Heat Exchangers

Most fluids used in the chemical, pharmaceutical, food, and biomedical industries can be classified as non-Newtonian, ie, the viscosity varies with shear rate at a given temperature. In contrast, Newtonian fluids such as water, air, and glycerin have constant viscosities at a given temperature. Examples of non-Newtonian fluids include molten polymer, aqueous polymer solutions, slurries, coal–water mixture, tomato ketchup, soup, mayonnaise, purees, suspension of small particles, blood, etc. Because non-Newtonian fluids are nonlinear in nature, these are seldom amenable to analysis by classical mathematical techniques.

The optimum design of process equipment which handles non-Newtonian fluids could be significantly improved once predictive capability were increased. However, the basic understanding of the fluid mechanical and heat-transfer behavior of non-Newtonian, ie, viscous and viscoelastic, fluids is limited (22). A better understanding of pressure drop and heat-transfer behavi...