Showing papers by "Andrews Nirmala Grace published in 2018"

Thermostatic properties of nitrate molten salts and their solar and eutectic mixtures.

Abstract: Nitrate molten salts are extensively used for sensible heat storage in Concentrated Solar Power (CSP) plants and thermal energy storage (TES) systems They are the most promising materials for latent heat storage applications By combining classical molecular dynamics and differential scanning calorimetry experiments, we present a systematic study of all thermostatic, high temperature properties of pure KNO3 and NaNO3 salts and their eutectic and "solar salt" mixtures, technologically relevant We first study, in solid and liquid regimes, their mass densities, enthalpies, thermal expansion coefficients and isothermal compressibilities We then analyze the cP and cV specific heats of the pure salts and of the liquid phase of the mixtures Our theoretical results allow to resolve a long-standing experimental uncertainty about the cP(T) thermal behaviour of these systems In particular, they revisit empirical laws on the cP(T) behaviour, extensively used at industrial level in the design of TES components employing the "solar salt" as main storage material Our findings, numerically precise and internally consistent, can be used as a reference for the development of innovative nanomaterials based on nitrate molten salts, crucial in technologies as CSP, waste heat recovery, and advanced adiabatic compressed air energy storage

Hydrothermal Synthesis and Electrochemical Properties of CoS2–Reduced Graphene Oxide Nanocomposite for Supercapacitor Application

Abstract: A Cobalt disulfide–reduced graphene oxide (CoS2-RGO) nanocomposite was prepared by a simple hydrothermal method and the prepared nanocomposite was characterized using various techniques like XRD, SEM and FTIR. The results of these techniques indicated the uniform deposition of CoS2 nanoparticles on Graphene sheets. Further, the prepared nanocomposites were tested for its activity towards energy storage and the test results showed a specific capacitance of 28F/g in an aqueous 20% KOH electrolyte at a current density of 0.5A/g. All these materials showed highly reversible charge–discharge cycles. The overall electrochemical performance of this composite is shown to be drastically improved when compared to bare CoS2 nanoparticles. Thus with the good electrochemical properties, CoS2–RGO nanocomposites could be effectively used as an electrode material for supercapacitors.

Synthesis of NiS–Graphene Nanocomposites and its Electrochemical Performance for Supercapacitors

Abstract: The aim of this work is to synthesize nickel sulfide–graphene (NiS/G) nanocomposites with different compositions and to analyze the structural and electrochemical capacity and compatibility for the...

Wet Chemical Synthesis of SnS/Graphene Nanocomposites for High Performance Supercapacitor Electrodes

Abstract: A series of SnS/Graphene (SnS/G) nanocomposites at various concentrations of graphene were synthesized by a wet chemical route and the prepared composites were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), High Resolution Transmission Electron Microscopy (HRTEM) for its structural and morphological investigation. Results show that the prepared SnS nanoparticles in the composite are ∼30nm sized and uniformly dispersed on graphene sheets. To test the supercapacitance behavior, electrochemical measurements were carried out in 6M KOH electrolyte. A maximum specific capacitance of 984F/g was observed for SnS/G-c at 5mVs−1 scan rate. Galvanostatic charge/discharge curves showed an excellent cyclic stability with higher charge/discharge duration, and hence could be used for high performance supercapacitor applications.

Enhanced energy storage in polyvinylidenefluoride (PVDF) + BaZrO 3 electroactive nanocomposites

Abstract: PVDF + BaZrO3 electroactive nanocomposite thin film has been prepared by solution casting method. The structural analysis was carried out by using x-ray diffraction pattern and atomic force microscopy (AFM). Generally, the performance of dielectric capacitors toward higher energy density and higher operating temperatures has been drawing increased interest. In this regard, the present study was focussed on the fabrication and characterization of PVDF + BaZrO3 electroactive nanocomposites in view of enhancing the energy density at elevated temperature. Cole-Cole plot is an agreement with multiple relaxation process in electroactive nanocomposites. Dielectric energy storage performance is assessed for PVDF nanocomposites with different wt% of BaZrO3 at different frequencies and temperature. It has been observed that with increase of temperature, the permittivity increased while the energy density slightly decreased but significantly higher than pure polymer PVDF. A high energy density of 6.88 J/cm3 was obtained for BaZrO3 electroactive nanocomposites at 50 °C and 5.06 J/cm3 at 70 °C. Overall, the testing results indicate that using nanocomposites of PVDF and BaZrO3 as a dielectric component is promising for implementation to preserve high energy density values up to temperatures of 70 °C.The enhancement of dielectric permittivity and the energy density is attributed due to increase of interracial charge density. The effect of BaZrO3 nanoparticles in energy density of PVDF is first time reported.