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Papers by Sivaraman Savithri
Robustness of FTIR-Based Ultrarapid COVID-19 Diagnosis Using PLS-DA
ACS Omega
Rapid estimation of the chemical composition of rice straw using FTIR spectroscopy: a chemometric investigation
Biomass Conversion and Biorefinery
Techno-Economic Analysis of Microalgae-based Liquid fuels Production from Wastewater via Hydrothermal Liquefaction and Hydroprocessing
Bioresource Technology
In this work, a conceptual process design of wastewater-based algal biofuels production through h... more In this work, a conceptual process design of wastewater-based algal biofuels production through hydrothermal liquefaction and hydroprocessing is proposed. Then a steady-state process simulation is performed to calculate the mass and energy analysis of the whole process for the production of hydrocarbons such as diesel, jet, gasoline, and H2. A discounted cash flow analysis is used to calculate a minimum selling price (MSP) of the hydrocarbon fuels. The MSP of the hydrocarbon fuels is found at US$4.3/GGE. This value is comparable with the previously reported value in the literature. In addition, the sensitivity study is carried out to study the influence of both processes and economic parameters on the minimum selling price (MSP) of the hydrocarbon fuels.
ACS Omega
A lightweight super hydrophilic hybrid sponge is designed and demonstrated out of water glass and... more A lightweight super hydrophilic hybrid sponge is designed and demonstrated out of water glass and an organic polymer, which has a macroporous flaky nature and is superflexible with an apparent density of 0.069 g cc −1 , ∼97% porosity, and 3000% water uptake. The octadecyltrimethoxy silane-modified hybrid sponge exhibits selective absorption of oil and organic solvents in open water. An absorption capacity in the range 12−23 g g −1 for the test liquids light crude oil, engine oil, paraffin oil, chloroform, kerosene, and hexane is revealed. Absorption capacity by a weight basis was directly proportional to the density and inversely proportional to the viscosity of test liquids. Trials under both stagnant and turbulent conditions verify selective uptake of oil from sea water. Complete regeneration of the absorbent was possible for ten cycles for the test liquids. The work provides design of an affordable water clean-up material alternative to commonly used polyurethane sponges.
Computational Fluid Dynamics simulation of hydrothermal liquefaction of microalgae in a continuous plug-flow reactor
Bioresource technology, 2018
Computational Fluid Dynamics (CFD) technique is used in this work to simulate the hydrothermal li... more Computational Fluid Dynamics (CFD) technique is used in this work to simulate the hydrothermal liquefaction of Nannochloropsis sp. microalgae in a lab-scale continuous plug-flow reactor to understand the fluid dynamics, heat transfer, and reaction kinetics in a HTL reactor under hydrothermal condition. The temperature profile in the reactor and the yield of HTL products from the present simulation are obtained and they are validated with the experimental data available in the literature. Furthermore, the parametric study is carried out to study the effect of slurry flow rate, reactor temperature, and external heat transfer coefficient on the yield of products. Though the model predictions are satisfactory in comparison with the experimental results, it still needs to be improved for better prediction of the product yields. This improved model will be considered as a baseline for design and scale-up of large-scale HTL reactor.
CFD based investigations on hydrodynamics and energy dissipation due to solid motion in liquid fluidised bed
Chemical Engineering Journal, Aug 1, 2007
... Syamlal and O'Brien [M. Syamlal, TJ O'Brien, Simulation of ... more ... Syamlal and O'Brien [M. Syamlal, TJ O'Brien, Simulation of granular layer inversion ... to improve the understanding of the hydrodynamics of liquidsolid fluidised beds through experimental and theoretical ... In comparison to reactors such as the bubble column, the flow patterns of ...
Chemical Engineering Research and Design
CFD Simulation of Gas–Liquid–Solid Fluidised Bed Reactor Using Population Balance
Mathematical modelling of the dynamics of Granular materials in a rotating cylinder
Synthesis of ultrafine rutile phase titanium dioxide particles
Process simulation of the carbothermal reduction of ilmenite in rotary kiln reactors
A model for the formation of interdendritic cavities from pores pre-existing in the melt
Résumé/Abstract A model has been developed describing the growth of pores in a dendritic network.... more Résumé/Abstract A model has been developed describing the growth of pores in a dendritic network. It is assumed that the growing pores originate from pores (bubbles that pre-exist in the melt and contain soluble and insoluble gases. The growth of an individual pore is ...
Synthesis of Ultrafine Rutile Phase Titanium Dioxide Particles at Low Temperature
Refinement of higher-order laminated plate theories
AIAA Journal, 1989
As one of the important process alternatives for the synthesis of nano materials with lower costs... more As one of the important process alternatives for the synthesis of nano materials with lower costs, flexibility and versatility, vapor phase synthesis of titania nano particles continue to attract attention. A low temperature aerosol process for the synthesis of titania nano particles is demonstrated by elucidating the influence of temperature, molar ratio of H 2 O/TiCl 4 and concentration of precursors on particle size and phase composition. This paper highlights the advantages of employing amorphous phase titania powder as solid precursor for its transformation to the rutile phase at temperatures less than 973K through vapor phase hydrolysis of TiCl 4. A mechanistic hypothesis is proposed to explain the catalytic role of water vapor in the enhancement of amorphous to anatase phase transformation at high (15 to 27) molar ratio of H 2 O/TiCl 4 .
On various refined theories in the bending analysis of angle-ply laminates
The accuracies of six shear-deformation theories are compared by analyzing the bending of angle-p... more The accuracies of six shear-deformation theories are compared by analyzing the bending of angle-ply laminates and studying the results in the light of exact solutions. The shear-deformation theories used are those by: Ren (1986), Savithri and Varadan (1990), Bhaskar and Varadan (1991), Murakami (1986), and Pandya and Kant (1988), and combinations of these. The analytical methods are similar in that the number of unknown variables in the displacement field is independent of the number of layers in the laminate. The model by Ren is based on a parabolic distribution of transverse shear stresses in each laminate layer. This model is shown to give good predictions of deflections and stresses in two-layer antisymmetric and three-layer symmetric angle-ply laminates.
As one of the important process alternatives for the synthesis of nano materials with lower costs... more As one of the important process alternatives for the synthesis of nano materials with lower costs, flexibility and versatility, vapor phase synthesis of titania nano particles continue to attract attention. A low temperature aerosol process for the synthesis of titania nano particles is demonstrated by elucidating the influence of temperature, molar ratio of H 2 O/TiCl 4 and concentration of precursors on particle size and phase composition. This paper highlights the advantages of employing amorphous phase titania powder as solid precursor for its transformation to the rutile phase at temperatures less than 973K through vapor phase hydrolysis of TiCl 4 . A mechanistic hypothesis is proposed to explain the catalytic role of water vapor in the enhancement of amorphous to anatase phase transformation at high (15 to 27) molar ratio of H 2 O/TiCl 4 .
Bending analysis of angle-ply laminates
The accuracy and the applicability of the higher-order theory developed by Savithri and Varadan (... more The accuracy and the applicability of the higher-order theory developed by Savithri and Varadan (1990) for the analysis of symmetric angle-ply laminates were assessed by comparing results obtained with this theory, which incorporates the continuity of transverse shear stresses at the interfaces, with results obtained with the smeared laminate theory of Reddy (1984). For this comparison a laminate plate is used which is composed of a finite number of anisotropic layers, each of which has only a single plane of elastic symmetry parallel to the XY plane; the plate is assumed to be simply supported on the boundaries and subjected to normal traction (q(X,Y)) on the upper surface. It was found that the new theory is highly accurate for symmetric laminates, and, for comparable accuracies, the computation cost is much less than that of the corresponding smeared laminate theory.
CFD Simulations of Electromagnetic stirring of melt alloys
Chaotic dynamics of a periodically forced slender body in a simple shear flow
Physics Letters A, 1994
ABSTRACT The dynamics of a periodically forced slender body in a simple shear flow is analysed. T... more ABSTRACT The dynamics of a periodically forced slender body in a simple shear flow is analysed. This represents the simplest case of a class of problems that have not attracted attention in the literature. The system undergoes a quasiperiodic transition to chaos in the range of parameters investigated. It also exhibits chaotic transients obtained by the apparent collision of a stable nonchaotic attractor and a chaotic attractor with the transients scaling in a manner similar to that analysed by Grebogi et al. [Ergodic Theory Dynamical Systems 5 (1985)341] with the exponent of scaling approximately equal to -0.5. The class of problems to which this paper is an introduction is technologically important and can lead to new methods of processing composites, electrorheological fluids and polymer solutions.
Robustness of FTIR-Based Ultrarapid COVID-19 Diagnosis Using PLS-DA
ACS Omega
Rapid estimation of the chemical composition of rice straw using FTIR spectroscopy: a chemometric investigation
Biomass Conversion and Biorefinery
Techno-Economic Analysis of Microalgae-based Liquid fuels Production from Wastewater via Hydrothermal Liquefaction and Hydroprocessing
Bioresource Technology
In this work, a conceptual process design of wastewater-based algal biofuels production through h... more In this work, a conceptual process design of wastewater-based algal biofuels production through hydrothermal liquefaction and hydroprocessing is proposed. Then a steady-state process simulation is performed to calculate the mass and energy analysis of the whole process for the production of hydrocarbons such as diesel, jet, gasoline, and H2. A discounted cash flow analysis is used to calculate a minimum selling price (MSP) of the hydrocarbon fuels. The MSP of the hydrocarbon fuels is found at US$4.3/GGE. This value is comparable with the previously reported value in the literature. In addition, the sensitivity study is carried out to study the influence of both processes and economic parameters on the minimum selling price (MSP) of the hydrocarbon fuels.
ACS Omega
A lightweight super hydrophilic hybrid sponge is designed and demonstrated out of water glass and... more A lightweight super hydrophilic hybrid sponge is designed and demonstrated out of water glass and an organic polymer, which has a macroporous flaky nature and is superflexible with an apparent density of 0.069 g cc −1 , ∼97% porosity, and 3000% water uptake. The octadecyltrimethoxy silane-modified hybrid sponge exhibits selective absorption of oil and organic solvents in open water. An absorption capacity in the range 12−23 g g −1 for the test liquids light crude oil, engine oil, paraffin oil, chloroform, kerosene, and hexane is revealed. Absorption capacity by a weight basis was directly proportional to the density and inversely proportional to the viscosity of test liquids. Trials under both stagnant and turbulent conditions verify selective uptake of oil from sea water. Complete regeneration of the absorbent was possible for ten cycles for the test liquids. The work provides design of an affordable water clean-up material alternative to commonly used polyurethane sponges.
Computational Fluid Dynamics simulation of hydrothermal liquefaction of microalgae in a continuous plug-flow reactor
Bioresource technology, 2018
Computational Fluid Dynamics (CFD) technique is used in this work to simulate the hydrothermal li... more Computational Fluid Dynamics (CFD) technique is used in this work to simulate the hydrothermal liquefaction of Nannochloropsis sp. microalgae in a lab-scale continuous plug-flow reactor to understand the fluid dynamics, heat transfer, and reaction kinetics in a HTL reactor under hydrothermal condition. The temperature profile in the reactor and the yield of HTL products from the present simulation are obtained and they are validated with the experimental data available in the literature. Furthermore, the parametric study is carried out to study the effect of slurry flow rate, reactor temperature, and external heat transfer coefficient on the yield of products. Though the model predictions are satisfactory in comparison with the experimental results, it still needs to be improved for better prediction of the product yields. This improved model will be considered as a baseline for design and scale-up of large-scale HTL reactor.
CFD based investigations on hydrodynamics and energy dissipation due to solid motion in liquid fluidised bed
Chemical Engineering Journal, Aug 1, 2007
... Syamlal and O'Brien [M. Syamlal, TJ O'Brien, Simulation of ... more ... Syamlal and O'Brien [M. Syamlal, TJ O'Brien, Simulation of granular layer inversion ... to improve the understanding of the hydrodynamics of liquidsolid fluidised beds through experimental and theoretical ... In comparison to reactors such as the bubble column, the flow patterns of ...
Chemical Engineering Research and Design
CFD Simulation of Gas–Liquid–Solid Fluidised Bed Reactor Using Population Balance
Mathematical modelling of the dynamics of Granular materials in a rotating cylinder
Synthesis of ultrafine rutile phase titanium dioxide particles
Process simulation of the carbothermal reduction of ilmenite in rotary kiln reactors
A model for the formation of interdendritic cavities from pores pre-existing in the melt
Résumé/Abstract A model has been developed describing the growth of pores in a dendritic network.... more Résumé/Abstract A model has been developed describing the growth of pores in a dendritic network. It is assumed that the growing pores originate from pores (bubbles that pre-exist in the melt and contain soluble and insoluble gases. The growth of an individual pore is ...
Synthesis of Ultrafine Rutile Phase Titanium Dioxide Particles at Low Temperature
Refinement of higher-order laminated plate theories
AIAA Journal, 1989
As one of the important process alternatives for the synthesis of nano materials with lower costs... more As one of the important process alternatives for the synthesis of nano materials with lower costs, flexibility and versatility, vapor phase synthesis of titania nano particles continue to attract attention. A low temperature aerosol process for the synthesis of titania nano particles is demonstrated by elucidating the influence of temperature, molar ratio of H 2 O/TiCl 4 and concentration of precursors on particle size and phase composition. This paper highlights the advantages of employing amorphous phase titania powder as solid precursor for its transformation to the rutile phase at temperatures less than 973K through vapor phase hydrolysis of TiCl 4. A mechanistic hypothesis is proposed to explain the catalytic role of water vapor in the enhancement of amorphous to anatase phase transformation at high (15 to 27) molar ratio of H 2 O/TiCl 4 .
On various refined theories in the bending analysis of angle-ply laminates
The accuracies of six shear-deformation theories are compared by analyzing the bending of angle-p... more The accuracies of six shear-deformation theories are compared by analyzing the bending of angle-ply laminates and studying the results in the light of exact solutions. The shear-deformation theories used are those by: Ren (1986), Savithri and Varadan (1990), Bhaskar and Varadan (1991), Murakami (1986), and Pandya and Kant (1988), and combinations of these. The analytical methods are similar in that the number of unknown variables in the displacement field is independent of the number of layers in the laminate. The model by Ren is based on a parabolic distribution of transverse shear stresses in each laminate layer. This model is shown to give good predictions of deflections and stresses in two-layer antisymmetric and three-layer symmetric angle-ply laminates.
As one of the important process alternatives for the synthesis of nano materials with lower costs... more As one of the important process alternatives for the synthesis of nano materials with lower costs, flexibility and versatility, vapor phase synthesis of titania nano particles continue to attract attention. A low temperature aerosol process for the synthesis of titania nano particles is demonstrated by elucidating the influence of temperature, molar ratio of H 2 O/TiCl 4 and concentration of precursors on particle size and phase composition. This paper highlights the advantages of employing amorphous phase titania powder as solid precursor for its transformation to the rutile phase at temperatures less than 973K through vapor phase hydrolysis of TiCl 4 . A mechanistic hypothesis is proposed to explain the catalytic role of water vapor in the enhancement of amorphous to anatase phase transformation at high (15 to 27) molar ratio of H 2 O/TiCl 4 .
Bending analysis of angle-ply laminates
The accuracy and the applicability of the higher-order theory developed by Savithri and Varadan (... more The accuracy and the applicability of the higher-order theory developed by Savithri and Varadan (1990) for the analysis of symmetric angle-ply laminates were assessed by comparing results obtained with this theory, which incorporates the continuity of transverse shear stresses at the interfaces, with results obtained with the smeared laminate theory of Reddy (1984). For this comparison a laminate plate is used which is composed of a finite number of anisotropic layers, each of which has only a single plane of elastic symmetry parallel to the XY plane; the plate is assumed to be simply supported on the boundaries and subjected to normal traction (q(X,Y)) on the upper surface. It was found that the new theory is highly accurate for symmetric laminates, and, for comparable accuracies, the computation cost is much less than that of the corresponding smeared laminate theory.
CFD Simulations of Electromagnetic stirring of melt alloys
Chaotic dynamics of a periodically forced slender body in a simple shear flow
Physics Letters A, 1994
ABSTRACT The dynamics of a periodically forced slender body in a simple shear flow is analysed. T... more ABSTRACT The dynamics of a periodically forced slender body in a simple shear flow is analysed. This represents the simplest case of a class of problems that have not attracted attention in the literature. The system undergoes a quasiperiodic transition to chaos in the range of parameters investigated. It also exhibits chaotic transients obtained by the apparent collision of a stable nonchaotic attractor and a chaotic attractor with the transients scaling in a manner similar to that analysed by Grebogi et al. [Ergodic Theory Dynamical Systems 5 (1985)341] with the exponent of scaling approximately equal to -0.5. The class of problems to which this paper is an introduction is technologically important and can lead to new methods of processing composites, electrorheological fluids and polymer solutions.