scholarly journals Will mixing rule or chemical reactions dominate the ash behavior of biomass mixtures in combustion processes on laboratory and pilot scales?

Fuel ◽  
2022 ◽  
Vol 308 ◽  
pp. 122050
Author(s):  
Emile Atallah ◽  
Françoise Defoort ◽  
Matthieu Campargue ◽  
Alexander Pisch ◽  
Capucine Dupont
Keyword(s):  
Chemical Reactions ◽  
Mixing Rule ◽  
Combustion Processes

Chemical Reactions and Gaseous Equilibrium

2003 ◽  
Vol 31 (1) ◽  
pp. 32-62
Author(s):  
J. D. Lewins
Keyword(s):  
Chemical Reactions ◽  
Chemical Equilibrium ◽  
Computer Programme ◽  
Gibbs Function ◽  
Explicit Formulae ◽  
Combustion Processes

The article gives a methodology for determining the direction of a reaction and the point where gaseous equilibrium exists, emphasising the minimum of the Gibbs function at chemical equilibrium. A new result is offered, Lewins' law on the effect of dilution and explicit formulae are given for some major reactions. The calculations involved can be readily performed with the aid of a computer programme. This approach is seen as particularly helpful for students of combustion processes who lack a chemistry background.

scholarly journals Role of Semenov’s Theory of Chain Reactions in the Formation of Modern Concepts on the Processes of Combustion, Explosion, and Detonation of Gases

2021 ◽  
Vol 15 (2) ◽  
pp. 278-284
Author(s):  
V. V. Azatyan
Keyword(s):  
Flame Propagation ◽  
Chemical Reactions ◽  
Atmospheric Pressure ◽  
Chemical Control ◽  
Experimental Studies ◽  
Decisive Role ◽  
Chain Reactions ◽  
Self Heating ◽  
Combustion Processes

Abstract This paper presents the results of the theoretical and experimental studies of ignition, flame propagation, explosion, and detonation of gases, showing that, contrary to previous concepts, chain mechanisms in combustion reactions play a decisive role not only at pressures tens of times lower than atmospheric pressure in the absence of self-heating but also at higher pressures and any temperature conditions. Examples of the chemical control of all these processes are given. At the same time, the results show the outstanding role of N.N. Semenov’s theory of chain reactions in the development of the theory of the rates of chemical reactions and combustion processes.

Surface reactions observed by photoemission electron microscopy (PEEM)

1992 ◽  
Vol 50 (1) ◽  
pp. 286-287
Author(s):  
H.H. Rotermund
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Work Function ◽  
Chemical Reactions ◽  
Reaction Diffusion ◽  
Dynamic Processes ◽  
Clean Surface ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Photoemission Electron

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.

Microwaves: Application in Electron Microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 140-141
Author(s):  
Anthony S-Y Leong ◽  
David W Gove
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Chemical Reactions ◽  
Electromagnetic Waves ◽  
Tissue Fixation ◽  
Primary Method ◽  
Dipolar Molecules ◽  
Wide Range ◽  
Time Required ◽  
Cryostat Sections

Microwaves (MW) are electromagnetic waves which are commonly generated at a frequency of 2.45 GHz. When dipolar molecules such as water, the polar side chains of proteins and other molecules with an uneven distribution of electrical charge are exposed to such non-ionizing radiation, they oscillate through 180° at a rate of 2,450 million cycles/s. This rapid kinetic movement results in accelerated chemical reactions and produces instantaneous heat. MWs have recently been applied to a wide range of procedures for light microscopy. MWs generated by domestic ovens have been used as a primary method of tissue fixation, it has been applied to the various stages of tissue processing as well as to a wide variety of staining procedures. This use of MWs has not only resulted in drastic reductions in the time required for tissue fixation, processing and staining, but have also produced better cytologic images in cryostat sections, and more importantly, have resulted in better preservation of cellular antigens.

Fine structure and properties of defects in naturally occurring silicates and oxides

1990 ◽  
Vol 48 (4) ◽  
pp. 460-461
Author(s):  
David R. Veblen
Keyword(s):  
Chemical Reactions ◽  
High Resolution Electron Microscopy ◽  
Extended Defects ◽  
Single Chain ◽  
Naturally Occurring ◽  
Resolution Electron ◽  
Fine Structures ◽  
Image Simulations ◽  
Similar Crystal Structure

Extended defects and interfaces control many processes in rock-forming minerals, from chemical reactions to rock deformation. In many cases, it is not the average structure of a defect or interface that is most important, but rather the structure of defect terminations or offsets in an interface. One of the major thrusts of high-resolution electron microscopy in the earth sciences has been to identify the role of defect fine structures in reactions and to determine the structures of such features. This paper will review studies using HREM and image simulations to determine the structures of defects in silicate and oxide minerals and present several examples of the role of defects in mineral chemical reactions. In some cases, the geological occurrence can be used to constrain the diffusional properties of defects.The simplest reactions in minerals involve exsolution (precipitation) of one mineral from another with a similar crystal structure, and pyroxenes (single-chain silicates) provide a good example. Although conventional TEM studies have led to a basic understanding of this sort of phase separation in pyroxenes via spinodal decomposition or nucleation and growth, HREM has provided a much more detailed appreciation of the processes involved.

Gum Arabic in Chemical Reactions

1883 ◽  
Vol 15 (366supp) ◽  
pp. 5844-5844
Author(s):  
MM. Jules Lefort ◽  
P. Thibault
Keyword(s):  
Chemical Reactions ◽  
Gum Arabic
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