Articles
<![CDATA[Dynamic Behavior of Reverse Flow Reactor for Lean Methane Combustion ]]>
<![CDATA[Budhi, Yogi W.]]>;
<![CDATA[Effendy, M.]]>;
<![CDATA[Bindar, Yazid]]>;
<![CDATA[Subagjo, S.]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 46, No 3 (2014) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/j.eng.technol.sci.2014.46.3.5
<![CDATA[The stability of reactor operation for catalytic oxidation of lean CH4 has been investigated through modeling and simulation, particularly the influence of switching time and heat extraction on reverse flow reactor (RFR) performance. A mathematical model of the RFR was developed, based on one-dimensional pseudo-homogeneous model for mass and heat balances, incorporating heat loss through the reactor wall. The configuration of the RFR consisted of inert-catalyst-inert, with or without heat extraction that makes it possible to store the energy released by the exothermic reaction of CH4 oxidation. The objective of this study was to investigate the dynamic behavior of the RFR for lean methane oxidation and to find the optimum condition by exploring a stability analysis of the simple reactor. The optimum criteria were defined in terms of CH4 conversion, CH4 slip, and heat accumulation in the RFR. At a switching time of 100 s, the CH4 conversion reached the maximum value, while the CH4 slip attained its minimum value. The RFR could operate autothermally with positive heat accumulation, i.e. 0.02 J/s. The stability of the RFR in terms of heat accumulation was achieved at a switching time of 100 s.]]>
<![CDATA[Determination of Kinetic Parameters for Methane Oxidation over Pt/γ-Al2O3 in a Fixed-Bed Reactor ]]>
<![CDATA[Wonoputri, Vita]]>;
<![CDATA[Effendy, Mohammad]]>;
<![CDATA[Budhi, Yogi Wibisono]]>;
<![CDATA[Bindar, Yazid]]>;
<![CDATA[Subagjo, S.]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 45, No 2 (2013) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/j.eng.technol.sci.2013.45.2.7
<![CDATA[This paper describes akinetic study for the determination of the kinetic parameters of lean methane emission oxidation over Pt/γ-Al2O3 in a dedicated laboratory scale fixed bed reactor. A model ofthemechanistic reaction kinetic parameters has been developed. The reaction rate model was determined using therate-limiting step method, which was integrated and optimized to find the most suitable model and parameters. Based on this study, the Langmuir-Hinshelwood reaction rate model with the best correlationis the one where the rate-limiting step is thesurface reaction between methane and one adsorbed oxygen atom. The pre-exponential factor and activation energy were 9.19 x 105 and 92.04 kJ/mol, while the methane and oxygen adsorption entropy and enthalpy were â17.46 J/mol.K, â2739.36 J/mol,â16.34 J/mol.K, and â6157.09 J/mol, respectively.]]>
<![CDATA[Structured Mathematical Modeling of Industrial Boiler ]]>
<![CDATA[Aziz, Abdullah Nur]]>;
<![CDATA[Nazaruddin, Yul Yunazwin]]>;
<![CDATA[Siregar, Parsaulian]]>;
<![CDATA[Bindar, Yazid]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 46, No 1 (2014) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/j.eng.technol.sci.2014.46.1.7
<![CDATA[As a major utility system in industry, boilers consume a large portion of the total energy and costs. Significant reduction of boiler cost operation can be gained through improvements in efficiency. In accomplishing such a goal, an adequate dynamic model that comprehensively reflects boiler characteristics is required. This paper outlines the idea of developing a mathematical model of a water-tube industrial boiler based on first principles guided by the bond graph method in its derivation. The model describes the temperature dynamics of the boiler subsystems such as economizer, steam drum, desuperheater, and superheater. The mathematical model was examined using industrial boiler performance test data.It can be used to build a boiler simulator or help operators run a boiler effectively.]]>
<![CDATA[The Power Consumption Performance of an Orbiting Screw Solid-Solid Mixer ]]>
<![CDATA[Senda, Semuel Pati]]>;
<![CDATA[Renanto, Renanto]]>;
<![CDATA[Roesyadi, Achmad]]>;
<![CDATA[Sumaryono, Wahono]]>;
<![CDATA[Bindar, Yazid]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 44, No 3 (2012) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/itbj.eng.sci.2012.44.3.6
<![CDATA[In this work we have investigated mixing in a modified orbiting screw mixer (MOSM) designed for solid-solid mixing. Mixing was carried out using urea powder and natural zeolite powder (UZ) of three varying particle sizes (50-60, 60-80 and 80 mesh). Power consumption was calculated from the measured torque of orbit and screw, obtained from computerized records. It was found that the mixing process in the modified orbiting screw mixer with air injection required a lower power consumption for each particle-size group when compared to mixing without air injection. With UZ mixing in MOSM with air injection, the lowest E was obtained for the 60-80 mesh particle-size group (4,297 Joule/kg-1),whereas when mixing without air injection, the value was 10,296 J/kg. The best mixing operation in this experiment was achieved at NFr = 1.18x10-3 and in the range of values NReâ 8.77x107 to 2.63x108. Moreover, in this study, we have developed an equation to estimate the power consumption required for mixing and determined its correlation with dimensionless numbers.]]>
<![CDATA[New Correlations for Coal and Biomass Pyrolysis Performances with Coal-Biomass Type Number and Temperature ]]>
<![CDATA[Bindar, Yazid]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 45, No 3 (2013) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/j.eng.technol.sci.2013.45.3.5
<![CDATA[The pyrolysis of coal and biomass is generally reported as the mass yield of released chemicals at various temperatures, pressures, heating rates and coal or biomass type. In this work, a new coal-biomass type number, NCT, is introduced. This number is constructed from the mass fractions of carbon, hydrogen, and oxygen in the ultimate analysis. This number is unique for each coal or biomass type. For 179 different species of coal and biomass from the literature, the volatile matter mass yield can be expressed by the second order polynomial function ln(NCT). This unique correlation allows the effects of the temperature and heating rate on the volatile yield YVY for coal and biomass to be empirically correlated as well. The correlation for the mass fraction of each chemical component in the released volatile matter correlation is obtained from the YVY correlation. The weight factor for some of the components is constant for the variation of NCT, but not for others. The resulted volatile matter and yield correlations are limited to atmospheric pressure, very small particles (less than 0.212 mm) and interpreted for wire-mesh pyrolysis reactor conditions and a nitrogen gas environment.]]>
<![CDATA[Pressure Drop Correlation Covering Dilute to Dense Regimes of Solid Particle-Gas Flow in a Vertical Conveying Pipe ]]>
<![CDATA[Bindar, Yazid]]>;
<![CDATA[Sutrisniningrum, N. A.]]>;
<![CDATA[Santiani, D.]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 41, No 1 (2009) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/itbj.eng.sci.2009.41.1.5
<![CDATA[More general correlations between pressure drop and gas-solid flow variables are developed from the present experimental data. The correlation was modeled for a pneumatic conveying system in a vertical pipe. The transition boundary between dense and dilute regimes is constructed from the pressure drop correlations. The gas-solid particle flow variables are quantified by the gas Reynolds (Nref) and the solid Froude (Frp) numbers. The  dense flow regime is indicated by the decrease of the pressure drop with the increase of the gas Reynolds number. In contrary, the dilute regime exhibits the increase of the pressure drop with the gas Reynolds number. The proposed correlations were built at the range of gas Reynolds number f from 360 to 500 and solid Froude number from 0,01 to 0,02.]]>
<![CDATA[Homogeneity of Continuum Model of an Unsteady State Fixed Bed Reactor for Lean CH4 Oxidation ]]>
<![CDATA[Subagjo, S.]]>;
<![CDATA[Budhi, Yogi Wibisono]]>;
<![CDATA[Effendy, M.]]>;
<![CDATA[Bindar, Yazid]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 46, No 2 (2014) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/j.eng.technol.sci.2014.46.2.6
<![CDATA[In this study, the homogeneity of the continuum model of a fixed bed reactor operated in steady state and unsteady state systems for lean CH4 oxidation is investigated. The steady-state fixed bed reactor system was operated under once-through direction, while the unsteady-state fixed bed reactor system was operated under flow reversal. The governing equations consisting of mass and energy balances were solved using the FlexPDE software package, version 6. The model selection is indispensable for an effective calculation since the simulation of a reverse flow reactor is time-consuming. The homogeneous and heterogeneous models for steady state operation gave similar conversions and temperature profiles, with a deviation of 0.12 to 0.14%. For reverse flow operation, the deviations of the continuum models of thepseudo-homogeneous and heterogeneous models were in the range of 25-65%. It is suggested that pseudo-homogeneous models can be applied to steady state systems, whereas heterogeneous models have to be applied to unsteady state systems.]]>
<![CDATA[Utilizing Shear Factor Model and Adding Viscosity Term in Improving a Two-Dimensional Model of Fluid Flow in Non Uniform Porous Media ]]>
<![CDATA[Bindar, Yazid]]>;
<![CDATA[Makertihartha, IGBN]]>;
<![CDATA[Supardan, M. Dani]]>;
<![CDATA[Buchori, Luqman]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 39, No 2 (2007) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/itbj.eng.sci.2007.39.2.3
<![CDATA[In a packed bed catalytic reactor, the fluid flow phenomena are very complicated because the fluid and solid particle interactions dissipate the energy. The governing equations were developed in the forms of specific models. The shear factor model was introduced in the momentum equation for covering the effect of flow and solid interactions in porous media.  A two dimensional numerical solution for this kind of flow has been constructed using the finite volume method. The porous media porosity was treated as non-uniform distribution in the radial direction. Experimentally, the axial velocity profiles produce the trend of having global maximum and minimum peaks at distance very close to the wall. This trend is also accurately picked up by the numerical result. A more comprehensive shear factor formulation results a better velocity prediction than other correlations do. Our derivation on the presence of porous media leads to an additional viscosity term. The effect of this additional viscosity term was investigated numerically. It is found that the additional viscosity term improves the velocity prediction for the case of higher ratio between tube and particle diameters]]>
<![CDATA[Geometry Effect Investigation on a Conical Chamber with Porous Media Boundary Condition Using Computational Fluid Dynamic (CFD) Technique ]]>
<![CDATA[Bindar, Yazid]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 41, No 2 (2009) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/itbj.eng.sci.2009.41.2.1
<![CDATA[The present study is an attempt to introduce a method for optimizing the geometry of a unit process. The comprehensive unit process performances are generated by a CFD engine. The CFD engine can simulate the unit process performances at whatever conditions. Both design geometry and operating variables were used on the CFD simulation. The burden on a simplified process was taken out from CFD simulation. A complex geometry of a unit process is represented by a secondary reformer. A secondary reformer has a conical chamber as a space to undergo a combustion reaction before entering a catalyst bed. This complexity is added by the boundary on a porous solid surface as the top surface of the catalyst bed. The conical angle affects the flow pattern inside the conical chamber having a porous solid surface as its base. The conical angle above 65° results the disappearing of the recirculation flow. The inlet distance from the porous solid surface also can exhibit different characteristics of recirculation flow. The closer the distance to the porous solid surface, the stronger the recirculation is. The inlet velocity values have no significant effect on the flow pattern. The introduction of a  solid volume inside the geometry creates distortion in the flow pattern. In the application, the inserted solid volume is equivalent to a burner. It means that the use of the burner inherently produces some problems of the flow distribution.]]>
<![CDATA[Development of Instant Microbial Starter for Production of Fermented Cassava Flour: Effect of Vacuum Drying Temperature, Carrier Media, and Storage Temperature ]]>
<![CDATA[Kresnowati, Made Tri Ari Penia]]>;
<![CDATA[Bindar, Yazid]]>;
<![CDATA[Rahmina, Fathya]]>
<![CDATA[ Journal of Engineering and Technological Sciences Vol 50, No 6 (2018) ]]>
Publisher : <![CDATA[ITB Journal Publisher, LPPM ITB ]]>
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DOI: 10.5614/j.eng.technol.sci.2018.50.6.6
<![CDATA[Cassava is an important crop for tropical countries such as Nigeria, Brazil, Thailand, and Indonesia. The potential utilization of cassava in the food industry can be enhanced by processing cassava into fermented cassava flour (fercaf), which has been shown to have a neutral color and aroma as well as low cyanogenic content. The use of specific microbial starter in the cassava chip fermentation for fercaf production will direct the fermentation process, maintaining a high quality of the produced flour. Thereby, the availability of an easy-to-use microbial starter is important for the production of fermented cassava flour. The aim of this study was to evaluate vacuum drying methods in the preparation of microbial starter for fermented cassava flour production. In particular, the effects of carrier media, drying and storage temperature on cell viability in dry starter were tested. The results showed that different methods should be applied to different microbial species. Bacillus subtilis and Aspergillus Oryza should be prepared using fercaf as the carrier media at a drying temperature of 55 °C, whereas Lactobacillus plantarum starter should be prepared using skim milk as the carrier media at a drying temperatur of 40°C. Apart from B. subtilis, the starters should be stored in a refrigerator.]]>
