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A User’s Guide

The demand for petroleum has risen rapidly due to increasing industrialization and modernization of the world. This economic development has led to a huge demand for energy, where the major part of that energy is derived from fossil sources such as petroleum, coal and natural gas. However, the limited reserve of fossil fuel has drawn the attention of many researchers to look for alternative fuels which can be produced from renewable feedstock. Biodiesel has become more attractive because of its environmental benefits and it is obtained from renewable resources. There are four primary methods to make biodiesel: blending, microemulsion, pyrolysis and transesterification. The most commonly used method is the transesterification of triglycerides (vegetable oil and animal fats) with alcohol in the presence of a catalyst. There is a growing interest in using Jatropha curcas L. oil as the feedstock for biodiesel production because it is non-edible and thus does not compromise the edible oils, which are mainly used for food consumption. Non-edible oils are not suitable for human consumption because of the presence of toxic components. Further, J. curcas L. seed has a high content of oil and the biodiesel produced has similar properties to that of petroleum-based diesel. In this paper, an attempt has been made to review the different approaches and techniques used to generate biodiesel from Jatropha curcas oil. The main factors affecting the biodiesel yield, for example the molar ratio of alcohol to oil, catalyst concentration, reaction temperature and reaction time are discussed. Lastly, the environmental considerations and economic aspects of biodiesel are also addressed.

/pdf/a-review-of-biodiesel-production-from-jatropha-curcas-l-oil-198dc8kg92.pdf

A review of biodiesel production from Jatropha curcas L. oil

https://web.ics.purdue.edu/~lqiao/Publications_files/Combustion%20characteristics%20of%20fuel%20droplets%20with%20addition%20of%20nano%20and%20micron-sized%20aluminum%20particles.pdf

Combustion characteristics of fuel droplets with addition of nano and micron-sized aluminum particles

A detailed chemical kinetic model has been used to study dimethyl ether (DME) oxidation over a wide range of conditions. Experimental results obtained in a jet-stirred reactor (JSR) at I and 10 atm, 0.2 < 0 < 2.5, and 800 < T < 1300 K were modeled, in addition to those generated in a shock tube at 13 and 40 bar, 0 = 1.0 and 650 :5 T :5 1300 K. The JSR results are particularly valuable as they include concentration profiles of reactants, intermediates and products pertinent to the oxidation of DME. These data test the Idnetic model severely, as it must be able to predict the correct distribution and concentrations of intermediate and final products formed in the oxidation process. Additionally, the shock tube results are very useful, as they were taken at low temperatures and at high pressures, and thus undergo negative temperature dependence (NTC) behavior. This behavior is characteristic of the oxidation of saturated hydrocarbon fuels, (e.g. the primary reference fuels, n-heptane and iso- octane) under similar conditions. The numerical model consists of 78 chemical species and 336 chemical reactions. The thermodynamic properties of unknown species pertaining to DME oxidation were calculated using THERM.

/pdf/wide-range-modeling-study-of-dimethyl-ether-oxidation-pnag57ojwu.pdf

Wide range modeling study of dimethyl ether oxidation

Modelling of fuel droplet heating and evaporation: Recent results and unsolved problems

Abstract Interactions of fuel-rich and fuel-lean mixtures and formation of interlinked multiple flame zones are observed in gas turbines and industrial furnaces. For fundamentally understanding such flames, numerical investigation of heat and mass transport, and chemical reaction processes, in laminar, counter flowing partially premixed rich and lean streams of methane and air mixtures, is presented. An axisymmetric numerical reactive flow model, with C2 detailed mechanism for describing methane oxidation in air and an optically thin radiation sub-model, is used in simulations. The numerical results are validated against the experimental results from literature. The equivalence ratios of counter flowing rich and lean reactant streams and the resulting strain rates have been varied. The effect of these parameters on the flame structure is presented. For a given rich and lean side equivalence ratios, by varying the strain rates, triple, double and single flame zones are obtained.

Numerical Parametric Studies of Laminar Flame Structures in Opposed Jets of Partially Premixed Methane-Air Streams

Due to recent interest in methanol economy, it is seen that a numerical study of combustion of methanol in a comprehensive manner is necessary. Motivated from this interest and based on the studies...

Numerical study of methanol flames in laminar forced convective environment using short chemical kinetics mechanism

Renewable and alternative fuels such as ethanol find application in several combustion devices. Fundamental characteristics of these fuels in terms of ignition and burning rate are to be understood in order to use them in these applications. In this study, a numerical analysis of auto ignition characteristics of ethanol is presented. Opposed flow configuration, in which fuel and nitrogen emerges from the bottom duct and hot air flows down from the top duct, has been employed. Commercial CFD software FLUENT is used in the simulations. Global single step mechanism is used to model kinetics. For various mass fractions of fuel, the air temperature at which auto-ignition occurs has been recorded. The numerical results are compared with the experimental data available in literature.

/pdf/numerical-analysis-of-auto-ignition-of-ethanol-5ku3ke7hnz.pdf

Numerical Analysis of Auto-ignition of Ethanol

A numerical investigation of the flame characteristics and mass burning rates of steady laminar diffusion flames established over methanol surface under co-flow configuration is presented. A numerical model that solves the transient, two-dimensional gas-phase governing conservation equations using global single-step reaction kinetics for methanol-air oxidation is employed for the present investigations. The effect of liquid-phase transport is neglected for the present quasi-steady burning process by assuming that the fuel pool is thin and its level is maintained constant by supplying fuel at a rate at which it is being consumed. Since the gas-phase combustion occurs following evaporation from the liquid fuel surface, appropriate interfacial boundary conditions are specified. The model is validated using experimental and numerical temperature profile data across a methanol flame for a particular co-flow configuration reported in literature. Thereafter, parametric investigations are carried out by varying the co-flow air velocity in the range of 0.05–0.75 m/s, keeping the fuel pool length as 20 mm. A detailed discussion of the effect of co-flow air velocity on the thermal and flow fields, as well as on the local and average mass burning rates, is presented. It is observed that as the co-flow air velocity is increased, the mass burning rate attains a minima at an intermediate velocity of around 0.4 m/s for the present configuration. The thermal and flow fields, variation of fuel vapor mass fraction normal to the interface and the diffusion of oxidizer into the flame zone are investigated at various co-flow velocities to explore and explain the flame characteristics.

Steady laminar flame characteristics over methanol surface with air co-flow

A case study to evaluate the thermo-physical properties and chemical kinetics parameters, which are employed to model the gas-phase combustion taking place over the surface of a condensed fuel, has been presented. This procedure relies on accurate experimental measurements of gaseous pyrolysis products. The pyrolysis gases can be treated as a virtual fuel, namely CxHyOz, where x, y, and z are estimated by performing atom balances for C, H, and O atoms in all the pyrolysis species. Thermo-physical properties of this virtual fuel are calculated based on the temperature and species concentration of the pyrolysis mixture. Similarly, based on the rate constant values of the reactant species present in the pyrolysis mixture, Arrhenius parameters such as pre-exponential factor and activation energy have been calculated. Polymethylmethacrylate (PMMA) is used as an example fuel in this study, and a step-by-step procedure for the estimation of the thermo-physical properties and global reaction kinetics parameters o...

Vasudevan Raghavan

Papers

Numerical Parametric Studies of Laminar Flame Structures in Opposed Jets of Partially Premixed Methane-Air Streams

Numerical study of methanol flames in laminar forced convective environment using short chemical kinetics mechanism

Numerical Analysis of Auto-ignition of Ethanol

Steady laminar flame characteristics over methanol surface with air co-flow

An estimation of modelling parameters for condensed multi-component fuels