Heat exchangers design principles

The resultant calculations based on these models may therefore provide values of foulant thermal resistance that are just as much in error as the TEMA type recommendations. The principle advantage of the models however that must not be underrated, is they do show the interaction of the variables and by an iterative process the designer is led towards an improved heat exchanger design in respect of fouling. 

I ve read about the importance of shell-side cross-flow in heat-exchanger design books. Higher cross-flow velocities reduce film resistance and promote increased heat-transfer rates. Recently, I had a dramatic personal experience to support this engineering principle. 

There are three heat-transfer modes, ie, conduction, convection, and radiation, each of which may play a role in the selection of a heat exchanger for a particular appHcation. The basic design principles of heat exchangers are also important, as are the analysis methods employed to determine the right size heat exchanger. 

A design feature of ion-exchange plant whereby the regeneration flow or backwash flow are in the opposite direction to the service flow. Also, a principle used in heat exchangers whereby the medium being heated flows in the opposite direction to the medium supplying the heat. 

Figure A. Design procedure for shell-and-tube heat exchangers Example 12.2 and Figure A were developed by the author for the Open University Course T333 Principles and Applications of Heat Transfer. They are reproduced here by permission of the Open University.

The major advantage of the superstructure approach to heat exchanger network design is that, in principle, it is capable... 

Chemical process equipment is of two kinds custom designed and built, or proprietary off the shelf. For example, the sizes and performance of custom equipment such as distillation towers, drums, and heat exchangers are derived by the process engineer on the basis of established principles and data, although some mechanical details remain in accordance with safe practice codes and individual fabrication practices. 

Fortunately, most cryogens, with the exception of helium II, behave as classical fluids. As a result, it has been possible to predict their behavior by using well-established principles of mechanics and thermodynamics applicable to many room-temperature fluids. In addition, this has permitted the formulation of convective heat transfer correlations for low-temperature designs of simple heat exchangers that are similar to those used at ambient conditions and utilize such well-known dimensionless quantities as the Nusselt, Reynolds, Prandtl, and Grashof numbers. 

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