International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Issue: 07 | July -2017
p-ISSN: 2395-0072
www.irjet.net
Computational Heat Transfer and Fluid Dynamics Analysis for Titanium Dioxide (TiO2) Deposition Rahul Kumar1, M.K. Chopra2 1P.G.
Scholar, Dept. Of Mechanical Engineering, R.K.D.F Institute of Science & Technology, Bhopal, M.P., India 2Vice Principal, Dean Academic & Head, Dept. Of Mechanical Engineering, R.K.D.F Institute of Science & Technology, Bhopal, M.P., India ---------------------------------------------------------------------***--------------------------------------------------------------------2. LITERATURE REVIEW Abstract – This paper suggests the best possible model of Computational Fluid Dynamics to simulate the process of deposition of Titanium Dioxide (TiO2) over a substrate formed as a result of pyrolysis of Titanium Tetraisopropoxide(TTIP) as a precursor and argon as carrier gas. As a result of pyrolysis of TTIP if the solid particles of TiO 2 gets formed before impinging the substrate then Discrete Particle Model (DPM) has to be applied or else if the formation of TiO2 is in vapor form and its particles are formed after impinging the substrate where it has to be deposited then Species Transport Model (SPM). After carrying out literature reviews it has been found that SPM is the best model to solve the phenomena of TiO2 formation as a result of TTIP pyrolysis and for finding the deposition rate thickness. Key Words: Pyrolysis, Impinging, Titanium Dioxide, Discrete Particle Model, Species Transport Model.
1. INTRODUCTION Titanium Dioxide (TiO2) is of much relevance and is used extensively for the industrial purposes due to its optical, chemical and electrical properties. Out of all the applications the water splitting as in the case of electrolysis can be done using TiO2 as electrode and light as a current source thus we call it photolysis of water [1]. This photolysis of water gives us hydrogen gas which can be further used as energy sources for the various applications. For the proper photolysis of water using TiO2 as electrode the deposition of TiO2 over a substrate should be proper. There are several processes of TiO2 formation and deposition over a substrate but the formation of TiO2 by the pyrolysis of the Titanium Tetraisopropoxide (TTIP) and its deposition on the substrate using argon as carrier gas is considered to be cost effective, which also allows the controlling of the microstructure [2-7]. This process of pyrolysis can be attempted for various ranges of temperature, pressure and concentration of precursor. The proper combination of all these parameters decides the deposition thickness of TiO2 over the substrate, so one need to carry out the Computational Fluid Dynamic (CFD) analysis in order to estimate the optimized parameter for achieving the required deposited thickness of TiO2 over a substrate.
© 2017, IRJET
|
Impact Factor value: 5.181
|
Yiyang Zhang et al performed experiments and found that Nanoporous TiO2 thin films are deposited directly onto substrates by a one-step stagnation flame synthesis with organometallic precursors. Intensive study related to deposition mechanism in the stagnation-point boundary layer was carried out by them. The radial profile of nanoparticle deposition flux for the first time was measured using a novel method of concentric collecting rings, which depicted similar trend with the heat flux profile of stagnation-point flows. Then they developed the mathematical model of nanoparticle transport and deposition in the stagnation-point boundary layer for further clarifying experimental results, especially the effects of substrate temperatures and in-situ produced particle sizes. Both thermophoresis in an inner part of boundary layer and thermal compression/expansion of the gas phase are found to play important roles in determining the deposition flux. The contribution of Brownian diffusion, determined by a thermophoretic Peclet number, is inappreciable compared to thermophoresis until particle diameter is as small as 2 nm. The results in this work support a conclusion of sizeindependence of the thermophoretic velocity, implying that the rigid-body collision assumption of Waldmann's formula is not accurate for small particles especially less than 10 nm. This study can be generally applied to other deposition techniques of thin films [2]. Erik D. Tolmachoff et al proposed a new method to fabricate nanocrystalline titania (TiO2) films of controlled crystalline size and film thickness. The method uses the laminar, premixed, stagnation flame approach, combining particle synthesis and film deposition in a single step. A rotating disc serves as a combination of substrate-holder and stagnationsurface that stabilizes the flame. Disc rotation repetitively passes the substrates over a thin sheet, fuel-lean ethylene– oxygen–argon flame doped with titanium tetra isopropoxide. Convective cooling of the back side of the disc keeps the substrate well below the flame temperature, allowing thermophoretic forces to deposit a uniform film of particles that are nucleated and grown via the flame stabilized just below the surface. The particle film grows typically at ~1 μm/s. The film is made of narrowly distributed, crystalline TiO2 several nanometers in diameter and forms with a 90% porosity. Analysis shows that the rotation of the stagnationISO 9001:2008 Certified Journal
|
Page 2386