Heat Transfer and Pressure Drop of Liquids in Double-Pipe Fin-Tube Exchangers

Abstract

Abstract This paper presents data on the fin side of standard commercial-size longitudinally finned double-pipe exchangers. Three fin-tube sizes were investigated in heating and cooling for both heat transfer and pressure drop. The data indicate that the transition between laminar and turbulent flow begins at R < 400 for both heat transfer and pressure drop, corroborating results reported by previous investigators. Methods of evaluating heat-transfer coefficients and pressure drop for liquids inside tubes are applicable for liquids in the fin side of finned double-pipe exchangers. For values of R up to 4000 (approximately), recommended curves for fin-side heat transfer give higher coefficients than the values obtained, by the procedure outlined by the Tubular Exchanger Manufacturers Association for liquids flowing in tubes. A method is presented for determining the weighted average temperature of the outside surface of the fin tube to be used in evaluating μw in the viscosity gradient correction μ/μw.