Journal of Engineering and Technological Sciences
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Mobile Rice Husk Gasifier Performance and Techno-Economic Analysis as Micro Scale Power Generation: Modeling and Experiment
Get PDFIndonesia annually produces significant amounts of biomass waste in the agriculture sector. Rice husk, one of the highest produced agricultural waste materials, has sufficient caloric value to produce syngas in a gasification system to generate sustainable energy. However, the production of tar from rice husk gasification is significantly high, damaging the equipment and internal combustion engine. This study carried out performance analysis on a small-scale rice husk gasifier. A simulation provided a syngas composition overview and showed a maximum LHV value of 6.47 MJ/Nm3 at ER 0.25, and a maximum CGE value of 83% at a temperature of 900 ℃. Furthermore, the economic aspect of integrating renewable technology was also considered. The gasifier had an LCOE value ranging from 0.014 to 0.089 USD/kW, depending on the use of the gasifier. The feasibility of using a mobile rice husk gasifier was also inspected, based on net present value, benefit-to-cost ratio, and payback period
Microwave Absorbing Material of Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) with Broadband Characteristic at X-band Frequency
Get PDFIn this study, hexaferrite Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) was synthesized and characterized, which can be applied as microwave absorber in the X-band frequency range. It is a potential candidate for a radar absorbing material for microwave absorption, particularly for use in anti-radar paint in the defense sector. Samples were prepared using solid state reaction synthesis with high energy milling. After sintering at the right temperature, the samples were characterized using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a vibrating-sample magnetometer (VSM) and vector network analysis (VNA). The XRD characterization results indicated that all samples were in phase and had a hexagonal lattice structure with a P63/mmc space group and a crystallite size between 38 and 45 nm. The surface morphology of the characterization results using SEM showed a heterogeneous particle shape with particle sizes ranging from 140 to 200 nm. Substitution of Ti4+ ions for Fe3+ ions by Zn2+ ions resulted in a decrease of the magnetic saturation (Ms), the magnetic remanence, and the sample’s coercivity field. With a sample thickness of 1.5 mm, the VNA results confirmed that the ability to absorb microwaves and bandwidth will increase along with increase of the substitution value x. The reflection loss value was about -13.3 dB at a frequency of around 11 GHz, with a bandwidth of 1.4 GHz for the sample with x = 1.0 composition
The Implementation of Soundscape Composition to Identify the Ideal Soundscape for Various Activities
Get PDFSoundscapes are affected by several factors and one of them is the activities done in the space concerned. People expect different acoustic environments for different activities, but there is no specific guidance for designing an ideal acoustic environment for different activities. This study aimed to identify ideal urban acoustic environments for four different activities: reading, relaxing, talking with friends, and playing with children. The ideal acoustic environment was evaluated using the soundscape composition concept. The concept was implemented by an acoustic environment simulator that enabled the respondents to compose their ideal acoustic environment and identify the perception of their composition. The sound source selection and perception rating were analyzed to understand the ideal acoustic environment and perception for different activities. This study identified the ideal soundscapes for four different activities and the perception expected to be present in the ideal environments for those activities. The result can be beneficial as guidance for urban soundscape design
Blasting Vibration Monitoring and a New Vibration Reduction Measure
Get PDFVibration waves generated by blasting can cause shock to buildings. Different responses occur in different parts of the building. Therefore, a single standard is inaccurate. At the same time, methods to reduce vibration are needed. In this paper, the variation of peak particle velocity (PPV) and principal frequency was analyzed. The energy variation of blast vibration waves was analyzed by wavelet packet decomposition. A numerical model was established to verify the new vibration reduction measure. The results showed that the PPV on the walls increases with their height. The PPV and principal frequency of different structures of single-story brick-concrete buildings are different. The amplification factor of PPV does not change much when the principal frequency ratio is larger than 0.75. Measuring points at different heights have different sensitivities to blasting vibration waves of different principal frequencies. Therefore, different structures will respond differently to the same blasting operation. The PPV can be reduced by waveform interference. However, the cycle of blasting vibration waves decreases with increasing distance. Therefore, it is necessary to determine a reasonable interval to reduce the PPV. This requires further research
Vitamin E Extraction from Magnesium Salts of Palm Fatty Acid Distillates
Get PDFThis research studied how the type of organic solvent and the number of extraction stages affect the vitamin E cumulative extraction yield and recovery rate from Mg-PFAD. First, PFAD was saponified to produce Mg-PFAD, then vitamin E was extracted from the Mg-PFAD using ethanol, isopropanol, or hexane, followed by evaporation to produce vitamin E concentrate. Three-stage hexane extraction with a solvent to Mg-PFAD mass ratio of 3 kg solvent/kg Mg-PFAD produced the highest vitamin E recovery rate. Organic solvent with a lower polarity gave a higher extraction yield and recovery rate of vitamin E from Mg-PFAD. In general, an increase of the number of extraction stages led to an increase of the vitamin E extraction yield and recovery rate from Mg-PFAD
Powdered Activated Carbon (PAC)-Ceramic Composite Adsorbent for Iron and Aluminum Cations Removal from Acid Mine Drainage
Get PDFAcid mine drainage has become a serious problem globally, polluting groundwater with heavy metals. Adsorption is considered a simple and effective approach to addressing this emerging issue. A commonly used adsorbent is powdered activated carbon (PAC), but this is susceptible to being washed into the waste stream, either during or after the adsorption process due to its low density. This research combined PAC with clay that was molded into small clay balls (~1 cm in diameter) then baked at a very high temperature of 1000 °C to create a ceramic adsorbent. The adsorbent activation used NaOH 48% alkali solution to improve its capability in binding metallic cations. This research demonstrated that the PAC-ceramic composite is an efficient adsorbent for the removal of Fe (iron) and Al (aluminum) cations from acid mine drainage. The results showed that the most favorable contaminant removal was 60.87% for Fe and 52.13% for Al, using a PAC:clay ratio of 45:55 (w/w) in 10 hours contact time
Silicon on Isolator Ribbon Field-Effect Nanotransistors for High-Sensitivity Low-Power Biosensors
Get PDFSilicon field-effect transistors (FETs) are an established technology for sensing applications. Recent advancements and the use of high-performance multigate FETs in computing technology raise new opportunities and questions about the most suitable device sensing architecture. In this work, we propose pH sensors exploiting ribbon (tri-date) FETs fabricated on investigated silicon nanowires and silicon-on-insulator substrates by a fully CMOS compatible approach. The FET characteristics were optimized using 3D modeling performed by the TCAD computer-aided design software package, depending on the topological parameters of the transistor and the level of control voltage. N-channel fully depleted ribbon FETs with critical dimensions in the order of 30 nm and SiO2 as a subgate insulator were developed and characterized. It was established that thin structures with a width of slightly than more 100 nm, a thickness of 40 nm, and a reduced doping level have high sensitivity and low energy consumption. They showed excellent electrical properties, subthreshold swing (SS) was about 90 mV/dec, and the on-to-off current ratio, Ion/Ioff, was about 105. The same architecture was tested as a highly sensitive, stable and reproducible pH sensor. The average internal sensitivity, S, was equal 34 mV/pH or 360 nA/pH. Sensitivity to pH, estimated in terms of relative changes in the threshold voltage, was 74%, and the maximum drain current was 40%. The maximum drain current of 85 μA at V ds = 1.0 V suggests successful low-power operation of the proposed device
Strength Enhancement, Ductility, and Confinement Effectiveness Index of Fly Ash-based Geopolymer Concrete Square Columns
Get PDFGeopolymer concrete is an environmentally friendly construction material that has the potential to be applied in building structures. It is important to understand the structural behavior of geopolymer concrete. This paper presents an experimental investigation into the performance of structural elements of geopolymer concrete under concentric axial loads. The specimens were twelve square columns with a size of 170 x 170 mm and a height of 480 mm. The study variables were the tie spacing and the compressive strength of unconfined geopolymer concrete (f’c). The test results showed that the increase in f'cc was not as significant as the increase in unconfined concrete compressive strength (f'c). The value of strength enhancement (K) tended to decrease. The column ductility (m) and confinement effectiveness index (Ic) had optimum values. The effect of increasing the tie spacing (s) decreased the K, Ic, and m values of the column. The proposed f’cc formulation for geopolymer concrete is compatible
Performance Evaluation of a Continuous Downdraft Gasification Reactor Driven by Electric Motors with Manual Mode of Operation
Get PDFGasification is considered a promising option for harnessing energy potential from agricultural waste, such as rice husks. This paper presents a 10-kW rice husk fixed bed gasifier system. This system is an improved version of a prototype previously developed by our research group. Some of the optimized features added to the gasifier include the use of a circular air intake, an improved gas cleaning system, and electric motors that are regulated by a programmable logic controller. Keeping the gasifier system’s operation stable is critical for producing high-quality synthetic gas (syngas). Therefore, performance evaluation of the presented gasifier system was conducted, and the resulting syngas outputs were analyzed. The evaluation also included an investigation into the performance of the motors, particularly those used for feeding and char removal, which are critical components of the system. The results showed that the improved gasifier system was stable with a proper feedstock. A discussion of the parameters affecting the composition of the synthetic gas is also presented
Design Optimization of Propellant Grain and Nozzle Contour to Improve Performance of Solid Rocket Propulsion
Get PDFA rocket is a spacecraft, guided missile, or flying vehicle that boosted by a chemical reaction resulting from the combustion of propellant in the rocket motor. One of the essential parameters in the development of rocket motors is design optimization to improve the propulsion performance of the rocket. Increasing the propulsion performance of the rocket will increase the flight performance of the rocket, in terms of its maximum range or the altitude of the rocket trajectory. This study examined the determination of the design parameter values of a rocket motor by looking at it as an optimization problem with constraints. The problem studied was limited to the case of the second-stage rocket motor. A genetic algorithm was used to solve the resulting optimization problem of propellant grain configuration cases and a characteristic method for designing the bell nozzle. The results obtained indicated an increase in total impulse by 10% compared to the results before optimization