Slamet Wahyudi

Biogas Laminar Burning Velocity and Flammability Characteristics in Spark Ignited Premix Combustion

Spherically expanding flames propagating at constant pressure were employed to determine the laminar burning velocity and flammability characteristics of biogas-air mixtures in premixed combustion to uncover the fundamental flame propagation characteristics of a new alternative and renewable fuel. The results are compared with those from a methane-air flame. Biogas is a sustainable and renewable fuel that is produced in digestion facilities. The composition of biogas discussed in this paper consists of 66.4% methane, 30.6% carbon dioxide and 3% nitrogen. Burning velocity was measured at various equivalence ratios (ϕ) using a photographic technique in a high pressure fan-stirred bomb, the initial condition being at room temperature and atmospheric pressure. The flame for methane-air mixtures propagates from ϕ=0.6 till ϕ=1.3. The flame at ϕ≥1.4 does not propagate because the combustion reaction is quenched by the larger mass of fuel. At ϕ≤0.5, it does not propagate as well since the heat of reaction is insufficient to burn the mixtures. The flame for biogas-air mixtures propagates in a narrower range, that is from ϕ=0.6 to ϕ=1.2. Different from the methane flame, the biogas flame does not propagate at ϕ≥1.3 because the heat absorbed by inhibitors strengthens the quenching effect by the larger mass of fuel. As in the methane flame, the biogas flame at ϕ≤0.5 does not propagate. This shows that the effect of inhibitors in extremely lean mixtures is small. Compared to a methane-air mixture, the flammability characteristic (flammable region) of biogas becomes narrower in the presence of inhibitors (carbon dioxide and nitrogen) and the presence of inhibitors causes a reduction in the laminar burning velocity. The inhibitor gases work more effectively at rich mixtures because the rich biogas-air mixtures have a higher fraction of carbon dioxide and nitrogen components compared to the lean biogas-air mixtures.

Laminar Burning Velocity and Flammability Characteristics of Biogas in Spark Ignited Premix Combustion at Reduced Pressure

Biogas as a “Powergas” is an alternative fuel produced in digestion facilities, that is sustainable and renewable. Based on chemical analysis, the composition of the biogas produced in East Java is 66.4% methane, 30.6% carbon dioxide and 3% nitrogen. Methane is a flammable gas, whereas, nitrogen and carbon dioxide are inhibitors. Given it has a different composition to traditional fuels, a fundamental study of biogas flame propagation characteristics is desirable to quantify this important fuel property. Spherically expanding flames propagating at constant pressure are employed to measure the laminar burning velocity and flammability characteristics as mixture function of the mixture composition. These important parameters were measured using a photographic technique in a high pressure fan-stirred bomb. The characteristics of biogas-air flames were initially studied at reduced pressure and at various equivalence ratios from the lower flammable limit to the upper flammable limit. The results were compared with those from biogas-air flames at atmospheric pressure. Based on this experimental investigation, the laminar burning velocities of biogas-air mixtures at reduced pressure were 0.218 m/s for ϕ=0.75, 0.246 m/s for ϕ=0.80 and 0.269 m/s for ϕ=0.85 respectively and only for these biogas mixtures propagated at reduced pressure. At the same equivalence ratio (ϕ), the laminar burning velocities of the biogas-air mixtures at reduced pressure are higher than those at atmospheric pressure. The flammable region of biogas became narrower by reducing initial pressure. The dilution effect is stronger at reduced pressure. Therefore, the flammable composition mixture areas of biogas-air mixtures are more limited at reduced pressure than those at atmospheric pressure.

Experimental Study of the Cross Flow Turbine

The experimental study was intended to investigate characteristics of the cross flow turbine based to the three models designed on the same runner diameter with different runner length of each. The Flow rates were measured by magnetic flow meter, the forces were detected by using spring balance and turbine speeds were detected by tachometer. The performance characteristics are shown by the relation of Power and efficiency versus jet entry arc, as well as the relation of Power and efficiency versus ratio between diameter and width of runner. The study indicated that the efficiency of the models were slightly difference, the highest efficiency indicated by the turbine with the ratio between length of runner and the diameter of the runner was 2; It was corresponding to the 75 degree entry arc.

Optimization of Chemical Environment Condition towards Corrosion Rate of Sulfuric Acid Resistant Alloy Metal (Saramet) Using Response Surface Methodology

This study investigates the variation of sulphuric acid concentration, temperature, and time towards the corrosion rate of saramet using response surfacemethod. Method used in this study is true experimental research. Sarametis material which is included into type of austenitic stainless steel which contains high amount of silicon. Starting at these past 2 years, the material has been widely used.This research used weight loss method. It has been found that minimum corrosion rate is achieved at concentration combination of 89.49% in 3.682 hoursandat temperature of 106,8 °C. From the variation combination, it is seen that the low concentration will decrease ion mobility corrossive ion from saramet.The long period of exposure supports the forming of passive layer which prevent the corrosive ions gets into the steel surface. As a result, corrosion rate decreases. At high temperature, steel which has high silicon content will be stable in terms of its atomic bound which therefore makes it posses high corrosion resistance.

Performance Analysis of a Combined Blade Savonius Wind Turbines

The Savonius wind turbine has a lower performance than other types of wind turbines which may attract more study focus on this turbine. This study aimed to improve wind turbine performance by combining a conventional blade with an elliptical blade into a combined blade rotor. The analysis was performed on three blade models in computational fluid dynamics (CFD) using ANSYS_Fluent Release 14.5. Then the results were verified experimentally using an open wind tunnel system. The results of the numerical simulation were similar to the experimental and showed that the combined blade rotor has better dragging flow and overlap flow than the conventional and elliptical blade. Experimental verification showed that the combined blade was to increase the maximum coefficient of power (Cpmax.) by 11% of the conventional blade and to 5.5% of the elliptical blade.

A simulation for predicting potential cooling effect on LPG-fuelled vehicles

Liquefied Petroleum Gas vehicles (LPG Vehicles) provide a potential cooling effect about 430 kJ/kg LPG consumption. This cooling effect is obtained from the LPG phase change from liquid to vapor in the vaporizer. In the existing system, energy to evaporate LPG is obtained from the coolant which is circulated around the vaporizer. One advantage is that the LPG (70/30 propane / butane) when expanded from 8 bar to at 1.2 bar, the temperature is less than −25 °C. These conditions provide opportunities to evaporate LPG with ambient air flow, then produce a cooling effect for cooling car’s cabin. In this study, some LPG mix was investigated to determine the optimum condition. A simulation was carried out to estimate potential cooling effects of 2000 cc engine from 1000 rpm to 6000 rpm. In this case, the mass flow rate of LPG is a function of fuel consumption. The simulation result shows that the LPG (70/30 propane/butane) provide the greatest cooling effect compared with other mixtures. In conclusion, the 2000 cc engine fueled LPG at 3000 rpm provides potential cooling effect more than 1.3 kW, despite in the low engine speed (1000 rpm) only provides about 0.5 kW.Liquefied Petroleum Gas vehicles (LPG Vehicles) provide a potential cooling effect about 430 kJ/kg LPG consumption. This cooling effect is obtained from the LPG phase change from liquid to vapor in the vaporizer. In the existing system, energy to evaporate LPG is obtained from the coolant which is circulated around the vaporizer. One advantage is that the LPG (70/30 propane / butane) when expanded from 8 bar to at 1.2 bar, the temperature is less than −25 °C. These conditions provide opportunities to evaporate LPG with ambient air flow, then produce a cooling effect for cooling car’s cabin. In this study, some LPG mix was investigated to determine the optimum condition. A simulation was carried out to estimate potential cooling effects of 2000 cc engine from 1000 rpm to 6000 rpm. In this case, the mass flow rate of LPG is a function of fuel consumption. The simulation result shows that the LPG (70/30 propane/butane) provide the greatest cooling effect compared with other mixtures. In conclusion, the 2000 ...

Simulation Savonius Wind Turbine with Multi-Deflector

This paper aims to study the windmill Savonius with multi-deflector. Multi-deflector placed around the windmill, which aims to reduced negative torque to the returning blade and directing the flow of wind to the advancing blade . CFD analysis with ANSYS software. The initial conditions with variation wind speeds 3, 4, 5 and 6 m / s. The result indicated by velocity distribution at positions 00, 450, 900 and 1350. The largest static torque occurs at position 450 caused by the greater the Coand-like flow, dragging flow and overlap flow. The greater the static torque that occurs with increasing wind speeds.

A CFD Analysis of the Viscous Fluid Behavior of Glycerin in Various of Stirring Patterns

The important matter of mixing at both micro and macro-fluidic levels has to be studied for determining how to achieve proper stirring ways. In order to analyse this matter, the first problem was how to visualise and especially how to measure the stirring process in a certain flow. In this study, the behavior of viscous glycerin employing various stirring patterns was investigated. The changes in glycerin solutions were observed by means of streamline flow topology and particle track arising from four variations in configurations: the same stirring directions of rod and vessel (RUN 1), opposite stirring directions of rod and vessel (RUN 2), stationary rod and rotating vessel (RUN 3), stirring rod and stationary vessel (RUN 4). The flow pattern was analyzed with ANSYS computational fluid dynamic tool. The simulation results shows that the opposite direction stirring pattern configuration produced more vortices than those of the same direction stirring patterns and the stirring rod pattern generated more vortices in almost all parts of the vessel than stationary rod pattern.

The Influence of High Content of Silicon in Austenitic Stainless Steel to Corrosion Rate in Sulphuric Acid

This study is aimed at investigating the performance of saramet compared to other austenitic stainless steel (SS) types. Saramet is a type of austenitic SS which contains Silicon (Si) higher than others. The research treatment was divided into 2 activities which were at room temperature and high temperature. The material used were saramet, SS 304 and SS 316L. Corrosion test was conducted by using weight losing method and electrochemical. The findings show that saramet is more resistant to corrosion compared to SS 304 and SS 316L both at high and room temperature. Saramet has better performance at high temperature.

Flammability Limit and Flame Visualization of Gaseous Fuel Combustion Inside Meso-scale Combustor with Different Thermal Conductivity

This study experimentally investigated effect of thermal conductivity on the combustioncharacteristics of gaseous fuel inside a meso-scale combustor. Combustion characteristics that wereobserved in this research include flame visualization and flammability limit. Quartz glass, stainlesssteel and copper tubes with inner diameters of 3.5 mm were used as combustors. Stainless steel wiremesh was inserted inside meso-scale combustor as a flame holder. Liquid petroleum gas (LPG),which is common fuel use by Indonesian people, was used as a gaseous fuel. A stable blue flame wasestablished inside meso-scale combustor at the downstream of wire mesh for all combustor withdifferent thermal conductivity. Furthermore, flame color is blue for combustion of fuel lean orstoichiometric mixture, and blue-green for combustion of fuel rich mixture. Meso-scale combustorwith the highest thermal conductivity has the narrowest flame cross section area, especially at lowerreactant velocity. Vice versa, this combustor has the widest flammability limit, mainly at the higherreactant velocity.