Faculty Publications
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Item Photo-electrochemical green-hydrogen generation: Fundamentals and recent developments(Elsevier Ltd, 2024) Baiju, S.; Masuda, U.; Datta, S.; Tarefder, K.; Chaturvedi, J.; Ramakrishna, S.; Tripathi, L.N.Scalable, cost-effective production and earth-abundant material platforms for clean energy sources such as green hydrogen are key research problems. Understanding the fundamentals is the basis of the advancement of research in green hydrogen production. Quantum materials such as two-dimensional materials are emerging material platforms for green-hydrogen generation. Quantum mechanical tools such as density functional theory play a crucial role in understanding quantum phenomena hence improving the efficiency of hydrogen production from the quantum materials. In this review article, we discuss the basic principles of green hydrogen generation using photo-electrochemical water splitting. The methods to evaluate the catalytic activity of the catalysts are discussed in detail. A broad classification of the photo/electro-catalysts for water splitting is further elaborated. We discuss methods to enhance the performance of the catalysts by doping the hetero-atoms, and the synergic effects of using other nanomaterials such as quantum dots and plasmonic nanostructures. The concept of electron transfer enhancement due to magnetic nanostructures is also discussed in detail. The introduction and application of surface plasmons for enhanced hydrogen generation are also discussed. Finally, we discuss the application of hydrogen in a fuel cell for the generation of electricity. © 2023 Hydrogen Energy Publications LLCItem Computational study of pressure side film cooling—effect of density ratio with combination of holes(Springer Heidelberg, 2017) Radheesh, D.; Pugazhendhi, P.; Gnanasekaran, N.; Panda, R.K.Film cooling is a proven cooling technique for gas turbine blades. The temperature distribution and flow phenomena vary with the suction and pressure sides. A computational investigation is carried out to understand the film cooling effectiveness and flow phenomenon on pressure side of a gas turbine aerofoil. A specific turbine blade profile is considered with combination of cylindrical and shaped holes in staggered fashion, oriented at different angles. Computations are carried out using the k-? Realizable model available in the commercial code FLUENT 6.3. Meshing of the present model is done by using GAMBIT. The parameter variation considered for the present study is the blowing ratio (0.5–1.25) with an interval of 0.25 and three different density ratios (DR) 1.25, 1.5 and 2. The film cooling performance is discussed with effectiveness distribution on the interface wall. It is inferred that the film cooling performance enhances with increasing density ratio values. Also the optimum value of blowing ratio lies close to 0.75 for higher density ratio values of 2. © Springer India 2017.Item Computational study of radial gap effect between impeller and diffuser on the unsteadiness of vaned diffuser in a centrifugal compressor(Korean Society of Mechanical Engineers, 2017) Anish, S.; Sitaram, N.Understanding the unsteady fluid dynamics inside the diffuser holds the key to improve the performance of centrifugal compressor. A detailed computational study has been conducted in a low-speed centrifugal compressor to understand the unsteady flow mechanisms that govern the static pressure recovery inside the vaned diffusers. Simulations are carried out for three different leading edge locations at design and off-design conditions. The study is carried out using Reynolds-averaged Navier-Stokes simulations. This study revealed that the unsteady fluctuations exhibit contrasting behavior at different radial gaps and flow coefficients. An optimum radial gap is strictly a function of the stage loading. A high radial gap helps contain the fluctuations at low flow coefficients, but it enhances the fluctuations at high flow coefficients. If the leading edge is kept close to the impeller blade, then the above design flow coefficient of the vaned passage facilitates a reduction in the unsteady fluctuations. On the contrary, keeping the leading edge close to the impeller blade can accelerate the unsteady fluctuations at low flow coefficients. © 2017, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature.Item Synthesis, characterization and electroluminescence studies of cyanopyridine-based ?-conjugative polymers carrying benzo[: C] [1,2,5]thiadiazole and naphtho[1,2- c:5,6- c ?]bis([1,2,5]thiadiazole) units(Royal Society of Chemistry orders@rsc.org, 2020) Pilicode, N.; Naik, P.; Acharya, M.; Vasudeva Adhikari, A.V.Four new donor-acceptor type cyanopyridine-based conjugative polymers, i.e.TDPy1-4, carrying different electron-donating aromatic/heteroaromatic moieties in the backbone were synthesized from their respective co-monomers by using the Suzuki cross-coupling polycondensation protocol. These polymers were designed to possess good control of color emission and to have balanced charge injection, and transport properties. Their structures were confirmed by spectroscopic studies and their thermal stability was evaluated using the TGA technique. The photophysical, electrochemical and electroluminescence properties of these materials were established in order to assess their suitability for PLED applications. DFT-based computational studies were performed to verify and elucidate the above-said properties. Evidently, they demonstrate good green fluorescence with optical band gap (Eg) values of 2.14-2.27 eV. Finally, new PLEDs based on TDPy1-4 were fabricated with a structure of ITO/PEDOT:PSS/polymer/Al, wherein they are able to act as green light emitters with stable electroluminescence behaviors. © 2020 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Computational and experimental studies on the development of an energy-efficient drier using ribbed triangular duct solar air heater(Elsevier Ltd, 2020) Nidhul, K.; Kumar, S.; Yadav, A.; Anish, S.Triangular duct cross-section is introduced for solar air heater (SAH) of an indirect type of solar dryer (ITSD). Using computational study, the thermo-hydraulic performance of triangular duct SAH with inclined ribs for varying rib inclination (30° < ? < 75°) in the turbulent flow regime (5000 < Re < 17500) is studied. With the rib configuration providing maximum thermos-hydraulic performance, a ribbed rectangular duct SAH is designed, and the performance of the same is compared to the former for similar heat input. Results show that the ribbed (? = 45°) triangular duct has 17% higher effectiveness compared to the latter and 79% when compared to smooth SAH. Ribs in triangular duct solar air heater facilitate the increase in temperature even in the core of the duct, delivering the air at 6 K additional temperature relative to a rectangular ribbed duct for same heat input and flow Re. The superiority of the ribbed triangular SAH is further confirmed by studying the drying characteristics of Okra and two variants of banana, namely Nendran and Robusta for the maximum temperature obtained at the outlet of the respective SAH. Various thin layer drying models available in the literature were analyzed, and Modified page model represented the drying behaviour with R2 = 0.99. For ITSD, ribbed triangular duct SAH exhibits a maximum of 60.3% reduction in moisture ratio with a maximum increase of 97.9% increase in average values of diffusivity coefficient confirming that it is an energy-efficient design for an ITSD. © 2020 International Solar Energy SocietyItem Synthesis, physicochemical properties and computational study of donor–acceptor polymer for optical limiting application(Springer Nature, 2020) Vishnumurthy, K.A.; Girish, K.H.; Vasudeva Adhikari, A.V.A new donor–acceptor configured ?-conjugated polymer P1 with alkoxy pendant groups having cyclic diimide and thiophene core moieties in polymer backbone were efficiently synthesized via polycondensation reaction. The incorporation of cyclic diimide in polymer increased the rigidity and thermal stability of polymer backbone aided by its high Tg value. These chromophores assisted in reducing the steric interaction of bulky alkoxy pendants which supported lowering the bandgap. The donor and acceptor moieties along with ? spacers were particularly chosen to enhance the ?-conjugation length in the polymer thereby increasing its nonlinear optical absorption i.e. two-photon absorption. The various structure–property relationships of the polymer were characterized by UV–Vis absorption, fluorescence emission, cyclic voltammetry, and density functional theory studies. The molecular nonlinear properties were theoretically evaluated through the calculation of polarizabilities and hyperpolarizabilities using time-dependent Hartree–Fock method. The polymer showed enhanced effective two-photon absorption with an absorption coefficient (?eff) of 2.031 × 10?10 m/W obtained from open aperture Z-scan analysis which is in good agreement with theoretical study. © 2020, Springer Nature Switzerland AG.Item Effective inhibition of mild steel corrosion by 6-bromo-(2,4-dimethoxyphenyl)methylidene]imidazo [1,2-a]pyridine-2-carbohydrazide in 0.5 M HCl: Insights from experimental and computational study(Elsevier B.V., 2021) Vranda Shenoy, K.; Venugopal, P.P.; Reena Kumari, P.D.; Chakraborty, D.A new inhibitor, 6-bromo-(2,4-dimethoxyphenyl)methylidene]imidazo [1,2-a]pyridine-2-carbohydrazide (DMPIP) was evaluated as a corrosion inhibitor for Mild Steel (MS) in 0.5 M HCl solution at 303–323 K using potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) techniques. Both the techniques confirmed an increase in inhibition efficiency with the concentration of DMPIP but decrease with temperature. The highest inhibitive action (96.7%) was registered at 303 K for 500 ppm of DMPIP concentration. Polarization study revealed mixed inhibition action by DMPIP. Nyquist plot obtained for MS using EIS technique showed two capacitive loops on addition of inhibitor to HCl solution confirmed the inhibitory action of DMPIP via adsorption at the metal/solution interface. The surface morphology analysis was carried out by SEM, EDX and FTIR techniques. The adsorption process was demonstrated using Langmuir's adsorption isotherm model. The thermodynamic parameters (?Goads, ?Hoads) indicated that the adsorption was spontaneous and done by physisorption. Further, quantum chemical studies using Density Functional Theory (DFT) elucidated that the formation of Fe-DMPIP complex presumably due to the interaction of protonated form of DMPIP with the empty d orbitals of the iron atom. © 2021 Elsevier B.V.Item Lateral Migration of Variously Shaped Particles: A Computational Study(John Wiley and Sons Inc, 2023) Neeraj, M.P.; Maniyeri, R.The current work deals with the simulation of lateral migration of differently shaped particles in a straight channel through which fluid flows with a Poiseuille pattern of flow. The immersed boundary method based on feedback force is adopted for the current work. The equilibrium positions and migration times for circular, elliptical, rectangular, square, and biconcave particles are studied and presented. The cases of neutral and massive (high ratio of particle density to fluid density) particles are presented, and in both scenarios the biconcave particle attains its equilibrium position closest to the bottom wall and the elliptical particle acquires its equilibrium position closest to the channel center. Also, the migration time is highest for the biconcave particle, whereas it is lowest for the rectangular particle. © 2023 Wiley-VCH GmbH.Item Inertial migration and control force in pulsatile flow- a computational study(Taylor and Francis Ltd., 2024) Neeraj, M.P.; Maniyeri, R.The current work proposes a numerical model for analysing the inertial migration of cylindrical-shaped rigid particles in pulsatile flow. The particle is non-neutrally buoyant, and the numerical model is built using a feedback forcing-based immersed boundary scheme. For shifting particle equilibrium position towards the channel centre, an opposing flow control force is applied. The relationship between control force and parameters such as particle diameter, Reynolds number, and density ratio is thoroughly investigated and reported here. The magnitude of the control force increases with Reynolds number and decreases with particle diameter. With density ratio, on the other hand, the magnitude of the control force first drops and then rises. Based on the results of the parametric study a prediction model for the control force is developed with the help of a linear regression algorithm. © 2024 Indian Institute of Chemical Engineers.Item Meso-tris(2-furyl/2-thienyl) substituted porphyrin-ferrocene ‘click’ conjugates: synthesis, experimental, and computational studies(Royal Society of Chemistry, 2024) Shet, S.N.; Patil, M.; Shetti, V.S.The chemical synthesis of 5-(4-azidophenyl)-10,15,20-tris(2-furyl/2-thienyl)porphyrins and their utilization in a Cu(i) catalyzed alkyne-azide ‘click’ reaction (CuAAC) with ethynylferrocene to obtain the hitherto unknown meso-tris(2-furyl/2-thienyl) substituted porphyrin-ferrocene ‘click’ conjugates are reported. These new ‘click’ conjugates were studied along with the reference ‘click’ conjugates containing all-meso-aryl substituted porphyrins by experimental and computational methods. Compared to the reference, the new conjugates displayed red-shifted absorption/emission bands, easier porphyrin ring reduction, and an efficient photoinduced electron transfer (PET) process from ferrocene to a porphyrin unit. Density functional theory (DFT) calculations performed on these conjugates revealed a good correlation with the experimental results. © 2024 The Royal Society of Chemistry.