A Thermodynamic Analysis of the Lean Flammability Limits of Fuel-Diluent Mixtures in Air

1994 ◽  
Vol 116 (3) ◽  
pp. 181-185 ◽  
Author(s):  
I. Wierzba ◽  
S. O. Bade Shrestha ◽  
G. A. Karim
Keyword(s):  
Thermodynamic Analysis ◽  
Initial Mixture ◽  
Flammability Limits ◽  
Temperature Range ◽  
Gaseous Fuels ◽  
Wide Range ◽  
Predicted Values ◽  
Experimental Values ◽  
Good Agreement

A procedure is described for calculating the lean flammability limits of fuel-diluent mixtures in air over a wide range of fuel-diluent combinations and for different initial mixture temperatures. Good agreement is shown to exist between the predicted values of the limits with the corresponding experimental values for some common gaseous fuels that include CH4, C2H6, C2H4, C3H8, C4H10, H2, and CO and the diluents CO2, N2, He, and Ar over the temperature range of −60°C up to 400°C.

An Analytical Examination of the Combustion of a Turbulent Jet in an Environment of Air Containing a Premixed Fuel or a Diluent

1995 ◽  
Vol 117 (3) ◽  
pp. 234-238 ◽  
Author(s):  
P. Wierzba ◽  
G. A. Karim ◽  
I. Wierzba
Keyword(s):  
Flame Length ◽  
Turbulent Jet ◽  
Simple Analytical Model ◽  
Flammability Limits ◽  
Gaseous Fuels ◽  
Gaseous Environment ◽  
Fuel Jet ◽  
Predicted Values ◽  
Experimental Values ◽  
Good Agreement

A simple analytical model for the mixing and combustion of an axisymmetric turbulent gaseous fuel jet discharging into a co-flowing streaming gaseous environment of an auxiliary fuel and/or a diluent homogeneously mixed with air is presented. A number of gaseous fuels and diluents are considered. It is shown that the combustion characteristics of a fuel jet can be modified significantly by the presence of a relatively small amount of a fuel in the surrounding air at concentrations well below the corresponding local flammability limits. Correlative procedures are presented for estimating changes in the flame length, the size of the combustion zone, and the blowout limits with changes in the type and concentration of the fuel in the surroundings. Predicted values showed generally good agreement with the corresponding experimental values.

A Thermodynamic Analysis of the Rich Flammability Limits of Fuel-Diluent Mixtures in Air

1995 ◽  
Vol 117 (3) ◽  
pp. 239-242 ◽  
Author(s):  
S. O. Bade Shrestha ◽  
I. Wierzba ◽  
G. A. Karim
Keyword(s):  
Atmospheric Temperature ◽  
Flammability Limit ◽  
Flammability Limits ◽  
Wide Range ◽  
Temperature And Pressure ◽  
The Rich ◽  
Predicted Values ◽  
Experimental Values ◽  
Good Agreement ◽  
Propane Butane

A simple approach is described for the calculation of the rich flammability limits of fuel-diluent mixtures in air for a wide range of initial temperatures based only on the knowledge of the flammability limit of the pure fuel in air at atmospheric temperature and pressure conditions. Various fuel-diluent mixtures that include the fuels methane, ethylene, ethane, propane, butane, carbon monoxide, and hydrogen, and the diluents nitrogen, carbon dioxide, helium, and argon have been considered. Good agreement is shown to exist between predicted values of the rich flammability limits and the corresponding available experimental values for the fuel-diluent mixtures.

A Predictive Approach for the Flammability Limits of Methane-Nitrogen Mixtures

1990 ◽  
Vol 112 (4) ◽  
pp. 251-253 ◽  
Author(s):  
I. Wierzba ◽  
G. A. Karim
Keyword(s):  
Natural Gas ◽  
Simple Procedure ◽  
Fuel Mixture ◽  
Flammability Limits ◽  
Present Contribution ◽  
Wide Range ◽  
Predictive Approach ◽  
Experimental Values ◽  
Good Agreement

The present contribution describes a relatively simple procedure for predicting the lean and rich flammability limits of methane-nitrogen mixtures in air from a knowledge of the composition of the fuel mixture and the corresponding limit for methane. It is shown that this approach can be extended similarly to consider the limits of natural gas-nitrogen mixtures yielding relatively good agreement with experimental values over a relatively wide range of composition and pressure.

scholarly journals DFT calculation and assignment of vibrational spectra of aryl and alkyl chlorophosphates

2014 ◽  
Vol 12 (2) ◽  
pp. 153-163
Author(s):  
Viktor Anishchenko ◽  
Vladimir Rybachenko ◽  
Konstantin Chotiy ◽  
Andrey Redko
Keyword(s):  
Vibrational Spectra ◽  
Basis Sets ◽  
Heavy Atoms ◽  
Wide Range ◽  
Complete Assignment ◽  
Key Factor ◽  
Polarization Functions ◽  
Experimental Values ◽  
Semi Empirical ◽  
Good Agreement

AbstractDFT calculations of vibrational spectra of chlorophosphates using wide range of basis sets and hybrid functionals were performed. Good agreement between calculated and experimental vibrational spectra was reached by the combination of non-empirical functional PBE0 with both middle and large basis sets. The frequencies of the stretching vibrations of the phosphate group calculated using semi-empirical functional B3LYP for all basis sets deviate significantly from the experimental values. The number of polarization functions on heavy atoms was shown to be a key factor for the calculation of vibrational frequencies of organophosphates. The importance of consideration of all the stable rotamers for a complete assignment of fundamental modes was shown.

Experimental and Computational Determination of LBV of Hydrogen Enriched Methane Mixtures

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Vinod Kumar Yadav ◽  
Ranjeet Singha ◽  
Abhishek Kumar Pandey ◽  
Saumya   ◽  
Ashish Kumar Singh ◽  
...  
Keyword(s):  
Coming Out ◽  
Burning Velocity ◽  
Laminar Burning Velocity ◽  
Flammability Limits ◽  
Ambient Temperatures ◽  
Gaseous Fuels ◽  
Wide Range ◽  
Hydrogen Enrichment ◽  
Institute Of Technology ◽  
Set Up

One of the major causes of environmental pollution and ozone layer depletion is the emissions coming out of the combustion devices including industrial burners, automobile vehicles and household appliances. Most of the conventional fuels used now days have high GWP and ODP. So the greatest challenges among the combustion researchers and scientists are to develop some sustainable and non conventional sources of energy that possesses capability to replace the conventional ones. One of the important gaseous fuels in non conventional category is hydrogen, which is a cleaner fuel and reduces pollution enormously. In the present work, experimental & computational analysis of laminar burning velocity (LBV) of premixed gaseous fuels (primary focus on Hydrogen enrichment) was carried out. For experimental investigation the experimental set up available in Fuel and pollution lab of Indian Institute of Technology Delhi is used. Experiments were carried out on mixtures of methane- Air and Methane-Hydrogen-Air for wide range of equivalence ratios and compared with the computational results of PREMIX with full GRI-Mech 3.0 mechanism. Most of the experiments available in literature were carried out at 298 K. In the present work it has been tried to relate the effect of low temperatures on laminar burning velocity of mixtures. The experiments have been conducted at 1 bar pressure and around 292 Kelvin with equivalence ratio ranging from 0.8 to 1.2. Methane gas is enriched with hydrogen in varying proportions and the effect of hydrogen enrichment on its laminar burning velocity studied. The objective of the addition of hydrogen to methane was to increase its laminar burning velocity as well as to extend its lean flammability limits at lower ambient temperatures.

Transition from dripping to jetting

1999 ◽  
Vol 383 ◽  
pp. 307-326 ◽  
Author(s):  
CHRISTOPHE CLANET ◽  
JUAN C. LASHERAS
Keyword(s):  
Weber Number ◽  
Free Edge ◽  
Newtonian Liquid ◽  
Inviscid Limit ◽  
Inertia Effects ◽  
Wide Range ◽  
Critical Weber Number ◽  
Experimental Values ◽  
Outside Diameter ◽  
Good Agreement

We consider the critical Weber number (Wec≡ ρV20D/σ) at which the transition from dripping to jetting occurs when a Newtonian liquid of density ρ and surface tension σ is injected with a velocity V0 through a tube of diameter D downward into stagnant air, under gravity g. We extend Taylor's (1959) model for the recession speed of a free edge, and obtain in the inviscid limit an exact solution which includes gravity and inertia effects. This solution provides a criterion for the transition which is shown to occur at a critical Weber numberformula herewhere Bo and Boo are the Bond numbers (Bo≡[ρgD2/(2σ)]1/2), respectively based on the inside and outside diameter of the tube, and K is a constant equal to 0.37 for the case of water injected in air. This critical Weber number is shown to be in good agreement with existing experimental values as well as with new measurements performed over a wide range of Bond numbers.

scholarly journals Effects of Parameters on Solvent Extraction of Oil From Sandbox (Hura Crepitans) Seed Oil Using 2^4 Factorial Design

2021 ◽  
Vol 15 ◽  
pp. 48-55
Author(s):  
Owhor Sampson Chisa ◽  
J. D. Amine ◽  
Abdul Gambo Alim ◽  
Luka Bobby Shakarau ◽  
Isaiah Kehinde Ogbobame ◽  
...  
Keyword(s):  
Solvent Extraction ◽  
Seed Oil ◽  
Hydraulic Press ◽  
Biodiesel Production ◽  
Extraction Temperature ◽  
Physiochemical Properties ◽  
Hura Crepitans ◽  
Predicted Values ◽  
Experimental Values ◽  
Good Agreement

The present work deals with the production of biodiesel from Sandbox (Hura crepitans) seed oil and the optimization of the parameters that influence the transesterification of Sandbox (Hura crepitans)seed oil into biodiesel using Response Surface Methodology. Hura crepitans oil was obtained from by using hydraulic press for Mechanical and n-hexane for solvent extraction. Esterification was done using methanol and sodium hydroxide. A total of 48 experiments using Central Composite Design were carried out. The R-Squared, Adequate Precision, Predicted and Adjusted R-Squared values were 0.9367, 19.219, 0.8576 and 0.9070 respectively. The result of the extraction of oil, physiochemical properties, and optimization process shows that sandbox (Hura crepitans) seed oil has characteristics that are more favorable to biodiesel production. The optimal conditions for extraction of oil from sandbox seed oil were given as alcohol/ oil ratio of 5.0, catalyst amount of 20 g/ml, extraction temperature of 60 ºC, and extraction time of 45.01 minutes, with the predicted oil yield as 97.33% respectively which shows that the experimental values are in good agreement with predicted values.

Liquid side mass transfer coefficient and interfacial area at vertical liquid flow on expended metal sheet packing

1980 ◽  
Vol 45 (11) ◽  
pp. 3089-3100 ◽  
Author(s):  
Zdeněk Brož ◽  
Mirko Endršt
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Liquid Flow ◽  
Empirical Relation ◽  
Interfacial Area ◽  
Expanded Metal ◽  
Wide Range ◽  
Predicted Values ◽  
Good Agreement

Prediction of the liquid side mass transfer coefficient k1 at vertical liquid flow on the expanded metal packing is based on the penetration model according to Higbie. The experimental value of mass transfer coefficient k1 at absorption of sparingly soluble gases with differing diffusivities in water (propane, carbon dioxide and helium) are in a good agreement with the predicted values in a wide range of linear wetting densities. Interfacial area is determined by the chemical method and is correlated by an empirical relation.

VLE Determination of Carbon Dioxide Loaded Aqueous Alkanolamine Mixtures Using Modified Kent Eisenberg Model

2017 ◽  
Vol 231 (11-12) ◽  
Author(s):  
Humbul Suleman ◽  
Abdulhalim Shah Maulud ◽  
Zakaria Man
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Model Parameters ◽  
Thermodynamic Models ◽  
Carbon Dioxide Absorption ◽  
Proposed Model ◽  
Wide Range ◽  
Experimental Values ◽  
Good Agreement

AbstractA computationally simple thermodynamic framework has been presented to correlate the vapour-liquid equilibria of carbon dioxide absorption in five representative types of alkanolamine mixtures. The proposed model is an extension of modified Kent Eisenberg model for the carbon dioxide loaded aqueous alkanolamine mixtures. The model parameters are regressed on a large experimental data pool of carbon dioxide solubility in aqueous alkanolamine mixtures. The model is applicable to a wide range of temperature (298–393 K), pressure (0.1–6000 kPa) and alkanolamine concentration (0.3–5 M). The correlated results are compared to the experimental values and found to be in good agreement with the average deviations ranging between 6% and 20%. The model results are comparable to other thermodynamic models.

An Analytical Examination of the Behavior of Oil Sand Fragments in Heated Streams

1982 ◽  
Vol 104 (2) ◽  
pp. 121-129
Author(s):  
A. Hanafi ◽  
G. A. Karim
Keyword(s):  
Analytical Study ◽  
Chemical Processes ◽  
Operating Conditions ◽  
Transient Effects ◽  
Oil Sand ◽  
Wide Range ◽  
Experimental Values ◽  
Physical And Chemical ◽  
Simultaneous Heat ◽  
Good Agreement

The physical and chemical processes that occur typically within and around an oil sand fragment are considered when the fragment is suddenly introduced into a hot, low-uniform velocity, gaseous oxidizing stream. In this analytical study, the extent of bitumen volatilization was obtained from a consideration of the simultaneous heat and mass transfer within spherical oil sand fragments combined with a simplified cracking scheme of the heavy oil and asphaltene into coke and distillate. The resulting system of equations together with the boundary conditions arising from subjecting the fragments to hot convective streams were solved using Laplace transformation. The transient concentrations of bitumen and temperature within the fragments were then obtained under a wide range of operating conditions. The similarity of the expression obtained for the extent of bitumen volatilization to the expression derived from simplified analysis, based on a dropletlike model, was demonstrated for cases where the transient effects within the fragments were considered to be negligible. The results of the theoretical analysis show relatively good agreement with their corresponding experimental values at high stream temperatures, while they showed relatively inferior agreement at low temperatures.

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