Heat transfer to pseudoplastic fluids in laminar flow

A simple temperature dependent equation τ = K [Ṡ exp(ΔH‡/RT)]n is proposed to represent the rheological properties of pseudoplastic fluids. This equation is combined with the differential equations describing steady state laminar flow and heat conduction to a moving fluid when natural convection and thermal energy generation are negligible. The resulting equations are solved numerically for heating of both Newtonian and non‐Newtonian fluids in laminar flow in tubes of circular cross section with constant wall temperature. These numerical solutions are presented as generalized plots of Nusselt number vs. Graetz number with n and (ΔH‡/R) (1/Ti — 1/Tw) as parameters. Extensive experimental data were obtained for two pseudoplastic fluids, and, in the range where natural convection was unimportant, the mean deviation between the computed Nusselt numbers and measured Nusselt numbers was ± 7%.