• TAMAL BANERJEE

Articles written in Bulletin of Materials Science

• Evaluation and conceptual design of triphenylphosphonium bromide-based deep eutectic solvent as novel thermal nanofluid for concentrated solar power

In a concentrated solar power (CSP) plant, an increase of heat transfer effect of the working fluid is a key deliverable which is usually obtained by enhancing its thermo-physical properties. The current work reports the synthesis of heat transfer fluids (HTF) based on deep eutectic solvents (DESs) consisting of a hydrogen bond donor (HBD), namely, triphenylphosphonium bromide, and a hydrogen bond acceptor (HBA), namely, ethylene glycol. Initially, the thermophysical properties, namely, density, viscosity, thermal conductivity (TC) and specific heat capacity were measured and compared with the conventional solvents. The properties were further enhanced by the dispersion of spherical Al$_2$O$_3$ nanoparticles in DESs. The alumina nanoparticles were found to have a negligible effect on the physical properties (density and viscosity) of the base fluid, thereby limiting the pressure drop and also the coefficient of friction. For their potential application as thermal fluids for CSP plants, the thermal properties of DESs and nanoparticle dispersed deep eutectic solvents (NDDESs)were measured within a temperature range of 25–60$^{\circ}$C. The TC of 1 wt% Al$_2$O$_3$ with the base fluid was around eight times higher than the base DES. It was found that the TCs of DES and NDDES were higher when compared to the commercial HTF, namely, Therminol VP-1. Eventually, the Aspen plus flowsheet was conceptualized to ascertain the steam generation rate and the overall heat transfer coefficient of these novel solvents. A combination of U-shaped for latent heat and shell and tube heat for sensible heat was employed in the flowsheet. The CSP scheme gave a steam generation rate of 1.7 kg h$^{−1}$ at 180$^{\circ}$C with a corresponding DES flow rate of 1 m$^3$ h$^{−1}$.

• Electrochemical performance of 1-butyl-4-methylpyridinium tetrafluoroborate ionic liquid electrolyte for graphene-based double layer capacitor

Ionic liquids (ILs) have been emerged as the most promising class of electrolytes to achieve high energy density in electrochemical double layer capacitors (EDLCs) due to their unique properties. In this study, 1-butyl-4-methylpyridinium tetrafluoroborate ([BMPy][BF$_4$]) was explored as the electrolyte for graphene based EDLC in presence of co-solvent. Highly viscous [BMPy][BF$_4$] was diluted with two different organic solvents, namely acetonitrile (AN) andpropylene carbonate (PC). Different weight ratios of [BMPy][BF$_4$]: organic solvents were investigated and corresponding variation of EDLC’s performance was observed. Dynamic viscosity of these IL+solvent mixtures was also measured. Three electrochemical techniques, namely cyclic voltammetry, galvanometric charge discharge, electrochemical impedance spectroscopy were employed to analyse the effectiveness of these electrolyte–electrode systems. Maximum operating voltage 2.2 V was achieved for the four out of six studied systems. For PC based electrolytes, no effect of concentration of PC on operating potential window was observed. However with AN, electrochemical stability decreased with increase in solvent weight percentage. The highest specific energy (49 Wh kg$^{-1}$) and power (4.13 kW kg$^{-1}$) were obtained for 3:1 weight ratio of IL to AN. Reverse effect on specific capacitance and internal resistance was noticed for AN and PC based electrolytes.

• # Bulletin of Materials Science

Volume 45, 2022
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020