Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item Advances in Computational Fluid Dynamics Modeling for Biomass Pyrolysis: A Review(Multidisciplinary Digital Publishing Institute (MDPI), 2023) Kulkarni, A.; Mishra, G.; Palla, S.; Ramesh, P.; Surya, D.V.; Basak, T.Pyrolysis, a process for extracting valuable chemicals from waste materials, leverages computational fluid dynamics (CFD) to optimize reactor parameters, thereby enhancing product quality and process efficiency. This review aims to understand the application of CFD in pyrolysis. Initially, the need for pyrolysis and its role in biomass valorization are discussed, and this is followed by an elaboration of the fundamentals of CFD studies in terms of their application to the pyrolysis process. The various CFD simulations and models used to understand product formation are also explained. Pyrolysis is conducted using both conventional and microwave-assisted pyrolysis platforms. Hence, the reaction kinetics, governing model equations, and laws are discussed in the conventional pyrolysis section. In the microwave-assisted pyrolysis section, the importance of wavelength, penetration depth, and microwave conversion efficiencies on the CFD are discussed. This review provides valuable insights to academic researchers on the application of CFD in pyrolysis systems. The modeling of pyrolysis by computational fluid dynamics (CFD) is a complex process due to the implementation of multiple reaction kinetics and physics, high computational cost, and reactor design. These challenges in the modeling of the pyrolysis process are discussed in this paper. Significant solutions that have been used to overcome the challenges are also provided with potential areas of research and development in the future of CFD in pyrolysis. © 2023 by the authors.Item Determination of Lockhart-Martinelli parameter using CFD in 2D vertical rectangular and offset mini-channels with R717(Research India Publications subscription@ripublication.com, 2017) Kutty, S.S.; Ashok Babu, T.P.A.Study of mini-channels has become more popular in the current scenario due to the increasing developments in the field of compact heat exchangers due to the inherent property of increased heat transfer coefficients. Two types of vertical mini-channels, rectangular and offset channels are studied at six different configurations. The flow properties are analyzed using commercial CFD code by varying hydraulic diameters from 1 – 3 mm and mass flux from 5 – 75 kg/m2s. The friction factor is determined using CFD in two dimensional steady state conditions. The results are compared with available empirical correlations. Modified correlations are proposed for friction factor to determine Lockhart-Martinelli parameter based on CFD results. The Lockhart-Martinelli parameters are determined from modified friction factor correlations. © Research India Publications.Item Performance assessment of a semi-circular breakwater through CFD modelling(MDPI AG rasetti@mdpi.com Postfach Basel CH-4005, 2020) Gomes, A.; Pinho, J.L.S.; Valente, T.; Antunes Do Carmo, J.S.A.; Hegde, A.V.Coastal defence works, such as breakwaters, are structures that aim to support the action of waves and dissipate their energy. Therefore, they provide conditions for stabilizing the coast, protecting ports, beaches and other coastal infrastructures and ecosystems. Semicircular breakwaters have been applied in different locations around the world due to their aesthetic advantages and high structural performance. Marine structures are subject to hydrodynamic actions normally estimated through physical models. However, these models are complex to implement, involving high costs and long experimental procedures. Thus, alternative methodologies for studying the hydrodynamic performance of these structures are of great use. This work presents the results of the application of a computational fluid dynamics (CFD) tool to study the stability of a perforated semicircular breakwater, based on a rubble mound foundation. The model was validated against experimental results of the critical weight necessary to resist sliding, taking into account the effects of water depth and different characteristics of the waves. A comparison is made between the perforated and the non-perforated solution in terms of the breakwater's performance to dissipate wave energy. Dissipation conditions of this energy, in the exposed face, are also evaluated in detail, in order to assess the potential of this structure as a biological refuge for marine species. Both solutions show similar performance in terms of results obtained for the wave reflectivity coefficient. The turbulence dissipation on the exposed face of the perforated breakwater is limited to a region of restricted extension around it, which is advantageous in terms of the passage of species into the breakwater. © 2020 by the authors.Item Effect of baffle configuration on performance of batch stirred vessel(Springer, 2022) Ali, B.A.; Falleiro, L.H.Crystallization is often carried out in batch stirred vessels. However, it is difficult to obtain uniform crystal size distribution (CSD), as it strongly depends on prevailing flow field operating conditions. This is adversely affected by the geometry of stirred vessels. Hence in this work, CFD simulations were performed to investigate flow field, mixing and crystallization phenomena in a stirred vessel. The performance of the stirred vessel was compared with draft tube baffled stirred vessel. The flow field was quantified through liquid circulation and vorticity. The mixing was analyzed through macromixing time in the stirred vessel. The solubility data, nucleation, and growth kinetics were integrated with CFD through a user-defined function (UDF) to predict crystallization phenomena. The predicted results were validated with experimental data available in the literature. The effects of seed mass, size and temperature on CSD were investigated and optimum conditions [750 gm (seed mass); 500 µm (seed size); 308 K (temperature)] for favourable crystal growth were identified. The performance of the proposed baffled stirred vessel was found to be significant, and it supports enhancing flow field, mixing and crystallization process. © 2022, The Korean Institute of Chemical Engineers.Item EFFECT OF INDENTATIONS ON THE PERFORMANCE OF PEM FUEL CELL(University of Chemical Technology and Metallurgy, 2023) Ali, B.A.; Roy, A.K.Proton Exchange Membrane Fuel Cell (PEMFC) is an electrochemical device that converts H2 and O2 to electricity. The performance of a fuel cell is influenced by the flow field of gas reactants and product distribution. In this work, the performance of a single channel PEMFC is numerically investigated through Computational Fluid Dynamics (CFD). The performance of a fuel cell is investigated for a wide range of operating conditions such as operating voltage, temperature, relative humidity, and geometric parameters such as membrane thickness. The predicted polarization, power density, contours of temperature, and fuel utilization are analysed to identify an optimum condition for the operation of PEMFC. To improve the performance of PEMFC, indentations (rectangular and shark fin) are proposed in the flow channel. This supports significantly enhancing the performance of PEMFC without using any conventional H2 recirculation system. © 2023, Journal of Chemical Technology and Metallurgy. All Rights Reserved.Item Optimization of a numerical wave flume for efficient simulations(Techno-Press, 2023) Kumaran, V.; Mahalingaiah, A.V.; Rao, M.; Rao, S.The present work investigates the wave generation and propagation in a 2-D wave flume to assess the effect of wave reflection for varying beach slopes by using a numerical tool based on computational fluid dynamics. At first, a numerical wave flume (NWF) is created with different mesh sizes to select the optimum mesh size for time efficient simulation. In addition, different beach slope conditions are introduced such as 1:3, 1:5 and numerical beach at the far end of the NWF to optimize the wave reflection solutions. In addition, several parameters are analysed in order to optimize the solutions. The developed numerical model and its key findings are compared with analytical and experimental surface elevation results and it reveals a good correlation. Finally, the recommended numerical solutions are validated with the experimental findings. © 2023 Techno-Press, Ltd.Item EFFECT OF NOZZLE CONFIGURATION ON PERFORMANCE OF A SPRAY DRYER(University of Chemical Technology and Metallurgy, 2024) Ali, A.A.; Kumar, S.S.In this work, hydrodynamics and drying characteristics of spray dryer is numerically investigated using computational fluid dynamics (CFD) using Euler-Lagrangian (EL) approach. The gas phase is modelled as the continuous phase and solid particle as the dispersed phase. The turbulence in the gas phase is predicted using RNG version of k-ε model. As airflow pattern influences the time spent by particle in drying chamber, the spatial variation of air velocity and its circulation rate is quantified. Accordingly, optimum conditions for drying the feed slurry are determined. Further, five different outlet pipe locations are chosen and the optimum location is identified which supports the highest evaporation rate. To improve the product quality, conventional nozzle is modified and particle impact positions are analyzed. The particles impact positions on the dryer’s surface are found to be minimum for the proposed nozzle configuration and it improves the final product quality. © (2024), (University of Chemical Technology and Metallurgy). All Rights Reserved.Item CFD MODELLING OF NON-ISOTHERMAL PROTON EXCHANGE MEMBRANE FUEL CELL (PEMFC): ROLE OF BAFFLES(University of Chemical Technology and Metallurgy, 2024) Ali, A.A.; Ganta, N.Through oxidation (H2 ) and reduction (O2 ) reactions, the chemical energy of the fuel is converted by proton exchange membrane fuel cell (PEMFC) into electricity and is therefore considered an energy converter. In this work, performance of a PEMFC is numerically investigated using computational fluid dynamics (CFD). To characterize the non-isothermal behavior of PEMFC, 3D transient CFD simulations are performed. The distribution of H2 and O2 mass fractions, temperature, and current density profiles are analyzed for various operational conditions. The optimum condition (voltage = 0.1 V; thickness of gas diffusion layer (GDL) = 0.0127mm; thickness of catalyst layer (CL) = 0.014mm) for an operation of PEMFC is identified Trapezoidal and rectangular baffles are proposed into the flow channels to enhance the performance of PEMFC. The rectangular baffle configuration supports maximum conversion of reactant gases (H2 = 24.16 %, O2 = 41.72 %) in comparison with the trapezoidal baffle. A significant increase in conversion is reported when the number of baffles in the gas flow channel is increases. Thus, PEMFC performance is enhanced with baffle configuration. © (2024), (University of Chemical Technology and Metallurgy). All Rights Reserved.Item CFD Modeling and Analysis of the Effect of Baffles in an Immobilized Annular Photocatalytic Reactor for Ethylene Degradation(Springer, 2025) Sandesh, V.H.; Mohanan, S.; Surenjan, A.In recent years, the adverse effect of indoor air pollution on human well-being has become a topic of concern. Although conventional treatment approaches have demonstrated success in pollutant degradation, they often prove inadequate when dealing with persistent pollutants. Photocatalysis is a sustainable technique which can degrade such pollutants without harmful by-products. The study focuses on the photocatalytic degradation of ethylene in an annular photocatalytic reactor with different baffle configurations using computational fluid dynamics. The results indicate that the use of Longitudinal baffles in reactors has improved the reactor efficiency owing to the flow uniformity and Longer flow path length. Different baffle configurations were modeled using ANSYS Fluent, and the flow, species concentration, distribution, and reaction rates were studied. The novel design of a four-baffled reactor was found to have an efficiency of 68.96% for a hydraulic retention time of 5.597 s and a flow rate of 58.34 L/min. © The Author(s), under exclusive licence to Springer Nature Singapore Pte Ltd. 2025.