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Satyanarayanan S
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Satyanarayanan S
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Satyanarayanan S
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Satyanarayanan, S.
Seshadri, Satyanarayanan
Seshadri, S.
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15 results
Now showing 1 - 10 of 15
- PublicationLIBS technique combined with blow gas and vacuum suction to remove particle cloud and enhance emission intensity during characterization of powder samples(01-07-2021)
;Rajavelu, Hemalaxmi; The present study reports developing a bench-top Laser-Induced Breakdown Spectroscopy (LIBS) set up for the online analysis of powder samples without sample preparation. The powder particle blow-off during pulsed laser ablation was mitigated by adding a blow gas (an inert gas blown across the ablation surface) and a suction unit (for extraction of the blow gas and blown-off particle cloud) to the existing LIBS setup. The influence of a blow-gas combined with a suction unit on LIBS emission intensity from coal powder and flyash particles is studied in the present work. The effect of the blow gas flow rate and the suction pressure was studied on the LI-BS emission intensity and removal of the laser blown-off particle cloud. The combination gas flow at 2 lpm (liter per minute) flow rate and suction at 925 mbar (absolute) show an increase in the LIBS emission intensity and effective particle removal. The ratio of LIBS emission intensity of the powder sample and solid-target (pellet) sample improved from 0.25 without the Ar gas flow and the suction unit to 0.85, which is by a factor of 3.4 times with the proposed approach. - PublicationA polarization-resolved light scattering method for eliminating the interference of water aerosol in industrial stack PM measurement(02-06-2020)
;Dogra, VipulIn this study we report polarization resolved intensity measurements for flyash and water aerosol, respectively, in an industrial stack like environment, for the purpose of developing a methodology for in-situ PM measurements in wet stacks. Flyash and water aerosols up to 4 (Formula presented.) mass concentration were seeded in a lab scale simulated industrial stack operated at velocities up to 15 m/s. Scattering of non-polarized (NP) and horizontally polarized light by these two aerosols were observed at (Formula presented.) back-scatter and (Formula presented.) forward-scatter angles for horizontal and vertical polarization states at the detector. Complete depolarization of horizontally polarized incident light was observed for ash at (Formula presented.) while negligible effects were observed for water. Thus the cross-polarization measurement in this angle, where the scattering energy from the mixed flow could directly represent the flyash concentration, can be the best possible measurement configuration for minimizing the impact of interference from water carryover in industrial emission stacks. Further, the change in depolarization ratio of the mixture (δm) when compared to flyash (δa) alone is proportional to the scattering intensity ratios of ash and water, respectively, and could be used to estimate the individual mass concentrations. With this development, we could propose the design of an instrument that can in-situ correct for errors from counting water droplet, and also enable real time estimation of individual mass concentrations. Copyright © 2020 American Association for Aerosol Research. - PublicationOverview of the factors affecting the performance of vanadium redox flow batteries(01-09-2021)
;Sankaralingam, Ram Kishore; ;Sunarso, Jaka ;Bhatt, Anand I.Kapoor, AjayRedox flow batteries are being utilised as an attractive electrochemical energy storage technology for electricity from renewable generation. At present, the global installed capacity of redox flow battery is 1100 MWh. There are several parameters that significantly govern redox flow battery performance amongst which electrode activation, electrode material, felt compression, electrolyte additive, electrolyte temperature, membrane, and flow field design are notable. This review article presents an overview of the influence of individual components by comparing the performance of a parametrically modified cell with a default cell, which has 0% felt compression, inactivated electrode, zero electrolyte additives, and ambient condition operation. From the reviewed studies, electrode activation (thermal, chemical, laser perforation) and felt compression were identified as the most significant parameters. Electrolyte additive and flow field design were identified to be reasonably significant. Electrolyte temperature and membrane type were identified as the least significant amongst all the parameters. Based on this survey, a parametric matrix has been outlined that will aid researchers to identify appropriate parameters to focus research efforts onto improved redox flow battery performance. - PublicationParametric optimisation using data model to improve the energy efficiency of vanadium redox flow batteries(01-08-2023)
;Sankaralingam, Ram Kishore; Sunarso, JakaRenewable energy utilisation has become indispensable to attain carbon-zero goals in the near future. Given the intermittent nature of renewable energy sources, it is vital to have an efficient and steadfast storage medium to maintain a stable energy supply. Vanadium redox flow batteries (VRFB) are promising energy storage devices that can be utilised effectively in grid storage applications. Despite their advantages, VRFBs still struggle to compete with lithium-ion batteries in round-trip efficiency. The round-trip efficiency of VRFB can be maximised if all the physical and chemical parameters are optimised simultaneously. To do this, several experimental trials need to be performed to determine the individual and collective effects of the parameters. Hence, in this work, we built a data model for VRFB using literature data, and we revamped the model to be 90 % accurate in assessing the round-trip efficiency (energy efficiency) within the error range of ±2 %. Finally, we used the data model to optimise the parameters for improving the energy efficiency to around 97–98 % for a 4 cm2 active area cell at a current density of 50 mA cm−2. Researchers can utilise this approach for any batteries that need performance improvement with minimal experimental efforts. - PublicationPhase doppler particle analyser (PDPA) characterization and modeling of sprays from orthogonally interacting water and air jets(01-01-2020)
;Mallik, Arnab Kumar ;Sarma, Tushar Pratim ;Roy, Aritras; Atomization of a jet in air cross flow has numerous applications in industrial and natural systems. In this study, spray characteristics (i.e., droplet mean diameter, Sauter mean diameter, and volume flux distribution) generated from perpendicularly interacting air jet of 7.5-mm diameter and water jet of 0.8-mm diameter are characterized using a phase Doppler particle analyzer (PDPA) in a forward scattering mode. The investigation is done for seven momentum ratios (q), where the momentum ratios are varied by varying the jet flow rate while keeping air flow rate constant. The jet Weber number is calculated to be 42.56, which is constant for all the cases and falls under the multimode breakup regime. PDPA measurements are done at different spatial locations, 40 mm below the tip of the injector to avoid ligaments and to ensure stable droplets. From the experimental results, it is found that for all flow conditions, volume flux is maximum near the geometric center of the spray and decreases towards the edges indicating the solid cone structure of the spray. The volume flux also increases with increase in q. The maximum of mean droplet diameter (D10) and Sauter mean diameter (SMD or D32) is found at the geometric center of the spray in the x direction, whereas in the y direction the maximum D10 and D32 are shifted towards the windward side of the jet. The diameter–velocity correlation is negative at the center of the spray and positive at the edges for both x and y directions. The correlation model for volume flux is found to be in accordance with the experimental data, while a few outliers are found in the diameter model due to the presence of large droplets that skew the data. - PublicationHollow-core optical fiber-based laser-induced breakdown spectroscopy technique for the elemental analysis of pulverized coal(01-10-2022)
;Rajavelu, Hemalaxmi; The present study proposed and demonstrated the feasibility of the fiber-based LIBS technique for the analysis of pulverized coal. A hollow-core fiber was employed to replace the air medium in the conventional LIBS setup for the delivery of high-power laser pulses to the target. It was observed that the hollow-core fiber could effectively deliver the laser energy for target ablation with a transmission efficiency of 50–60%. The LIBS spectra captured using the fiber LIBS technique prove that the addition of hollow-core fiber can upgrade the conventional LIBS technique into a remote characterization unit. Convincing results were obtained in terms of quantitative carbon measurement using the proposed approach. - PublicationEnergy, exergy, environmental, and economic (4E) analysis and selection of best refrigerant using TOPSIS method for industrial heat pumps(01-12-2022)
;Koundinya, SandeepThe global implementation of the Montreal Protocol has accelerated research in the last decade to develop low GWP refrigerants, and numerous low GWP refrigerants have been uncovered. A broad energy, exergy, environmental and economic (4E) analysis is required to know the overall benefits of the new low GWP refrigerants, especially in the context of heat pumps for industrial heating. In this paper, an attempt has been made to analyze the popular refrigerants based on 4E analysis, and the best refrigerants are selected based on the technique for order of preference by the similarity of ideal solution (TOPSIS). Total equivalent warming impact (TEWI) has been considered for environmental analysis. Fourteen refrigerants that include the popular hydrofluorocarbons, alkenes, and hydrocarbon refrigerants have been considered for the study. The condenser temperature was varied from 45 − 95 °C. Considering the present emission factor of India, R407C, R1270, R290, R152a, and R1234ze(E) are found to be the best refrigerants for the condenser temperatures ranging from 45 to 65 °C, 66 – 68 °C, 69 – 77 °C, 78 – 92 °C, and 93 – 95 °C, respectively. This paper will be a helpful guide for the industries to select the best refrigerant for their applications. - PublicationNumerical study on the effect of port geometry of intake manifold in a steam Wankel expander(01-01-2023)
;Mukherjee, AuronilA Wankel steam expander has numerous advantages over other positive displacement machines as an expansion device due to its high power-to-weight ratio, compactness, lower noise, vibration, and potentially lower specific cost. In these expanders, the pressure drop of steam during admission through rotary valves is inevitable across the intake manifold of the expander during admission duration. These pressure losses during intake change the design pressure ratio across the expander, reducing power output by a reasonable margin of 20 to 30 %. Therefore, reducing it to improve the net power output is crucial. The goal of the present research is twofold. In the first part, we estimate the pressure losses across the intake manifold of the expander for a rectangular port geometry. In the second part, a trapezoidal port profile of the same hydraulic diameter is designed for the intake manifold to reduce the intake losses, thereby delivering a higher power output. The thermodynamic analysis, with state points from REFPROP, is performed for the theoretical pressure–volume cycle of the expander to derive the boundary conditions for a CFD model. We observe that the trapezoidal port significantly reduces the pressure losses by around 50 %, delivering around 7 to 21 % higher net power output. The increase in isentropic efficiency is about 14 % over a range of rotational speeds from 1200 to 3000 RPM. Further, we study the effect of different fluid flow and turbulent parameters on the expander's pressure loss, power output and isentropic efficiency. - PublicationA novel transcritical-recuperative two-stage Organic Rankine Cycle for dual/multi-source heat recovery applications(01-03-2022)
;Surendran, AnanduThe Transcritical Regenerative Series Two-stage Organic Rankine Cycle (TR-STORC) has improved performance over STORC and single-stage ORC. However, the TR design requires vapor extraction between turbine stages, which prevents the use of compact two-stage ORC turboexpanders. An alternative Transcritical-Recuperative (TREC) design is proposed which eliminates vapor extraction allowing direct integration of compact two-stage turbines. The novel TREC-STORC operates with a recuperator acting as an additional evaporator at the low-pressure turbine exit (LP mode). Another TREC design requiring vapor extraction from the high-pressure turbine stage (HP mode), similar to the TR design, is also presented for comparison purposes. TREC-STORC in LP mode presents a marginally improved performance of 1–3% over HP mode for various IC engine heat source conditions. With cyclopentane as working fluid, at engine design point conditions, LP mode delivers 4% higher power outputs over HP mode and TR-STORC. Compared to STORC and single-stage ORC, the LP mode of TREC-STORC delivers 21% and 28% higher power outputs, respectively. For other working fluids, TREC-STORC (LP mode) delivers between 2–5% additional power output over TR-STORC, with 18–38% and 20–56% increased power outputs over STORC and single-stage ORC, respectively. TREC-STORC (LP mode) presents a superior and robust ORC architecture for dual/multi-source heat recovery applications. - PublicationAn ejector based Transcritical Regenerative Series Two-Stage Organic Rankine Cycle for dual/multi-source heat recovery applications(01-01-2022)
;Surendran, AnanduThe Transcritical Regenerative Series Two-stage Organic Rankine Cycle (TR-STORC) was shown to deliver improved performance than Series Two-stage ORC (STORC) and single-stage ORC for dual-source heat recovery applications. However, TR-STORC utilizes partial evaporation for regeneration which requires precise control of two-phase flows. In real-time operations involving dual/multiple heat sources, this is difficult to achieve due to fluctuating heat inputs, leading to liquid carryover and subsequent corrosion of turbine blades. This study explores a novel Transcritical Ejector Regenerative STORC (TER-STORC), which replaces the need for two phase flows with a avapor-vapor regeneration via an ejector operating entirely with fully evaporated vapor (FE mode). Partial evaporation (PE) mode of TER-STORC requiring two-phase flows is also analyzed for comparison. Results indicate that the FE mode of TER-STORC can achieve performance comparable to PE mode and TR-STORC. FE mode of ejector operation is less sensitive to variations in ejector pressure drop than PE mode while delivering 0.2–4% lower power outputs with lower heat exchanger requirements than TR-STORC by up to 18%.At the engine design point, only a 2% drop in power output is seen for FE mode compared to TR-STORC. TER-STORC presents a robust system with reduced complexity for multisource heat recovery.