Faculty Publications
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Item Removal of ammonia and particulate matter using a modified turbulent wet scrubbing system(2012) Byeon, S.-H.; Lee, B.-K.; Raj Mohan, B.Conventional scrubbers are typically modified to serve the needs of modern industries that discharge effluents that cause synergetic, adverse effects on the environment. We designed and developed a modified turbulent wet scrubber (MTWS) to remove air pollutants as they emerge from a coal furnace. Experiments were conducted to estimate the pressure drop and the efficiencies of ammonia gas and particulate removal via the MTWS. The optimum water levels and gas flow rates for effective scrubbing of ammonia gas at different concentrations and particulate matter at different feed rates were estimated. For ammonia gas at a concentration of 45 ppm, a gas flow rate of 3.5 m 3/s and a water level of 58 cm in MTWS and position B (central position of the nozzle) in the water level of the nozzle yielded efficient ammonia gas removal for the given time. Similarly, for a fly ash feeding rate of 140 mg/min, the same gas flow rate and water level in the MTWS yielded high efficiencies even for particles at the submicron level. © 2012 Elsevier B.V. All rights reserved.Item Evaluating the performance of a turbulent wet scrubber for scrubbing particulate matter(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2013) Lee, B.-K.; Raj Mohan, B.; Byeon, S.-H.; Lim, K.-S.; Hong, E.-P.A turbulent wet scrubber was designed and developed to scrub particulate matter (PM) at micrometer and submicrometer levels from the effluent gas stream of an industrial coal furnace. Experiments were conducted to estimate the particle removal efficiency of the turbulent scrubber with different gas flow rates and liquid heads above the nozzle. Particles larger than 1 ?m were removed very efficiently, at nearly 100%, depending upon the flow rate, the concentration of the dust-laden air stream, and the water level in the reservoir. Particles smaller than 1 ?m were also removed to a greater extent at higher gas flow rates and for greater liquid heads. Pressure-drop studies were also carried out to estimate the energy consumed by the scrubber for the entire range of particle sizes distributed in the carrier gas. A maximum pressure drop of 217 mm H2O was observed for a liquid head of 36 cm and a gas flow rate of 7 m3/min. The number of transfer units (NTU) analysis for the efficiencies achieved by the turbulent scrubber over the range of particles also reveals that the contacting power achieved by the scrubber is better except for smaller particles. The turbulent scrubber is more competent for scrubbing particulate matter, in particular PM2.5, than other higher energy or conventional scrubbers, and is comparable to other wet scrubbers of its kind for the amount of energy spent. Copyright © 2013 A&WMA.Item Improved subject-independent acoustic-to-articulatory inversion(Elsevier, 2015) Afshan, A.; Ghosh, P.K.In subject-independent acoustic-to-articulatory inversion, the articulatory kinematics of a test subject are estimated assuming that the training corpus does not include data from the test subject. The training corpus in subject-independent inversion (SII) is formed with acoustic and articulatory kinematics data and the acoustic mismatch between training and test subjects is then estimated by an acoustic normalization using acoustic data drawn from a large pool of speakers called generic acoustic space (GAS). In this work, we focus on improving the SII performance through better acoustic normalization and adaptation. We propose unsupervised and several supervised ways of clustering GAS for acoustic normalization. We perform an adaptation of acoustic models of GAS using the acoustic data of the training and test subjects in SII. It is found that SII performance significantly improves (?25% relative on average) over the subject-dependent inversion when the acoustic clusters in GAS correspond to phonetic units (or states of 3-state phonetic HMMs) and when the acoustic model built on GAS is adapted to training and test subjects while optimizing the inversion criterion. © 2014 Elsevier B.V. All rights reserved.Item Effect of exhaust gas recirculation (EGR) on diesel engine using Simarouba glauca biodiesel blends(Regional Energy Resources Information Center (RERIC) enreric@ait.ac.th, 2015) Bedar, P.; Pandey, J.K.; Kumar, G.N.This article deals with the usage of non-edible Simarouba glauca (paradise) oil as a biodiesel for single cylinder diesel engine with application of exhaust gas recirculation (EGR) rates. Biodiesel blends B10, B20 with EGR rates of 10%, 15%, and 20% are used for different load conditions. Parameters like brake thermal efficiency (BTE), nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC) and smoke opacity were evaluated from the experimental study. The results show that Simarouba glauca biodiesel usage decreases HC, CO and smoke emissions with slight increase of NOx, also an improvement in the performance was observed for B10 blend. EGR rates 10% and 15% are beneficiated in terms of performance and emission but negative trend is observed for 20% EGR rate. On the whole it is concluded that a better trade-off between NOx and other emissions is attained with simultaneous application of EGR (15%) and biodiesel blend (B10) without compromising engine performance.Item Optimization of process parameters to achieve spectrally selective TiAlC/TiAlCN/TiAlSiCN/TiAlSiCO/TiAlSiO high temperature solar absorber coating(Elsevier Ltd, 2016) Jyothi, J.; Latha, S.; Bera, P.; Nagaraja, H.S.; Barshilia, H.C.TiAlC/TiAlCN/TiAlSiCN/TiAlSiCO/TiAlSiO tandem absorber was deposited on stainless steel substrate by using four cathode reactive direct current unbalanced magnetron sputtering system. The reactive gas flow rates (C2H2, N2 and O2) and thicknesses of each individual layers were varied to obtain the selective properties of the tandem absorber. The detailed effects of reactive gas flow rates and thicknesses of the individual layers on the optical properties were studied by using UV–vis–NIR spectrophotometer. Guiding factor in optimizing various process parameters was to achieve low reflectance in the solar spectrum region and high reflectance in the infrared region. The change in growth rate of the tandem absorber with reactive gas flow rate was studied using the thickness data, target voltage and target current. These results indicate a decrease in the growth rate of each individual layer of the tandem absorber with an increase in the flow rates of the reactive gases. The changes in bonding structure and chemical composition with reactive gas flow rates were studied by X-ray photoelectron spectroscopy. The optimized tandem absorber deposited on stainless steel substrate shows absorptance of 0.960 and emittance of 0.15. The thicknesses of the optimized individual layers were ?62, 18, 20, 16, 27 nm, respectively. © 2016 Elsevier LtdItem Combined effect of oxygen enrichment and exhaust gas recirculation on the performance and emissions of a diesel engine fueled with biofuel blends(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2018) Dinesha, P.; Mohanan, P.The present study investigates the combined effect of oxygen enrichment and exhaust gas recirculation (EGR) on the performance and emission characteristics of a cardanol biofuel blend, namely B20M10 (20% cardanol, 70% diesel and 10% methanol by volume). The tests are conducted on a four-stroke single-cylinder diesel engine at different loading conditions. Intake air is enriched by 7% of the atmospheric oxygen concentration and exhaust gas is recirculated by 10, 15 and 20% of the total intake charge. Research results reveal that the oxides of nitrogen (NOx) emission decreases as the percentage of EGR increases from 0 to 20%. The results shows 11.8% lower NOx B20M10 at 7% oxygen enrichment and 20% EGR when compared to B20M10 without oxygen enrichment and 0% EGR. Higher carbon monoxide (CO), unburnt hydrocarbon (HC) and smoke, and lower brake thermal efficiency are obtained for higher EGR percentages. From the studies it can be stated that B20M10 cardanol biofuel blend with 7% intake air oxygen enrichment and 15% EGR shows better reduction in NOx emissions with minimum penalty of performance and other emission characteristics. © 2016 Informa UK Limited, trading as Taylor & Francis Group.Item Optimized ANN-GA and experimental analysis of the performance and combustion characteristics of HCCI engine(Elsevier Ltd, 2018) Anarghya, A.; Rao, N.; Nayak, N.S.; Tirpude, A.R.; Harshith, D.N.; Samarth, B.R.HCCI (Homogeneous Charge Compression Ignition) engine has the benefit of operating at high thermal efficiency and low emissions of NOx and soot. However, it has challenges of complex combustion phase controlling and low operating range. This research work investigated the performance and combustion characteristics of HCCI engine with numerical simulations on ANSYS FLUENT and neural network models. The numerical and neural network results were validated by experimental observations with different fuel properties and reduced valve lifts for trapping of the exhaust gases. Experiments were performed on a SMART engine for different speeds and inlet air temperature, with various reference fuels (PRF30, PRF50, PRF70) and methanol to validate the CFD and ANN-GA observations. The engine performance was analyzed for IMEP, ISFC and thermal efficiency, which were found to be 8.2 bar, 205 g/kWh and 44.5% respectively as the optimum performance with PRF-70 fuel. The trapping of the residual gases was performed with various fuel blends in order to overcome the cyclic variations and to improve the operating zones near the knock boundary. The heat release rate was significantly reduced with trapped exhaust gases, and operating region was improved with the use of methanol fuel. Overall the trapping of the hot residual gases resulted in the maximum increase in the operating region by 12% and reduced cyclic variations by 15% for methanol fuel. The exhaust emissions were analyzed and ultra-low emissions of NOx at lean operating conditions were observed with the reduced valve lifts. The study results indicated thermal NO emissions on an average were decreased by 7.8%, CO emissions reduced by 6% and HC emissions increased by 9%. Methanol had ultra-low emissions of HC and CO, but higher emissions of NO and PRF30 had lower emissions of NO. However, ANN-GA model gave satisfactory combustion characteristics and emissions with respect to experimental results. Thus, CFD simulations, Neural Network methods and experimental study gave valuable thoughts of trapped residual gases approach on performance, combustion and emission characteristics of HCCI with PRF's and methanol fuel. © 2017 Elsevier LtdItem Effect of RANS-Type Turbulence Models on Adiabatic Film Cooling Effectiveness over a Scaled Up Gas Turbine Blade Leading Edge Surface(Springer, 2018) Yepuri, G.B.; Talanki Puttarangasetty, A.B.; Kolke, D.K.; Jesuraj, F.Increasing the gas turbine inlet temperature is one of the key technologies in raising gas turbine engine power output. Film cooling is one of the efficient cooling techniques to cool the hot section components of a gas turbine engines in turn the turbine inlet temperature can be increased. This study aims at investigating the effect of RANS-type turbulence models on adiabatic film cooling effectiveness over a scaled up gas turbine blade leading edge surfaces. For the evaluation, five different two equation RANS-type turbulent models have been taken in consideration, which are available in the ANSYS-Fluent. For this analysis, the gas turbine blade leading edge configuration is generated using Solid Works. The meshing is done using ANSYS-Workbench Mesh and ANSYS-Fluent is used as a solver to solve the flow field. The considered gas turbine blade leading edge model is having five rows of film cooling circular holes, one at stagnation line and the two each on either side of stagnation line at 30° and 60° respectively. Each row has the five holes with the hole diameter of 4 mm, pitch of 21 mm arranged in staggered manner and has the hole injection angle of 30° in span wise direction. The experiments are carried in a subsonic cascade tunnel facility at heat transfer lab of CSIR-National Aerospace Laboratory with a Reynolds number of 1,00,000 based on leading edge diameter. From the Computational Fluid Dynamics (CFD) evaluation it is found that K–? Realizable model gives more acceptable results with the experimental values, compared to the other considered turbulence models for this type of geometries. Further the CFD evaluated results, using K–? Realizable model at different blowing ratios are compared with the experimental results. © 2016, The Institution of Engineers (India).Item Combustion, performance, and tail pipe emissions of common rail diesel engine fueled with waste plastic oil-diesel blends(American Society of Mechanical Engineers (ASME) infocentral@asme.org, 2018) Lamani, V.T.; Yadav, A.K.; Kumar, G.N.The demand for plastic is eternally growing in urban areas and producing enormous quantity of plastic waste. The management and disposal of plastic waste have become a major concern worldwide. The awareness of waste to energy retrieval is one of the promising modes used for the treatment of the waste plastic. The present investigation evaluates the prospective use of waste plastic oil (WPO) as an alternative fuel for diesel engine. Different blends (WPO0, WPO30, and WPO50) with diesel are prepared on a volume basis and the engine is operated. Experiments are conducted for various injection timings (9 deg, 12 deg, 15 deg, and 18 deg BTDC) and for different exhaust gas recirculation (EGR) rates (0%, 10%, 15%, and 20%) at 100 MPa injection pressure. Combustion, performance, and tail pipe emissions of common rail direct injection (CRDI) engine are studied. The NOx, CO, and Soot emissions for waste plastic oil-diesel blends are found more than neat diesel. To reduce the NOx, EGR is employed, which results in reduction of NOx considerably, whereas other emissions, i.e., CO and Soot, get increased with increase in EGR rates. Soot for WPO-diesel blends is higher because of aromatic compounds present in plastic oils. Brake thermal efficiency (BTE) of blends is found to be higher compared to diesel. © 2018 by ASME.Item Sensitivity Study of Nanocrystalline Fe3BO6 Sensor for Methane Gas Detection(Institute of Electrical and Electronics Engineers Inc., 2018) Kumari, K.; Ram, S.The iron borate Fe3BO6 with functionalized properties in a nanostructure is an important material useful for electrodes, gas sensors, and biological probes. In this paper, we studied the X-ray diffraction pattern, field-emission electron microscopy, and methane (CH4) gas sensing properties of synthesized Fe3BO6 nanocrystallites in a shape of nanoplates and nanobars from an iron borate glass 40Fe2O3-60B2O3 by annealing it in microwave for 15 min at 823 and 1023 K, respectively, in air. The temperature dependent sensitivity for CH4 (1000 ppm) illustrates a maximum value of 43% at an operating temperature 525 K for the 1023 K annealed sample. The sensitivity is found to be varied from 9% to 39% when the CH4 gas concentration is increased from 50 to 1000 ppm. Thus, the sample has a reasonably good sensitivity for methane. Furthermore, the sensor exhibits fast response (1 min) and a good recovery time (1.6 min) as compared with other oxide materials. © 2001-2012 IEEE.