Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Department of Thermal and Energy Engineering

A three-dimensional numerical study on two-phase flow boiling is conducted for raccoon and straight microchannels. The effect of flow boiling instability is observed under conjugate conditions with water as coolant. Bubble coalescence in bubble dynamics is carefully studied, and the forces acting are identified. Eotvos and Weber number are calculated to determine the bubble behavior and shape in a raccoon microchannel. Boiling number is also considered to predict the two-phase flow boiling heat transfer. The bubble flow pattern for two-phase boiling in straight and raccoon microchannel are investigated under different parameters such as Waviness (γ∼0 - 0.267) and Mass flux (G ∼ 118 – 590&nbsp;kg/m2s), keeping saturation temperature constant at Tsat&nbsp;=&nbsp;310&nbsp;K corresponding to pressure (p sat&nbsp;=&nbsp;6500 pa). It is observed that the Eotvos and Boiling numbers are comparatively higher for values of waviness 0 – 0.067 than other raccoon microchannels. This happens due to the presence of long elongated bubbles, causing the flow boiling instability. On the other hand, as the waviness increases, the bubble size changes periodically. Effect of forces on bubble coalescence for different waviness and mass flux is also observed.

World University root node

School of Mechanical Engineering

Vellore Campus

International Journal of Heat and Mass Transfer

Effect of bubble coalescence on two-phase flow boiling heat transfer in raccoon microchannel - A numerical study

In the present era, production of municipal solid waste (MSW) has become unrestrained due to rapid growth in population and urbanization. Therefore, people are facing various challenges such as health and environmental safety. But, this huge potential of MSW can be used as a promising source for electricity production to reduce the greenhouse gas (GHG) emissions. Incineration is well-known technique which has been extensively used to produce economically affordable energy from MSW. The purpose of the incineration plant is to get the maximum desirable outputs (heat and power) out of waste and minimize undesirable outputs (emissions and bottom ash). The value of heat or power recovered from waste burning in incineration plant depends on the heating value of the waste. Determining this heating value of each waste sample has been considered as complex and time consuming task due to different moisture, ash, and chemical composition. Under the present study, an attempt has been made to develop a correlation to calculate efficiency of the plant using composition of waste. In order to develop this correlation, concept of deep neural network model from machine learning has been used in this paper. The developed application may be useful for plant design engineer to predict the performance of plant for given range of parameters.

Advances in Clean Energy Technologies

<a href="https://link.springer.com/chapter/10.1007/978-981-16-0235-1_11">Development of Correlation for Efficiency of Incineration Plants Using Deep Neural Network Model</a>

Due to the depletion of natural energy resources, worldwide, solar energy is accepted as an emerging energy source because it is free, endless and can be convertible to other forms, but it is intermittent. Therefore, in the present study, different energy storage techniques, that is, sensible heat, latent heat and thermochemical heat storage techniques, suitable to store solar thermal energy are discussed and compared. Based on the energy storage density, reaction kinetics, operating temperature range and volume of storage material, the metal hydride-based thermal energy storage (MH-TES) system is observed to be the most promising for thermochemical energy storage applications. In continuation, the current work enlightens on the screening of MHs best-suited to the MH-TES, which results in the alloy pairs of MmNi4.15Fe0.85-TiCrMn and LaNi4.85Al0.15-MmNi4.6Fe0.4, working on high-pressure and low-pressure sides, respectively. The thermodynamic performances are observed to be 140.25 and 188.16 kJ of heat generation with a coefficient of performance of 0.47 and 0.50 for MmNi4.15Fe0.85-TiCrMn and LaNi4.85Al0.15-MmNi4.6Fe0.4 pairs, respectively, working at a temperature range of 403 (storage), 298 (ambient), 373 (regeneration) and 423 K (heat output). The study is extended to investigate the influence of operating temperatures on system performance and observed that the heat generation may be reduced by ~5% by increasing heat output temperature by 20 K due to reduction in mass transfer. © 2021 John Wiley & Sons Ltd.

International Journal of Energy Research

Metal hydrides for thermochemical energy storage applications

In the present study, the performance of H2-metal hydrides-based (HSRS) and CO2-adsorbent-based refrigeration systems (CSRS) are investigated and compared. The pair of metal hydrides (MH) used for HSRS is La0.9Ce0.1Ni5-LaNi4.7Al0.3 whereas, for CSRS, it is Activated Carbon – Pore Expanded Mesoporous Silica (PEMS) adsorbents. The above pairs are chosen due to their suitability toward the sorption refrigeration system, which results from the screening of different pairs. The performances of these systems are investigated through the thermodynamic simulation as well as computational fluid dynamics (CFD) approach. The thermodynamic cycles of both the systems are analyzed for the operating temperatures of 0°C (Tr; refrigeration), 25°C (Ta; heat sink), and 100°C (Ts; heat source). Upon thermodynamic simulation, the refrigeration output, coefficient of performance (COP), specific refrigeration power, and second law efficiency are observed as 87.04 kJ, 0.91, 24.17 W/kg, and 41.6% for HSRS whereas, it is 49.32 kJ, 0.72, 20.55 W/kg, and 33.1% for CSRS, respectively, using 0.5 kg of each alloy. The CFD simulation results in the behavior of absorbent/adsorbent beds concerning temperature and gas mass variations. The minimum bed temperature is observed to be −31°C in HSRS, which is lower than that of CSRS (i.e., -9°C). The overall cycle time is predicted to be 3600 seconds for HSRS and 2400 seconds for CSRS. The shorter cycle time in CSRS is due to the high-pressure differential between coupled beds during reactions and higher reaction rates of adsorbent materials than metal hydrides. Though CSRS possessed shorter cycle time, HSRS is found to be more suitable for refrigeration application due to better thermodynamic performance, in the given operating temperature range. Besides, the influence of variations in operating temperatures on the system performance is investigated and obtained the optimum temperature range of Tr = 5°C, Ta = 20°C, and Ts = 95°C. Finally, the thermodynamic performances of HSRS, CSRS, and CO2-based vapor adsorption refrigeration system (CO2 VARS) are compared and observed that HSRS possessed better refrigeration performance among three. © 2020 John Wiley & Sons Ltd

Performance comparison between H2-metal hydrides and CO2-adsorbents-based sorption refrigeration systems

The national biofuel policy of the Indian government support to put a great emphasis on the synthesis of biodiesel from the nonedible feedstock. A potential option in this regard is Neem oil which is found in abundance in India (~1,00,000 tonnes). The major hindrance to the commercialization of biodiesel is its shelf life due to poor oxidation and stability characteristics. The current work investigates the oxidation stability of Neem biodiesel as per EU standard (EN14214) using the Rancimat apparatus. The oxidation stability of 12.3 hours without doping any chemical antioxidant in the synthesized Neem biodiesel makes it highly suitable for commercial acceptance. The impact of pyrogallol (PY) antioxidant was also investigated on the shelf life of Neem biodiesel build on response surface methodology (RSM) in accordance with Box-Behnken Design (BBD). Moreover, the execution and excretion characteristic of the Neem biodiesel blends: B15, B25, B35, and B45 are investigated on direct injection automotive compression ignition engine. Based on this broad experimental investigation B15 blend can be used as a fuel to power the existing automotive compression ignition engine with no compromise in the execution and excretion characteristics of the engine. From the analysis of the data of life-cycle assessment of the Neem biodiesel, it was found that it possesses the global warming potential of 45.72gCO2-eq Functional Unit−1 which is six times lesser than mineral diesel. Moreover, the Neem plantation has a carbon dioxide isolation potential of around 10 t ha−1 year −1. All these factors make the Neem Biodiesel highly suitable for blending with mineral diesel to power the existing compression ignition engines. © 2021 Taylor &amp; Francis Group, LLC.

Energy Sources, Part A: Recovery, Utilization and Environmental Effects

Investigation of the shelf life of the optimized Neem biodiesel and its execution and excretion characteristics on automotive diesel engine

The wake dynamics behind a sinusoidally pitching custom designed symmetrical airfoil is analyzed computationally. The effect of pitching frequency and pitching amplitude is investigated independently at a constant Reynolds number. The wake patterns are found to exhibit a transition from von Karman to reverse von Karman vortex street and from symmetric reverse von Karman vortex street to asymmetric deflected wake as established. For laminar flow under investigation, the contours of time-varying velocity fluctuations are presented. The mean profiles of velocity and the fluctuations at different locations in the wake show that the thrust wakes are generated at the expense of energy of the surrounding fluid. The temporal behavior of the flow field is analyzed using the phase plot. The time series plots of force coefficients show a periodic loading on the airfoil. Proper orthogonal decomposition (POD) analysis of drag, neutral and thrust wakes displayed the evolution of coherent structures in the flow field. The evolution of these structures portray the transitions in the wake of the airfoil. The merging of coherent structures in an asymmetric deflected wake turns out to be an efficient way of identifying the location of deflection. © 2020 Elsevier Masson SAS

European Journal of Mechanics, B/Fluids

Investigations into transient wakes behind a custom airfoil undergoing pitching motion

Internal combustion (IC) engines increase the growth of our society and civilization. This research focuses to investigate the emission, combustion and performance behaviour of single cylinder DI diesel engine fuelled by diesel/watermelon seed oil biodiesel (WMB) blends. The oil from watermelon seed was converted into biodiesel (methyl-ester) through Trans-esterification process. The watermelon seed biodiesel was blended with at different proportions to diesel fuel at 20, 30 and 40%. Among the blends B20 gave better performance, improved CO and HC emission in all aspects except NOx emission. The BSFC of B20 is 0.275 kg/kWh and BTE is 32.5% at full load these are on par with diesel. Therefore, B20 of watermelon seed oil biodiesel as a best alternative fuel in coming years. © 2021 Elsevier Ltd. All rights reserved.

Materials Today: Proceedings

Performance and emission behaviour of diesel and blends of watermelon seed oil biodiesel in direct injection diesel engine

Comparative study on W-shaped roughened solar air heaters by using booster mirror

Fulltext

Journal of Building Engineering

Sustainable reflective triple glazing design strategies: Spectral characteristics, air-conditioning cost savings, daylight factors, and payback periods

Purpose: Vibration is a major issue in turbomachines which causes damage to them and leads to reduction in life and efficiency. This paper reviews various methods to measure the amount of vibration in various turbomachines and also discusses various reasons for the same. This will significantly assist in articulating these vibrations. Procedure: This paper lists various experiments done, causes, factors, comparison of different turbomachines and their results. Turbomachines which are taken into consideration are Francis turbine, radial turbines, axial turbines, compressors, pumps and fans. Result: The outcome elucidates the changes in vibrations as a function of different input parameters. Conclusion: It can be concluded through various experiments on different types of turbomachines that the major causes of vibrations are cavitation and resonance while excess speed and longer operating periods too contribute to them.