Numerical Analysis of the Thermophysical Properties of Hybrid Nanofluids for Industrial Use
Loading...
Date
2022
Authors
Okello John Achola
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Hybrid nanofluids engineered using two or more different types of nanoparticles
suspended in the base fluid have numerous industrial and engineering applications.
The applications range from heat transfer (coolant) fluids in industrial thermal
processes, automotive industry, electronic devices, to being used in the biomedical
field in areas such as nanocryosurgery, nano-drug delivery, magnetic fluid
hyperthermia, etc. The current study examines the thermophysical properties of
hybrid nanofluids for application as industrial coolants and lubricant additives
(nanolubricants). The hybrid nanofluid (hybrid nanocoolant) consists of ethyleneglycol
as the base fluid with Copper-Alumina (Cu-Al2O3), Copper-Titania (Cu-TiO2),
and Titania-Alumina (TiO2-Al2O3) as the hybrid nanoparticles. The partial differential
equations governing the flow of the hybrid nanofluid are formulated and transformed
into a system of coupled non-linear ordinary differential equations using suitable
similarity transformation variables. The shooting technique together with the fourthorder
Runge-Kutta-Fehlberg integration scheme was used to obtain the numerical
solutions to the coupled non-linear ordinary differential equations. The numerical
analysis and simulation is achieved using MATLAB and the graphical results are
depicted for the various pertinent parameters involved in the flow. The presence of
nanoparticles makes the fluid susceptible to the effects of magnetic field. Increasing
magnetic field intensity (𝐻𝑎) applied to the flow retards the flow of the fluid and
enhances the fluid’s thermal boundary layer thickness maximizing the cooling effect
of the hybrid nanofluid. The (TiO2-Al2O3/EG) hybrid nanofluid maintains a low
temperature profile thus emerging as the optimal industrial coolant. For the
nanolubricant study, the fluid’s velocity profiles, temperature profiles, local Nusselt
number and skin friction coefficient were investigated for different pertinent
parameters namely; Eckert number (𝐸𝑐), suction/injection parameter (𝑓𝑤), magnetic
field intensity (𝐻𝑎), slip parameter (𝛽), nanoparticle volume fraction (𝜙), and
Grashof number (𝐺𝑟). The study considered MHD incompressible boundary layer
flow of engine oil-based ((MWCNTs-Cu), (MWCNTs-Al2O3), and (MWCNTs-
TiO2)) conducting hybrid nanofluids past a convectively heated vertical porous plate
with Navier slip boundary conditions. The study revealed increment in fluids velocity
and a decrease in local skin friction with increasing values of the slip parameter (𝛽).
The (MWCNTs-TiO2/engine oil) hybrid nanofluid registered the least coefficient of
skin friction thus emerging as the most suitable nanolubricant. The (TiO2-Al2O3/EG)
hybrid nanofluid that emerged as the best nanocoolant can be utilized in the cooling
of electronic devices, transformers, in the automobile radiators, cooling of drilling
equipment and sensors used in the extraction of geothermal energy, cooling of nuclear
reactors etc. The best nanolubricant (MWCNTs-TiO2/engine oil) can be used as a
lubricant in high temperature applications (lubrication).
Description
A Thesis Submitted in Full Fulfillment of the Requirement for the Award of the Degree of Doctor of Philosophy in Applied Mathematics in the School of Pure and Applied Sciences of Kenyatta University
Keywords
Numerical Analysis, Thermophysical Properties, Hybrid, Nanofluids, Industrial Use