Effect of conical cut-out turbulators with internal fins in a circular tube on heat transfer and friction factor

2013 ◽  
Vol 44 ◽  
pp. 64-68 ◽  
Author(s):  
C. Muthusamy ◽  
M. Vivar ◽  
I. Skryabin ◽  
K. Srithar
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Circular Tube ◽  
Internal Fins

Heat Transfer in Internally Finned Tubes

1976 ◽  
Vol 98 (2) ◽  
pp. 257-261 ◽  
Author(s):  
J. H. Masliyah ◽  
K. Nandakumar
Keyword(s):  
Heat Transfer ◽  
Circular Tube ◽  
Uniform Heat Flux ◽  
Heat Transfer Characteristics ◽  
Fully Developed Flow ◽  
Maximum Heat ◽  
Finned Tubes ◽  
Maximum Heat Transfer ◽  
Internal Fins ◽  
Laminar Forced Convection

Heat transfer characteristics for a laminar forced convection fully developed flow in an internally finned circular tube with axially uniform heat flux with peripherally uniform temperature are obtained using a finite element method. For a given fin geometry, the Nusselt number based on inside tube diameter was higher than that for a smooth tube. Also, it was found that for maximum heat transfer there exists an optimum fin number for a given fin configuration. The internal fins are of triangular shape.

Heat Transfer in Round Tube with Rectangular-Winglet Vortex Generators

2014 ◽  
Vol 931-932 ◽  
pp. 1173-1177
Author(s):  
Sompol Skullong ◽  
Pongjet Promvonge
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Thermal Performance ◽  
Circular Tube ◽  
Convection Heat Transfer ◽  
Test Tube ◽  
Tube Diameter ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
The One

Effect of 30° rectangular-winglet vortex generators (WVGs) mounted in the central core of a circular tube on convection heat transfer and friction loss is experimentally investigated in the present work. The rectangular-WVGs with two different winglet-height to tube-diameter ratios (called blockage ratio, BR = b/D = 0.1 and 0.2) and three winglet-pitch to tube-diameter ratios (PR=P/D=0.5, 1.0, and 1.5) are introduced. In the experiment, air at ambient condition is passed through the uniform heat-fluxed circular tube for Reynolds numbers (Re) in a range of 500024,000. The use of WVGs is to generate longitudinal vortex flows in the tube. The experimental results of heat transfer and pressure loss presented in terms of Nusselt number and friction factor are compared between the inserted and the smooth tubes. It is found that the BR and PR provide a significant effect on the thermal performance of the test tube. The results reveal that at smaller PR, the WVG with BR=0.2 provides the highest heat transfer and friction factor but the one with BR=0.2, PR=1.5 yields the best thermal performance.

Thermohydraulic Study of Laminar Swirl Flow Through a Circular Tube Fitted With Twisted Tapes

2001 ◽  
Vol 123 (3) ◽  
pp. 417-427 ◽  
Author(s):  
S. K. Saha ◽  
A. Dutta
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Prandtl Number ◽  
Friction Factor ◽  
Circular Tube ◽  
Swirl Flow ◽  
Short Length ◽  
Full Length ◽  
Twisted Tape ◽  
Twisted Tapes

Heat transfer and pressure drop characteristics in a circular tube fitted with twisted tapes have been investigated experimentally. Laminar swirl flow of a large Prandtl number 205<Pr<518 viscous fluid was considered. The swirl was generated by short-length twisted-tape inserts; regularly spaced twisted-tape elements with multiple twists in the tape module and connected by thin circular rods; and smoothly varying (gradually decreasing) pitch twisted-tapes. The heat transfer test section was heated electrically imposing axially and circumferentially constant wall heat flux (UHF) boundary condition. Reynolds number, Prandtl number, twist ratio, space ratio, number of tuns in the tape module, length of the twisted-tape and smoothness of the swirling pitch govern the characteristics. Friction factor and Nusselt number are lower for short-length twisted-tape than those for full-length twisted-tape. On the basis of constant pumping power and constant heat duty, however, short-length twisted-tapes are found to perform better than full-length twisted-tapes for tighter twists. Thermohydraulic performance shows that twisted-tapes with multiple twists in the tape module is not much different from that with single twist in the tape module. Friction factor and Nusselt number are approximately 15 percent lower for twisted-tapes with smooth swirl having the average pitch same as that of the uniform pitch (throughout) twisted-tape and the twisted-tapes with gradually decreasing pitch perform worse than their uniform-pitch counterparts.

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