created by the suction force of the compressor. The coolant immediately boils and vaporizes, its temperature dropping to its boiling point, -26.6° C. The inside of the fridge becomes cold. The vapor gets sucked into the compressor and the cycle repeats. The thermostat cuts in/out to reduce operating time to the minimum.

The refrigerator is nothing more than a cooling device, an advanced version of the icebox of yore. The fridge generally has two compartments, one rather large and at a temperature just a couple of degrees above 0° C (32° F), the freezing point of water. The second compartment, the freezer, is maintained at -18° C (0° F) and is much smaller. Fridges usually operate at temperatures between 3-5° C as the container is too large to maintain at one temperature. It has shelves and racks, storing a wide variety of items, each of which releases heat in differing quantities. The much smaller freezer can be controlled more accurately. Ice cubes are made here.

A refrigerator is designed to store both raw foodstuff like vegetables, canned eatables, meat and fruit as well as cooked food. The cooked food could be an untouched dish prepared for the next meal, or leftovers. The temperature best suited for maintaining such foodstuff edible is again 3-5° C. Meat and potato dishes should be kept close to the freezer, just below the chill tray, as they are more temperature and bacteria sensitive. Other dishes/items may be stored in any shelf. The lowest shelf is generally boxed in and fully covered by the tray directly above it and is used for keeping fruit and vegetables fresh.

The refrigerator is best kept in cold spaces, minimizing its load. It should not be exposed to direct sunlight nor should it be close to any kind of cooker. Its heat dissipating coils should have breathing space, for efficient cooling. They should be at least 15 cm (6") away from walls and clean. Remove dust and cloying grime from the grill. Switch off the fridge before cleaning it, as abundant precaution. Keep the fridge at least half full, for best results. Never leave the door ajar and check that the door compressive seal is flexible and not stiff. Also, keep open-mouthed containers like mugs and jugs covered, to prevent vapor from escaping.

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