A Numerical forced convection heat transfer analysis of nanofluids considering performance criteria

Download
index.pdf
2012
Kirez, Oğuz
Show full item record
167
views
75
downloads
A nanofluid is a new heat transfer fluid produced by mixing a base fluid and solid nano sized particles. This fluid has great potential in heat transfer applications, because of its increased thermal conductivity and even increased Nusselt number due to higher thermal conductivity, Brownian motion of nanoparticles, and other various effects on heat transfer phenomenon. In this work, the first aim is to predict convective heat transfer of nanofluids. A numerical code is created and run to obtain results in a pipe with two different boundary conditions, constant wall temperature and constant wall heat flux. The results for laminar flow for thermally developing region in a pipe are obtained for Al2O3/water nanofluid with different volumetric fraction and particle sizes with local temperature dependent conductivity approach. Various effects that influence nanofluid heat transfer enhancement are investigated. As a result, a better heat transfer performance is obtained for all cases, compared to pure water. The important parameters that have impact on nanofluid heat transfer are particle diameter of the nanoparticles, nanoparticle volumetric fraction, Peclet number, and viscous dissipation. Next, a heat transfer performance evaluation methodology is proposed considering increased pumping power of nanofluids. Two different criteria are selected for two boundary conditions at constant pumping power. These are heat transfer rate ratio of the nanofluid and the base fluid for constant wall temperature boundary condition and difference between wall temperature of the pipe at the exit and inlet mean temperature of the fluid ratio for constant wall heat flux case. Three important parameters that influence the heat transfer performance of nanofluids are extracted from a parametric study. Lastly, optimum particle size and volumetric fraction values are obtained depending on Graetz number, Nusselt number, heat transfer fluid temperature, and nanofluid type.
Nanoparticles, Nanofluids, Fluid dynamics, Fluid mechanics, Heat
http://etd.lib.metu.edu.tr/upload/12615174/index.pdf
https://hdl.handle.net/11511/22199
Graduate School of Natural and Applied Sciences, Thesis

Suggestions

Improving flow structure and natural convection within fin spacings of plate fin heat sinks
Özet, Mehmet Erdem; Tarı, İlker; Department of Mechanical Engineering (2015)
The main objectives of this thesis are to numerically investigate the previously observed recirculation zones and longitudinal vortices that occur in low fin height plate finned horizontal heat sinks and to improve the flow structures and heat transfer in these zones using various approaches with the help of simulations performed using commercially available CFD software. The approaches used for improvements are replacing the outer most fins with higher ones, introducing gaps on the length of the fins in va...
A CSCM approximation of steady MHD flow and heat transfer between parallel plates with hydrodynamic slip and convective boundary conditions
Tezer, Münevver; Türk, Önder (null; 2019-10-04)
The steady magnetohydrodynamic (MHD) flow together with its heat transfer between parallel plates is considered in which the electrically conducting fluid has temperature dependent properties such as viscosity, thermal and electrical conductivity. The fluid is driven by a constant pressure gradient, and a uniform external transverse magnetic field is applied perpendicular to the plates. The effects of viscous and Joule dissipations are considered in the energy equation, and the fluid is assumed to be slippi...
A numerical study of solidification and viscous dissipation effects on polymer melt flow in plane channels
Tutar, Mustafa; Karakuş, Ali (Walter de Gruyter GmbH, 2013-04-01)
The combined effects of solidification and viscous dissipation on the hydrodynamic and thermal behavior of polymer melt flow during the injection process in a straight plane channel of constant cross section are numerically studied by considering the shear-rate and temperature-dependent viscosity and transient-phase change behavior. A numerical finite volume method, in conjunction with a modified form of the Cross constitutive equation to account for shear rate, temperature-dependent viscosity changes and a...
AN ACCELERATED NODAL DISCONTINUOUS GALERKIN METHOD FOR THERMAL CONVECTION ON UNSTRUCTURED MESHES: FORMULATION AND VALIDATION
Karakuş, Ali (2022-04-01)
We present a GPU-accelerated method for large scale, coupled incompressible fluid flow and heat transfer problems. A high-order, nodal discontinuous Galerkin method is utilized to discretize governing equations on unstructured triangular meshes. A semi-implicit scheme with explicit treatment of the advective terms and implicit treatment of the split Stokes operators are used for time discretization. The pressure system is solved with a conjugate gradient method together with a fully GPU-accelerated multigri...
An experimental investigation on performance of annular fins on a horizontal cylinder in free convection heat transfer
Yildiz, S; Yüncü, Hafit (Springer Science and Business Media LLC, 2004-02-01)
Natural convection heat transfer in annular fin-arrays mounted on a horizontal cylinder was experimentally investigated. An experimental set-up was constructed to investigate heat transfer characteristics of 18 sets of annular fin-arrays mounted on a horizontal cylinder of 24.9-mm diameter in atmospheric conditions. Keeping the fin thickness fixed at 1 mm, fin diameter is varied from 35 mm to 125 mm and fin spacing is varied from 3.6 mm to 31.7 mm. The base-to-ambient temperature difference was also varied ...
Citation Formats
O. Kirez, “A Numerical forced convection heat transfer analysis of nanofluids considering performance criteria,” M.S. - Master of Science, Middle East Technical University, 2012.
METU IIS - Integrated Information Service open@metu.edu.tr