Air cooling evaporators
Air cooling evaporators for coldrooms, shock freezing, air conditioning and others, will finned tubes in coils (see Fig. 7.2). In all but very small coolers, there will be fans blow air through the coil.
Construction materials will be the same as air-cooled condensers. Aluminium plates on copper pipes are the most common for halocarbons, stainless steel or aluminium, pipes for ammonia. Frost or condensation will form on the fin surface and must be drained away. To allow this, the fins will be vertical and air flow horizontally, with drain tray provided under.
The size of the tube will be such that the speed of boiling liquids in it can lead to turbulence, to encourage the transfer of heat. Pipe diameter will vary from 9 mm to 32 mm, depending on the size of the coil.
Fin pitch will be a compromise between compactness (and cost) and trend Interfin gaps in block from condensed moisture and frost. Step will vary from 2 mm on the CD conditioner to 12 mm low-temperature refrigerated areas coils [8]...
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Evaporators 