Fermentors heat-transfer surfaces

Most industrial fermentors incorporate heat-transfer surfaces, which include ... 

Most industrial fermentors incorporate heat-transfer surfaces, which include (i) an external jacket or external coil (ii) an internal coil immersed in the liquid and (iii) an external heat exchanger, through which the liquid is recirculated by a pump. With small-scale fermentors, approach (i) is common, whereas approach (iii) is sometimes used with large-scale fermentors. These heat transfer surfaces are used for... 

If the rate of heat transfer to or from the broth is important, then the heat transfer area per unit volume of broth should be considered. As the surface area and the liquid volume will vary in proportion to the square and cube of the representative length of vessels, respectively, the heat transfer area of jacketed vessels may become insufficient with larger vessels. Thus, the use of internal coils, or perhaps an external heat exchanger, may become necessary with larger fermentors. 

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