Tantular Nurtono

Effect of turbulence modelling to predict combustion and nanoparticle production in the flame assisted spray dryer based on computational fluid dynamics

Flame assisted spray dryer are widely uses for large-scale production of nanoparticles because of it ability. Numerical approach is needed to predict combustion and particles production in scale up and optimization process due to difficulty in experimental observation and relatively high cost. Computational Fluid Dynamics (CFD) can provide the momentum, energy and mass transfer, so that CFD more efficient than experiment due to time and cost. Here, two turbulence models, k-e and Large Eddy Simulation were compared and applied in flame assisted spray dryer system. The energy sources for particle drying was obtained from combustion between LPG as fuel and air as oxidizer and carrier gas that modelled by non-premixed combustion in simulation. Silica particles was used to particle modelling from sol silica solution precursor. From the several comparison result, i.e. flame contour, temperature distribution and particle size distribution, Large Eddy Simulation turbulence model can provide the closest data to th...

Particle formation of hydroxyapatite precursor containing two components in a spray pyrolysis process

The particle formation mechanism of hydroxyapatite precursor containing two components, Ca(OOCCH3)2 and (NH4)2HPO4 with a ratio of Ca/P = 1.67, in a spray pyrolysis process has been studied by computational fluid dynamics (CFD) simulation on the transfer of heat and mass from droplets to the surrounding media. The focus included the evaporation of the solvent in the droplets, a second evaporation due to crust formation, the decomposition reaction of each component of the precursor, and a solid-state reaction that included the kinetic parameters of the precursor regarding its two components that formed the hydroxyapatite product. The rate of evaporation and the reacted fraction of the precursor both increased with temperature. The predicted average size of the hydroxyapatite particles agreed well with the experimental results. Therefore, the selected models were also suitable for predicting the average size of particles that contain two components in the precursor solution.

Effect of the flame temperature on the characteristics of zirconium oxide fine particle synthesized by flame assisted spray pyrolysis

Zirconium oxide fine particles were synthesized by flame assisted spray pyrolysis using zirconium chloride solution as precursor. Propane gas and air were used as a fuel and an oxidizer, respectively. The ratio of flow rate of oxidizer and fuel was maintained constant at 10:1 to ensure a complete combustion. Increasing fuel flow rate led to the increase of temperature distribution in the flame reactor. The intensity of XRD patterns increased with temperature and precursor concentration. Phase composition of zirconium oxide produced by this process consisted of monoclinic and tetragonal phases. The volume fraction of monoclinic phase of zirconium oxide increased with temperature and precursor concentration. The morphology particles observed by SEM resulted in spherical particles with size in the submicron range depending on the precursor concentration.

An integrated green process: Subcritical water, enzymatic hydrolysis, and fermentation, for biohydrogen production from coconut husk

The objective of this work is to develop an integrated green process of subcritical water (SCW), enzymatic hydrolysis and fermentation of coconut husk (CCH) to biohydrogen. The maximum sugar yield was obtained at mild severity factor. This was confirmed by the degradation of hemicellulose, cellulose and lignin. The tendency of the changing of sugar yield as a result of increasing severity factor was opposite to the tendency of pH change. It was found that CO2 gave a different tendency of severity factor compared to N2 as the pressurizing gas. The result of SEM analysis confirmed the structural changes during SCW pretreatment. This study integrated three steps all of which are green processes which ensured an environmentally friendly process to produce a clean biohydrogen.

Effect of fuel rate and annealing process of LiFePO4 cathode material for Li-ion batteries synthesized by flame spray pyrolysis method

In this study the effect of fuel rate and annealing on particle formation of LiFePO4 as battery cathode using flame spray pyrolysis method was investigated numerically and experimentally. Numerical study was done using ANSYS FLUENT program. In experimentally, LiFePO4 was synthesized from inorganic aqueous solution followed by annealing. LPG was used as fuel and air was used as oxidizer and carrier gas. Annealing process attempted in inert atmosphere at 700°C for 240 min. Numerical result showed that the increase of fuel rate caused the increase of flame temperature. Microscopic observation using Scanning Electron Microscopy (SEM) revealed that all particles have sphere and polydisperse. Increasing fuel rate caused decreasing particle size and increasing particles crystallinity. This phenomenon attributed to the flame temperature. However, all produced particles still have more amorphous phase. Therefore, annealing needed to increase particles crystallinity. Fourier Transform Infrared (FTIR) analysis showe...

Diffusion Flame Synthesis of Hydroxyapatite Nanoparticles using Urea Assisted Precursor Solution

Hydroxyapatite (HA) or (Ca10(PO4)6(OH)2 has been widely used in orthopedics and dental applications for human bone implant and teeth filler due to their biocompatibility and osteoconductive properties. Fine to nanoparticles of HA with appropriate stoichiometry and purity are preferred because they enhance densification and bioactive properties. Here, we reported the synthesis of hydroxyapatite particles in a diffusion flame reactor. LPG mainly consisting of butane and propane was used as fuel and compressed air was used as oxidizer and carrier gas. The effects of urea adding into precursor on morphology and crystallinity of the generated particles were investigated. Scanning electron microscopy (SEM) and X‐ray diffraction (XRD) were used to observe particles morphology and crystallinity, respectively. Purity of the generated particles was analyzed quantitatively from XRD pattern using Rietveld method. Spherical shape of particles morphology was obtained for particles synthesized without urea added into pr...

Synthesis of ZnO-SiO2 nanocomposite particles and their characterization by sonochemical method

ZnO-SiO2 nanocomposite particles were prepared by sonochemical method under continuous ultrasound irradiation for an hour. Zinc nitrate and sodium silicate were used as zinc oxide and silica sources, respectively. Silica concentration was varied to investigate the effect of silica on the characteristics of the generated composite particles and they were also compared to ZnO particles. Morphology, crystallinity, chemical bonding analysis, photoluminescence spectra, and photocatalytic activity were characterized by scanning electron microscopy (SEM), X-Ray diffraction, Fourier Transform Infrared (FTIR), luminescence spectrophotometer, and UV-Vis spectrophotometer, respectively. Nanorod structures were observed for pure ZnO, ZnO-SiO2 particles with 250 ppm and 750 ppm silica addition during synthesis. Spherical agglomerated particles were found for particle with 0.1 M silica addition. The crystalline size and photocalytic activity decreased with the silica addition. A strongest chemical bonding for ZnO and S...

Computational fluid dynamic in combustion process using pulse combustor

The advantages of Pulse Combustion process than the normal combustion was presented in this research. Reviews of phenomena and mechanisms of pulse combustion was compared with normal combustion which air or fuel was streamed continuously. Multi-dimensional simulation of turbulent flow in the combustion chamber was performed by computational fluid dynamics (CFD) with ANSYS FLUENT 15.0 software. 2D illustration axis symmetry with turbulence models k-turbulence combustion reaction using Eddy Dissipation models was used to analyze this process that has a high turbulence. Propane was used as the type of fuel with flow rate of 15 L/min. the flowrate 375 L/min of air was used as oxidizer, to meet the needs of propane and oxygen ratio of 1: 5. Based on the result, pulse combustion has higher combustion efficiency than normal combustion. This result was judged from fewer fuel that was not burned. Another advantage of using pulse combustion was the back flow of tailpipe that decrease the number of unburned reactant...

The influence of fuel type to combustion characteristic in diffusion flame drying by computational fluid dynamics simulation

Diffusion flame spray drying has become promising method in nanoparticles synthesis giving several advantages and low operation cost. In order to scale up the process which needs high experimentation time and cost, Computational Fluid Dynamics (CFD) by Ansys Fluent 15.0 software has been used. Combustion characteristic in diffusion flame reactor may affects particle size distribution. This study aims to observe influence of fuel type to combustion characteristic in the reactor. Large Eddy Simulation (LES) and non-premixed combustion model are selected for the turbulence and combustion model respectively. Methane, propane, and LPG in 0.5 L/min were used as type of fuel. While the oxidizer is air with 200% excess of O2. Simulation result shown that the maximum temperature was obtained from propane-air combustion in 2268 K. However, the stable temperature contour was achieved by methane-air combustion.

Combined subcritical water and enzymatic hydrolysis for reducing sugar production from coconut husk

Coconut husk wastes are abundantly available in Indonesia. It has a potential to be used into alternative renewable energy sources such as hydrogen using enzymatic hydrolysis followed by a fermentation process. Unfortunately, enzymatic hydrolysis is hampered by the complex structure of lignocellulose, so the cellulose component is hard to degrade. In this study, Combined Subcritical Water (SCW) and enzymatic hydrolysis are applied to enhance fermentable, thereby reducing production of sugar from coconut husk. There were two steps in this study, the first step was coconut husk pretreated by SCW in batch reactor at 80 bar and 150-200°C for 60 minutes reaction time. Secondly, solid fraction from the results of SCW was hydrolyzed using the mixture of pure cellulose and xylanase enzymes. Analysis was conducted on untreated and SCW-treated by gravimetric assay, liquid fraction after SCW and solid fraction after enzymatic hydrolysis using DNS assay. The maximum yield of reducing sugar (including xylose, arabinos...