Analysis of Heat Transfer Enhancement in a Circular tube With Twisted Tape Inserts

Abstract

Heat transfer enhancement methods are used to overcome heat consumption, due to this capital and operating expenditures are brought down in the manufacture of heat exchangers. newlineIn this work, the flow and heat transfer properties for three-dimensional domains of plain and plain twisted tape tube for different flow regimes of laminar and turbulent under constant heat flux boundary conditions with a twist ratio of y/w = 3 are investigated. Further to improve heat transfer effects circular and elliptical protruded twisted tape through circular duct geometry is investigated. newlineNumerical analysis of laminar flow regime of plain, plain twisted tape, circular protruded twisted tape and elliptical protruded twisted tape tube is carried out. From the results it is observed that Nusselt number versus Reynolds number for circular and elliptical protruded tube are 15 to 24, and 30 to 33 percent higher, respectively, than for PTT tube, in terms of friction factor 6 times and 7 to 8 times higher than that of plain tube. With respect to thermal enhancement factor of circular and elliptical protruded twisted tape tube it is approximately 1.5 and 1.5-2 times that of plain twisted tape tube. Further an empirical correlation is developed for CPTT and EPTT tube in order to match numerical data with an 11 and 7.5 to 8.5 percent variance in the Nusselt number and an 8.5 and 6 to 8 percent variation in the friction factor. The variables of numerical results for CPTT and EPTT are validated using a piecewise approximation approach and found that there is good agreement with each other. newlineNumerical analysis of turbulent flow regime of plain, plain twisted tape, circular protruded twisted tape and elliptical protruded twisted tape tube is carried out. From the results it is observed that Nusselt number versus Reynolds number for circular and elliptical protruded tube are 20.5 to 28.5 and 33 to 35 percent higher, respectively, than for PTT tube, in terms of friction factor 4 times and 7 times higher than that of plain tube. An empirical correlati