Papers by Keyword: Reynolds Number

Abstract: Monosodium Glutamate (MSG) [1] was invented more than 100 years ago from its first invention in 1908 by Japanese biochemist Kikunae Ikeda, who was trying to isolate and duplicate the savory taste of kombu, an edible seaweed used as a base for many Japanese soups. From 2016, most MSG worldwide is produced by bacterial fermentation in a process similar to making vinegar or yogurt. Sodium is added later, for neutralization. During fermentation, Corynebacterium species, cultured with ammonia and carbohydrates from sugar beets, sugarcane, tapioca (cassava tuber) or molasses, excrete amino acids into a culture broth from which L-glutamate is isolated. In this process, Monosodium Glutamate companies buy cassava [2] pulps from farmers that contain a lot of sand and impurities. In order to increase the productivity with lowest expense, the filtration of sand and solid impurities’ is performed by separation cyclone. In this paper, we study all the measure to design a system of effective pump, cyclone to extract as much as possible all of solid impurities included sand out of cassava slurry before providing to the bacterial fermentation in a process.

Abstract: The present work focuses on the mold design and production of the multifunctional device laryngoscope with surface quality through the injection molding process. A laryngoscope is a device used by anesthesiologists to lift the tongue that facilitates to fix the air pipe in the larynx. Demand still exists in the laryngoscope part to assist anesthesiologists to take care of the airway without causing chest compression and ensure visualization of vocal cords. Therefore, the present work aims at developing a laryngoscope with a double channeled device, wherein one for aligning the camera and another for the air pipe. The paper outlines the design parameters required for manufacturing a single cavity mold to produce a laryngoscope viz. injection molding machine. The mold has multiple plates with complex fluid channels which ensures effective thermal management in-mold system. The mold is manufactured using high-strength tool steel materials and the product laryngoscope (ABS: Acrylonitrile butadiene styrene) is fabricated from the designed mold. Taguchi L9 experimental array was used to determine the optimal conditions (injection pressure, injection velocity, mold and melt temperature) for desired surface finish in the laryngoscope parts. The designed mold and optimized injection molding conditions resulted in a lower surface roughness value equal to 0.214 µm. Thereby, injection-molded laryngoscope parts can be used for large-scale productions for the benefit of medical applications.

Abstract: A new approach to evaluate the Newtonian flow between concentric rotating spheres is introduced in this paper. A general analytic solution to the problem is deduced using a perturbation method that takes into account the primary and secondary flows produced between the spheres, as well as an alternative analytical method. In order to exemplify the results of the previous analysis, six particular cases were studied. The results of the perturbation method show that under certain circumstances the secondary flow is no negligible, as is usually considered, but it is comparable to the value of the primary one. While the analytical method allows us to simulate the flow with results very similar to those of other authors.

Abstract: Numerical model of the convective-radiative heat transfer of porous media was proposed. A stainless wire-net was used as porous media. The physical properties, consisting of porosity (φ) and optical thickness (τ₀), of porous media were independent variables. The air velocity was reported in the form of Reynolds number (Re). Two equations of the conservative energy with local thermal non-equilibrium were analyzed. The gas (θ_f) and solid (θ_s) phases of conservative energy equation inside porous media were investigated. The radiative heat flux (ψ) at down-stream of solid phase emitted into outside was dealt by the P₁ approximation. From the study, it was found that the level of θ_f and θ_s decreased as Re increased because the effect of convection heat transfer. Inversely, the level of ψ increased as increasing Re. The level of θ_f, θ_s and ψ were decreased as φ increased owing to a lower volume of material depended on the increasing level of φ resulting to the heat transfer rate became lower. The level of θ_f, θ_s and ψ gave increased with τ₀ becaues a wider distance in absorping energy leading to a higher emission energy from the porous media was achieved.

Abstract: Air core is an important parameter in pressure swirl atomizer since formation of air core determines the thickness of the discharged liquid sheet and the effective flow area of nozzle discharge. This consequently will affect the coefficient of discharge and the spray angle. This study conducted for the investigation of the relation between dimensionless numbers on the air core diameter. Dimensionless numbers are helpful aid for the quantification of independent parameters involving atomizer design and operating conditions simultaneously. Reynolds number, Re and orifice-to-swirl chamber diameter ratio, N are the dimensionless numbers selected for this study. Despite of the availability of study on the effect of dimensionless numbers on air core diameter, more study requires especially for smaller N. An experimental test-rig was constructed to conduct the performance test of the atomizer. Acquired images were analyzed using image-processing software. It was found that N has more significant effect on the change of air core diameter compared to Re. However, it is observed that at Re = 40000, N = 0.07 produces almost similar air core diameter with N = 0.25 at Re < 20000. In contrast, with N = 0.5, air core diameter produces are larger even at Re < 20000. Hence, it can be concluded that both Re and N are important parameters in characterizing the air core diameter in pressure-swirl atomizer.

Abstract: This paper presents a computer software application (using the Maple programming language) together with numerical applications which allow the determination of the pressure drop uniformly distributed in the pipes with circular-eccentric section, which appears in the case of critical transition flow subdomain I.

Abstract: In this investigation, a magnetohydrodynamic (MHD) flow of AlO /water nanofluid and Cu-AlO /water hybrid nanofluid through a porous channel is analyzed in the presence of a transverse magnetic field. An exact solution of the governing equations has been obtained in closed form. The entropy generation number and the Bejan number are also obtained. The influences of each of the governing parameters on velocity, temperature, entropy generation and Bejan number are displayed graphically and the physical aspects are discussed. In addition, a comparison of the heat transfer enhancement level due to the suspension of AlO and Cu nanoparticles in water as regular nanofluids and as hybrid Cu-AlO /water nanofluid is reported.

Abstract: Nanotechnology has become one of the fastest growing scientific and engineering disciplines. Nano fluids have been established to possess enhanced thermal and physical properties such as thermal conductivity, thermal diffusivity, viscosity and convective heat transfer coefficients. The aim of this research article is to analyze the overall heat transfer coefficient by doing an experimental investigation on the convective heat transfer and flow characteristics of a nano fluid. In this research, an attempt was made for the nano fluid consisting of water and 1% volume concentration of Al₂O₃/water Nano fluid flowing in a parallel flow, counter flow in shell and tube heat exchanger under laminar flow condition. The 50nm diameter Al₂O₃nanoparticles are used in this investigation and was found that the overall heat transfer coefficient and convective heat transfer coefficient of nano fluid to be slightly higher than that of the base liquid at same mass flow rate and inlet temperature. Three samples of dissimilar mass flow rates have been identified for conducting the experiments and their results are continuously monitored and reported. The experimental analysis results were concluded that the heat transfer and overall heat transfer coefficient enhancement is possible with increase in the mass flow rate of fluid and Al₂O₃/water nano fluid on a comparative basis.

Abstract: Nanotechnology is a novel approach in thermal engineering science to enhance the overall thermal performance of compact heat exchangers by the homogeneous dispersion of solid nanoparticles of higher thermal conductivity in conventional base fluid like water, oil, ethylene glycol etc. The heat transfer rate is substantially intensified by the addition of nanosized solid particles which provide superior thermo-physical properties in comparison with base fluid. In the present study, a numerical simulation is performed to investigate the turbulent convective heat transfer characteristics of Al₂O₃-water nanofluid of volume fractions (1%, 3% and 5%) through a rough circular tube subjected to constant heat flux for a range of Reynolds number 10,000 to 30,000. The finite volume method is employed for solving the governing equations and k-ω SST turbulent model for single phase analysis is considered. At a Reynolds number of 25000, application of nanofluid combined with rough tube enhances the Nusselt number by 13.10%, 21.86% and 63.03% in case of relative roughness of the wall of 0.001, 0.005 and 0.01 respectively.

Abstract: Jet impingement is one of cooling method used in order to achieve high heat transfer coefficient and widely used in industry applications such as drying of textile and film, glass and plastic sheets, cooling of electronic equipment, and heat treatment of metals. In this research, it focused on the effectiveness of the jet impingement cooling system on the convex surface based on mass blowing rate and nozzle exit to surface parameters. The scope of experiment research encompasses are convex surface made of aluminum alloy and diameter 12.5cm. For mass blowing rate parameters, it use ʋjet = 1.98m/s, 3.03m/s, 4.97m/s and 6.00m/s which has Reynolds number range from 643 until 1946. Nozzle exit to surface distance,s/d = 4.0, 8.0 and 12.0. In this experiment model, a major components that involved are a compressor, nozzle, convex surface model, K thermocouple and heater. For the result of the experiment, it is based on the data obtain through a heat transfer coefficient and Nusselt number which the plotted graph focus on the space spacing and Reynolds number parameters. For the graph Nusselt number versus s/d at stagnation point c/d=0, it shown that when the Reynolds number increase, the Nusselt number also increase. In term of effectiveness, the s/d=12.0 has a good effectiveness jet impingement cooling system. For the graph of Nusselt number versus Reynolds at stagnation point, c/d=0, as Reynolds number increase, the Nusselt number increase too. From this experiment the better cooling effect is at Reynolds number, Re=1946. Thus, it can conclude that, effectiveness for jet impingement cooling system on the convex surface occurs at the highest Reynolds number.