refrigerator A refrigerator, commonly shortened to fridge, is a commercial and home appliance consisting of a thermal insulation, thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from its inside to ...

s, defrosting (or thawing) is the removal of

frost Frost is a thin layer of ice on a solid surface, which forms from water vapor that deposits onto a freezing surface. Frost forms when the air contains more water vapor than it can normally hold at a specific temperature. The process is simila ...

and

ice Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...

. A defrosting procedure is generally performed periodically on refrigerators and

freezer A refrigerator, commonly shortened to fridge, is a commercial and home appliance consisting of a thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from its inside to its external enviro ...

s to maintain their operating efficiency. Over time, as the door is opened and closed, letting in new air,

water vapour Water vapor, water vapour, or aqueous vapor is the gaseous phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Water vapor ...

from the air condenses on the cooling elements within the cabinet. Types of frost (in various environments) include crystalline frost (

hoar frost Frost is a thin layer of ice on a solid surface, which forms from water vapor that deposits onto a freezing surface. Frost forms when the air contains more water vapor than it can normally hold at a specific temperature. The process is similar ...

or radiation frost) from deposition of water vapor from air of low humidity, white frost in humid conditions, window frost on glass surfaces, advection frost from cold wind over cold surfaces,

black frost Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without chroma, like white and grey. It is often used symbolically or figuratively to represent darkness.Eva Heller, ''Ps ...

without visible ice at low temperatures and very low humidity, and rime under

supercooled Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid below its freezing point without it becoming a solid. Per the established international definition, supercooling means ''‘cooling a substance be ...

wet conditions. The resulting ice inhibits heat transfer out of the cabinet increasing running costs. Furthermore, as the ice builds up it takes increasing space from within the cabinet - reducing the space available for food storage. Many newer units employ automatic defrosting (often called "frost-free" or "no frost") and do not require manual defrosting in normal use. Although, in some cases, users of Frost Free fridge/freezers have noted ice blocking the vent that allows air into the refrigerator compartment.

References

{{ref-list Cooling technology