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Numerical Modeling and Analysis of Fluid Flow and Heat Transfer in Circular Tubes Fitted with Different Helical Twisted Core-Fins

Dongaonkar, Amruta J.
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377866455

Abstract Details

2013, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Passive techniques of enhanced heat transfer that create swirl flows inside tubes are useful in many applications in the process industry. Use of twisted inserts is one such type of swirl flow device. Steady, incompressible, laminar, constant property, fully developed flow and heat transfer has been computationally modeled in this study. Two cases, with 4 and 8 helically twisted fins inside a tube are considered, where the radial protrusions of the fins are highly conductive and have negligible thickness. The axial helical geometry of the fins of negligible thickness (δ=0) is defined by the twist ratio y (180° pitch H to tube inside diameter d). Using the vorticity and stream function formulation the governing equations for mass, momentum and energy transport are reduced in a helical coordinate system for the fully-developed swirl-flow condition. These are resolved in their conservative form and discretized using the control volume approach. For the heat transfer, both uniform wall temperature (T or UWT) and Uniform heat flux conditions (H1 or UHF) are considered. The diffusion terms are discretized using central-difference scheme and the power law scheme is used for the convective fluxes. Computed results highlight the effects of helical twist of the fin (3.0 ≤ y ≤ 12.0), number of fins N (4 and 8), flow Reynolds number (10 ≤ Re ≤ 1000), and fluid Prandtl number (1.0 ≤ Pr ≤ 25). The results show that effects of swirl flows, produced by the helical surface curvature of the fins, dominate in flows with Re > 100 and more so with decreasing y. Up to 1.1 to 2.8 times higher Nusselt numbers, relative to those in straight fin cases, and depending upon N, y, and Pr are obtained in this regime. The corresponding friction loss penalty is only 1.1 to 1.4 times that with straight fins, thereby making helical fin an attractive enhancement technique.
Milind Jog, Ph.D. (Committee Chair)
Shaaban Abdallah, Ph.D. (Committee Member)
Raj Manglik, Ph.D. (Committee Member)
83 p.
Mechanical Engineering
swirl flow and heat transfer; swirl flow and heat transfer; enhanced heat transfer; friction factor and Nusselt Number; nusselt and prandtl number; convection heat transfer

Recommended Citations

Citations

  • Dongaonkar, A. J. (2013). Numerical Modeling and Analysis of Fluid Flow and Heat Transfer in Circular Tubes Fitted with Different Helical Twisted Core-Fins [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377866455

    APA Style (7th edition)

  • Dongaonkar, Amruta. Numerical Modeling and Analysis of Fluid Flow and Heat Transfer in Circular Tubes Fitted with Different Helical Twisted Core-Fins. 2013. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377866455.

    MLA Style (8th edition)

  • Dongaonkar, Amruta. "Numerical Modeling and Analysis of Fluid Flow and Heat Transfer in Circular Tubes Fitted with Different Helical Twisted Core-Fins." Master's thesis, University of Cincinnati, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377866455

    Chicago Manual of Style (17th edition)

ucin1377866455
396
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This open access ETD is published by University of Cincinnati and OhioLINK.