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

This paper experimentally investigates the performance of an absorber tube with heat transfer enhancer in solar flat plate water heater. The objective of the work is to increase the convective heat transfer by reducing the cross sectional area between the absorbing fluid and inner wall of the tube. The heat transfer enhancers are frictionally engaged with the inner side of the tube wall, and it is kept in the axial flow direction of the fluid flow path. Two types of heat transfer enhancers, namely, rod heat transfer enhancer and tube heat transfer enhancer, are used herein and compared with each other. The efficiency, heat transfer coefficient and pumping power for flat plate solar collector were analyzed, and it was found that, the rod heat transfer enhancer provides higher heat transfer with a small increase in pumping power than tube heat transfer enhancer and plain tube flat plate solar collector. The maximum increase in pumping power is 1.081 and 1.044 times higher for rod and tube heat transfer enhancers respectively, compared to plain tube solar collector. © 2016

School of Mechanical Engineering

Vellore Campus

World University root node

Applied Thermal Engineering

Experimental investigation on heat transfer and pumping power of forced circulation flat plate solar collector using heat transfer enhancer in absorber tube

Solar water heaters are widely used for heating water for both domestic as well as industrial purpose. In this paper, thermal efficiency performance of V-Through SWH installed at Jaipur, India for varying tilt angle and presence of dust particles on glass cover are examined. It has been found that increasing the tilt angle from 15°to 25°, average thermal efficiency of SWH increased from 27% to 30% and dust deposition reduced the thermal efficiency of SWH from 30% to 20% for fully clear glass to fully dusty glass for a constant tilt angle of 25°. © 2017 The Authors.

Fulltext

Energy Procedia

Experimental Study of V-Through Solar Water Heater for Tilt Angle and Glass Transmissivity

The loss generated due to direct current gas flow in pulse tube refrigerator (PTR) is one of the major problems which significantly affect the cooling performance. It generates temperature fluctuation at the cold end of the PTR. A new type PTR has been proposed in the present work to diminish the DC flow problem by attaching an additional connection at the hot end from a secondary compressor and investigated numerically using CFD simulation software FLUENT. It is reported a significant enhancement of cooling performance by means of the proposed model. The numerical outcomes of the proposed model are equated with the outcomes of the orifice type pulse tube refrigerator (OPTR) model. The model used for analysis is an axisymmetric model. At 34 Hz operating frequency and 1.2 pressure ratio the numerical simulation is conducted. The proposed model achieves a temperature of 98 K at cold end where as a simple OPTR having same dimension riches a temperature of 130 K. To get an optimum result experimentally for the pulse tube refrigerator, is a very difficult and also high expensive hence the numerical approach is an alternate solution. © 2017 The Authors.

Numerical Analysis of a Modified Type Pulse Tube Refrigerator

Buildings consume plenty of power for providing thermal and visual comfort inside the buildings. This paper aims at presenting the experimental results of spectral optical properties of the most widely used window glazing materials. The window glazing materials studied include clear glazing, bronze glazing, green glazing and grey coloured glazing materials. A Matlab code employing the British standard method was developed to compute transmittance and reflectance of window glasses at normal incidence angle. This code uses experimentally obtained spectral optical property data from Perkin Elmer lambda 950 spectrophotometer for the computation of transmission and reflection of window glasses. A computer program was developed for computing the total solar radiation passing through glass materials. The heat gain through different glass windows of eight coordinal orientations such as east, west, north, south, northeast, northwest, southeast and southwest in four climatic zones of India was investigated. The solar radiation through south oriented glass was found to be the least among all other orientations studied in four Indian climatic zones. The cooling load through south oriented bronze, glass, green glass and grey glass window were reduced by 23%, 31% and 37%, respectively, as compared to the south oriented clear glass window in four climatic zones of India. The grey glass window is observed to be the most energy efficient as it reduces maximum cooling loads within the building as compared to the other considered glazing materials. The results of this paper are helpful in designing energy efficient commercial buildings for reduced cooling loads. © 2017 The Authors.

Experimental and Theoretical Studies of Window Glazing Materials of Green Energy Building in Indian Climatic Zones

A detailed experimental study has been done to understand the shock wave-turbulent boundary layer interaction (SWTBLI) over a forward-facing step (FFS) of height (h) in a Mach 2.5 flow using particle-image velocimetry (PIV). In addition to PIV, high-speed schlieren and surface oil flow visualization have been studied. Flow separation using surface oil flow visualization was observed around 4.1 step heights upstream of the step face. High-speed schlieren measurements show that the shock oscillates with a peak frequency of approximately 1000 Hz, which is two orders smaller than the characteristic frequency of the incoming boundary layer. Instantaneous PIV velocity vector fields show that the shock location is related to the separation bubble formed ahead of the forward-facing step. © Springer India 2017.

Lecture Notes in Mechanical Engineering

Study of shock wave/turbulent boundary layer interaction over a forward-facing step

The influence of the Samarium ions (Sm3+) on the electrochemical properties TiO2 nanoparticles has been analyzed by incorporating Sm ions in two different combinations using the sol-gel method. The bare and doped samples have been characterized using XRD, SEM, TEM and EDX, for its structural, morphological and compositional analysis of the sample. The Galvanostatic cycling, Cyclic voltammetry and Impedance analyzer has been employed to point out the electrochemical properties of the assembled batteries. The electrochemical properties of the sol-gel derived bare TiO2 are comparable with the literature. The Sm0.1Ti0.9O2 exhibits better capacity and lower capacity fading over multiple cycles. The higher Sm concentration exhibits more capacity fading after the initial cycles. The study reveals that the lower concentration doping of Sm stabilizes the TiO2 nanoparticles which makes it as a better candidate for its application potential towards lithium ion batteries. © 2017 Elsevier B.V.

Department of Information Security

School of Computer Science and Engineering

Department of Chemistry

School of Advanced Sciences

Journal of Alloys and Compounds

Investigations on the influence of Sm3+ion on the nano TiO2 matrix as the anode material for lithium ion batteries

This paper deals with the effect of different biomass fuels used in a fixed bed advanced micro-gasifier cook stove’s combustion process. Combustion of different biomass fuels like coconut shells, Prosopis Juliflora and wood pellets were investigated in an advanced cook stove for an air velocity of 3 m/s. The actual testing procedure followed to evaluate full performance characteristics of the stove was as per the world standard protocol WBT 4.2.3, and the results were analyzed in terms of thermal efficiency. The measured variables like bed temperatures, mass loss and exit gas composition were used to estimate the combustion characteristics of each fuel in terms of flame propagation, fuel burning rate and the combustion quality. The two mode operations of combustion processes namely flaming and char mode of the fuels were also studied. The experimental outcomes provide a clear idea on the impact of the different fuel properties on flame propagation, burning rate and indoor air quality. Thus, the flame propagation rates are 0.063, 0.071 and 0.05 mm/s with an average fuel burning rate of 16, 12 and 10 g/min are achieved. Also the thermal efficiency of fixed bed micro-gasifier is found to be about 36.7±1 % for coconut shell, 36±1 % for Prosopis Juliflora and for wood pellets it is about 38.5±1 %. © 2017, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

Journal of Mechanical Science and Technology

Combustion characteristics of biomass fuels in a fixed bed micro-gasifier cook stove

Effects of Single, Double, Triple and Quadruple Window Glazing of Various Glass Materials on Heat Gain in Green Energy Buildings

Droplet evaporation under confinement is ubiquitous to multitude of applications such as microfluidics, surface patterning, and ink-jet printing. However, the rich physics governing the universality in the underlying dynamics remains grossly elusive. Here, we bring out hitherto unexplored universal features of the evaporation dynamics of a sessile droplet entrapped in a 3D confined fluidic environment. We show, through extensive set of experiments and theoretical formulations, that the evaporation timescale for such a droplet can be represented by a unique function of the initial conditions. Moreover, using same theoretical considerations, we are able to trace and universally merge the volume evolution history of the droplets along with evaporation lifetimes, irrespective of the extent of confinement. We also showcase the internal flow transitions caused by spatio-temporal variation of evaporation flux due to confinement. These findings may be of profound importance in designing functionalized droplet evaporation devices for emerging engineering and biomedical applications. © 2017 Author(s).

Applied Physics Letters

Universal evaporation dynamics of a confined sessile droplet

This paper illustrates about the design and implementation of 2.2 kW battery charger for electric locomotive using Texas controller with temperature sensing unit. The full bridge DC-DC converter approach of the battery charger caters mainly to high robustness, small size and low weight, low complexity, high efficiency and high conversion ratio. This topology is best suitable for handling high power, provides reduced Electromagnetic Interference (EMI) and known for reduced component stress. In this battery charger application, IGBTs are switched at 40 KHz for high efficiency and reduction in losses using Texas controller. The isolated buck topology is favoured for converter optimization and also helps in voltage regulation. The efficient variation of duty cycle in this proposed technique is used to regulate the output voltage at light loads. Also the presented DC-DC converter shows great conversion efficiency for large range of varying load conditions. The performance of the above DC-DC converter is evaluated via PSIM and hardware results are also been carried out.