Browsing by Author "Yadav, A.K."

Now showing 1 - 20 of 66

A DFT study of the adsorption behavior and sensing properties of CO gas on monolayer MoSe2 in CO2-rich environment
(Springer Science and Business Media Deutschland GmbH, 2024) Vinturaj, V.; Yadav, A.K.; Singh, R.; Garg, V.; Bhardwaj, R.; Ajith, K.M.; Pandey, S.K.
Context: Carbon monoxide, also known as the “silent killer,” is a colorless, odorless, tasteless, and non-irritable gas that, when inhaled, enters the bloodstream and lungs, binds with the hemoglobin, and blocks oxygen from reaching tissues and cells. In this work, the monolayer MoSe2-based CO gas sensors were designed using density functional theory calculation with several dopants including Al, Au, Pd, Ni, Cu, and P. Here, Cu and P were found to be the best dopants, with adsorption energies of −0.67 eV (Cu) and −0.54 eV (P) and recovery times of 1.66 s and 13.8 ms respectively. Cu conductivity for CO adsorption was found to be 2.74 times that of CO2 adsorption in the 1.0–2.26 eV range. P displayed the highest selectivity, followed by Pd and Ni. The dopants, Pd and Ni, were found suitable for building CO gas scavengers due to their high recovery times of 9.76 × 1020 s and 2.47 × 1011 s. Similarly, the adsorption of CO2 on doped monolayer MoSe2 was also investigated. In this study, it is found that monolayer MoSe2 could be employed to create high-performance CO sensors in a CO2-rich environment. Method: The electrical characteristics of all doped MoSe2 monolayers are obtained using a DFT calculation with the PBE-GGA method from the Quantum ESPRESSO package. The self-consistent field (SCF) computations were performed using a 7 × 7 × 1 k-point grid and a norm-conserving pseudo potential (NCPP) file. To determine electrical conductivity, the semi-classical version of Boltzmann transport theory, implemented in the Boltz Trap code, was used. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.
A novel optimized liquid cooled heat sink integrated with 3D lattice structure under different blockage ratios
(Elsevier Ltd, 2025) Narkhede, A.; Gnanasekaran, N.; Yadav, A.K.
In this numerical work, investigation is focused on thermo-hydraulic nature of a periodic metal foam-integrated heat sink with an octet lattice-structure topology. Heat sink is partially filled with octet structure based periodic metal foam having 2.5 mm unit cell length with blockage ratios of 0.25/0.5/0.75/1, porosity of 0.83/0.87/0.91, and flow velocity of 0.02–0.05 m/s for electronic thermal management. The effect of porosity and blockage ratio on the wall temperature and pressure gradient of the heat sink is examined. Among all configurations, the lowest value of wall temperature of 311.24 K and the highest value of pressure gradient of 5091 Pa/m are observed for the case of blockage ratio 1, porosity 0.83, and flow velocity of 0.05 m/s. Additionally, the thermo-hydraulic performance enhancement owing to the partly packed configuration is observed based on the enhancement ratio and thermo-hydraulic performance parameter (THPP). The highest enhancement ratio is observed for the case with a blockage ratio of 1, porosity of 0.83, and a velocity of 0.02 m/s. The thermal design with a velocity of 0.03 m/s, a blockage ratio of 0.75, and a porosity of 0.83 is considered the optimal design in accordance with the THPP, which has a value of approximately 1.7. © 2025 Elsevier Ltd
Biomass-derived 5-(tolylmethyl)furfural as a promising diesel additive: preparation, process scale-up, and engine studies
(Royal Society of Chemistry, 2025) Yadav, A.K.; Yadav, S.K.; Kumar, G.N.; Madav, V.; Dutta, S.
Furanic fuel oxygenates, renewably produced from biomass, have received significant interest in lessening dependence on petroleum-derived liquid fuels and reducing emissions. 5-(Tolylmethyl)furfural (TMF) was prepared by the Friedel-Crafts reaction between cellulose-derived 5-(acetoxymethyl)furfural (AcMF) and petroleum-derived toluene. The process was optimized on various parameters, such as reaction temperature, molar ratio of reagents, catalyst loading, and duration. Anhydrous ZnCl2 was the best catalyst for the reaction, affording a 67% isolated yield of TMF under optimized conditions (120 °C, 4 h). TMF was prepared on a 30 g scale and blended (1-5 vol%) with diesel. The physicochemical properties of the TMF-diesel blended fuel mixtures were studied, and then they were employed as fuel for a direct injection single-cylinder diesel engine. The results show good fuel properties and reduced emissions compared to unblended diesel fuel. © 2025 The Royal Society of Chemistry.
CFD and exergy analysis of subcritical/supercritical CO2 based naturally circulated solar thermal collector
(Elsevier Ltd, 2022) Biradar, M.K.; Parmar, D.N.; Yadav, A.K.
Solar water heating system is inefficient during winter due to the chances of water freezing and higher viscosity at low temperatures. Several investigations are being done to increase the efficiency of the solar water heater using various secondary fluids for different climatic conditions. This paper emphasises on the study of heat transfer and fluid flow behavior of CO2 based naturally circulated indirect solar water heating system. Subcritical (liquid and vapour) and supercritical CO2 are considered as loop fluid, and the results are compared with water based system. Three-dimensional computational fluid dynamics simulations are carried out for two different weather conditions i.e., winter (278 K) and summer (305 K). Results are obtained for 33° collector inclination angle from horizontal at various operating pressures 50–70 bar for subcritical and 80–100 bar for supercritical CO2. The CO2 based system yields very high Reynolds number (subcritical liquid: ∼160 times; subcritical vapour: ∼204 times; supercritical vapour: ∼260 times) and very high Nusselt number (subcritical liquid: ∼14 times; subcritical vapour: ∼19.5 times; supercritical vapour: ∼48 times) compared to water based system. Supercritical CO2 based system exhibits 12% higher energy efficiency compared to water. Whereas, subcritical vapour based system exhibits 140% higher exergy efficiency relative to water based system. © 2022 Elsevier Ltd
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.
Comparative Numerical Appraisal of Subcritical and Supercritical CO2-Based Natural Circulation Loop
(Springer Science and Business Media Deutschland GmbH, 2022) Wahidi, T.; Yadav, A.K.
A natural circulation loop (NCL) is a passive heat transfer system in which circulation occurs solely due to density differences caused by thermal imbalance and the elevational difference between the source and sink of the loop. Carbon dioxide (CO2)-based NCL is highly sensitive to operating conditions and vulnerable to unstable behaviour, mainly due to intense changes in the thermo-physical properties of CO2. Therefore, NCLs always require precise design assessment that focusses on the interaction of all the transient responses of buoyancy and friction forces, ensuring a stable zone of operation. In this article, a three-dimensional computational fluid dynamics study has been carried out for over a range of pressures (30 to 100Â bar) and heat inputs (500 to 1500Â W) to do the comparative investigation of fluid flow and heat transfer phenomenon of subcritical/supercritical CO2-based NCLs with water-based NCL. The simulations quantify the degree of instability and heat transfer rate for subcritical/supercritical CO2 and water. A possible mechanism for continuous flow oscillation and measurement of instability with different pressure in unstable loops is also proposed in this study. Obtained results are validated with the correlations available in the literature; it shows an amicable agreement. Â© 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Comparative studies on air, water and nanofluids based Rayleigh–Benard natural convection using lattice Boltzmann method: CFD and exergy analysis
(Springer Science and Business Media B.V., 2022) Karki, P.; Arumuga Perumal, D.A.; Yadav, A.K.
The present study incorporates laminar natural convection and entropy generation in Rayleigh–Benard (R–B) convection with air, water and alumina–water nanofluid as working fluids. The fluid flow and energy equations are solved using D2Q9 and D2Q5 LBM models, respectively. The effects of Rayleigh numbers (Ra = 5 × 103, 104, 105) and volume fractions (? = 0 to 0.08) of nanoparticles on heat transfer and irreversibility are investigated. Results show that the heat transfer evaluated based on Nusselt number is enhanced due to addition of nanoparticles in the base fluid. The maximum enhancement in Nusselt number is found to be 13.93% at Ra = 105 with 8% of nanoparticle in base fluid. The various irreversibilities considered in this study are thermal, fluid flow and total irreversibility, where fluid flow and total irreversibilities in the study depend on irreversibility ratio. The irreversibility ratios taken into account are 10–2, 10–3, 10–4 and 10–5. One facet of study shows the deviation in onset of critical Rayleigh number for air is 1.58%. The other facet indicates dimensionless heat transfer, fluid flow and total irreversibility decrease with the increase in volume fraction of nanoparticles in the base fluid. The analyzed results of irreversibilities are presented in normalized form. In addition, dimensionless entropy generation maps and Bejan number contours are also plotted. © 2021, Akadémiai Kiadó, Budapest, Hungary.
Comprehensive Modeling of High-Performance All-Inorganic Cs2TiBr6-Based Perovskite Solar Cells
(John Wiley and Sons Inc, 2024) Kumar, S.; Thiyyakkandy, J.; Yadav, A.K.; Vinturaj, V.; Garg, V.; Prabhu, S.; Pandey, S.K.
The perovskites are desirable materials for photovoltaic and other renewable green energy technologies. Lead-based perovskite solar cells (PSC) have recently gained considerable attention due to the abrupt rise in power conversion efficiency, but lead's well-known toxicity prevents its large-scale commercialization. One compelling option is Cs2TiBr6, which offers a nontoxic alternative. Herein, the electronic and optical characteristics of Cs2TiBr6 absorber material using density functional theory employing the WIEN2K tool are investigated. The energy band structure of Cs2TiBr6 shows an indirect bandgap of 2.2 eV. Additionally, optical properties are calculated, and the suitability of this material as an absorber for indoor and outdoor photovoltaic devices is investigated. The Cs2TiBr6 material has a peak absorption coefficient of 39.57 × 104 cm−1 and optical conductivity of 1.98 × 1015s−1, demonstrating its suitability as an absorber material. After that, a PSC is modeled using SCAPS-1D by using the computed parameters. The performance of the modeled perovskite is enhanced by optimization of various parameters, resulting in the achievement of a high-performance Cs2TiBr6-based PSC, boasting a power conversion efficiency of 19.9% for air mass AM1.5 G spectra and power conversion efficiency of 16.76% for light emitting diode and 17.18% for incandescent light for indoor light conditions. © 2024 Wiley-VCH GmbH.
Computation of fluid flow in double sided cross-shaped lid-driven cavities using Lattice Boltzmann method
(Elsevier Ltd, 2018) Bhopalam, S.B.; Arumuga Perumal, D.A.; Yadav, A.K.
This work implements Lattice Boltzmann method to compute flows in double-sided cross-shaped lid-driven cavities. Firstly, a complicated geometry which is a symmetrized version of the staggered lid-driven cavity namely, the double-sided cross-shaped lid-driven cavity with antiparallel uniform wall motion is studied employing Single as well as Two Relaxation time models. The streamline patterns and vorticity contours obtained for low to moderate Reynolds numbers (150–1000) are compared with published results and found to be in good accordance. Next, this code is extended to simulate flows in a double-sided cross-shaped lid-driven cavity with parallel uniform wall motion. The effect of three dimensionality is also studied for low Reynolds numbers. Lattice Boltzmann method is then used to investigate the oscillating double-sided cross-shaped lid-driven cavity with antiparallel and parallel wall motions. The movement and formation of primary and secondary vortices have been well captured with the variation of Reynolds numbers and oscillating frequencies for uniform and oscillating wall motions. Reasonable agreements with the established results have been observed for the double-sided cross-shaped cavity with uniform wall motions, while new results have been obtained in the case of oscillating wall motions. © 2018 Elsevier Masson SAS
Computational appraisal of fluid flow behavior in two-sided oscillating lid-driven cavities
(Elsevier Ltd, 2021) Bhopalam, S.R.; Arumuga Perumal, D.A.; Yadav, A.K.
The current work employs lattice Boltzmann simulations to compute incompressible flows in two-sided oscillating lid-driven cavities. Vortex dynamics in oscillatory lid-driven cavity flows is more complex than steady lid-driven cavity flows due to the strong dependence of the evolutionary flow field on several parameters of interest: Reynolds number (Re), dimensionless oscillating frequency (?) and Speed Ratio (SR), to name a few. A comprehensive study on the variation of flow patterns in both antiparallel and parallel oscillating wall motions has been performed by systematically varying the parameters (Re, ? and SR) over a wide range of values. To make it easier for the reader, these flow patterns have been appropriately classified into several flow modes, which are later explained using streamline patterns, centerline velocity profiles and three-dimensional flow maps. Simulations show that Re and ? control the penetration depth of the fluid inside the cavity, while SR controls the size and strength of additional primary or corner vortices generated from the bottom lid motion. The significance of the current work may be found in industrial applications, where Re, ? and SR may have to appropriately tuned to yield a specific flow mode. © 2021 Elsevier Ltd
Computational fluid dynamic analysis of the effect of inlet valve closing timing on common rail diesel engines fueled with butanol–diesel blends
(Frontiers Media SA, 2024) Lamani, V.T.; Shivaprasad, K.V.; Roy, D.; Yadav, A.K.; Kumar, G.N.
The inlet valve closing (IVC) timing plays a crucial role in engine combustion, which impacts engine performance and emissions. This study attempts to measure the potential to use n-butanol (Bu) and its blends with the neat diesel in a common rail direct injection (CRDI) engine. The computational fluid dynamics (CFD) simulation is carried out to estimate the performance, combustion, and exhaust emission characteristics of n-butanol–diesel blends (0%–30% by volume) for variable valve timings. An experimental study is carried out using standard valve timing and blends to validate the CFD model (ESE AVL FIRE). After validation, the CFD model is employed to study the effect of variable valve timings for different n-butanol–diesel blends. Extended coherent flame model-3 zone (ECFM-3Z) is implemented to conduct combustion analysis, and the kappa–zeta–f (k–ζ–f) model is employed for turbulence modeling. The inlet valve closing (IVC) time is varied (advanced and retarded) from standard conditions, and optimized valve timing is obtained. Advancing IVC time leads to lower cylinder pressure during compression due to reduced trapped air mass. The brake thermal efficiency (BTE) is increased by 4.5%, 6%, and 8% for Bu10, Bu20, and Bu30, respectively, compared to Bu0. Based on BTE, optimum injection timings are obtained at 12° before the top dead center (BTDC) for Bu0 and 15° BTDC for Bu10, Bu20, and Bu30. Nitrogen oxide (NOx) emissions increase due to complete combustion. Due to IVC timing, further carbon monoxide and soot formation decreased with blends and had an insignificant effect. © © 2024 Lamani, Shivaprasad, Roy, Yadav and Kumar.
Critical review of ribbed solar air heater and performance evaluation of various V-rib configuration
(Elsevier Ltd, 2021) Nidhul, K.; Yadav, A.K.; Anish, S.; Kumar, S.
The low heat transfer rate in a flat plate solar air heater (SAH) is due to the development of a laminar sub-layer near the heated absorber plate. Owing to this, the plate temperature rises substantially, instigating losses and thus reducing the efficiency. Extensive research has been carried out to mitigate this problem, of which passive technique emerged to be a promising solution. The passive method involves the application of fins/turbulators/ribs on the surface where the boundary layer develops so that it breaks the same. Various profiles and configurations of the ribs ranging from transverse to inclined and continuous to discrete have been presented concisely. Correlations on Nusselt number (Nu) and friction factor (f) for different rib configurations have been summarized in order so that it can be accessed for future research. 3-D CFD analysis is carried out to gain insight into the flow pattern of various V-ribbed SAH, and with the help of streamlines and contours, the findings are established. Furthermore, various exergy destruction has been studied in detail for different V-rib configurations, namely– V-rib, multiple V-rib, and multiple V-rib with the gap, and analyzed in detail for prospective studies. Exergetic performance study of these rib configurations indicates that the multiple ribs and the multiple rib-gap combinations enhance exergetic efficiency (ηex) by 12% and 31.6%, respectively, in comparison to V-rib SAH. © 2021 Elsevier Ltd
Detailed thermo-hydraulic investigation of 3D octet lattice structure integrated heat sink
(Elsevier Ltd, 2025) Narkhede, A.; Gnanasekaran, N.; Yadav, A.K.
The present research work examined the thermo-fluidic characteristics of a heat sink packed with octet-structured periodic metal foam having varying porosity (0.83–0.93) and unit cell lengths (UCL) of 2.5–5 mm for electronic cooling application. AlSi10Mg material is considered for the octet lattice structure with water as the cooling medium, with the inlet velocity ranging from 0.02 to 0.05 m/s and a steady heat flux of 10 W/cm2 applied at base of the substrate. The effect of the porosity, unit cell length, and inlet velocity on pressure gradient, friction factor, Nusselt number, wall temperature, heat transfer coefficient, and thermo-hydraulic performance parameter is analyzed. Larger pressure gradients are observed for lower values of porosity and unit cell length, with a maximum value of approximately 5000 Pa/m for the thermal system having 0.83 porosity, 2.5 mm UCL, and 0.05 m/s inlet velocity. The wall temperature drops with a rise in inlet velocity and a reduction in porosity and UCL, with the lowest value of 311 K for the case of 0.83 porosity, 2.5 mm UCL, and 0.05 m/s inlet velocity. The case of 0.83 porosity, 5 mm UCL, and 0.02 m/s velocity was determined as optimum design based on thermo-hydraulic performance parameter. © 2024
DFT Calculations for Temperature Stable Quantum Capacitance of VS2 Based Electrodes for Supercapacitors
(Institute of Electrical and Electronics Engineers Inc., 2024) Yadav, A.K.; Shreevathsa, N.S.; Singh, R.; Das, P.P.; Garg, V.; Pandey, S.K.
Using density functional theory calculations, we demonstrate the quantum capacitance of the VS2 electrode which can be improved by doping with non-metallic elements such as nitrogen (N), phosphorus (P), and arsenic (As) atoms. The radius, charge, and morphology of these non-metallic elements help to improve the performance of VS2 material as electrodes of supercapacitors. The As-doped VS2 monolayer demonstrated the maximum quantum capacitance of 31.2369 μF/cm2 at 300 K. At 1200 K, quantum capacitance reaches the value of 25.2149 μF/cm2, showing the inconsiderable change in value for this wide range of temperature variation. Additionally, the other important properties of undoped and doped VS2 monolayers such as density of states, energy band structure, electrical conductivity, thermal conductivity, and the Seebeck coefficient were also computed and examined in detail. The band structure of the P and As-doped VS2 monolayers showed a metallic nature, which is suitable for electrode application. In the case of As-doped VS2 material, a high figure of merit of 3.536 was observed by using DFT-D2 calculations, due to the large Seebeck coefficient and significant electrical conductivity. Our findings will be helpful in further exploring the suitability of VS2 monolayers as electrodes of supercapacitors. © 2002-2012 IEEE.
DFT Study about the Effect of Doping on the Properties of GaSb Material and Designing of High-Efficiency Infrared Photodetector
(John Wiley and Sons Inc, 2023) Bhandari, B.; Yadav, A.K.; Singh, R.; Kiran, G.; Singh, A.K.; Garg, V.; Pandey, S.K.
The gallium antimonide (GaSb) material has very attractive electronic and optoelectronic properties which are suitable for next-generation infrared (IR) photodetector applications. In this work, properties of undoped GaSb material such as density of states, bandstructure, electron density, absorption coefficient, dielectric function, refractive index, and extinction coefficient are calculated using density-functional theory (DFT). Moreover, the effects of doping with Ge, Sn, and Zn elements on these properties of GaSb material are investigated. It is found that undoped GaSb material exhibits a direct gap of ≈0.72 eV. Among different doping elements, Ge-doped GaSb produces a very significant enhancement in optical properties. The Ge-doped GaSb demonstrates a four times higher absorption coefficient in comparison to undoped GaSb in the IR region at 0.8 eV photon energy. GaSb-based photodetector device is designed using the Solar Cell Capacitance Simulator (SCAPS) 1D tool. The efficiency of the designed photodetector with optimum thicknesses and doping of different layers is found to be improved from 21.34% to 25.91% after incorporating the absorption data set obtained from the DFT calculations. Additionally, the photodetector with optimum parameters demonstrates maximum responsivity of value ≈0.31 A W−1. In the previous findings, it is demonstrated that GaSb is a very suitable material for next-generation IR photodetector applications. © 2023 Wiley-VCH GmbH.
Effect of bioethanol–diesel blends, exhaust gas recirculation rate and injection timing on performance, emission and combustion characteristics of a common rail diesel engine
(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2019) Lamani, V.T.; Baliga M, A.U.; Yadav, A.K.; Kumar, G.N.
This investigation is focused on the effect of exhaust gas recirculation (EGR) and injection timing on the performance, combustion and exhaust emission characteristics of common rail direct injection (CRDI) engine fueled with bioethanol-blended diesel using computational fluid dynamics (CFD) simulation. Simulation is carried out for various EGR rates (0, 10, 20 and 30%), two different injection timings, and two different bioethanol–diesel blends (10 and 20%) at injection pressure. The equivalence ratio is kept constant in all the cases of bioethanol–diesel blends. The results indicate that the mean CO formation and ignition delay increase, whereas mean NO formation and in-cylinder temperature decrease, with increase in the EGR rate. Further, with an increase in percentage of the bioethanol blends, CO and soot formation decrease as compared to neat diesel. A significant increase in in-cylinder pressure (15%) is found at 14° before top dead centre (BTDC) compared to 9° BTDC, which leads to an increase in indicated thermal efficiency of 4% for neat diesel at 30% EGR. In the present study, maximum indicated thermal efficiency is obtained in the case of 10 and 20% bioethanol–diesel blend, and remains constant for all EGR rates considered in the study. Obtained results are validated with the available literature data and indicate good agreement. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group.
Effect of CO2 based natural circulation loop for low temperature applications: CFD analysis
(Toronto Metropolitan University, 2019) Wahidi, T.; Nagrani, P.P.; Yadav, A.K.
Natural circulation loop (NCL) is a simple and economical heat transfer device in which flow occurs due to the buoyancy effect caused by thermally generated density gradient. In the present study, computational fluid dynamics (CFD) analyses are carried out to emphasize on the fluid ow and heat transfer characteristics of carbon dioxide (CO2 ) based NCL at low temperature (-38Â°C to 12Â°C). Studies are conducted in a three-dimensional (3-D) CFD model of NCL at different heat inputs i.e., 100W, 250W, 350W and 500W by keeping the loop fluid at pressure of 50 bar. Methanol is used as coolant in the heat exchanger at a fixed mass flow rate. Effect of loop operating pressure 50 bar on system performance is also investigated. Result are presented in the form of heat transfer rate, pressure drop, Reynolds number (Re) and temperature. Obtained results are validated with available correlations in the form of non-dimensional numbers, and found in good agreement. Â© 2019, Toronto Metropolitan University. All rights reserved.
Effect of DEE added Karanja biodiesel fuel on the performance, combustion and emission characteristics of CI engine under variable injection timing and engine load
(Taylor and Francis Ltd., 2023) Wogasso Wodajo, A.; Yadav, A.K.; Gottekere Narayanappa, K.
The higher density and viscosity of biodiesel reduce the engine's performance due to poor atomisation. The present study aims to investigate the effect of DEE and injection time on engine characteristics fueled with KME-diesel blends. For this purpose, single cylinder CI engine is used. The injection timing is advanced and retarded by 2° from the base injection timing (27° bTDC), and the load is varied from 0% to 100%. The addition of DEE to the blends results in a reduction of density and viscosity. At 29° bTDC, the brake thermal efficiency for 5% DEE is increased by 3.1% compared to a blend without DEE at full load. For 5% DEE, compared to 27° bTDC, 29° bTDC reduces the HC and CO emission by 4.5% and 42.8%, respectively at full load. It is concluded that the 5% DEE operating at 29° bTDC improves the engine's performance with a small rise in NOX emission. Highlights: DEE added biodiesel blend has lower viscosity and density than biodiesel. 5% DEE addition in biodiesel blend at advanced injection timing improves BTE and reduces emission. Lower in-cylinder temperature is achieved due to higher latent heat of evaporation. The CO and HC emissions for B25DE5 at 29° bTDC are reduced by 4.5% and 42.8% than 27° bTDC at full load. At advanced injection timing NOX emission for 5% DEE addition increased by 2.7% than 27° bTDC. © 2022 Informa UK Limited, trading as Taylor & Francis Group.
Effect of fuel preheating on performance, emission and combustion characteristics of a diesel engine fuelled with Vateria indica methyl ester blends at various loads
(Academic Press, 2022) Kodate, S.V.; Raju, P.S.; Yadav, A.K.; Kumar, G.N.
The present study examines the preheated (95 °C) and unheated (35 °C) Vateria indica methyl ester (VIME) blends by studying the engine performance, combustion, and emission characteristics at various loads. A single-cylinder, TV1 Kirloskar direct injection diesel engine is used to carry out the tests. Biodiesel produced from Dhupa fat through the transesterification process is used as a renewable fuel in a diesel engine. In this work, diesel (B0), VIME (B100), and two binary blends (B30 and B50) are used. VIME has a higher viscosity, higher density, and lower calorific value than diesel, resulting in lesser brake thermal efficiency (BTE) and higher brake specific energy consumption (BSEC). Due to high viscosity of the biodiesel, preheating of fuel is done before injecting into cylinder. Preheating reduces the viscosity, and enhances the atomization and vaporization of fuel, resulting in improved engine performance. For a given blend of VIME biodiesel and diesel, the preheated blend has better BTE, decreased BSEC and lesser CO and HC emissions, with a slight increment in NOX emission compared to the unheated blend. The preheated B30 blend has a BTE value of 30.3% which is close to the BTE value of 30.1% of unheated diesel at 100% load condition. CO, HC, and soot emissions are decreased by 16.2%, 34.4%, and 16.5%, respectively, for preheated B100 fuel compared to unheated B100, at full load. © 2021 Elsevier Ltd
Effect of loop tilting on the heat transfer and pressure drop in two-phase CO2 based natural circulation loop: An experimental study
(American Society of Mechanical Engineers (ASME), 2021) Thippeswamy, L.R.; Yadav, A.K.
The natural circulation loop (NCL) is widely used where the safe and economic heat transfer device is desired. However, the instability associated with the regular change in fluid flow behavior due to the imbalance between friction and buoyant forces is a major disadvantage. One of the erudite solutions to overcome this is to tilt the entire loop by a certain angle, with an inherent penalty in heat transfer and pressure drop. In the present study, experimental studies have been carried out on two-phase carbon dioxide (CO2) based NCL, which has gained popularity because of its compactness and higher heat transfer rate. Pressure drop and heat transfer performance of the loop for various tilt angles (0 deg, 30 deg, and 45 deg) in different planes (XY and YZ planes) have been investigated. Methanol is used as the external fluid in cold and hot heat exchangers in order to maintain low operating temperature in the loop. Results show that the tilting of the loop causes a marginal drop in the heat transfer rate of two-phase CO2 based NCL. Hence, tilting of the loop could be a solution to instability problem without conceding the performance of the loop. © © 2020 by ASME