Effects of a flow mode transition on natural convection heat transfer in a heat tracing enclosure

Abstract

This paper presents a numerical study of transient buoyancy-induced fluid flow and heat transfer between two horizontal, differentially heated pipelines inside a circular, air-filled enclosure. Numerical simulations based on the finite difference method were conducted to investigate the flow mode transition of the buoyant airflow and its effects on the heat transfer characteristics of the pipelines. The results indicate that the fluid flow complexity and the heat transfer of air between the pipelines are strongly affected by the Rayleigh number. When Ra = 6 × 10⁵ and 1.2 × 10⁶, both the flow field and the temperature distribution exhibit periodic variations with different patterns. The former (Ra = 6 × 10⁵) is a complete alteration of the flow direction from clockwise to counterclockwise, whereas the latter is a variation in the flow field strength that varies between strong and weak. The latter has a lower variation frequency than that of the former.

Keywords

Natural convection enclosure flow heat tracing energy numerical simulation

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References

Kohli

. Steam tracing of pipelines. Chem Eng 1979; 86: 156–163.

Atayılmaz

ŞÖ

Teke

. Experimental and numerical study of the natural convection from a heated horizontal cylinder. Int Commun Heat Mass Transf 2009; 36: 731–738.

Demir

. Experimental and numerical studies of natural convection from horizontal concrete cylinder heated with a cylindrical heat source. Int Commun Heat Mass Transf 2010; 37: 422–429.

Reymond

Murray

O'Donovan

. Natural convection heat transfer from two horizontal cylinders. Exp Therm Fluid Sci 2008; 32: 1702–1709.

Baïri

Zarco-Pernia

García de María

J-M

. A review on natural convection in enclosures for engineering applications. The particular case of the parallelogrammic diode cavity. Appl Therm Eng 2014; 63: 304–322.

Butler

Newport

Geron

. Natural convection experiments on a heated horizontal cylinder in a differentially heated square cavity. Exp Therm Fluid Sci 2013; 44: 199–208.

Wang

Lei

Wang

et al.

Natural convection around a pair of hot and cold horizontal microtubes at low Rayleigh numbers. Appl Therm Eng 2014; 72: 114–119.

Atayılmaz

ŞÖ

. Experimental and numerical study of natural convection heat transfer from horizontal concentric cylinders. Int J Therm Sci 2011; 50: 1472–1483.

Rahnama

Mehrabian

Mansouri

et al.

Numerical simulation of laminar natural convection in horizontal annuli with radial fins. Proc IMechE, Part E: J Process Mechanical Engineering 1999; 213: 93–97.

10.

Fattahi

Farhadi

Sedighi

. Lattice Boltzmann simulation of natural convection heat transfer in eccentric annulus. Int J Therm Sci 2010; 49: 2353–2362.

11.

Lee

Shu

. Application of the GDQ method for the study of natural convection in horizontal eccentric annuli. Numer Heat Transf A Appl 2002; 41: 803–815.

12.

Garoosi

Bagheri

Talebi

. Numerical simulation of natural convection of nanofluids in a square cavity with several pairs of heaters and coolers (HACs) inside. Int J Heat Mass Transf 2013; 67: 362–376.

13.

Khalili

Saboonchi

Saghafian

. Natural convection of Al₂O₃ nanofluid between two horizontal cylinders inside a circular enclosure. Heat Transf Eng 2016; 38: 177–189.

14.

Sheikhzadeh

Fattahi

Mehrabian

et al.

Effect of geometry on magneto-convection in a square enclosure filled with a low Prandtl number fluid. Proc IMechE, Part E: J Process Mechanical Engineering 2011; 225: 53–61.

15.

Chang

Wang

. Natural convection between two horizontal cylinders in an adiabatic circular enclosure. J Heat Transf 1993; 115: 158–165.

16.

Cheng

Wang

. Natural convection between two horizontal cylinders inside a circular enclosure subjected to external convection. Int J Heat Fluid Flow 1994; 15: 299–306.

17.

Dai

Lei

et al.

Numerical simulation of natural convection between hot and cold microtubes in a cylinder enclosure. Int J Therm Sci 2015; 95: 115–122.

18.

Thompson

Thames

Mastin

. Automatic numerical generation of body-fitted curvilinear coordinate system for field containing any number of arbitrary two-dimensional bodies. J Comput Phys 1974; 15: 299–319.

19.

Thomas

Middlecoff JF . Direct control of the grid point distribution in meshes generated by elliptic equations. AIAA J 1980; 18: 652–656.

20.

Adlam

. Computation of two-dimensional time-dependent natural convection in a cavity where there are internal bodies. Comput Fluids 1986; 14: 141–157.

21.

Patankar

. Numerical heat transfer and fluid flow, Washington, DC: Hemisphere, 1980.

22.

Park

Chang

. Numerical study on an interactive laminar natural convection from a pair of vertically separated horizontal cylinders. Numer Heat Transf 1988; 14: 61–74.