FUOYE Journal of Engineering and Technology, Volume 4, Issue 2, September 2019 ISSN: 2579-0625 (Online), 2579-0617 (Paper) FUOYEJET © 2019 158 http://dx.doi.org/10.46792/fuoyejet.v4i2.377 engineering.fuoye.edu.ng/journal Numerical Simulation of Conjugate Heat Transfer in Forced Convective Boundary Bilayered Cylindrical Pipe with Different Peclet Numbers Oluwasegun S. Omosehin and *Adekunle O. Adelaja 1 Department of Mechanical Engineering, University of Lagos, Akoka, Yaba, Lagos State, 101017, Nigeria omosehin_oluwasegun@yahoo.com|aadelaja@unilag.edu.ng Abstract - The heat transfer performance of bilayered composite systems through which thermally developing laminar fluids flow for cases in which axial conduction is either significant or negligible has been investigated. The heat transfer problems considered as two dimensional conjugate problems with appropriate boundary conditions were solved via computational fluid dynamics (CFD) approach in ANSYS 16.0. A parametric study was conducted to investigate the effects of Péclet number (Pe), ratio of the thermal conductivity of the laminate composite (k21) and the laminate composite dimensionless-thickness ratio ( 21 ) on the wall-fluid interfacial temperature and interfacial heat flux for Pe of 5, 100 and 1000,  21 varying between 0.4 and 1.6, Bi of 5, kwf of 20, k21 between 0.025 and 1, and  1 of 0.71. The effect of Pe was found to be more pronounced on the interfacial heat flux. Also, the changes in k21 and  21 were shown to reduce with reduction in Pe. Keywords - Composite cylinder, convective heat transfer, Numerical simulation; thick-walled pipes —————————— ◆ —————————— 1 INTRODUCTION ilayered cylindrical pipes are widely used for thermal insulation in oil- and gas-pipeline facilities to minimize the rate of heat loss and to prevent wax and hydrate formation during the conveyance of hot fluids between reservoirs and discharge units, especially in cold environments. Laminated material also has numerous applications in pressure vessels, aerospace components, naval structures, electronic equipment, and in the metal-forming and -rolling industries. They are very effective for design flexibility, increased strength- to-weight ratios, and dimensional stability under thermal loading, corrosion resistance, impact resistance, and high-fatigue strength. Pe however is the ratio of the rate of advection of a physical quantity by the flow to the rate of diffusion of the same quantity. The parameter (Pe) is used to characterize fluid flow and flow conditions into three regimes. A low Peclet number (Pe ≤ 50) describes a flow regime that accommodates both axial and radial conductions in the fluid, for instance, low Prandtl number flow in a single thick-walled cylinders (Darici et al. 2015; Ate et al., 2010). When Pe = 100, the length of the heating zone around the flow is considered short (Weigand and Lauffer, 2004), and for turbulent pipe flow (Lee, 1982). For very high Pe = 1000, axial conduction in the fluid is considered negligible Low Pe flows are often regarded as flows involving low Prandtl numbers and/or flows with low Reynolds numbers such as liquid metals. Axial conduction cannot be neglected in these types of fluid flows. Also, in thick-walled pipes, wall axial conduction cannot be neglected. However, as wall thickness becomes extremely thin, wall axial conduction can be negligible. When Pe increases, wall and fluid axial conduction decrease and become negligible at high value. This can be approximated to the no axial- conduction condition case. Faghri and Sparrow (1980) in reported that interfacial heat flux is more informative in characterizing fluid flow than Nusselt number. Additionally, from literature, in relation to analysis of flow in single channels and over flat plates, few studies have been conducted on conjugate heat transfer in multilayered composite cylindrical pipes or slabs. *Corresponding Author For instance, some investigations have been done on the thermo-mechanical and mechanical properties of composite laminates (Chao et al. 2007; Pradeep and Ganesan, 2008). Therefore, the present work is centred on adaptation of wall-fluid interfacial temperature and heat flux distribution for the characterization of conjugate heat transfer dynamics in bilayered cylindrical pipe. Norouzi and AmiriDelouei (2015) and Lu et al. (2006) presented detailed reviews of the thermal analysis of multilayer composites. But, it is equally expedient that some explorations of few existing works on conduction heat transfer in multilayered composite as well as conjugate heat transfer in single and multilayered composite is undertaken. This is imperative in order to establish the landscape of research in conjugate heat transfer in multi-layered composite structure. Yuen (1994) investigated the transient temperature distribution in a multilayered medium representing hot processing of flat plates subject to radiative surface cooling. Johansson and Lesnic (2009) employed the method of fundamental solutions to obtain the temperature field in transient heat conduction problems in layered materials. Tarn and Wang (2003, 2004) studied heat conduction in functionally graded and composite laminated cylinders. Torabi and Zhang (2015) investigated the temperature distribution and entropy generation rate within two-layer composite walls with combined convection and radiation boundary conditions. The thermal conduction and internal heat generation were assumed to be temperature dependent. The differential transformation method (DTM) was employed to solve the non-linear problem. It was shown that the ratio of the thermal conductivity and the interfacial location has a great effect on the rate of total entropy generation. De Monte (2003, 2004) investigated the heat conduction in homogeneous materials for one- dimensional and two-dimensional problems using the separation of variables method. On two dimensional analysis of a single hollow cylinder, Zhang et al. (2010) numerically studied the effect of two- dimensional wall conduction in a thick-walled hollow cylinder with simultaneously developing laminar flow subjected to constant outside wall temperature. It was observed that for kwf ≤ 25, increasing δ/ri and decreasing B