Refrigerator

Freezers keep their contents frozen. They are used in households and in industry and commerce. Most freezers operate around 0 °F (-18 °C). Domestic freezers can be included as a separate compartment in a refrigerator, or can be a separate appliance. Domestic freezers are generally upright units resembling refrigerators, or chests resembling upright units laid on their backs. Many upright modern freezers come with an ice dispenser built into their door.

In the kitchen of nearly every home in America there is a refrigerator. Every 15 min­utes or so you hear the motor turn on, and it magically keeps things cold. Without refrigeration, we'd be throwing out our leftovers instead of saving them for another meal.

The refrigerator is one of those miracles of modern living that totally changes life. Prior to refrigeration, the only way to preserve meat was to salt it, and iced beverages in the summer were a real luxury.

The basic idea behind a refrigerator is very simple: It uses the evaporation of a liquid to absorb heat. In this article, you'll find out how your refrigerator performs its magic based on this simple principle. We'll also look at cold packs, electronic coolers and the propane refrigerators found in RVs.

The fundamental reason for having a refrigerator is to keep food cold. Cold temperatures help food stay fresh longer. The basic idea behind refrigeration is to slow down the activity of bacteria (which all food contains) so that it takes longer for the bacteria to spoil the food.

For example, bacteria will spoil milk in two or three hours if the milk is left out on the kitchen counter at room temperature. However, by reducing the temperature of the milk, it will stay fresh for a week or two -- the cold temperature inside the refrigerator decreases the activity of the bacteria that much. By freezing the milk you can stop the bacteria altogether, and the milk can last for months (until effects like freezer burn begin to spoil the milk in non-bacterial ways).

Refrigeration and freezing are two of the most common forms of food preservation used today. For more information on other ways to preserve food.