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Jag Sankar - One of the best experts on this subject based on the ideXlab platform.

  • Processing of yttria stabilized zirconia thin films by Liquid Fuel Combustion chemical vapor deposition
    MRS Online Proceedings Library, 2011
    Co-Authors: Qiuming Wei, Jag Sankar
    Abstract:

    Yttria fully stabilized zirconia (YSZ) thin films have been successfully synthesized with atmospheric Combustion chemical vapor deposition (ACCVD) technique with Liquid Fuel. Key processing parameters, such as the ratio of oxygen to Liquid Fuel in the flame, the concentration of metal reagents in the solution, the temperature of the substrate and substrate material, have been investigated. The as-grown films are characterized with X-ray diffraction and scanning electron microscopy. Within the range of experimental parameters, the phase of the film is predominantly of cubic structure. The phase and crystallinity of the films are strongly dependent upon the experimental variables.

  • Yttria-stabilized zirconia coatings produced using Combustion chemical vapor deposition
    Surface & Coatings Technology, 2003
    Co-Authors: Jag Sankar, Sergey Yarmolenko
    Abstract:

    A Liquid Fuel Combustion chemical vapor deposition technique had been developed for oxide thin film deposition. Yttria-stabilized zirconia thin films had been processed using this technique operated in open air. Combustion flame had been modulated for high-quality film deposition by studying the effect of the ratio of the oxidant gas to the Liquid Fuel. Another key processing parameter, i.e. the substrate temperature, had been investigated. The as-grown films were characterized with X-ray diffraction and scanning electron microscope. The phase and crystallinity of the films were found strongly dependent on the experimental variables. Moderate increase of the ratio of the oxidant gas to the Liquid Fuel can accelerate the decomposition of the Fuel and improve the quality of the deposited film. Two film growth kinetic modes were found with the transition temperature at approximately 1343 K. The microstructural zone transition temperature from zone 1 to zone 2 was found to be at approximately 1473 K. The processing variables were optimized with regard to both the phase quality and the growth rate.

  • Nucleation And Growth of Yttria-Stabilized Zirconia Thin Films Using Combustion Chemical Vapor Deposition
    MRS Online Proceedings Library, 2003
    Co-Authors: Jag Sankar, Sergey Yarmolenko, Qiuming Wei
    Abstract:

    Liquid Fuel Combustion chemical vapor deposition technique was successfully used for YSZ thin film processing. The nucleation rates were obtained for the samples processed at different temperatures and total-metal-concentrations in the Liquid Fuel. An optimum substrate temperature was found for the highest nucleation rate. The nucleation rate was increased with the total-metal-concentration. Structural evolution of the thin film in the early processing stage was studied with regard to the formation of nuclei, crystallites and final crystals on the films. The films were found to be affected by high temperature annealing. The crystals and the thin films were characterized with scanning electron microscopy.

  • Deposition of YSZ Thin Films by Liquid Fuel Combustion Chemical Vapor Deposition
    Materials: Processing Characterization and Modeling of Novel Nano-Engineered and Surface Engineered Materials, 2002
    Co-Authors: Jag Sankar, Qiuming Wei, J. Lua, Sergey Yamolenko, Devdas Pai
    Abstract:

    Thin film of YSZ electrolyte is highly desired to reduce the electrical resistance in SOFCs. YSZ thin Films have been successfully produced using Liquid Fuel Combustion chemical vapor deposition (CCVD) technique. Nucleation of the YSZ particles were investigated based on two processing parameters, i.e., substrate temperature and total-metal-concentration in the Liquid Fuel. An optimum substrate temperature was found for highest the nucleation density. The nucleation density was increased with the total-metal-concentration. Microstructure evolution of the YSZ particles in the early stage in film growth was also studied. It was found that the particle growth rate was linear with processing time, and the particle orientation was varying with the time in the early stage of the film processing. To enhance the film growth rate, the effect of thermophoresis was studied. By increase the temperature gradient towards substrate, the effect of thermophoresis was enhanced and the film growth is also increased.© 2002 ASME

Sergey Yarmolenko - One of the best experts on this subject based on the ideXlab platform.

  • Yttria-stabilized zirconia coatings produced using Combustion chemical vapor deposition
    Surface & Coatings Technology, 2003
    Co-Authors: Jag Sankar, Sergey Yarmolenko
    Abstract:

    A Liquid Fuel Combustion chemical vapor deposition technique had been developed for oxide thin film deposition. Yttria-stabilized zirconia thin films had been processed using this technique operated in open air. Combustion flame had been modulated for high-quality film deposition by studying the effect of the ratio of the oxidant gas to the Liquid Fuel. Another key processing parameter, i.e. the substrate temperature, had been investigated. The as-grown films were characterized with X-ray diffraction and scanning electron microscope. The phase and crystallinity of the films were found strongly dependent on the experimental variables. Moderate increase of the ratio of the oxidant gas to the Liquid Fuel can accelerate the decomposition of the Fuel and improve the quality of the deposited film. Two film growth kinetic modes were found with the transition temperature at approximately 1343 K. The microstructural zone transition temperature from zone 1 to zone 2 was found to be at approximately 1473 K. The processing variables were optimized with regard to both the phase quality and the growth rate.

  • Nucleation And Growth of Yttria-Stabilized Zirconia Thin Films Using Combustion Chemical Vapor Deposition
    MRS Online Proceedings Library, 2003
    Co-Authors: Jag Sankar, Sergey Yarmolenko, Qiuming Wei
    Abstract:

    Liquid Fuel Combustion chemical vapor deposition technique was successfully used for YSZ thin film processing. The nucleation rates were obtained for the samples processed at different temperatures and total-metal-concentrations in the Liquid Fuel. An optimum substrate temperature was found for the highest nucleation rate. The nucleation rate was increased with the total-metal-concentration. Structural evolution of the thin film in the early processing stage was studied with regard to the formation of nuclei, crystallites and final crystals on the films. The films were found to be affected by high temperature annealing. The crystals and the thin films were characterized with scanning electron microscopy.

Ajay K. Agrawal - One of the best experts on this subject based on the ideXlab platform.

  • Low-Emission, Liquid Fuel Combustion System for Conventional and Alternative Fuels Developed by the Scaling Analysis
    Journal of Engineering for Gas Turbines and Power, 2015
    Co-Authors: Yonas G. Niguse, Ajay K. Agrawal
    Abstract:

    The objective of this study is to develop a theoretical basis for scalability considerations and design of a large-scale combustor utilizing flow blurring (FB) atomization. FB atomization is a recently discovered twin-fluid atomization concept, reported to produce fine spray of Liquids with wide range of viscosities. Previously, we have developed and investigated a small-scale swirl-stabilized combustor of 7-kWth capacity. Spray measurements have shown that the FB injector's atomization capability is superior when compared to other techniques, such as air blast atomization. However, despite these favorable results, scalability of the FB injector and associated combustor design has never been explored for large capacity; for example, for gas turbine applications. In this study, a number of dimensionless scaling parameters that affect the processes of atomization, Fuel–air mixing, and Combustion are analyzed, and scaling criteria for the different components of the Combustion system are selected. Constant velocity criterion is used to scale key geometric components of the system. Scaling of the nonlinear dimensions and complex geometries, such as swirler vanes and internal parts of the injector is undertaken through phenomenological analysis of the flow processes associated with the scaled component. A scaled-up 60-kWth capacity combustor with FB injector is developed and investigated for Combustion performance using diesel and vegetable oil (VO) (soybean oil) as Fuels. Results show that the scaled-up injector's performance is comparable to the smaller scale system in terms of flame quality, emission levels, and static flame stability. Visual flame images at different atomizing air-to-Liquid ratio by mass (ALR) show mainly blue flames, especially for ALR > 2.8. Emission measurements show a general trend of lower CO and NOx levels at higher ALRs, replicating the performance of the small-scale Combustion system. Flame liftoff height at different ALRs is similar for both scales. The scaled-up combustor with FB injector preformed robustly with uncompromised stability for the range of firing rates (FRs) above 50% of the design capacity. Experimental results corroborate with the scaling methodology developed in this research.

  • Low Emission, Liquid Fuel Combustion System for Conventional and Alternative Fuels Developed by the Scaling Analysis
    Volume 3: Coal Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration, 2015
    Co-Authors: Yonas G. Niguse, Ajay K. Agrawal
    Abstract:

    The objective of this study is to develop a theoretical basis for scalability considerations and design of a large scale combustor utilizing flow blurring (FB) atomization. FB atomization is a recently discovered twin-fluid atomization concept, reported to produce fine spray of Liquids with wide range of viscosities. Previously, we have developed and investigated a small scale swirl-stabilized combustor of 7-kWth capacity. Spray measurements have shown that the FB injector’s atomization capability is superior when compared to other techniques, such as air blast atomization. However, despite these favorable results, scalability of the FB injector and associated combustor design has never been explored for large capacity, for example, for gas turbine applications. In this study, a number of dimensionless scaling parameters that affect the processes of atomization, Fuel-air mixing, and Combustion are analyzed, and scaling criteria for the different components of the Combustion system are selected. Constant velocity criterion is used to scale key geometric components of the system. Scaling of the nonlinear dimensions and complex geometries, such as swirler vanes and internal parts of the injector is undertaken through phenomenological analysis of the flow processes associated with the scaled component. A scaled up 60-kWth capacity combustor with FB injector is developed and investigated for Combustion performance using diesel and vegetable oil (soybean oil) as Fuels. Results show that the scaled-up injector’s performance is comparable to the smaller scale system in terms of flame quality, emission levels, and static flame stability. Visual flame images at different air to Liquid ratio by mass (ALR) show mainly blue flames, especially for ALR > 2.8. Emission measurements show a general trend of lower CO and NOx levels at higher ALRs, replicating the performance of the small scale Combustion system. Flame liftoff height at different ALRs is similar for both scales. The scaled-up combustor with FB injector preformed robustly with uncompromised stability for the range of firing rates above 50% of the design capacity. Experimental results corroborate with the scaling methodology developed in this research.Copyright © 2015 by ASME

  • Passive Mitigation of Noise in a Duel Fuel Combustor Using Porous Inert Media
    Volume 2: Combustion Fuels and Emissions Parts A and B, 2012
    Co-Authors: Joseph Meadows, Ajay K. Agrawal
    Abstract:

    In the past, we have utilized porous inert media (PIM) to suppress noise and thermo-acoustic instabilities in swirl-stabilized Combustion systems operated on gaseous Fuels. The same concept will also be shown to work in Liquid Fueled Combustion systems. This study presents experimental results to evaluate the PIM concept for suppressing Combustion noise in a duel Fuel combustor. Experiments for gaseous Fuel Combustion are performed using natural gas premixed with air upstream of the combustor dump plane. Experiments for Liquid Fuel Combustion are performed using kerosene Fuel supplied through a commercial air-blast atomizer. In this combustor, the flame stabilizes downstream of the dump plane by central and corner recirculation zones. Multiple ring shape PIM pieces are inserted into the combustor to alter the flow field in an advantageous manner. Each PIM piece has the same outer diameter but different inner diameters. Results are presented to investigate the effects of equivalence ratio and heat release rate for gaseous Fuel Combustion and air to Liquid mass ratio and heat release rate for Liquid Fuel Combustion. Attempts were also made to create thermo-acoustic instabilities by positioning four loudspeakers radially around the primary air flow upstream of the combustor. Measurements of sound pressure levels (SPL), and CO and NOx emissions were taken to characterize the Combustion process. Results show that PIM can passively mitigate Combustion noise in a duel Fuel combustor without adversely affecting the emissions.© 2012 ASME

  • Passive Mitigation of Combustion Noise in Liquid Fuel Combustion Using Porous Inert Media
    50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012
    Co-Authors: Joseph Meadows, Ajay K. Agrawal
    Abstract:

    In this study, the Combustion noise is passively mitigated using ring shaped porous inert media (PIM). Kerosene, simulating Fuel commonly used in jet engines, is combusted in a swirl-stabilized combustor. In this combustor, the flame stabilizes within the recirculation zone downstream of the dump plane. The ring shaped PIM is placed on the dump plane of the combustor to alter the flow field in an advantageous manner. Multiple PIM rings of same OD but different ID are stacked together to form various geometric configurations. For each PIM configuration, a parametric study is conducted by varying the atomizing air to Liquid mass ratio and heat release rate. Sound pressure levels (SPLs) and CO and NOx emissions are measured for Combustion with no PIM and with PIM. Results show that the PIM insert mitigates the Combustion noise, and that the converging PIM configuration provides the most noise reduction overall the full frequency range.

  • Liquid Fuel Combustion Using Heat Recirculation Through Annular Porous Media
    Journal of Engineering for Gas Turbines and Power, 2007
    Co-Authors: E. Ryan Newburn, Ajay K. Agrawal
    Abstract:

    A counter-flow annular heat recirculating burner was designed for lean prevaporized, premixed Combustion. Prior to entering the combustor, the reactants are passed through a porous media-filled preheating annulus surrounding the combustor. Kerosene is dripped by gravity onto the porous media and vaporized by the heat conducted through the combustor wall. Experiments were conducted to evaluate heat transfer and Combustion performance at various equivalence ratios, heat release rates, and inlet air temperatures. Results show low CO emissions over a range of equivalence ratios. NOx emissions were high at high heat release rates, indicating inadequate prevaporization and premixing of Fuel with air. Heat recirculation and heat loss characteristics are presented at various operating conditions.

Qiuming Wei - One of the best experts on this subject based on the ideXlab platform.

  • Processing of yttria stabilized zirconia thin films by Liquid Fuel Combustion chemical vapor deposition
    MRS Online Proceedings Library, 2011
    Co-Authors: Qiuming Wei, Jag Sankar
    Abstract:

    Yttria fully stabilized zirconia (YSZ) thin films have been successfully synthesized with atmospheric Combustion chemical vapor deposition (ACCVD) technique with Liquid Fuel. Key processing parameters, such as the ratio of oxygen to Liquid Fuel in the flame, the concentration of metal reagents in the solution, the temperature of the substrate and substrate material, have been investigated. The as-grown films are characterized with X-ray diffraction and scanning electron microscopy. Within the range of experimental parameters, the phase of the film is predominantly of cubic structure. The phase and crystallinity of the films are strongly dependent upon the experimental variables.

  • Nucleation And Growth of Yttria-Stabilized Zirconia Thin Films Using Combustion Chemical Vapor Deposition
    MRS Online Proceedings Library, 2003
    Co-Authors: Jag Sankar, Sergey Yarmolenko, Qiuming Wei
    Abstract:

    Liquid Fuel Combustion chemical vapor deposition technique was successfully used for YSZ thin film processing. The nucleation rates were obtained for the samples processed at different temperatures and total-metal-concentrations in the Liquid Fuel. An optimum substrate temperature was found for the highest nucleation rate. The nucleation rate was increased with the total-metal-concentration. Structural evolution of the thin film in the early processing stage was studied with regard to the formation of nuclei, crystallites and final crystals on the films. The films were found to be affected by high temperature annealing. The crystals and the thin films were characterized with scanning electron microscopy.

  • Deposition of YSZ Thin Films by Liquid Fuel Combustion Chemical Vapor Deposition
    Materials: Processing Characterization and Modeling of Novel Nano-Engineered and Surface Engineered Materials, 2002
    Co-Authors: Jag Sankar, Qiuming Wei, J. Lua, Sergey Yamolenko, Devdas Pai
    Abstract:

    Thin film of YSZ electrolyte is highly desired to reduce the electrical resistance in SOFCs. YSZ thin Films have been successfully produced using Liquid Fuel Combustion chemical vapor deposition (CCVD) technique. Nucleation of the YSZ particles were investigated based on two processing parameters, i.e., substrate temperature and total-metal-concentration in the Liquid Fuel. An optimum substrate temperature was found for highest the nucleation density. The nucleation density was increased with the total-metal-concentration. Microstructure evolution of the YSZ particles in the early stage in film growth was also studied. It was found that the particle growth rate was linear with processing time, and the particle orientation was varying with the time in the early stage of the film processing. To enhance the film growth rate, the effect of thermophoresis was studied. By increase the temperature gradient towards substrate, the effect of thermophoresis was enhanced and the film growth is also increased.© 2002 ASME

Yong Huang - One of the best experts on this subject based on the ideXlab platform.

  • A two-phase turbulent Combustion model and its validation for spray flames
    Fuel, 2013
    Co-Authors: Fang Wang, Yong Huang
    Abstract:

    Abstract A two-phase turbulent Combustion model (FSM) with the inclusion of individual droplet burning behavior was applied in a methanol air spray flame. The FSM model results were compared with the experimental data and results of the traditional two-phase turbulent Combustion model (TM). The comparison of the results showed that in most regions the FSM model results were in good agreement with the experimental data. In all the three cases, the FSM model predictions showed the same tendency as the experimental data, which was better than the TM model results. So in the Liquid methanol spray flame cases simulated in this paper under atmospheric condition, the FSM model is reasonable for temperature profiles prediction, which could be applied in other Liquid Fuel Combustion simulation in the future.