Turbulent heat transfer in drag reducing fluids

Abstract

An analysis is presented which extends the analogy between energy and momentum transport for turbulent pipe flow of purely viscous fluids to include drag reducing, non-Newtonian fluids. The correlation by Meyer is used to predict friction factor and sublayer thickness for the drag reducing fluids. The use of the friction factor correlation with the heat transfer analogy makes it possible to predict heat transfer rates from simple measurements of pressure drop and flow rate for the drag reducing fluids. Some recent experimental data for two effective drag reducing fluids and for water are compared with the predicted heat transfer rates, and the mean deviation in Nusselt number is found to be +8.5% for all of the data. The heat transfer analysis predicts a reduction in Nusselt number accompanying a reductionin friction factor for a given Reynolds number and for Prandtl numbers greater than 1. ANALYSIS AND CORRELATION FORMULAFrom reference 3, the Reynolds-Prandtl analogy for the

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“…Previous studies on the heat transfer have indicated that drag reduction is accompanied by a decrease in the heat transfer coefficient [9,10]. Some others concluded that the reduction in the heat transfer is much more conspicuous than reduction in momentum transfer [11][12][13]. It was believed that the heat transfer reduction is due to the decrease in the turbulent heat flux in the wall-normal direction [14][15][16][17].…”