Faculty Publications
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Item NiO nanoplates for energy storage application: Role of electrolyte concentration on the energy storage property(Elsevier Ltd, 2020) Sethi, M.; Bhat, D.K.Here in, synthesis of NiO nanoplates by employing a mixed solvent system under solvothermal method followed by calcining the obtained product nickel hydroxide in air is reported. Diffraction, microscopic, and spectroscopic results confirmed the formation of NiO phase. The as synthesized NiO nanoplates are tested as a robust material for energy storage applications. The effect of electrolyte concentration on the capacitive behavior of NiO is studied thoroughly. The outcome from the electrochemical analysis reveals that NiO nanoplates have a high specific capacity value of 108.4 C g-1 (270 F g-1) in 6 M KOH electrolyte and the value decreases to 85.0 C g-1 (212.5 F g-1) and 78.2 C g-1 (195.5 F g-1) for 4 M, and 2 M KOH electrolyte, respectively. The resistance values also decreased with increase in the KOH concentration. The better electrochemical performance depicted by the 6 M KOH electrolyte is mainly ascribed to the availability of plenty of OH- ions in the electrolyte solution, which helped in the proper wettability of the sample so that the OH- ions can participate to higher extent during the electrochemical redox reactions, due to which the observed charge storage capacity is more in higher electrolyte concentration and vice-versa. Thus, the results suggest the usefulness of this material for energy storage applications. © 2019 Elsevier Ltd. All rights reserved.Item Numerical Study of PCM-Based Energy Storage System Using Finite Difference Method(Springer Science and Business Media Deutschland GmbH, 2024) Abhijith, C.; Maniyeri, R.Energy storage systems incorporating phase change material (PCM) are becoming the answer to intermittent energy availability in the area of solar cooking vessels and solar room heating systems. These thermal energy storage systems are efficient, reliable and can reduce running costs and investments. The present work investigates the melting of n-octadecane using enthalpy formulation method by using finite difference method-based discretization. Accordingly, a numerical model is developed in MATLAB which is validated first by comparing with previous works. Further using the developed model studies on wall materials, thickness, different PCMs and temperatures are carried out. It is found that metal containers with higher thermal conductivities provided significant boost in energy storage. The increased thickness of walls adds significant change only if containers are of lower thermal conductivity such as steel. Different PCMs are analysed, and their operating temperature and energy storage capabilities are studied. In addition, enthalpy equation in cylindrical coordinates is solved since practical PCM storages are commonly cylindrical in shape. At the end, the numerical results are compared with an experimental case with paraffin wax as PCM. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd 2024.Item Recent advances in 2D MXenes for enhanced cation intercalation in energy harvesting Applications: A review(Elsevier B.V., 2020) Hemanth, N.R.; Balasubramanian, B.An advanced energy harvesting device that can be powerful with rapid storage mechanism, effective conservation, intact and secure recycling presently fascinate and are increasingly developed with the proper synthesis strategy and combination of nanomaterials with complementary properties. In 2011 extensive research has led to the wide emanating family of two-dimensional (2D) multi-layered transition metal carbides, carbonitrides and nitrides in conjunction with surface terminations namely fluorine, hydroxyl or oxygen which add hydrophilicity to their surfaces, these are collectively known as MXenes, they are derived from a selective etching of atomically thin sheets of ‘A’ element from MAX phases in the acidic solutions which contain aqueous fluoride. The gifted chemistry and unique morphology of MXenes allow us to use them for distinct applications which includes energy storage, electromagnetic interference shielding, anti-bacterial activity, nanofiltration of water, reinforcements, nuclear waste management, and catalysis. The excellent properties inclusive of high lithium (Li) storage capacity, rapid diffusion of Li, and low operating voltage make the MXenes a promising electrode, the macroporous Ti3C2Tx sheets display gravimetric nearly 210 Fg−1 at scan rates of 10 Vs−1 which exceeds finest carbon supercapacitor and MXene hydrogels can have volumetric capacitances nearly 1500 F·cm−3. In this context, this review provides state of the art for the synthesis of MXenes, it's structure, intercalation, delamination, properties and thorough understanding between nanostructure and electrochemical performance which will encourage further study of 2D MXenes in energy harvesting applications. © 2019 Elsevier B.V.Item Performance analysis of a variable-speed wind and fuel cell-based hybrid distributed generation system in grid-connected mode of operation(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Ayyappa, S.K.; Gaonkar, D.N.This article presents the performance study of a variable-speed wind and solid oxide fuel cell-based hybrid distributed generation system, along with the energy storage devices in the grid connected mode of operation. The developed model has a salient feature of utilizing fluctuating output power of wind systems to produce hydrogen and also to charge the ultra capacitor. The presented model in the article also uses the stored energy in the ultra capacitor to compensate for the slow response time of the fuel cell. The distributed generation systems and energy storage devices considered in this study are integrated at common distributed generation links to form the hybrid system. The hybrid system is interfaced to the grid through the three-phase voltage source inverter in this article. The detailed modeling of the individual components of the hybrid distributed generation system, along with the necessary power electronic converter control schemes, are presented. The simulation results reported in this article show the effective performance of the hybrid model to produce reliable, low-cost electricity and hydrogen from the variable wind generation system. © 2016 Taylor & Francis Group, LLC.Item A Computer Aided Cooling Curve Analysis method to study phase change materials for thermal energy storage applications(Elsevier Ltd, 2016) Sudheer, R.; Prabhu, K.N.The suitability of a simple Computer Aided Cooling Curve Analysis (CACCA) technique for characterizing thermal energy storage phase change materials (PCM) was proposed in the present work. Two modes of CACCA, namely, Newtonian and Fourier techniques were used to predict the phase transition temperatures, the latent heat of fusion and thermal diffusivities of PCMs. Solidification of potassium nitrate and zinc-8% aluminium alloy (ZA8) was studied using CACCA method. These PCMs were chosen to demonstrate the ability of the proposed technique to characterize PCMs freezing at a single temperature as well as over a range of temperatures. CACCA method showed that potassium nitrate and ZA8 are suitable candidate materials for TES applications operating at 300-350 °C and 350-450 °C respectively. © 2015 Elsevier Ltd.Item Gridable Electric Vehicle (GEV) Aggregation in Distribution Network to Support Grid Requirements: A Communication Approach(Walter de Gruyter GmbH info@degruyter.com, 2017) Hampannavar, S.; Chavhan, S.; Yaragatti, U.R.; Naik, A.Electric Vehicles (EV) can be connected to the grid for power transaction and also serve as distributed resource (DR) or distributed energy storage system (DESS). The concept of connecting group of EVs or gridable EVs (GEV) to the grid is called Vehicle-To-Grid (V2G). V2G is a prominent energy storage system as it is flexible and can be used to support the grid requirements in order to meet the time varying load demand. Optimal placement of GEV aggregation in power distribution network is very challenging and helps in maintaining stability of the power system for a shorter duration of time. In this paper, algorithm is developed for estimating parameters like Ploss, Qloss, Vpu based on past history and wireless access support for Control and Monitoring Unit (CMU) to aggregator agent communication is proposed using Long Term Evolution (LTE) protocol. The load flow studies are carried using MiPOWER software in order to obtain the optimal location for the placement of GEV aggregation in power distribution network. LTE physical layer is modeled using MATLAB/SIMULINK and the performance is analyzed using bit error rate (BER) v/s signal to noise ratio (SNR) curves. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.Item Cooling Curve Analysis of Micro- and Nanographite Particle-Embedded Salt-PCMs for Thermal Energy Storage Applications(Springer New York LLC barbara.b.bertram@gsk.com, 2017) Sudheer, R.; Prabhu, K.N.In recent years, the focus of phase change materials (PCM) research was on the development of salt mixtures with particle additives to improve their thermal energy storage (TES) functionalities. The effect of addition of microsized (50 ?m) and nanosized (400 nm) graphite particles on TES parameters of potassium nitrate was analyzed in this work. A novel technique of computer-aided cooling curve analysis was employed here to study the suitability of large inhomogeneous PCM samples. The addition of graphite micro- and nanoparticles reduced the solidification time of the PCM significantly enhancing the heat removal rates, in the first thermal cycle. The benefits of dispersing nanoparticles diminished in successive 10 thermal cycles, and its performance was comparable to the microparticle-embedded PCM thereafter. The decay of TES functionalities on thermal cycling is attributed to the agglomeration of nanoparticles which was observed in SEM images. The thermal diffusivity property of the PCM decreased with addition of graphite particles. With no considerable change in the cooling rates and a simultaneous decrease in thermal diffusivity, it is concluded that the addition of graphite particles increased the specific heat capacity of the PCM. It is also suggested that the additive concentration should not be greater than 0.1% by weight of the PCM sample. © 2017, ASM International.Item Porous cobalt chalcogenide nanostructures as high performance pseudo-capacitor electrodes(Elsevier Ltd, 2017) Bhat, K.S.; Shenoy, S.; Nagaraja, H.S.; Sridharan, K.Electrochemical supercapacitor is an essential technology that is pivotal for the development of reliable energy storage devices. Herein, we report the fabrication of supercapacitor electrodes using nanostructured porous cobalt chalcogenide (CoTe2 and CoSe2) electrodes, anticipating an enhanced performance owing to their higher contact area with electrolyte and large pore volume enabling shorter diffusion paths for ion exchange. In this regard, we synthesized CoTe2 and CoSe2 nanostructures via an anion-exchange-reaction between pre-synthesized Co(OH)2 hexagonal nanosheets and chalcogen (tellurium and selenium) ions under hydrothermal conditions. Structural, morphological and compositional properties of the as-synthesized materials are examined using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. Pseudo-capacitive properties of CoTe2 and CoSe2 nanostructures as working electrodes are studied through cyclic voltammetry and galvanostatic charge-discharge methods using an electrochemical workstation. CoSe2 electrode delivered a specific capacitance of 951 F g?1 at a scan rate of 5 mV s?1, which surprisingly is almost three times higher in comparison to CoTe2 electrode (360 F g?1). Both CoTe2 and CoSe2 electrodes exhibited good capacitance retention capability for 2500 CV cycles. The superior electrochemical performance of the nanoporous CoSe2 electrode indicate their applicability for high-performance energy storage device applications. © 2017 Elsevier LtdItem Assessment of Solidification Parameters of Salts and Metals for Thermal Energy Storage Applications Using IHCP-Energy Balance Combined Technique(Springer, 2018) Agarwala, S.; Prabhu, K.N.Solar energy storage technologies have proved to be promising in terms of providing uninterrupted power supply. The phase change materials (PCMs) with their higher heat storage capacity are more efficient than sensible heat storage materials. In this study, a new method for thermal analysis of PCM salts was proposed. The method was based on the estimation of heat flux at the mold–salt interface using solution to inverse heat conduction problem and characterizing the salt using a simplified energy balance method. It was advantageous over other computer-aided cooling curve analysis methods as it eliminated the use of curve fitting approach involved in baseline calculations. KNO3 and NaNO3 salts were used to validate this method. The solidification parameters like cooling rate, liquidus and solidus temperatures, solidification time and latent heat were assessed. The results of the analysis were in agreement with the data reported in the literature. © 2018, The Indian Institute of Metals - IIM.Item Characterization of metals and salts-based thermal energy storage materials using energy balance method(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2019) Agarwala, S.; Prabhu, N.K.Thermal energy storage technologies minimize the imbalance between energy production and demand. In this context, latent heat storage materials are of great importance as they have a higher density of energy storage as compared with the sensible heat storage materials. The present study involves the characterization of energy storage materials using an energy balance cooling curve analysis method. The method estimates the convective heat transfer coefficient in the solidification range to characterize the phase change materials for applications in energy storage. The method is more beneficial than the Computer Aided Cooling Curve analysis methods as it eliminates baseline calculations and the associated fitting errors. Metals (Sn) and salts (KNO3 and NaNO 3) were used in the present work. Phase change characteristics like the rate of cooling, liquidus and solidus temperatures, time for solidification, and enthalpy of phase change were estimated for both metals and salts. It was observed that the energy balance cooling curve analysis method worked very well for metals but not well suited for low conductivity salts. Salts could not be characterized since the thermal gradient existing within the salt sample was not considered in this method. © 2019 Wiley Periodicals, Inc.