The Transfer Number of Hydrocarbon Liquids

1992 ◽  
Vol 114 (2) ◽  
pp. 346-352
Author(s):  
J. Odgers ◽  
D. Kretschmer
Keyword(s):  
Operating Conditions ◽  
Liquid Fuels ◽  
Transfer Number ◽  
Critical Temperatures ◽  
Combustion Behavior ◽  
Specific Heats ◽  
Wide Range ◽  
Prediction Techniques ◽  
Latent Heats ◽  
And Diffusion

The transfer number (B) assumes considerable importance in the evaporation and diffusion of fuels prior to their combustion. Quite often the transfer number is assumed to be a constant for a given fuel. These notes examine the feasibility of this assumption. New correlations have been derived for the specific heats of the liquid fuels and their latent heats, over a wide range of temperatures and pressures, as also the effects of pressure upon the boiling characteristics. New prediction techniques are also proposed for critical temperatures and pressures. Taking note of the above correlations, it becomes possible to assess the values of B for a wide range of combustor operating conditions for any given fuel. The significance of these variations upon the probable combustion behavior of the fuels is then commented upon. The results show that the assumption of a constant value for B could lead to a significant misinterpretation of combustion behavior due to operating conditions and/or the use of different fuels.

The Transfer Number of Hydrocarbon Liquids

1991 ◽  
Author(s):  
J. Odgers ◽  
D. Kretschmer
Keyword(s):  
Operating Conditions ◽  
Liquid Fuels ◽  
Considerable Importance ◽  
Transfer Number ◽  
Critical Temperatures ◽  
Specific Heats ◽  
Wide Range ◽  
Prediction Techniques ◽  
Latent Heats ◽  
And Diffusion

The Transfer Number (B) assumes considerable importance in the evaporation and diffusion of fuels prior to their combustion. Quite often the Transfer Number is assumed to be a constant for a given fuel. These notes examine the feasibility of this assumption New correlations have been derived for the specific heats of the liquid fuels and their latent heats, over a wide range of temperatures and pressures, as also the effects of pressure upon the boiling characteristics. New prediction techniques are also proposed for critical temperatures and pressures. Taking note of the above correlations, it becomes possible to assess the values of B for a wide range of combustor operating conditions for any given fuel. The significance of these variations upon the probable combustion behaviour of the fuels is then commented upon. The results show that the assumption of a constant value for B could lead to a significant mis-interpretation of combustion behaviour due to operating conditions and/or the use of different fuels.

CFD Analysis of Turbec T100 Combustor at Part Load by Varying Fuels

2015 ◽  
Author(s):  
Raffaela Calabria ◽  
Fabio Chiariello ◽  
Patrizio Massoli ◽  
Fabrizio Reale
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Combustion Process ◽  
Calorific Value ◽  
Operating Conditions ◽  
Liquid Fuels ◽  
Cfd Analysis ◽  
Part Load ◽  
Gaseous Fuels ◽  
Wide Range

In recent years an increasing interest is focused on the study of micro gas turbines (MGT) behavior at part load by varying fuel, in order to determine their versatility. The interest in using MGT is related to the possibility of feeding with a wide range of fuels and to realize efficient cogenerative cycles by recovering heat from exhaust gases at higher temperatures. In this context, the studies on micro gas turbines are focused on the analysis of the machine versatility and flexibility, when operating conditions and fuels are significantly varied. In line of principle, in case of gaseous fuels with similar Wobbe Index no modifications to the combustion chamber should be required. The adoption of fuels whose properties differ greatly from those of design can require relevant modifications of the combustor, besides the proper adaptation of the feeding system. Thus, at low loads or low calorific value fuels, the combustor becomes a critical component of the entire MGT, as regards stability and emissions of the combustion process. Focus of the paper is a 3D CFD analysis of the combustor behavior of a Turbec T100P fueled at different loads and fuels. Differences between combustors designed for natural gas and liquid fuels are also highlighted. In case of natural gas, inlet combustor temperature and pressure were taken from experimental data; in case of different fuels, such data were inferred by using a thermodynamic model which takes into account rotating components behavior through operating maps of compressor and turbine. Specific aim of the work is to underline potentialities and critical issues of the combustor under study in case of adoption of fuels far from the design one and to suggest possible solutions.

The Combustion of Droplets Within Gas Turbine Combustors Some Recent Observations on Combustion Efficiency

1992 ◽  
Author(s):  
J. Odgers ◽  
D. Kretschmer ◽  
G. F. Pearce
Keyword(s):  
Experimental Data ◽  
Droplet Size ◽  
Gas Turbines ◽  
Research Laboratory ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
Transfer Number ◽  
Wide Range ◽  
Inlet Conditions ◽  
Experimental Values

For many years investigators studying the combustion behaviour within gas turbines have presumed droplet size to play a very important role in defining combustion efficiency. Recently a very large number of experiments have been conducted jointly by Laval University and the Aeronautical Research Laboratory in Melbourne. In the course of these investigations, over a wide range of operating conditions, a single combustor has been investigated using three different Simplex atomisers at each of the conditions for three fuels. In addition, the same combustor has been used to investigate a very wide range of fuels (87) at ambient inlet conditions. The measured combustion efficiencies show no measurable effects due to droplet size, although volatility effects have been noted (measured as TAV). It is thought that these effects are reflected in terms of a Transfer Number and related to diffusional phenomena, rather than evaporative phenomena. A great number of experimental data are reviewed, and in addition to showing the absence of effects of droplets, a small section deals with the precision of experimental values of combustion efficiency and how it might influence models predicting combustion efficiency, especially with respect to possible future pollution requirements.

Influence of Liquid and Gaseous Fuel on Lifted Flames at Elevated Pressure Stabilized by Outer Recirculation

2014 ◽  
Author(s):  
Julia Sedlmaier ◽  
Peter Habisreuther ◽  
Nikolaos Zarzalis ◽  
Peter Jansohn
Keyword(s):  
Elevated Pressure ◽  
Operating Conditions ◽  
Liquid Fuels ◽  
Reacting Flow ◽  
Ratio Distribution ◽  
Wide Range ◽  
Lifted Flames ◽  
Lift Off ◽  
Safety Considerations ◽  
The Impact

Lifting a flame from the flow generating nozzle to some distance apart has a wide variety of effects on the properties of the resulting combustion phenomenon. The reason of this influence is the generation of a non-reacting flow domain where mixing takes place prior to the combustion reaction. It is obvious that the quality of premixing that can be achieved strongly depends on the time that is given to flow and the intensity of the turbulence that is mixing fuel and air. The most important parameter that is characterizing this time is the size of the premixing zone quantified by the so called lift-off height (LOH). Additionally, when employing liquid fuel the lift-off of a flame provides time to achieve better pre-evaporation of the fuel. As a consequence, better mixing of fuel and air helps to avoid high temperature regions that may be a result from an inhomogeneous equivalence ratio distribution. From safety considerations a major advantage of this method compared to the application of a premixing duct is that the risk of hardware destruction by flame flash back can be eliminated. The current work extents the knowledge on lifted flames by the investigation of flames that are generated with an airblast atomizing nozzle that was designed to resemble systems close to application. Lifting of the flame is achieved applying a combination of swirling and non-swirling inflow ducts. A wide range of operating conditions as well as gaseous and liquid fuels are used to investigate their influence on the lift-off height. The lift-off height and location of the reaction zone was determined by means of chemiluminescence of OH* and it is shown, that the impact of pressure drop and preheating temperature on the LOH is different for gaseous and liquid fuels.

The Combustion of Droplets Within Gas Turbine Combustors: Some Recent Observations on Combustion Efficiency

1993 ◽  
Vol 115 (3) ◽  
pp. 522-532 ◽  
Author(s):  
J. Odgers ◽  
D. Kretschmer ◽  
G. F. Pearce
Keyword(s):  
Experimental Data ◽  
Droplet Size ◽  
Gas Turbines ◽  
Research Laboratory ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
Transfer Number ◽  
Wide Range ◽  
Inlet Conditions ◽  
Experimental Values

For many years investigators studying the combustion behavior within gas turbines have presumed droplet size to play a very important role in defining combustion efficiency. Recently a very large number of experiments have been conducted jointly by Laval University and the Aeronautical Research Laboratory in Melbourne. In the course of these investigations, over a wide range of operating conditions, a single combustor has been investigated using three different Simplex atomizers at each of the conditions for three fuels. In addition, the same combustor has been used to investigate a very wide range of fuels (87) at ambient inlet conditions. The measured combustion efficiencies show no measurable effects due to droplet size, although volatility effects have been noted (measured as TAV). It is thought that these effects are reflected in terms of a transfer number and related to diffusional phenomena, rather than evaporative phenomena. A great number of experimental data are reviewed, and in addition to showing the absence of effects of droplets, a small section deals with the precision of experimental values of combustion efficiency and how it might influence models predicting combustion efficiency, especially with respect to possible future pollution requirements.

Analysis of Water Transport in Proton Exchange Membranes Using a Phenomenological Model

2005 ◽  
Vol 2 (3) ◽  
pp. 149-155 ◽  
Author(s):  
P. C. Sui ◽  
Ned Djilali
Keyword(s):  
Transport Properties ◽  
Water Transport ◽  
Phenomenological Model ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Design Parameters ◽  
Wide Range ◽  
Exchange Membrane ◽  
And Diffusion

An investigation of water transport across the membrane of a proton exchange membrane fuel cell is performed to gain further insight into water management issues and the overall behavior of a representative phenomenological model. The model accounts for water transport via electro-osmotic drag and diffusion and is solved using a finite volume method for a one-dimensional isothermal system. Transport properties including the water drag and diffusion coefficients and membrane ionic conductivity are expressed as functions of water content and temperature. An analytical solution based on a generalized form of the transport properties is also derived and used to validate the numerical solutions. The effects of property variations on the water flux across the membrane and on the overall membrane protonic conductivity are analyzed. The balance between transport via electro-osmotic drag and diffusion depends not only on operating conditions, such as current density and relative humidity at the membrane boundaries, but also on design parameters, such as membrane thickness and membrane material. Computed water fluxes for different humidity boundary conditions indicate that for a thick membrane (e.g., Nafion 117), electro-osmotic drag dominates the transport over a wide range of operating conditions, whereas for a thin membrane (e.g., Nafion 112), diffusion of water becomes equally important under certain humidification conditions and current densities. Implications for the resolution of membrane transport in CFD-based models of proton exchange membrane fuel cells are also discussed.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

Nitrogen Removal from Anaerobically-Treated Leachate

1984 ◽  
Vol 19 (1) ◽  
pp. 87-100
Author(s):  
D. Prasad ◽  
J.G. Henry ◽  
P. Elefsiniotis
Keyword(s):  
Nitrogen Removal ◽  
Air Flow ◽  
Operating Conditions ◽  
Air Flow Rate ◽  
Flow Rates ◽  
Anaerobic Filter ◽  
Ph Values ◽  
Wide Range ◽  
Ammonia Desorption ◽  
Effects Of Ph

Abstract Laboratory studies were conducted to demonstrate the effectiveness of diffused aeration for the removal of ammonia from the effluent of an anaerobic filter treating leachate. The effects of pH, temperature and air flow on the process were studied. The coefficient of desorption of ammonia, KD for the anaerobic filter effluent (TKN 75 mg/L with NH3-N 88%) was determined at pH values of 9, 10 and 11, temperatures of 10, 15, 20, 30 and 35°C, and air flow rates of 50, 120, and 190 cm3/sec/L. Results indicated that nitrogen removal from the effluent of anaerobic filters by ammonia desorption was feasible. Removals exceeding 90% were obtained with 8 hours aeration at pH of 10, a temperature of 20°C, and an air flow rate of 190 cm3/sec/L. Ammonia desorption coefficients, KD, determined at other temperatures and air flow rates can be used to predict ammonia removals under a wide range of operating conditions.

scholarly journals Applications of Biocatalysts for Sustainable Oxidation of Phenolic Pollutants: A Review

2021 ◽  
Vol 13 (15) ◽  
pp. 8620
Author(s):  
Sanaz Salehi ◽  
Kourosh Abdollahi ◽  
Reza Panahi ◽  
Nejat Rahmanian ◽  
Mozaffar Shakeri ◽  
...  
Keyword(s):  
Phenolic Compounds ◽  
Operating Conditions ◽  
Phenolic Pollutants ◽  
Petroleum Refinery Wastewater ◽  
Start Up ◽  
Low Concentrations ◽  
Effective Removal ◽  
Wide Range ◽  
Loading Effects ◽  
Spent Caustic

Phenol and its derivatives are hazardous, teratogenic and mutagenic, and have gained significant attention in recent years due to their high toxicity even at low concentrations. Phenolic compounds appear in petroleum refinery wastewater from several sources, such as the neutralized spent caustic waste streams, the tank water drain, the desalter effluent and the production unit. Therefore, effective treatments of such wastewaters are crucial. Conventional techniques used to treat these wastewaters pose several drawbacks, such as incomplete or low efficient removal of phenols. Recently, biocatalysts have attracted much attention for the sustainable and effective removal of toxic chemicals like phenols from wastewaters. The advantages of biocatalytic processes over the conventional treatment methods are their ability to operate over a wide range of operating conditions, low consumption of oxidants, simpler process control, and no delays or shock loading effects associated with the start-up/shutdown of the plant. Among different biocatalysts, oxidoreductases (i.e., tyrosinase, laccase and horseradish peroxidase) are known as green catalysts with massive potentialities to sustainably tackle phenolic contaminants of high concerns. Such enzymes mainly catalyze the o-hydroxylation of a broad spectrum of environmentally related contaminants into their corresponding o-diphenols. This review covers the latest advancement regarding the exploitation of these enzymes for sustainable oxidation of phenolic compounds in wastewater, and suggests a way forward.

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