Browsing by Author "Nayak, N.S."

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An experimental and numerical study on effects of exhaust gas temperature and flow rate on deposit formation in Urea-Selective Catalytic Reduction (SCR) system of modern automobiles
(Elsevier Ltd, 2017) Prabhu S, S.; Nayak, N.S.; Kapilan, N.; Hindasageri, V.
Urea Water Solution (UWS) is injected to generate NH3 in Selective Catalytic Reduction (SCR) system of modern automobiles. Thermal and fluid dynamic conditions such as temperature and Reynolds number of the flow favors ammonia generation in terms of heat transfer to UWS droplets by forced convection. During extremely cold weather conditions and low exhaust temperatures, the overdosing of UWS results in deposits of urea and its byproducts. As deposit depletion changes the stoichiometry of NOx/NH3, any predictive method becomes complementary to experimental studies on deposit formation. In the present work, we experimentally investigated deposit formation and its rate by a newer concept of usage of Stainless Steel (SS) foils considering temperature and flow rate as variables. According to numerical results, the droplet evaporation of UWS decreases as flow rate increases. For a fixed rate of UWS quantity of deposits decrease with increase in temperature and flow rate. Accordingly, structural changes are observed. Numerical values of time dependent deposit formation found slightly superior to the experimental values. The study revealed that deposit areas at low temperatures are comparable to numerical values. Phenomenological model is proposed to find deposit conversion factor for low temperatures (150–250°C), which helps in tuning of UWS dosage strategy to prevent NH3 slip. © 2016 Elsevier Ltd
Calculation of friction coefficients in journal bearings to determine the turning gear motor power
(2012) Manoj, Kumar, A.P.; Nayak, N.S.
Steam turbine turning gear is a gear train, driven by electric motor, which is used to drive the rotor at a given speed and capable of breaking away the turbine and its load equipment from a standstill. Steam turbine rotor trains are supported by journal bearing which require lube oil for cooling. The normal turning gear operation requires that lube oil and the lift oil systems must be inservice in order to reduce the friction coefficient at the journal bearings during breakaway. The rotor train breakaway and running torque is the resisting moments at each of the journal bearings. The resisting moments at each journal bearing are functions of bearing loading, pad type, journal diameter and friction. Therefore, it is important to determine the static and dynamic coefficient of friction in journal bearings of the rotor system to design the turning gear motor power. In the present work, a detailed study has been made for calculating the static and dynamic friction coefficients in the bearings and validated the values with experiments for designing a suitable motor to run the rotor of a steam turbine. � (2012) Trans Tech Publications, Switzerland.
Calculation of friction coefficients in journal bearings to determine the turning gear motor power
(2012) Manoj Kumar, A.P.; Nayak, N.S.
Steam turbine turning gear is a gear train, driven by electric motor, which is used to drive the rotor at a given speed and capable of breaking away the turbine and its load equipment from a standstill. Steam turbine rotor trains are supported by journal bearing which require lube oil for cooling. The normal turning gear operation requires that lube oil and the lift oil systems must be inservice in order to reduce the friction coefficient at the journal bearings during breakaway. The rotor train breakaway and running torque is the resisting moments at each of the journal bearings. The resisting moments at each journal bearing are functions of bearing loading, pad type, journal diameter and friction. Therefore, it is important to determine the static and dynamic coefficient of friction in journal bearings of the rotor system to design the turning gear motor power. In the present work, a detailed study has been made for calculating the static and dynamic friction coefficients in the bearings and validated the values with experiments for designing a suitable motor to run the rotor of a steam turbine. Â© (2012) Trans Tech Publications, Switzerland.
Development of low cost solar dryer for Oman conditions
(2018) Nayak, N.S.; Anarghya, A.; Abhishek, V.N.; Al, Bulushi, I.
Solar dryer is one of the technologies which are used in many countries to dry the agricultural products. In the present wok, development of low cost pebble bed solar dryer was made to suit for Oman weather conditions. The system consists of solar collector with pebbles for heat storage and cost effective food drying chamber. Initially, dryer performance was studied with banana and study results revealed that maximum dryer room temperature of 68�C and the moisture loss content of 52%. In addition, dryer chamber efficiency of 34% was achieved in the study. Overall, the study results indicated that late evening drying up to 7PM was noticed and the developed dryer system gave better results than dryers available in the market. � Published under licence by IOP Publishing Ltd.
Development of low cost solar dryer for Oman conditions
(Institute of Physics Publishing helen.craven@iop.org, 2018) Nayak, N.S.; Anarghya, A.; Abhishek, V.N.; Al-Bulushi, I.
Solar dryer is one of the technologies which are used in many countries to dry the agricultural products. In the present wok, development of low cost pebble bed solar dryer was made to suit for Oman weather conditions. The system consists of solar collector with pebbles for heat storage and cost effective food drying chamber. Initially, dryer performance was studied with banana and study results revealed that maximum dryer room temperature of 68Â°C and the moisture loss content of 52%. In addition, dryer chamber efficiency of 34% was achieved in the study. Overall, the study results indicated that late evening drying up to 7PM was noticed and the developed dryer system gave better results than dryers available in the market. Â© Published under licence by IOP Publishing Ltd.
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 Ltd
Thrust and torque force analysis in the drilling of aramid fibre-reinforced composite laminates using RSM and MLPNN-GA
(Elsevier Ltd, 2018) Anarghya, A.; Harshith, D.N.; Rao, N.; Nayak, N.S.; Gurumurthy, B.M.; Abhishek, V.N.; Patil, I.G.S.
Aramid Fibre Reinforced Plastic composites are difficult to be drilled due to anisotropic material properties. Currently, soft computing techniques are used as alternatives to conventional mathematical models, which is robust and can deal with inaccuracy and uncertainty. In this paper, drilling of Aramid Fibre Reinforced Plastics (AFRPs) was carried out using Taguchi L54 experimental layout. Drilling tool used in this experiment was solid carbide. The purpose of this study was to find optimum combination of drilling parameters to obtain minimum thrust and torque force to reduce the delamination. Also, this paper proposed a prediction model of Multilayer Perception Neural Network optimized by Genetic Algorithm (MLPNN-GA). Moreover, RSM technique was used to evaluate the influence of process parameters (spindle speed, feed rate, drill point angle and drill diameter on thrust force and torque. The prediction capability of both RSM and MLPNN-GA was compared with Response optimizer for thrust force and torque. The investigation demonstrated that drill point angle is the primary factor affecting thrust force and drill diameter influences the torque force on the drill bit. Overall, this study recommends the use of high speed and low feed combination and drill point angles of 90°–118° to reduce the delamination of the materials in the drilling of AFRP composites. © 2018 The Authors