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Sūrat, India

Rathod M.K.,SVNIT Surat | Banerjee J.,SVNIT Surat
Experimental Heat Transfer | Year: 2014

Thermal performance of a latent heat storage unit is evaluated experimentally. The latent heat thermal energy storage system analyzed in this work is a shell-and-tube type of heat exchanger using paraffin wax (melting point between 58°C and 60°C) as the phase change material. The temperature distribution in the phase change material is measured with time. The influence of mass flow rate and inlet temperature of the heat transfer fluid on heat fraction is examined for both the melting and solidification processes. The mass flow rate of heat transfer fluid (water) is varied in the range of 0.0167 kg/s to 0.0833 kg/s (1 kg/min to 5 kg/min), and the fluid inlet temperature is varied between 75°C and 85°C. The experimental results indicate that the total melting time of the phase change material increases as the mass flow rate and inlet temperature of heat transfer fluid decrease. The fluid inlet temperature influences the heat fraction considerably as compared to the mass flow rate of heat transfer fluid during the melting process of the phase change material. © Taylor and Francis Group, LLC.

Reddy P.G.,SVNIT Surat | Kundu P.,SVNIT Surat
2014 Annual International Conference on Emerging Research Areas: Magnetics, Machines and Drives, AICERA/iCMMD 2014 - Proceedings | Year: 2014

Partial Discharge (PD) measurement is a precise diagnosis to give the knowledge about the condition of the insulation. There are several methods to detect and measure the PD such as Electrical, Acoustic, Optical, Chemical and Ultra High Frequency (UHF) detection methods. Among all these methods, UHF sensor plays crucial role to detect the PD, efficiently with high sensitivity. PD pulses tend to appear only in the time of nano-seconds, which pulses can be detected without any power outage by using high bandwidth antenna i.e. UHF sensor. UHF sensor is conical in shape with base diameter 2.5cm and axial length 10cm. This sensor can detect the electromagnetic interference signals without any background noise in the range of 300 MHz to 1.5 GHz. In this paper, the experimental work was presented to study the characteristics of PD by using the designed UHF conical monopole antenna with the help of high bandwidth digital oscilloscope connected through co-axial cables in two distinct lengths. FFT analysis was applied to deduce the frequency response of the PD signal and sensitivity of the antenna. © 2014 IEEE.

Saladi S.,SVNIT Surat | Menghani J.,SVNIT Surat | Prakash S.,Indian Institute of Technology Roorkee
Journal of Materials Engineering and Performance | Year: 2014

Cyclic oxidation behavior of detonation-gun-sprayed Ni-5Al coating on Inconel-718 is discussed in the present study. Oxidation studies were carried out on both bare and coated superalloy substrates in air at 900 °C for 100 cycles. The thermogravimetric technique was used to establish kinetics of oxidation. X-ray diffraction, FESEM/EDAX, and x-ray mapping techniques were used to analyze the oxidation products of bare and coated samples. The weight gain of bare superalloy was higher than the Ni-5Al-coated superalloy. Both bare and Ni-5Al-coated superalloys followed nearly parabolic oxidation behavior. The Ni-5Al coating was able to reduce the overall weight gain by 26.2% in comparison with bare superalloy in the given environment. The better oxidation resistance of Ni-5Al coating may be due the formation of protective oxides phases such as NiO, Al2O3, and NiAl2O4 on the oxidized coating and Cr2O3 at the coating-substrate interface. The Ni-5Al coatings obtained from detonation-gun-spraying process showed very little porosity and low surface roughness values. © 2014, ASM International.

Jagtap K.R.,SVNIT Surat | Lal A.,SVNIT Surat | Singh B.N.,Indian Institute of Technology Kharagpur
International Journal of Mechanics and Materials in Design | Year: 2012

This study deals with the stochastic nonlinear bending response of functionally graded materials (FGMs) plate with uncertain system properties subjected to transverse uniformly distributed load in thermal environments. The system properties such as material properties of each constituent's material, volume fraction index and transverse load are taken as independent random input variables. The material properties are assumed to be temperature independent (TID) and temperature dependent (TD). The basic formulation is based on higher order shear deformation theory with von-Karman nonlinear strain kinematics using modified C 0 continuity. A direct iterative based nonlinear finite element method in conjunction with first-order perturbation technique developed by last two authors for the composite plate is extended for the FGM plate to compute the second order statistics (mean and standard deviation) of the nonlinear bending response of the FGM plates. Effects of TD, TID material properties, aspect ratios, volume fraction index and boundary conditions, uniform temperature and non-uniform temperature distribution on the nonlinear bending are presented in detail through parametric studies. The present outlined approach has been validated with the results available in the literature and independent Monte Carlo simulation. © 2011 Springer Science+Business Media, LLC.

Sharma P.J.,SVNIT Surat | Patel P.L.,SVNIT Surat | Jothiprakash V.,Indian Institute of Technology Bombay
ISH Journal of Hydraulic Engineering | Year: 2016

The monthly time step stochastic dynamic programming (SDP) model has been applied to derive the optimal operating policies of Ukai reservoir, a multipurpose reservoir in Tapi river basin, India. The initial reservoir storages and inflows into the reservoir in a particular month are considered as hydrological state variables. Since flood control and irrigation are the two major purposes of this reservoir, the SDP model is developed with the objective of minimizing annual sum of squared deviations of actual releases and actual storages from their respective target values. The uncertainty in the prediction of inflows into the reservoir system is addressed by incorporating the inflow transition probabilities. In this study, the effect of state variable discretization in deriving optimal operating policies using SDP for the reservoir is investigated. From the model results, it is inferred that, by adopting unequal interval storage discretization approach over equal interval storage discretization approach, there is an improvement of about 8–58% in the values of the objective function. The optimal operating policies derived using unequal interval storage discretization have been expressed in terms of final storages (levels) for each month for various combinations of inflows and initial storages. © 2016 Indian Society for Hydraulics

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