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Articles by Bambang Ariwahjoedi
Total Records ( 8 ) for Bambang Ariwahjoedi
  Rahmat Riza , Bambang Ariwahjoedi and Shaharin Anwar Sulaiman
  Solar radiation is the major energy source for entire earth. This causes the variation of solar radiation had strong relation with variation of global temperature. This relation was studied more detail by using simulation of zero-dimensional climate model. On this model, the equilibrium system was used to study the effect of solar radiation to temperature change. Overall, the model consists of two mathematical equations that describe condition for the atmospheric layer and earth surface system. The outputs of the model consisted of the temperature at the atmospheric layer and the earth surface. They were solved by three numerical methods, namely: Newton-Raphson, Quasi Newton-Raphson and Steepest Descent methods. Absolute error analysis was used to determine the solution for the Newton-Raphson and Quasi Newton-Raphson methods while alpha value for Steepest Descent method. Relation for the solar variation and global temperature change was obtained by assuming the other variables on the equations to be constant as the average value. The relation graphs describe that variation of the solar radiation could cause significant global temperature change.
  Ramzy E. Konda , Shaharin A. Sulaiman and Bambang Ariwahjoedi
  The huge amount of wasted Oil Palm Fronds (OPF) produced annually provides a very good opportunity for the oil palm industry in Malaysia to use it for power generation, especially in mill boilers. Recently, gasification technology is receiving more attention as it can be used to convert wasted biomass into gaseous fuel for power generation and thermal applications as well as it can be used as a fuel source for the production of other chemicals. This study addresses the design, fabrication and performance evaluation of an updraft fixed-bed-gasifier. A 50 kW updraft gasifier is designed and fabricated for gasification of Malaysian oil palm fronds. The gasifier is designed using the empirical data from literature and derived quantities. The gasifier was modified to be very flexible allowing the gasification air to be fed through several locations. The air gasification results of OPF showed volumetric percentage of 22.61-23.36% of CO, 6.48-6.68% of H2, 1.2-1.5% of CH4, 9.51-9.65% of CO2 and 59.20-58.1% of N2. The heating value of the product gas mixture varied between 4.1-4.4 MJ Nm-3 while the cold gas efficiency, carbon conversion efficiency and specific gasification rate of the gasifier was in the range of 57-59 and 95-97% and 103-109 kg m-2 h-1, respectively. The study has demonstrated that the oil palm frond waste is suitable for the designed and fabricated updraft gasifier and the produced gas from the gasification of OPF was successfully used in a domestic cooking stove.
  Mas Irfan P. Hidayat and Bambang Ariwahjoedi
  This study presents numerical simulation of velocity-field reconstruction in Fluid-structure Interaction (FSI) problem with the presence of a very step velocity jump at the fluid-solid interface. Models of Neural Network (NN) with sigmoid and radial basis functions were developed and utilized as approaches of investigation to fully reconstruct the velocity-field at the fluid-structure interface of the problem. As a numerical case, one-dimensional compressible fluid coupled with elastic solid under strong impact was simulated. This class of problem belongs to an Eulerian-Lagrangian Riemann problem in which the very step jump of velocity vector does exist. The resolution of the NN models in the vicinity of the interface was further investigated and analyzed in which the accuracy of the NN approach was validated to the problem analytical solution. From the results of the numerical study, high numerical accuracy of the NN models can be obtained in relation with the increase of the interface resolution through which useful insights of this study were also revealed.
  Bambang Ariwahjoedi and Setyamartana Parman
  By taking the analogy with bio-molecular systems, many systems containing simple molecular entities like water could have an information storage system. This storage system is similar to a gene locus which is presumably enclosed within the nucleus of its atoms. Information are stored in the form of perhaps such kind of fundamental interactions among sub-sub-atomic particles within each nucleons, just like hydrogen bonding among the nucleotides residue in the DNA. If this is true, then small molecules, water molecules for example, might be no longer as all-identical entities, instead they might all be organisms, which each of them is individually unique in their own. Furthermore, if this could someday be comprehended, many natural phenomena which are still not well understood due to their complexity such as cloud morphology in the sky, crystallization pattern of snow flakes and crack pattern in drying clay mud, etc., could be rationalized in a fundamental way, still by using physicochemical if not nucleo-chemical principles.
  Wan Amalina Wan Zaharuddin , Bambang Ariwahjoedi and Patthi Hussain
  Currently, solvent-based fire retardant coating is commonly used as a thermal barrier for construction building during fire hazard. Lack of awareness of the harmful impact of solvent-based fire retardant coating has taken the safety of the people in the building at high risk. Thus, this study was about the water-based fire retardant coating with vermiculite addition as an option to solvent-based fire retardant coating. The formulation contained two different acrylic media and the other three active ingredients which were Ammonium Polyphosphate, Pentaerythritol and Melamine. The significant of vermiculite on the formulation was investigated by thermogravimetric analysis (TGA). The surface morphology of formulations with and without vermiculite was observed using Scanning Electron Microscopy (SEM). The degradation result describes the high significant effect of vermiculite in enhance the formation of high temperature residue and the two acrylic media give same interaction with the other additives which indicate in the thermal degradation behavior.
  Abdul Munir Hidayat Syah Lubis , Mustafar Sudin and Bambang Ariwahjoedi
  Jatropha oil has been known as alternative substitute for diesel fuel but its potential use as lubricant is not much known yet. This work is meant to investigate the effect of Tricresyl Phosphate (TCP) to jatropha oil which subjected to be used for transmission oil. Crude jatropha oil was used as base oil and 0.5-5% v/v. of TCP were added to crude jatropha oil. Commercial SAE 80W/90 grade transmission oil was used as comparison. Ostwald-Fenske capillary viscometer was used to characterize viscosity of jatropha oil and TCP mixture. Four-ball method was used to characterize friction and wear of the oil samples. No significant changes were found on viscosity by addition of TCP. Anti wear characteristics of crude jatropha was greatly improved by addition of TCP. No significant effect to friction coefficient also found at 40 kgf load, but addition of sufficient amount of TCP was able to reduce friction at 80 kgf load.
  R.E. Konda , S.A. Sulaiman and Bambang Ariwahjoedi
  In present study, gasification of Oil Palm Fronds (OPF) is performed in a pilot-scale updraft gasifier. Gasification experiments were conducted at atmospheric pressure using air as oxidizing agent. The effects of equivalence ratio on temperature profile, gas composition and gas calorific value are studied. The equivalence ratios employed in this study are 0.18, 0.22, 0.29, 0.35 and 0.4. The results showed that the amount of combustible gases which are H2, CO and CH4 was found to be in the range of 16.79-33.9% of the total produced gases and the average composition of the syngas at an optimum equivalence ratio of 0.29 was found to be 20.10% CO, 10.41% CO2, 1.20% CH4 and 6.60% H2 with an average calorific value of 4.42 and 4.62 MJ Nm-3 as Low Heating Value (LHV) and Higher Heating Value (HHV). While the maximum molar ratios of H2/CO and CO/CO2 was found to be 0.3 and 2.51, respectively.
  Ramzy Elneel , Shaharin Anwar and Bambang Ariwahjoedi
  The heating value is one of the most important properties of biomass materials, as it can be used for design calculations or numerical simulations of the thermal conversion systems of biomass. The heating value can be determined experimentally or numerically. The determination of the heating value experimentally (by using a bomb calorimeter) involves laborious measurements while an ultimate analysis can be performed using automatic equipment. In this study, a multiple linear regression analysis was used to develop an empirical equation for the estimation of the higher heating value of Oil Palm Fronds (OPFs) using an ultimate analysis. An empirical equation based on the main elements carbon, hydrogen and oxygen (HHV = 0.879C+0.321H+0.056O-24.826) was the most accurate model, with a correlation coefficient (R2) of 0.92, Average Absolute Error (AAE) of 1.4% and Average Bias Error (ABE) of 0.16%.
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