Browsing by Author "Sahoo S.K."

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Application of TCE-PCM based heat sinks for cooling of electronic components: A review
(2016) Sahoo S.K.; Das M.K.; Rath P.
Generally, the commercial and industrial electronic devices are required to be operated under 100 �C.Therefore, there is a need to remove heat effectively from these devices under different loading conditions. Till now, Phase Change Material (PCM) based heat sinks are emerging as one of the effective techniques for removal of heat from the electronic devices. However, the low thermal conductivity of PCM situates a hindrance to the development. Thus, current research focuses on improving the thermal performance of PCM using thermal conductivity enhancer (TCE). At present internal fins, metallic foams and nano particles are mixed with PCM to enhance the performance of heat sinks. These are called as thermal conductivity enhancers. This article reviews methodologically various papers on the methods used for enhancement of PCM performance in cooling of electronic components. The effect of various parameters influencing the performance of the TCE-PCM based heat sinks are discussed in systematic order. The performance of these heat sinks under constant and variable thermal load are also evaluated. Out of these three TCE, metallic foams in heat sinks provides a higher surface area to volume ratio, good thermal conductivity and considerable weight advantage. � 2016 Elsevier Ltd. All rights reserved.
Conventional and AI models for operational guidance and control of sponge iron rotary kilns at TATA sponge
(2019) Shah C.; Choudhary P.; Deo B.; Malakar P.; Sahoo S.K.; Pothal G.; Chattopadhyay P.
Prediction models for temperature, pressure, and quality control in rotary sponge iron kilns are developed from operational data. The conventional and AI-based methods which are used to develop the models include extreme learning machine (ELM), artificial neural net (ANN), and multiple linear regression (MLR). The performance of the developed models is tested on shop floor in actual operation and compared. Extensive plant data is used to develop and validate the models on day-to-day basis of operation so as to take care of the dynamically changing situation inside the kiln, giving first preference to quality control and then to accretion control. Accretion control increases the life of lining and thus also the available time for production. Automatic pressure control greatly helps in chaos control inside the kiln. Dynamically changing Lyapunov exponent acts a guide line for automatic pressure control. � Springer Nature Singapore Pte Ltd. 2019.
Development of highly selective potentiometric thorium(iv) ion-selective electrode: Exploration supported with optical and DFT analysis
(2019) Selva Kumar R.; Ashok Kumar S.K.; Vijayakrishna K.; Sivaramakrishna A.; Brahmmananda Rao C.V.S.; Sivaraman N.; Sahoo S.K.
A new liquid membrane based on poly(vinyl chloride) composed of dibutyl(8-hydroxyquinolin-2-yl)methylphosphonate (L) as a neutral ion carrier, sodium tetraphenylborate (NaTPB) as a lipophilic salt dissolved in dioctyl phthalate (DOP) as a plasticizer-cum-membrane solvent was developed for the selective determination of Th4+. The best electrode response for Th4+ is achieved with the membrane composition of PVC:DOP:L:NaTPhB (33%:59%:4%:4%, w/w). The electrode response follows a super-Nernstian response with a slope 31.2 � 0.4 mV per decade at 25 �C over a wide concentration range of Th4+ from 1 � 10-7 to 1 � 10-1 M. The electrode has a response time of 5 s and detection limit of 1 � 10-8 M, working in the pH range of 4 to 6.5, with a service lifetime of about three months. The selectivity coefficient was determined by the match potential method (MPM) and the results show good selectivity towards Th4+ over a wide variety of selected metal ions (from s, d and f-block metals). The binding mechanism was investigated by FTIR, NMR (1H, 31P) and mass analysis complemented by density functional theoretical results. � 2019 The Royal Society of Chemistry.
Hybrid Cooling System for Electronics Equipment during Power Surge Operation
(2018) Sahoo S.K.; Das M.K.; Rath P.
The performance of a hybrid phase-change material (PCM)-based cooling system is investigated experimentally to meet the requirement of power surge effect in electronics equipment. The normal cooling operation of the electronic equipment for a long period using heat sink is also studied. The thermal performance of the hybrid heat sink is studied with three different PCMs: Eicosane, 1-Hexadecanol, and Paraffin. The hybrid PCM-based heat sink is studied for different orientations of PCM and convective cooling area in the heat sink to protect electronic components from the potentially dangerous and disruptive power surge operations. The performance of the hybrid PCM-based heat sinks is compared with conventional air-based heat sinks with and without a fan. In case of hybrid PCM-based heat sink, the fan is operated at 6 V all the time irrespective of the normal or power surge operation. Whereas, in case of air-based heat sink (without PCM), the fan is operated at 12 V during power surging and at 6 V during normal operation time. It is observed that the hybrid PCM-based heat sink with fan performs better than conventional air-based heat sink with fan during surging operation by reducing the peak temperature of 5.6 �C. However, their performance is comparable during post-surging operation. Thus, the power consumption, as well as the noise, gets reduced using hybrid PCM-based heat sink with fan during surging operation. Besides, the life of fan used in hybrid PCM-based heat sink increases, which in turn increases the service life of electronic components. � 2011-2012 IEEE.
A mixture theory based enthalpy porosity model for performance study of nano enhanced PCM heat sink
(2018) Sahoo S.K.; Rath P.; Das M.K.
Now-a-days, the use of electronic gadgets is becoming the inherent part of the modern lifestyle. For that, every manufacturer is in the search of making portable gadgets. For an electronic gadget to be portable, it should be compact and should have motionless parts. In most of the electronic gadgets, the well-established cooling method is the active cooling which has moving parts. The basic necessity for a compact gadget is that it should be embedded with motionless passive cooling technique. One of the most promising passive cooling techniques involves the use of PCM. The selection of phase change material (PCM) is justified by its inherent high latent heat of fusion per unit volume. To increase the thermal transport capability of PCM, researchers have started using thermal conductivity enhancers like nanoparticles, fins, foam etc. The current study focuses on use of eicosane as PCM mixed with copper nanoparticles. The resulting solution is termed as nanocolloid. A macroscopic one-fluid-mixture approach with the single-domain enthalpy-porosity method is used to model this nanocolloid system. In this study, the effect of the size (5 nm and 20 nm) of the nanoparticles on evolving nanoparticle distribution during melting and solidification is reported. Thermal-solutal convection as well as the Brownian and Thermophoretic effects is taken into account. The study entirely focuses on how the nanoparticles enhance the heat transfer and are distributed during melting and solidification. How the characteristics of nanoparticle distribution affect the thermal transport capability is highlighted. The effect of nanoparticle distribution on PCM melt fraction and heat sink base temperature variation is investigated. Finally, the thermal performance of nano enhanced PCM is compared with pure PCM. � 2018 International Heat Transfer Conference. All rights reserved.
Numerical study of cyclic melting and solidification of nano enhanced phase change material based heat sink in thermal management of electronic components
(2016) Sahoo S.K.; Das M.K.; Rath P.
The Present investigation has been carried out to study the performance of nano enhanced phase change material (NEPCM) based heat sink for thermal management of electronic components. Enthalpy based finite volume method is used for the analysis of phase change process in NEPCM. To enhance the thermal conductivity of phase change material (PCM), copper oxide nano particles of volume fractions 1%, 2.5% and 5% are added to PCM. A heat flux of 2500 W/m2 is taken as input to the heat sink. The thermal performance of the heat sink with PCM is compared with NEPCM for each volume fraction of nano particle for both finned and unfinned configurations. It is observed that the nano particle volume concentration plays a major role in removing the heat from the chip in case of unfinned heat sink configuration. However, for finned heat sink configuration, the volume concentration effect is not appreciable. In addition, the performance of NEPCM based finned heat sink is studied under cyclic loading in both natural and forced convection boundary conditions. It is observed that under forced convection the solidification time is reduced. � 2016 by ASME.
Numerical study of phase change material based orthotropic heat sink for thermal management of electronics components
(2016) Sahoo S.K.; Rath P.; Das M.K.
The benefits of orthotropic composite fins as the thermal conductivity enhancer in the design of phase change material (PCM) based heat sink are investigated. Composite fins reduce the system's overall weight as well as improve its thermal performance. A numerical model is developed considering conduction and natural convection in the liquid phase and pure conduction in the solid phase of PCM. Conduction in the fin region assumed orthotropic. The orthotropicity is modeled by adding a departure source term in the isotropic heat conduction. The finite volume method is used to discretize the governing mass, momentum and energy transport equations. The enthalpy porosity method is used to model the phase change in PCM. The Semi Implicit Pressure Linked Equation Revised (SIMPLER) algorithm is used to solve the flow field in liquid PCM region. The line-by-line TDMA is used to solve the resulting set of discrete algebraic equations. In order to reduce computational time, a symmetry section is considered in the present study. It is found that orthotropic fins gives better performance in reducing the base temperature compared to isotropic fins. Orthotropic fins of less volume can replace the isotropic fins of more volume. Also, uses of orthotropic fins under higher heat fluxes give better performance in comparison to isotropic fins. In addition, the numerical results show the effect of the Stefan number, the Rayleigh number and the Prandtl number on transient performance of orthotropic heat sink. Therefore, the use of orthotropic fins instead of isotropic one reduces the thermal constraint as well as weight burden on the electronic components. � 2016 Elsevier Ltd
Operation of coal-based sponge iron rotary kiln to reduce accretion formation and optimize quality and power generation
(2019) Mondal S.; Choudhary P.; Borah S.; Deo B.; Sahoo S.K.; Malakar P.; Pothal G.; Chattopadhyay P.
[No abstract available]
Optimal control of accretion growth and quality of sponge iron in a coal-fired rotary kiln at Tata Sponge, India
(2018) Vishal G.; Choudhary P.; Deo B.; Sahoo S.K.; Malakar P.; Pothal G.; Chattopadhyay P.
Conventional and AI techniques are used for prediction of temperature along the length of kiln and also quality of sponge iron produced. Actual measured temperature and other operational data such as feed rate of ore and coal, primary and secondary air blowing rate, kiln pressure is used to tune and update the model continuously. The model equations are suitably constrained to restrict accretion growth. A graphic user interface is used by the operator to control the process. Results of plant trials are described. Minimum response time of a large coal fired rotary kiln (80 m in length) is approximately 3-4 hours. � 2018 by AIST.
Physicochemical properties and supercapacitor behavior of electrochemically synthesized few layered graphene nanosheets
(2016) Sahoo S.K.; Ratha S.; Rout C.S.; Mallik A.
The study emphasizes on the scalable production and comparison of few layered graphene nanosheets (FLGNSs). The FLGNSs have been electrochemically synthesized by anionic intercalation from three different acids of 1�M of H2SO4 (S1), 1-M HClO4 (C1), and 1-M HNO3 (N1). The size distribution and stability of the as-prepared FLGNSs colloidal have been analyzed thoroughly. A yield of around 50�% was found irrespective of experimental condition. A mixed phase of graphene and its oxide form has been confirmed X-ray diffraction patterns. C1- and N1-conditioned FLGNSs had higher oxygenation as compared to S1, as confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The disorderness in the FLGNSs has been analyzed by Raman spectra. The aromaticity, surface hydroxylation, and oxygenation of the as-synthesized FLGNSs due to electrochemical reactions have been confirmed by Fourier transform infrared spectroscopy. The UV-visible spectra of FLGNSs colloidal show the electronic transition of ?-?* as well as n-?*. From morphological studies, the layered and crumpled edges of the exfoliated FLGNSs have been revealed. Again, from the probe conductivity analysis, the measured conductivity of the dispersed sulfate-, perchlorate-, and nitrate-intercalated FLGNSs has been found with a decreasing trend from 1.652, 0.315, to 0.300�mS/cm for S1, C1, and N1 conditions, respectively, due to increasing of oxygen endowment in the graphene sheets. Detailed supercapacitor investigations demonstrated that the S1-conditioned FLGNSs show enhanced supercapacitor performance than C1 and N1. It possesses a maximum energy density of 20�Wh�kg?1 and a maximum power density of 2.5�kW�kg?1. � 2016, Springer-Verlag Berlin Heidelberg.
Prediction of accretion growth from dynamic analysis of heat transfer in coal fired sponge iron rotary kiln at Tata Sponge, Joda, India
(2018) Choudhary P.; Vishal G.; Deo B.; Sahoo S.K.; Malakar P.; Pothal G.; Chattopadhyay P.
Control of accretion growth in a coal fired rotary kiln for production of sponge iron is important to achieve a long campaign life. Temperature is measured at 11 locations with embedded thermocouples along the entire length of rotary kiln. The surface temperature of kiln is also measured in the form of a thermograph. Heat transfer model is tried to account for both convective and radiation heat transfer inside and outside the kiln. Final accretion thickness is predicted within �16.5 cm towards the end of campaign. In the initial stages of campaign the error is much smaller. � 2018 by AIST.
Quality prediction and control in coal-fired rotary kilns at Tata Sponge Iron Ltd.
(2019) Borah S.; Mondal S.; Choudhary P.; Deo B.; Sahoo S.K.; Malakar P.; Pothal G.; Chattopadhyay P.
[No abstract available]
Solidification of phase change material nanocomposite inside a finned heat sink: A macro scale model of nanoparticles distribution
(2019) Sahoo S.K.; Rath P.; Das M.K.
The present work aims at developing a heat transfer model for phase change material nanocomposite (PCMNC)-based finned heat sink to study its heat rejection potential. The proposed model is developed in line with the binary alloy formulation for smaller size nanoparticles. The present study gives a more insight into the nanoparticle distribution while the nanocomposite is undergoing phase change. The nanocomposite is placed in the gap between the fins in a finned heat sink where solidification occurs from the top and lateral sides of fins. The proposed numerical model is based on finite volume method. Fully implicit scheme is used to discretize the transient terms in the governing transport equations. Natural convection in the molten nanocomposite is simulated using the semi-implicit-pressure-linked-equations-revised (SIMPLER) algorithm. Nanoparticle transport is coupled with the energy equation via Brownian and thermophoretic diffusion. Enthalpy porosity approach is used to model the phase change of PCMNC. Scheil rule is used to compute the nanoparticle concentration in the mixture consisting of solid and liquid PCMNC. All the finite volume discrete algebraic equations are solved using the line-by-line tridiagonal-matrix-algorithm with multiple sweeping from all possible directions. The proposed numerical model is validated with the existing analytical and numerical models. A comparison in thermal performance is made between the heat sink with homogeneous nanocomposite and with nonhomogeneous nanocomposite. Finally, the effect of spherical nanoparticles and platelet nanoparticles to the solidification behavior is compared. � 2019 by ASME
Texture weakening in pure magnesium during grain growth
(2019) Panda D.; Sabat R.K.; Suwas S.; Hiwarkar V.D.; Sahoo S.K.
The microstructure and texture evolution during annealing of rolled pure Mg, at temperatures ranging from 150 to 400�C, was characterised in the present study. A grain growth exponent of n = 13 was observed and the activation energy for grain growth kinetics was found to be 95.6 kJ mol ?1 . Further, broadening of the normalised grain size distributions, indicating abnormal grain growth, was also observed at all temperatures of annealing. The sample had a dominant basal texture before annealing. However, after annealing up to a temperature of 300�C, the alleviation of basal texture was observed in the samples. On further annealing at a temperature of 400�C, a strong basal texture was developed in the samples. The mobility of high angle grain boundaries, which is proportional to correlated misorientation distribution, was observed to be responsible for texture strengthening of the material. The grain boundary mobility changes during grain growth led to the growth of either small or large grains. It was further observed that the growth of small grains caused the formation of basal fibre and large grains led to the weakening of basal texture. � 2019, � 2019 Informa UK Limited, trading as Taylor & Francis Group.