Laminar Flow Through a Circular Tube Having Transverse Ribs and Twisted Tapes

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Manvendra Tiwari ◽  
Sujoy Kumar Saha
Keyword(s):  
Nusselt Number ◽  
Laminar Flow ◽  
Friction Factor ◽  
Circular Tube ◽  
Circular Duct ◽  
Viscous Oil ◽  
Twisted Tapes ◽  
Flow Through ◽  
The Individual ◽  
Better Than

The experimental friction factor and Nusselt number data for laminar flow of viscous oil through a circular duct having integral transverse rib roughness and fitted with twisted tapes with oblique teeth have been presented. Predictive friction factor and Nusselt number correlations have also been presented. The thermohydraulic performance has been evaluated. The major findings of this experimental investigation are that the twisted tapes with oblique teeth in combination with integral transverse rib roughness perform significantly better than the individual enhancement technique acting alone for laminar flow through a circular duct up to a certain value of fin parameter.

Friction and Thermal Characteristics of Laminar Flow of Viscous Oil Through a Circular Tube Having Axial Corrugations and Fitted With Helical Screw-Tape Inserts

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Sujoy Kumar Saha ◽  
Bikram Narayan Swain ◽  
G. L. Dayanidhi
Keyword(s):  
Nusselt Number ◽  
Laminar Flow ◽  
Friction Factor ◽  
Circular Tube ◽  
Thermal Characteristics ◽  
Circular Duct ◽  
Viscous Oil ◽  
Flow Through ◽  
The Individual ◽  
Better Than

The experimental friction factor and Nusselt number data for a laminar flow through a circular duct having axial corrugation and fitted with helical screw-tape inserts have been presented. Predictive friction factor and Nusselt number correlations have also been presented. The thermohydraulic performance has been evaluated. The major findings of this experimental investigation are that the helical screw-tape inserts, in combination with axial corrugation, perform better than the individual enhancement technique acting alone for laminar flow through a circular duct.

Heat Transfer Enhancement of Laminar Flow Through a Circular Tube Having Wire Coil Inserts and Fitted With Center-Cleared Twisted Tape

2012 ◽  
Vol 4 (3) ◽  
Author(s):  
Sujoy Kumar Saha ◽  
Bikash Kumar Barman ◽  
Soumitra Banerjee
Keyword(s):  
Nusselt Number ◽  
Laminar Flow ◽  
Friction Factor ◽  
Twisted Tape ◽  
Circular Duct ◽  
Twisted Tapes ◽  
Wire Coil ◽  
Flow Through ◽  
The Individual ◽  
Better Than

The experimental friction factor and Nusselt number data for laminar flow through a circular duct having wire coil inserts and fitted with center-cleared twisted tape have been presented. Predictive friction factor and Nusselt number correlations have also been presented. The thermohydraulic performance has been evaluated. The major findings of this experimental investigation are the center-cleared twisted tapes in combination with wire coil inserts perform better than the individual enhancement technique acting alone for laminar flow through a circular duct up to a certain amount of center-clearance.

Laminar Flow Heat Transfer and Pressure Drop in a Circular Tube Having Wire-Coil and Helical Screw-Tape Inserts

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Pratap Kumar Rout ◽  
Sujoy Kumar Saha
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Friction Factor ◽  
Circular Tube ◽  
Inertia Force ◽  
Large Reynolds Number ◽  
Nusselt Numbers ◽  
Wire Coil ◽  
Flow Through

The experimental friction factor and Nusselt number data for laminar flow through a circular duct having wire-coil and helical screw-tape inserts have been presented. Peripherally and axially local temperatures on the duct outside wall have been measured. The temperature drop across the duct wall has been calculated to obtain the duct inside wall temperatures. Peripherally averaged and axially local temperatures have been used to get axially local Nusselt numbers. These axially local Nusselt numbers have been averaged over the whole length of the duct to get the mean Nusselt number. Predictive friction factor and Nusselt number correlations developed by log-regression analysis have also been presented. Nusselt number correlation takes care of the thermal development length represented by the Graetz number, swirl and inertia force due to forced convection at large Reynolds number, buoyancy force due to natural convection at low Reynolds number represented by Rayleigh number and the geometrical parameters of wire-coil and helical screw-tape inserts. The thermohydraulic performance has been evaluated. The helical screw-tape inserts in combination with wire-coil inserts perform better than the individual enhancement technique acting alone for laminar flow through a circular tube up to a certain value of fin parameter.

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.

Heat Transfer and Pressure Drop Characteristics of Laminar Flow Through a Circular Tube With Longitudinal Strip Inserts Under Uniform Wall Heat Flux

2002 ◽  
Vol 124 (3) ◽  
pp. 421-432 ◽  
Author(s):  
S. K. Saha ◽  
P. Langille
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Friction Factor ◽  
Test Section ◽  
Circular Tube ◽  
Short Length ◽  
Full Length

Heat transfer and pressure drop characteristics in a circular tube fitted with full-length strip, short-length strip, and regularly spaced strip elements connected by thin circular rods have been investigated experimentally. The strips have been rectangular, square and crossed in cross-section with different aspect ratio. Laminar flow of water and other viscous liquids was considered. The rod diameter and length of the strip-rod assembly and the length of the strips were varied. Isothermal friction factor data has been generated. The heat transfer test section was heated electrically imposing axially and circumferentially constant wall heat flux (UWHF) boundary condition. Reynolds number, Prandtl number, strip length, strip ratio, space ratio, and rod-diameter govern the characteristics. Smaller rod-diameter in the strip-rod assembly or “pinching” of the strips in place rather than connecting the strip elements by rods performs better thermohydraulically. Short-length strips (upto a limited fraction of the test section tube length) perform better than the full-length strip. The friction factor correlation and the correlation for Nusselt number under UWHF condition for full-length strip have been modified to make them suitable for short-length strip as well as regularly-spaced strip elements. Thermal entrance length in the correlations is represented by Graetz number. Friction factor and Nusselt number correlations for short-length strips as well as regularly-spaced strip elements, in the limit, reduce to their full-length counterparts.

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