Satyanarayanan S

Dual-wavelength, broadband photoacoustic technique is demonstrated for measurement of multiple gas species using a supercontinuum laser source. H2O vapor and CO2 measurements are demonstrated near 1920 and 2000 nm.

Nanosecond and femtosecond laser Induced Breakdown Spectroscopy (ns- and fs-LIBS)were used for elemental analysis of Indian coal and ash. Emissions from C, Na, K, Al, Fe, Ca and molecular CN were identified and analyzed.

Process industry mostly uses steam as an indispensable source of energy. We are presenting a technique to measure quality in real time where single laser diode tuning capabilities is being utilized to generate arbitrary modulated laser intensity for non-absorbing and absorbing wavelength of water vapor and eliminates uses of multiple laser source.

The origin, formation mechanism, and emission persistence time of atomic (C I) and molecular (CN Violet system and C2 Swan system) carbon emissions from coal plasma generated by laser ablation were studied using Time-resolved LIBS.

The anticipated future growth in the electric vehicle market is driving research and development of alternative battery technologies to lithium batteries. Among the explored batteries, metal-air batteries are an exciting option given their high potential energy density. Currently, metal-air flow batteries have received more attention over conventional metal-air batteries due to their ability to reduce metal passivation. The separator for a metal-air flow battery should be both ion-conductive and partially hydrophobic to favour the ionic movement and suppress the electrolyte flooding on the cathode. In this work, we investigate the use of polyvinyl alcohol (PVA)-based potassium hydroxide (KOH) polymer gel electrolyte (KPGE) as a membrane separator for planar zinc-air flow battery (ZAFB). The KPGE samples, i.e., S20 and S33 with respective KOH wt.% of 20 and 33 were synthesised. Their surface morphology, porosity, tensile strength, and ionic conductivity were studied. Among the samples, S33 sample with higher KOH content showed higher ionic conductivity than S20 sample however the tensile strength of S33 sample was lower than the S20 sample. When tested in the battery, ZAFB with S33 sample demonstrated higher nominal voltage and improved polarisation characteristics when compared to the ZAFB with S20 sample.

Saturated steam dryness is derived from the refractive index measured using the Michelson Interferometer. For the measurement, the interdependence of the refractive index on wavelength, temperature, pressure, and density is used. The methodology is non-invasive and eliminates the use of multiple sources for dryness measurement.

A heat pump unit using CO2 as working fluid is designed to meet not only a part of the heating demand in the centralised kitchen at The Akshaya Patra Foundation, Bengaluru, India, but also the entire cooling demand to replace the existing HCFC units for AC. The proposed heat pump system generates hot water at ~90oC which is stored in hot water storage tanks for use in the cooking cauldrons. Moreover, the existing space cooling systems are replaced by a centralised cooling system which circulates chilled water. In order to handle the fluctuation in cold and hot water demand, thermal storage systems are proposed. This concept offers substantial reductions in GHG emissions from the cooling system (approximately 60%). Furthermore, for the overall system (cooking process and space cooling) the reduction in energy demand, energy cost and GHG emissions are all above 30%.

This paper presents the flow physics of condensing steam flow across a straight through labyrinth seal from numerical simulations performed using ANSYS CFX. Homogeneous nucleation model and droplet growth model, which are critical in predicting condensation, are validated with good agreement against a well-known experimental data set from convergentdivergent nozzle. Validation data includes static pressure drop, condensation location, condensate mass fraction and Sauter mean radius. CFD study is performed on a five teeth labyrinth geometry to predict leakage flow rate, location of condensate accumulation and condensation rate. Impact of subcooled and condensed steam on leakage flow, pressure and temperature field are also discussed. For condensing steam, the condensate accumulation trend is identified. Some of the key findings and physical insights of interest to the designer are listed including: The effect of cooling on the leakage flow (with and without condensation) and the minimum seal wall temperature to avoid condensation based on subcooling needed for droplet formation (at location condition). Also investigated is whether steam condensation continues or if existing condensate evaporates in the downstream pockets, and the effect of heat release from condensation on number of droplets formed and the Sauter mean radius.

Supercontinuum laser-based broadband photoacoustic technique is demostrated for sensing CO, CO2 and H2O around 2µm. The detection limit of 6 ppm, 736 ppm and 20 ppb respectively, is attained with SNR of 3 dB.

Supercontinuum laser-based broadband photoacoustic technique is demostrated for sensing CO, CO2 and H2O around 2 μm. The detection limit of 6 ppm, 736 ppm and 20 ppb respectively, is attained with SNR of 3 dB.