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Sungai Buloh, Malaysia

Teh A.L.,Monash University | Chin K.W.,Monash University | Teh E.K.,Monash University | Chin W.M.,Oyl d nter Sdn Bhd | And 2 more authors.
Chemical Engineering Research and Design | Year: 2015

The downstream hydrodynamic and thermal mixing performance of control and fractal orifice plates is numerically investigated. Each insert is positioned following a T-duct. Four blockage ratio plates σ=0.5, namely, square orifice (SO), circular orifice (CO), square fractal orifice (SFO), and the Koch snowflake orifice (KSFO), are employed to promote thermal mixing. In particular, orifice configuration effects that induced transverse and horizontal thermal convergence, turbulence kinetic energy, and pressure gradient changes are discussed. Numerical validations reveal good agreement between the experimental and numerical results for centerline velocity and temperature distributions along the channel. The results show that KSFO outperforms the rest with respect to effective hydrodynamic and thermal mixing. It is critical to note that the maximum cross-sectional temperature difference δθ for KSFO is the lowest and decreases further downstream. Clearly, such low δθ values along the channel ensure temperature uniformity. Furthermore, KSFO generated area-averaged turbulence kinetic energy levels approximately 37%, 48%, 371%, and 1454% higher than those of CO, SO, SFO, and the smooth channel without an insert, respectively, at x/H=1.04. It is also important to note that the studied fractal orifice pressure gradients are lower than those of CO and SO. These pressure drop observations are consistent with those of Nicolleau et al. (2011). Overall, the complex KSFO geometry forms a prominent balance between the pressure coefficient and thermal mixing at a Reynolds number of Reh=1.94×104. Most importantly, this finding may help guide the long-term sustainable development of heating, ventilation and free-cooling air conditioning systems. © 2015 The Institution of Chemical Engineers.

Nordin N.,University Tun Hussein Onn Malaysia | Karim Z.A.A.,Petronas University of Technology | Othman S.,University Tun Hussein Onn Malaysia | Raghavan V.R.,Oyl d nter Sdn Bhd
Advanced Materials Research | Year: 2013

In practice, it is basically difficult even with controlled measurement environment to acquire a steady, uniform and fully developed flow. The flow entering diffuser was severely distorted despite a sufficient hydrodynamic entrance length already introduced. This was mainly due to the imperfect joining of duct and the abrupt change of the inlet cross-section applied. In this study, several basic features of a low subsonic wind tunnel, i.e. a centrifugal blower with 3-phase inverter, a settling chamber, screens and a contraction cone, are designed and developed for a turning diffuser application in order to improve the flow quality. The flow profiles are examined using Pitot static probe at five measurement points within the range of inflow Reynolds number, Rein= 5.786E+04-1.775E+05. The steady, uniform and fully developed turbulent flow profiles with an average deviation with theory of about 3.5% are obtained. This proves that a good flow quality could be produced by means of incorporating some basic features of a low subsonic wind tunnel to the system. © (2013) Trans Tech Publications, Switzerland.

Seth N.N.,University Tun Hussein Onn Malaysia | Mat Isa N.B.,University Tun Hussein Onn Malaysia | Othman S.B.,University Tun Hussein Onn Malaysia | Raghavan V.R.,Oyl d nter Sdn Bhd
ARPN Journal of Engineering and Applied Sciences | Year: 2016

The aim of installing baffles is to reduce or eliminate, if possible, secondary flow which exists mostly at the inner wall of the turning diffuser. Furthermore, other than distortion at the inner wall, 3-dimensional turning diffuser has secondary flow at both left and right wall. This was due to the diffusing activities which were not only in x-y direction but in y-z direction as well. Experiment on 3-dimensional turning diffuser with baffle has been conducted using airfoil baffle with AOA=17°. Present study focuses on changing angle of attack of the installed baffle and their effects on flow uniformity and pressure recovery using numerical approach. The baffle was rotated 3° clockwise and anti-clockwise resulting in AOA=20° and AOA=14° respectively. Qualitative and quantitative comparison was discussed in this paper. AOA=14° offers higher quality of flow structure as compared to AOA= 20°, but still could not surpass the performance using preliminary design baffle with AOA= 17°. The abnormality of flow in AOA=20° resulting in higher pressure loss, thus affecting pressure recovery. The optimum configuration can be developed if the effort of improving the airfoil design could be enhance in future works. © 2006-2016 Asian Research Publishing Network (ARPN). All rights reserved.

Nohseth N.H.,University Tun Hussein Onn Malaysia | Nordin N.,University Tun Hussein Onn Malaysia | Othman S.,University Tun Hussein Onn Malaysia | Raghavan V.R.,Oyl d nter Sdn Bhd
Applied Mechanics and Materials | Year: 2014

Turning diffuser is an engineering device that is widely used in the industry to reduce the flow velocity as well as change the direction of the flow. Having a curvature shape causes its performance to decrease in terms of pressure recovery (Cp) and flow uniformity (σu). Therefore, this study presents the work done in designing baffles to be installed in the turning diffuser with ratio of AR=2.16 to improve the flow uniformity and pressure recovery. It also aims to investigate the mechanism of flow structure and pressure recovery in turning diffusers by means of turning baffles. The results with varying inflow Reynolds number (Rein) between 5.786E+04 - 1.775E+05 have been experimentally tested and compared with previous study. Particle image velocimetry (PIV) was used to determine the flow uniformity. On the other hand, a digital manometer provided the average static pressure of the inlet and outlet of turning diffuser. The best produced pressure recovery of Cp=0.526 were recorded when the system were operated at the highest Reynolds number tested Rein=1.775E+05. This result shows an improvement up to 54.625% deviation from previous study with Cp=0.239. The flow uniformity also shows an improvement of 47.127% deviation from previous study at the same Rein with σu=3.235 as compared to previous study σu=6.12. © (2014) Trans Tech Publications, Switzerland.

Seri S.M.,Petronas | Abdul Karim Z.A.,Petronas | Batcha M.F.M.,University Tun Hussein Onn Malaysia | Raghavan V.R.,Oyl d nter Sdn Bhd
Applied Mechanics and Materials | Year: 2014

Present study involves experimental and numerical work to investigate the effect of integral wake splitter towards the overall performance of cross-flow, circular tube, heat exchanger system. The experimental work was conducted to obtain local distribution of pressure coefficient around plain tube bank of staggered arrangement which was subjected to a cross-flow of air with Reynolds number of 15950. The numerical work consisted of 2-dimensional unsteady numerical simulation which was validated against the experimental data. The validated numerical approach was utilized to simulate cross-flow around similar tube bank but with integral wake splitter of length-to-diameter ratio of 0.5, 1, 1.5 and 2, at Reynolds number between 5000 to 50000. It is concluded that integral wake splitter is able to reduce pressure loss, which in turn reduces power requirement of a blower, which is intended in effort to increase the system efficiency. Splitter which acts as fin may improve the overall performance of the system by enhancing total heat removal via extended surface provided that certain value of fin efficiency is achieved. © (2014) Trans Tech Publications, Switzerland.

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