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Sustainable automotive air conditioning is the subject of a debate – also known as the Cool War – about the next-generation refrigerant in car air conditioning. An advocacy group, The Alliance for CO 2 Solutions , supports the uptake of carbon dioxide (CO 2 ) as a refrigerant in passenger cars, and the chemical industry is developing new ...
The absorption cycle is the one limiting the choice of the refrigerant. The most common refrigerants for absorption systems are ammonia and water. [13] Both are good for combined absorption-compression heat pumps. [14] [15] Ammonia has an exceptionally good solubility in water. This is an important aspect that increases the performance and ...
Adsorption refrigerators are available in the marketplace and are mainly used to produce chilled water from waste heat. Gas adsorption heat pumps are not currently available in the UK, but are just being introduced in Europe as small water or ground source packaged units that provide domestic, low-temperature space heating. [6]
A representative pressure–volume diagram for a refrigeration cycle. Vapour-compression refrigeration or vapor-compression refrigeration system (VCRS), [1] in which the refrigerant undergoes phase changes, is one of the many refrigeration cycles and is the most widely used method for air conditioning of buildings and automobiles.
Common absorption refrigerators use a refrigerant with a very low boiling point (less than −18 °C (0 °F)) just like compressor refrigerators.Compression refrigerators typically use an HCFC or HFC, while absorption refrigerators typically use ammonia or water and need at least a second fluid able to absorb the coolant, the absorbent, respectively water (for ammonia) or brine (for water).
Ice, for example, requires 333.55 J/g to melt, but then water will rise one degree further with the addition of just 4.18 J/g. Water/ice is therefore a very useful phase change material and has been used to store winter cold to cool buildings in summer since at least the time of the Achaemenid Empire .
A 50–60% aqueous solution of lithium bromide is used in air-conditioning systems as desiccant. It is also used in absorption chilling along with water (see absorption refrigerator ). Solid LiBr is a useful reagent in organic synthesis .
The air picks up moisture and cools in process 1 to 2. The moist air is now presented to the cooling surface (cooling coil of the air conditioner), which cools it below its dew point and dries the air in process 2 to 3. This represents the work done by the cold coil. In the meantime, the dried desiccant from below is rotated to the upper air ...