Heat eddy diffusivity for viscoelastic turbulent pipe flows

Abstract

A new semi-empirical equation for eddy diffusivity of heat in terms of friction drag reduction ratio and Weissenberg number was earlier reported. The assumptions made in the evaluation of the constants of the proposed equation are verified and its general applicability to various experimental data is further established. For this purpose experiments have been performed for Separan AP-273 and Polyox WSR-301 solutions with concentrations ranging from 10 to 1000 ppm and Separan AP-30 with concentration of 3000 ppm in thermally fully developed turbulent flow in pipes with diameters of 1.11 and 1.88 cm I.D. under constant wall heat flux. From the experiments it is concluded that the minimum asymptotes for friction and heat transfer and the critical Weissenberg number for heat transfer are universal and independent of the type of polymer used. The prediction of heat transfer coefficients with the use of the proposed equation for all of the experimental data is within a maximum deviation of 30%.