Half-coils

SHELL JACKET FULL/HALF COIL INTERNAL COIL s... 

The heat exchange area (A) may vary with time due to the volume increase by the feed. This variation is determined by the geometry of the reactor, especially by its height covered by the heat exchange system (jacket, internal coils, or welded half-coils). In case there is a significant change in the physical chemical properties of the reaction mixture, the overall heat exchange coefficient (U) will also be a function of time. 

Dhotre, T. Murthy, Z. V P. 2006. Modeling and Dynamic Studies of Heat Transfer Cooling of Liquid in Half-coil Jackets. Chem. Eng. J. 118(3) 183-188. 

Jayakumar, N. S. Farouq, S. M. 2008. The Dynamics of Liquid Cooling in Half-coil Jackets. Chemical Product and Process Modeling 3(1) 1-16. 

Li, Y X. Wu, J. H. 2011. Fluid Flow and Heat Transfer Characteristic of Outer and Inner Half Coil Jackets. Chin. J. Chem. Eng. 19(2) 253-261. 

The next step is to suddenly "open" the "switch," and an upward spike appears, meaning that a voltage has been generated in the top half-coil that adds to the bottom halfs voltage. The overall action therefore tends to prevent the current from stopping quickly. 

As a consequence, numerous schemes exist for heat removal in large fermentors including half coil baffles and draft tubes. No common design seems to have emerged. Manufacturers each have their own design scheme that they promote. 

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