An Analytical Study of Thermophoretic Particulate Deposition in Turbulent Pipe Flows

Abstract

The presence of a cold surface in non-isothermal pipe flows conveying submicron particles causes thermophoretic particulate deposition. In this study, an analytical method is developed to estimate thermophoretic particulate deposition efficiency and its effect on overall heat transfer coefficient of pipe flows in transition and turbulent flow regimes. The proposed analytical solution has been validated against experiments conducted at Oak Ridge National Laboratory. Exhaust gas carrying submicron soot particles was passed through pipes with a constant wall temperature and various designed boundary conditions to correlate transition and turbulent flow regimes. Prediction of the reduction in heat transfer coefficient and particulate mass deposited has been compared with experiments. The results of the analytical method are in a reasonably good agreement with experiments.

Notes

¹A constant wall temperature is an appropriate assumption in diesel engine EGR coolers since the liquid coolant temperature typically changes only a few degrees across the cooler, and the coolant-to-metal thermal resistance is much less that the gas-to-metal.