Nanocomposites and nanomaterials

Conjugate heat transfer in thick walled pipe with laminar nano-fluid flow
Baydo A.1, Ates A.2, Canli E.2
1 Mechanical Engineering Department, Konya Technical University, Konya-42003, Turkey. 
2 Mechanical Engineering Department, Selcuk University, Konya-42003, Turkey.
E-mail: ecanli@selcuk.edu.tr

Abstract: Nano-scale particles can mix with Newtonian fluids in such a way that flow is not altered significantly while average thermo-physical properties of the new fluid mixture are improved in terms of heat transfer. Since nano-scale is at stake, fouling and pressure drop do not constitute significant problems considering particle addition to the base fluid. In the present work, a fluid having nano-scale copper oxides particles in it is investigated by means of computational fluid dynamics for conjugate heat transfer through a thick walled pipe. Flow is arranged as laminar. Pipe has two regions, i.e. upstream and downstream parts. Outer pipe wall surface has constant temperature boundary condition while upstream wall outer surface is insulated. Therefore fluid is preheated due to the axial heat conduction, which is one of the major concerns of the present work. Thermal entry length becomes shorter with increasing nano-particle volume fraction. Also the temperature gradient from pipe axis towards the pipe wall becomes smaller in thermally developed region with increasing nano-particle volume fraction. Fluid axial heat conduction, radial heat transfer, interface heat flux and temperature distributions in wall and fluid are given in graphical forms including dimensionless values. Although there are dimensionless studies in the literature for similar case designs without nano-fluid mentionings, covering a wide range of fluids, this work focuses a narrower range in which the thermo-physical properties of the fluid are hard to obtain with conventional common fluids. Also a literature survey concentrating on the most recent works in the literature are prepared and presented. In the future, it will be tried to discriminate the differences between single phase solution procedure and more sophisticated models involving two or more material phases. 
Keywords: Conjugate heat transfer, fluid axial conduction, nano fluid, thick walled pipe