réfrigération
- Domaines
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- physiquethermodynamique et chaleur
- physiqueéchangeur de chaleur
- Date
Définition :
Technologie du refroidissement d'enceintes par extraction de chaleur.
Note :
Le procédé le plus employé est basé sur la compression d'un réfrigérant puis son évaporation qui absorbe la chaleur de l'enceinte à réfrigérer. L'autre procédé est basé sur un cycle à absorption dans lequel le réfrigérant est absorbé par un liquide, puis s'évapore en absorbant la chaleur. Il existe deux autres cycles de réfrigération, le cycle à air utilisé pour le conditionnement de l'air dans les avions, et le cycle à jet de vapeur qui a des applications limitées.
Terme :
- réfrigération n. f.
Traductions
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anglais
Date :Définition
The technology whereby cooling of spaces is achieved and maintained. All practical refrigeration processes rely on some kind of heat pump cycle to 'pump' heat out of cold spaces against its natural direction of flow.
Notes :
All practical refrigeration processes rely on some kind of heat pump cycle to "pump" heat out of cold spaces against its natural direction of flow.
The most commonly employed refrigeration process is that relying on a mechanical vapour compression, or "Rankine" cycle. The main elements of this cycle are a mechanically driven compressor, usually powered by an integral electric motor; a condenser where the compressed refrigerant gas gives out heat to the environment; a throttle or expansion valve, through which the liquid expands to low pressure; and an evaporator, in which the low pressure liquid is evaporated by absorption of heat from the space to be cooled. (This cycle can be used for heating, by using ambient heat to warm the evaporator and by using the heat given out by the condenser to warm a space.) The efficiency of such a refrigerator is measured by the "coefficient of performance" which is the ratio of the heat absorbed in the evaporator to the mechanical energy expended by the compressor. In the absorption cycle refrigerator, compression of the refrigerant is achieved by absorption in a liquid, chosen as one for which the refrigerant has high chemical affinity. Such absorption lowers the vapour pressure of the refrigerant, causing it to evaporate from the evaporator and transfer its heat of vaporization to the absorber. The latent heat necessary to vaporize the refrigerant is taken from the space to be cooled. The cycle is completed by the separation of the two substances in the generator, where refrigerant vapour is boiled off from the absorbant/refriguant mixture.Terme :
- refrigeration