Heat and Momentum Transfer Within the Thermal Entrance Region for Non-Newtonian Fluids in Laminar Flow

It was felt that a technique of experimentally evaluating thermal conductivities of liquids from a dynamic flow system was necessary for the analysis of functional relationships between thermal conductivity and shear stress for non-Newtonian fluids, and the present work was undertaken in an attempt to develop such a technique. Specifically, the objectives were: (a) to develop an experimental and mathematical method to evaluate point values of thermal conductivity as a function of temperature and shear stress, and (b) to evaluate the effect of liquid thermal conductivity variation on temperature profiles observed in laminar non-isothermal flow.

To achieve these objectives, a mathematical analysis was made to relate the desired fluid properties to quantities which could be measured experimentally. Next a series of rheological experiments were carried out to evaluate aqueous solutions of carboxypolymethylene (Carbopol-934) for use as the non-Newtonian fluid to be tested. Then a series of steady-state, laminar, pipe-flow experiments were made to determine actual temperature profiles in the thermal entrance region. Finally the data were analyzed with the aid of the IBM 1620 digital computer in the University of Tennessee Computer Center. This analysis yielded thermal conductivity values as functions of temperature and shear stress and also demonstrated the effect of thermal conductivity variations on the temperature profiles.