Refrigerator

File:Theater commercial, electric refrigerator, 1926.ogv

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A refrigerator (colloquially fridge) is a common household appliance that consists of a thermally insulated compartment and a heat pump (mechanical, electronic, or chemical) that transfers heat from its interior to its external environment so that its interior is cooled to a temperature below the room temperature. Refrigeration is an essential food storage technique in developed countries. Lower temperatures in a confined volume lower the reproduction rate of bacteria, so the refrigerator reduces the rate of spoilage. A refrigerator maintains a temperature a few degrees above the freezing point of water. Optimum temperature range for perishable food storage is 3 to 5 °C (37 to 41 °F). A similar device that maintains a temperature below the freezing point of water is called a freezer.

History

The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in 1748. The first practical vapor-compression refrigeration system was built by Jacob Perkins in 1834. The first commercial ice-making machine was invented in 1854, and the first refrigerator for domestic use was invented in 1913.

Types

Refrigerators come in various types, including:

• Top-freezer refrigerator
• Bottom-freezer refrigerator
• Side-by-side refrigerator
• French door refrigerator
• Compact refrigerator
• Wine refrigerator

Components

A typical refrigerator consists of the following components:

• Compressor
• Condenser
• Evaporator
• Expansion valve
• Refrigerant
• Thermostat

Refrigerants

Refrigerants are substances used in a heat cycle to transfer heat from one area and remove it to another. Common refrigerants include:

• Ammonia
• Freon
• HFC-134a
• R-600a

Energy Efficiency

Modern refrigerators are designed to be energy efficient. The Energy Star program certifies appliances that meet certain energy efficiency criteria. Features such as inverter compressors and improved insulation contribute to lower energy consumption.

Maintenance

Regular maintenance of a refrigerator includes:

• Cleaning the condenser coils
• Checking the door seals
• Defrosting the freezer
• Replacing the water filter (if applicable)

Environmental Impact

Refrigerators have an environmental impact due to the refrigerants used and the energy consumed. Older refrigerants like CFCs and HCFCs have been phased out due to their ozone-depleting properties. Modern refrigerants are designed to be more environmentally friendly.

See also

• Freezer
• Icebox
• Refrigeration
• Cold chain
• Food preservation