Heat transfer surface plate coil

Standard glass coils with 0.18 to 11.1 m (2 to 120 fF) of heat-transfer surface are available. Also available are plate-type units made of impervious graphite. 

A, = area of inside of. surface for heat transfer, such as coil, flat surface, or other barrier, sq ft/ft h = inside heat transfer fluid side coefficient, in coil, flat plate, or otlier barrier, Btu/hr/sq fl/°F ro = fouling resistance (factor) associated wTth fluid on outside (tank process side) of heat transfer... 

Jackets, internal helical pipe coils, tube baffles, and plate coil baffles are used to provide heat-transfer surface area. The only surface area effective for heat transfer is that portion that is wetted by both service and process fluids. The effective heat-transfer area for some items may be determined as follows ... 

When liquids are to be evaporated on a small scale, the operation is often accomplished in some form of jacketed kettle. This may be a batch or continuous operation. The rate of heat transfer is generally lower than for other types of evaporators and only a limited heat transfer surface is available. The kettles may or may not be agitated. Jackets may be of several types conventional jackets (formed with another cylinder concentric to the vessel), dimpled jackets, patterned plate jackets, and half-pipe coil jackets. (See Figure 11-1.) This variety provides a great deal of flexibility in the choice of heat transfer medium. 

Helical coils, pipe baffles, and plate coil baffles are the most common heat transfer surfaces within the vessel. 

Vibrating-conveyor dryers are suitable for free-flowing solids containing mainly surface moisture. Retention is limited by conveying speeds which range from 0.02 to 0.12 m/s. Bed depth rarely exceeds 7 cm, although units are fabricated to carry 30- to 46-cm-deep beds these also employ plate and pipe coils suspended in the bed to provide additional heat-transfer area. Vibrating dryers are not suit le for fibrous materials which mat or for sticky sohds which may ball or adhere to the deck. 

Surface area for process heat transfer is made available by means of jackets, coils, baffles, and plates. When these fail to adequately meet process requirements, pumps and external heat exchangers are commonly used. Under certain conditions, condensers can be designed to remove process heat through the refluxing of a solvent or reactant. 

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