Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Experimental Investigation of the Effect of Adding LECA and Pumice on Some Physical Properties of Porous Concrete: Some Physical Properties of Porous Concrete
No full textPorous concrete has high porosity and can be used for increasing the permeability of pavements and parking lots and reducing the urban runoff damages. In this research, light expanded clay aggregate (LECA) and pumice were substituted for 5, 10 and 15% of course aggregates in porous concrete cubes and their effects on the compressive strength (σ), hydraulic conductivity (K) and porosity (n) were investigated. Moreover, effect of adding 10% and 20% of fine grains (as filler) is studied, too. Results showed that fine grains increased σ and decreased K and n. But, samples without any fine grains didn’t have regular trend. The use of additives up to a certain amount reduced the σ, and then, because of filling the pores, increased the σ. The applied additives had almost the same performance in terms of σ; but in terms of permeability and porosity, the samples containing pumice had a better performance.Porous concrete has high porosity and can be used for increasing the permeability of pavements and parking lots and reducing the urban runoff damages. In this research, light expanded clay aggregate (LECA) and pumice were substituted for 5, 10 and 15% of course aggregates in porous concrete cubes and their effects on the compressive strength (σ), hydraulic conductivity (K) and porosity (n) were investigated. Moreover, effect of adding 10% and 20% of fine grains (as filler) is studied, too. Results showed that fine grains increased σ and decreased K and n. But, samples without any fine grains didn’t have regular trend. The use of additives up to a certain amount reduced the σ, and then, because of filling the pores, increased the σ. The applied additives had almost the same performance in terms of σ; but in terms of permeability and porosity, the samples containing pumice had a better performance
Drought Risk Assessment of Irrigation Project Areas in a River Basin
Get PDFA model is developed for drought risk estimation in a river basin with an irrigation project. Drought risk is expressed as a product of drought hazard, exposure and vulnerability. Drought hazard is a function of rainfall, groundwater potential, groundwater quality and water storage in reservoirs. Exposure is the presence of irrigation system and crop areas inside or outside the irrigation project. Vulnerability or the lack of resistance damages due to drought depends on types of irrigation system, types of crop and their economic values. Vulnerability and exposure can be combined as consequences. The product of normalized hazard and consequences is called risk. The model is applied to assess drought risk in drought year of 2015 in the Munbon-Lamsae River Basin in Northeast Thailand. Monthly data in the past 30 years are collected. This includes rainfall, stream flow, groundwater potential and groundwater quality; and available water storage in reservoirs. Maps of hazard, consequences and risk conditions of the study area are computed in drought months such as in June 2015. The maps are calibrated for consistency with the actual field conditions by adjusting the weighting factors or coefficients of the model parameters. The developed model is further applied to estimate change in drought risk due change of irrigation system, for example when the types of irrigation system is changed from surface irrigation system to sprinkler irrigation system. The drought risk in the study area is significantly reduced because the sprinkler system can supply irrigation water more efficiently with less water loss
Experimental Investigations and CFD Simulations of the Blade Section Pitch Angle Effect on the Performance of a Horizontal-Axis Hydrokinetic Turbine
Get PDFThree twisted blades of a 1 kW prototype hydrokinetic turbine were designed based on the Blade Element Momentum (BEM) theory with a tip speed ratio of 6.25; water velocity of 1.5 m/s; angle of attack and pitch angle of 5 and 0°, respectively; a power coefficient of 0.4382 and a drive train efficiency of 70%. S822 hydrofoil was used to generate the coordinates of the blade cross-section. Experimental investigations and Computational Fluid Dynamics (CFD) simulations were carried out to estimate the performance of the blade design and know the effect of the section pitch angle on the performance of a horizontal-axis hydrokinetic turbine. The obtained results showed that the increase in the section pitch angle enhanced the performance up to a certain value. Further increase in the section pitch angle resulted in a low performance and a reduction of the rotation velocity, which in turn requires a high gearing ratio of the transmission system
Adaptation of ‘Early Climate Change Disaster’ to the Northern Coast of Java Island Indonesia
Get PDFIn the last few decades, the tidal inundation and abrasion along northern coast of Java Indonesia have been grown very rapidly. These situations are far beyond the geological scale. These are way too fast. Time series of high resolution satellite image data shows very clearly the tidal inundation and abrasion existence. In the recent years in fact the tidal inundation is obviously going further deeper inland. Many of urban and other areas like farming area, fishpond, etc. have been suffered tidal inundation and becoming worse in times. First it was only few centimetres of inundation and come only at a high tide, but now it can be more than a half of meter and coming at regular tide, and even has comes permanently in certain places. Many of the area along northern coast of Java are also suffering abrasion due to frequently of bad weather with storm surge strike the coastal area. What is happening to the northern coast of Java Island Indonesia is one most clear pictures of ‘early climate change disaster’. Adaptation has been created against this ‘early climate change disaster’ such as build dykes, elevate the land, houses, infrastructures, etc. This paper will tell in details and comprehensively regarding adaptation of ‘early climate change disaster’ to the northern coast of Java Island Indonesia. This is one way to remain on what would happen in the future world wide as the global climate change consequences are finally coming. We have seen the news of the projection model of sinking of coastal cities in the world, vanishing Islands around the Pacific, etc. in the future
Speculation of Nano-gap Sensor for DNA sequencing technology: A Review on Synthetic Nanopores
Get PDFNano-gap sensor is the next generation of single molecule analysis that consumes less resources, costs, times and spaces. The ultimate goal of this technology is rendering the ability to determine any living genetic code in several seconds using a portable device. In principle, DNA decryption was determined by tracking electrical signal change when DNA is passed through either natural or synthetic nanometer size gap. This review focuses on the synthetic nanopore, which is more robust, reliable and manageable with ease. Biological nanopore has been researched in parallel; however, the device reproducibility is a controversial issue. The history and development toward the future of this prospect technology will be elaborated attentively. The main limitation of nanopore sensor device is the controlling of DNA translocation dynamic through tiny pore. Many attempts had been tried and the synopsis will be contemplated in the review. Nonetheless, the present results of DNA sequencing have not been satisfied, the development of nanogap sensor is promising for genomic sequencing and molecular biology
Experimental Study on Utilization of Indonesian Non-Recycled Organic Waste as Renewable Solid Fuel Using Wet Torrefaction Process
Get PDFMunicipal solid waste (MSW) is a complex problem in major cities in Indonesia that has not been resolved. MSW is currently only collected and disposed to final landfill. On the other hand, national energy security is also an issue to be solved. Utilization of MSW, which is dominated by organic waste, as solid fuel can be a solution for both problems. This paper discusses an experimental study on utilization of organic waste as renewable solid fuel using a wet torrefaction process. Four types of samples were chosen to represent the four types of organic waste in MSW with the highest mass fraction found in a field survey: leaf litter, food waste, vegetable waste and fruit waste. Each sample was treated with wet torrefaction under four conditions: 150, 175, 200 and 225 ºC with holding time 30 minutes. The experimental results showed that the optimum wet torrefaction temperature for mixed organic waste is between 200 and 225 °C, which is predicted to produce a solid product with a heating value (db) of 23.22-24.44 MJ/kg, volatile matter content of 61.18-66.00%, fixed carbon content of 26.04-31.35%, ash content of 7.47-7.96%, and energy yield equal to 58%. A higher operating temperature will increase the calorific value, followed by a decrease in mass yield as a consequence of the process severity degree. However, food waste torrefaction showed different characterisics: the increase in calorific value was followed by an increase in mass yield. This is unique and different from the results of wet torrefaction on other organic wastes.
Keywords: Indonesian organic MSW, national energy security, wet torrefaction, renewable solid fuel
The Prediction of Higher Heating Value, Lower Heating Value and Ash Content of Rice Husk Using FT-NIR Spectroscopy
No full textRice husk is the significant waste residue to be used as renewable energy. The growth of the use on rice husk for generating electricity lead to the verification of its properties. This research aimed to predict higher heating value (HHV), lower heating value (LHV), and ash content (A) of rice husk using Fourier Transform near infrared (FT-NIR) spectroscopy. Rice husk samples used in this experiment were collected from variable areas in Thailand in order to improve the model and get the robust model. The models were built using partial least squares (PLS) regression and validated by unknown sample collected from different area to calibration set. The prediction of HHV, LHV and A were represented the root mean square error of cross validation (RMSECV) of 199 J/g, 199 J/g, and 0.859%wb, respectively. The calibration model can predict the unknown sample successfully with the relative standard error of prediction (RSEP) of 1.104 %, 1.159 %, and, 5.975 %, which implied good performance of NIR model for future prediction. The results suggested that HHV, LHV, and A models should be able to assess the properties of rice husk samples and showed that NIR was reliable and suitable method for combustion system to screening material
Study of Microstructure and Mechanical Properties of Commercially Pure Sn and Sn-4%Bi Alloys Fabricated by Permanent Mold Gravity Casting and Forging
Get PDFThe influences of 4 wt% bismuth addition and room temperature strain on microstructure and mechanical properties in tin alloys were investigated in this study. Commercially pure tin and Sn-4%Bi alloys were fabricated by permanent mold gravity casting. The samples were then subjected to forging process at room temperature. As-cast microstructures were compared with 0.25 and 0.5 strained samples. Differential Scanning Calorimetry (DSC) was used to confirm the effect of bismuth on undercooling. The recrystallization and grain growth processes were confirmed by grain size distribution and misorientation study using Electron Backscattered Diffraction (EBSD). Furthermore, position and morphology of the bismuth precipitates were investigated by using Field Emission Scanning Electron Microscope (FESEM). X-ray Photoelectron Spectroscopy (XPS) revealed that tin oxide was the main species found on the surface of these alloys. There was no evidence of bismuth oxide on the surface. Furthermore, the Hall-Petch hardness approximation analysis revealed that there were other influences, which increased the hardness beyond the grain refinement effect
Design and Investigation of Miniature Solar Cell Source Inductive Wireless Power Transfer on Various Distances, Turns and Loads
Get PDFSolar energy is one of renewable and environmentally clean energy, which is very potential to meet electricity demand. Besides that, it is also necessary for wireless power transmission. The purpose of research was to transfer the electric energy in wireless using magnetic couplings and an inverter. It was also investigated the waveform characteristics due to various distances, turns and loads. The tests and measurements were performed by using a storage digital oscilloscope, as the main tool, to obtain the voltage magnitudes and harmonics. The results indicated that the receiver voltage magnitudes would decrease drastically, in hyperbolic curves, as the distances increased. The receiver voltage magnitudes would also decrease considerably as the turns reduced, with the average reductions as 0.095 and 0.357 volts, from 600 to 400 and 400 to 200 turn reductions respectively. The THDs in the transmitter voltages were fairly constant, as average of 26.75%. Nevertheless, the receiver voltage THDs would decrease significantly as the distances increased, with decreasing average as 38.09% of the three condition percentage reductions. While, the THDs would reduce considerably as the turns decreased, as 25.28% of percent average for the 200 to 400 and 400 to 600 turns on one cm of distance. Otherwise, the voltage magnitudes would decrease as the loads increased where from one to five lamp loads, as 0.489, 1.334 and 1.482 volts reductions for 200, 400 and 600 turns respectively. The THDs would decrease slightly as the loads increased, with the reducing average of 5.4% from one to five lamp loads, for the three conditions of turns. The receiver voltage magnitudes would increase steep linearly, with the average ratio of one per 9.30 as the transmitter voltage magnitudes increased. Nevertheless, the THDs of receiver voltages would reduce considerably as the transmitter voltage magnitudes increased, with 8.98% reduction for 1.4 to 5.2 volts of the transmitter voltage magnitudes
Minimum Jet Velocity for Unbounded Domain Fluidization as a New Dredging Methods
Get PDFUnlike for the bounded domain, the minimum fluidization velocity of the unbounded fluidization domain has not been well developed. The aimed of the research is to formulate the minimum jet (holes) velocity (voc) theoretically and experimentally as the criteria for unbounded domain fluidization. Physical experiments were conducted for bounded and unbounded fluidizations of 20 cm to 45 cm thickness of sand bed. The bounded fluidization was carried out using a transparent vertical tube, whilst the unbounded fluidization was conducted on a transparent box. The fluidization discharge and pressure were measured. Empirical equations on jet holes velocity based on the experiment was developed. It was found that voc depends on the required superficial velocity at the surface of sediment deposit (vc) and flow rate loose factor (y) due to unbounded domain conditions. The vc is greater than the minimum fluidization velocity in bounded domain (vmf). The conservative values of velocity conversion factor (ks) were found to be approximately 2.0