Thermal conductivity of South African sauces in a shear flow field

Abstract

The objectives of this work were to determine the thermal conductivity of sauces obtained from a South African supermarket in a shear flow field and to develop theoretical models to predict their thermal conductivities under these conditions. A coaxial cylinder apparatus with a rotating outer cylinder was used to measure the thermal conductivity. The thermal conductivities of the substances were determined as a function of temperature (20–50 C) and shear rates (0–1 000 s)1). The fluids were observed to be shear thinning and their thermal conductivity values increased with both temperature and shearing rate. The thermal conductivity was also observed to increase asymptotically with time of shear to a constant value. Temperature and shear rate-dependent models, which correlate the observed thermal conductivity data fairly well, were proposed and tested for the materials.