Journal of Engineering and Technological Sciences
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Study of the Evaporation Process in the Spray Zone of a Mechanical Draft Wet Cooling Tower
Get PDFThe evaporation process in the nozzle spray system of a cooling tower was the main object of study in order to determine its performance. This process involves liquid water in small size, usually at the droplet level. At this level, parameters that affect the droplet size, such as capacity, air velocity in the chamber, water pressure at the nozzle, atmospheric temperature, etc., influence the process of heat and mass transfer. In this study, capacity and fan rotation were varied to obtain a graph showing the evaporation. Radius, velocity, mass and temperature graphs and rate graphs were obtained from mathematical modeling of the governing equations. From the results it appears that evaporation occurs at a capacity of 6 liter per minute and above, but this requires further proof of the evaporation process along with the height of the tower, which will be the subject of a future study
Experimental Study and Numerical Model of Spruce and Teak Wood Strength Properties Under Compressive High Strain Rate Loading
Get PDFSpruce and teak wood as anisotropic materials have complex behavior, particularly in the relationship between strain-rate and strength. High strain-rate compression tests between 590 s-1 and 3300 s-1 were carried out using two types of split Hopkinson pressure bar (SPHB) in order to measure the behavior of the wood along three principal axes with respect to fiber direction and growth rings. Numerical simulation using finite element software of the wood materials under high strain rates was performed and showed results with only a difference of 10% to the experimental results. The strain rate affects the strength of materials. In this case, it follows the power function, which means the higher the strain rate, the stronger the material
Development of Laboratory-scale Lamb Wave-based Health Monitoring System for Laminated Composites
Get PDFThis paper presents the development process of a laboratory-scale Lamb wave-based structural health monitoring (SHM) system for laminated composite plates. Piezoelectric patches are used in pairs as actuator/sensor to evaluate the time of flight (TOF), i.e. the time difference between the transmitted/received signals of a damaged plate and those of a healthy plate. The damage detection scheme is enabled by means of evaluating the TOF from at least three actuator/receiver pairs. In this work, experiments were performed on two GFRP plates, one healthy and the other one with artificial delamination. Nine piezoelectric transducers were mounted on each plate and the detection of the delamination location was demonstrated, using 4 pairs and 20 pairs of actuators/sensors. The combinations of fewer and more actuators/sensor pairs both provided a damage location that was in good agreement with the artificial damage location. The developed SHM system using simple and affordable equipment is suitable for supporting fundamental studies on damage detection, such as the development of an algorithm for location detection using the optimum number of actuator/sensor pairs
Characteristics of Silica Nanoparticles from Rice Husk as Influenced by Surface Modification with Used Solvent Containing Silane
Get PDFSilica extracted from rice husk (silica nanoparticles, Si-NP RHA) has great potential for industrial use, particularly as filler in the rubber industry. However, silica is poorly dispersed in the matrix and needs to be modified by a silane linking agent (bis-(3-triethoxysilylpropyl) tetrasulfane (TESPT)) to improve its mixing properties. As a result, a large amount of used solvent containing silane TESPT is produced. This study aimed to evaluate the surface modification of silica nanoparticles from rice husk employing this used solvent and to characterize the particles’ physical properties. Silica nanoparticles were extracted from rice husk using a sol-gel method. FTIR spectography demonstrated that the TESPT on fresh solvent and the used solvent were successfully grafted onto the surface of Si-NP RHA. Si-NP RHA modified by Two Step Modification (TSM) employing used solvent had strong absorption peaks at wave numbers of 2927.94 cm-1 and 1446.61 cm-1, which are associated with vibration of the ‑CH2 group and deforming vibration of the -C-H group in TESPT compounds. Likewise, Si-NP RHA modified with One Step Modification (OSM), either using fresh solvent or the used solvent, exhibited absorption peaks at wave numbers 2935.66 cm-1 and 1404.18 cm-1. The result showed that the used solvent still effectively modified the silica nanoparticle surface.
Synthesis of Bio-hexane and Bio-Hexene from Sorbitol Using Formic Acid as Reducing Agent
Get PDFSorbitol (C6H14O6) is a sugar alcohol that can be synthesized from cellulose and has a similar skeletal structure as hexane (C6H14) so that it can straightforwardly be converted to hexane through deoxygenation. The bio-hydrocarbon synthesis from sorbitol in this investigation consisted of two main processes, namely synthesis of 2-iodohexane and deiodization of 2-iodohexane. The synthesis of 2-iodohexane from sorbitol and hydroiodic acid (HI) was conducted in a reflux system, to which formic acid as reducing agent was added gradually during the reaction to regenerate the iodine back to HI. The HI/sorbitol ratio (2:1 and 5:1), reaction temperature (90 °C, 105 °C, and 120 °C), and reaction time (between 2 and 6 hours) were varied throughout the experiment. Deiodization of 2-iodohexane was conducted via gas phase pyrolysis at various temperatures (265 °C to 285 °C) and reaction times (30 and 45 minutes). The sorbitol was effectively converted to a mixture of 2-iodohexane, hexane and other bio-hydrocarbons, with a 2-iodohexane yield of 23.15%. In the optimal reaction condition, pyrolysis of 2-iodohexane resulted in bio-hydrocarbon with a yield of 77.52%. The resulted hydrocarbon products were mixtures consisting of alkanes and alkenes