Effects of Reynolds number, baffle angle, and baffle distance on three-dimensional turbulent flow and heat transfer in a circular pipe

Abstract

In this study, steady-state three-dimensional turbulent forced convection flow and heat transfer characteristics in a circular pipe with baffles attached inside pipe have been numerically investigated under constant wall heat flux boundary condition. Numerical study has been carried out for Reynolds number Re of 3000-50,000, Prandtl number Pr of 0.71, baffle distances s/D of 1, 2, and 3, and baffle angle a of 30o-150o. Ansys Fluent 12.0.1 software has been used to solve the flow field. It is observed that circular pipe having baffles has a higher Nusselt number and friction factor compared to the smooth circular pipe without baffles. Maximum Nusselt number and friction factor are obtained for the baffle angle of 90o. Nusselt number increases while baffle distance increases in the range of studied; however, friction factor decreases. Periodically fully developed conditions are obtained after a certain module. Thermal performance factor increases with increasing baffle distance in the rage of studied but decreases with increasing Reynolds number; maximum thermal performance factor is obtained for the baffle angle of 150?. Results show that baffle distance, baffle angle, and Reynolds number play important role on both flow and heat transfer characteristics. The accuracy of the results obtained in this study is verified by comparing the results with those available in the literature for smooth circular pipes. All the numerical results are correlated within accuracy of ?10 and ?15% for average Nusselt number and Darcy friction factor, respectively.

Characteristics of Heat Transfer and Turbulent Flow in a Baffled Pipe with Different Arrangements

“…where 𝜎 6 and 𝜎 7 are the Prandtl numbers linking the eddy viscosity 𝜇 , , with diffusivities of k and ϵ, the strain rate tensor as a function of velocity can be written as (7).…”

“…They determined that the baffle with a trapezoidal shape is the optimal choice for improving heat transfer and reducing pressure drop as compared to other shapes. Turgut and Kizilirmak [7] performed a numerical simulation to examine the steady state of 3D turbulent forced convection flow in a circular pipe with a baffle. A numerical analysis was conducted by Selvaraj et al [8] to examine the flow and heat transfer in a circular pipe.…”

Unsteady Numerical Simulation of Turbulent Forced Convection in a Rectangular Pipe Provided With Waved Porous Baffles

“…Thermo-physical properties are assumed to be constant. Thus, the continuity equations, impulse, energy, and the standard k-ε turbulence model can be written as follows, respectively [20].…”

Investigation of Effects of Baffle Heights on Flow and Heat Transfer in a Trapezoidal Channel with Vertical Baffles

“…[30] dikdörtgen bir kanalda Z tipi saptırma türbülatörlerinin ısıl performans üzerindeki etkilerini deneysel ve sayısal olarak analiz etmişler ve düz kanallarla karşılaştırıldığında Z bölmelerin ısıl performans üzerinde önemli bir etkiye sahip olduğunu göstermişlerdir. Turgut ve Kızılırmak [31] bir kanal içerisinde farklı eğim açılarına (30 o ≤α≤150 o ) sahip bölmelerin akış ve ısı transferini türbülanslı akış için sayısal olarak incelemişler ve en yüksek ısıl performansın α=150 o 'de elde edildiğini bulmuşlardır. Promvonge vd.…”