I. N. G. Wardana

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.

Seed Oil of Morinda citrifolia L. as a Surfactant for Deinking Flotation

Surfactants are essential in the pulp recovery process for the removal of ink on paper to be recycled. In order to create a “green” surfactant, seed oil was extracted from Morinda citrifolia L. by Soxhlet extraction for 4–8 h and its composition evaluated by gas chromatography-mass spectrometry (GC-MS). The total ion chromatogram (TIC) of fatty acids of Morinda citrifolia L. (FAMC) indicated that extraction yields the largest amount of unsaturated fatty acids (UFA), specifically C19H34O2 and C21H38O2, at 6 h. All FAMC fractions were evaluated for their suitability as a surfactant for deinking flotation. FAMC isolated after 6 h of extraction yields fatty acids that are the most suitable surfactants, as the fraction consists of mostly unsaturated fatty acids that show good interactions with the structure of common ink molecules. Our results show that the performance of the FAMC taken after 6 h of extraction approaches that of a synthetic surfactant (SS). The appropriate viscous force for deinking flotation was found to be 1.5–2.0 × 10−4 mg/mm s2 when the synthetic surfactant is used compared to 1.0–1.5 × 10−4 mg/mm s2 for FAMC. The higher intermolecular bonding strength in the synthetic surfactant-ink particle system requires higher viscous force.

Role of Intermolecular Forces on the Contact Angle of Vegetable Oil Droplets during the Cooling Process

This study aims to experimentally determine the role of intermolecular forces on the contact angle of vegetable oil droplets. Contact angles were recorded using a microscope and measured using digital software. The results show that the surface tension of vegetable oils is influenced by the London force between the electron clouds of molecules. The process of cooling increases vegetable oil contact angles, due to the decreased kinetic energy of constituent molecules and increased London force on the molecules. A decrease in temperature causes the surrounding water vapor to condense, which adheres to the droplet surface (due to the hydrophilic properties of molecules). Hydrogen bonds develop after moisture adheres to the surface. Further, water molecules on the droplet surface reduce the surface tension, because of hydrogen bonds between the molecules on the droplet surface and moisture. Hydrogen bonds among the molecules force water molecules to accumulate on the droplet surface, which suppresses the droplet surface; therefore the contact angle decreases.

The Role of Fatty Acids Functional Group in Morinda citrifolia L. on Surface Tension and Diffusion Performance into Ink Particles

Abstract The interaction of fatty acid of Morinda citrifolia L. (FAMC) with ink was studied using Hele Shaw Cells. The interaction is compared to that of fatty acid derivates of synthetic surfactant. These interactions are modeled and explained through micro diffusion and its viscous fingering character. The results show that the molecule structure and the number of double bonds have a special effect on the surface tension and the micro diffusion character. FAMC at six-hour extraction has the highest speed of interaction and highest perimeter of diffusion among synthetic surfactants and other fatty acids in Morinda citrifolia L.

Characteristic of flotation deinking using bio and synthetic surfactant at different air flow rate

Flotation deinking has industrially applied but several problems keep unsolved because limitations have to compete with several variables present. Flotation deinking is multi variables process, so studying flotation deinking is still interesting. In this research, the amount of variables was reduced and focused to the performance comparison between flotation deinking of old newspaper (ONP) using biodegradable fatty acid of morinda citrifolia as the raw bio surfactant (RBS) and biodegradable fatty acid of palm oil that had been converted to be commercial surfactant (CS). The flotation was done at laboratory flotation cell equipped with orifice at different diameter (orifice number 20, 40 and 60) with adjustable airflow rate. Brightness and Effective Residual Ink Concentration (ERIC) of the deinked pulp were measured. The best results were achieved on orifice number 40 with the highest brightness of 41.96 °ISO and 40.96 °ISO when using CS and RBS respectively, and lowest ERIC of 896.82 ppm and 1001.72 ppm w...

Rheology Margarine on Non-Newtonian Fluid Proving through Small Gap

Theory and principles of rheology can be used for, process control, product design and as a tool for prediction process if the process could not actually be measured. The purpose of this research is to find rheological properties of margarine in dough/non-newtonian fluid developed on two parallel flat acrylic separated by an infinitesimally small gap. The driving force of the development fluid is CO2 fermented yeast. Fluid driven and expands passed a small gap in various sizes. Development time and time to pass through the small gap measured. The samples are used are two, dough without addition of margarine and other. Experiments showed that fluid added by margarine would be easier to pass through small gap than other, characterized by shorter time to pass through the small gap.

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.