scholarly journals The Influence of Small Additives of Alcohol Vapors on Combustion of Hydrogen and Methane in Air

2017 ◽  
Vol 6 (3) ◽  
pp. 171 ◽  
Author(s):  
V.V. Azatyan ◽  
I.A. Bolodiyan ◽  
S.N. Kopilov ◽  
Yu.N. Shebeko ◽  
V.I. Kalachev
Keyword(s):  
Flame Propagation ◽  
Methane Combustion ◽  
Horizontal Tubes ◽  
Upper Limits ◽  
The Difference ◽  
Combustion Processes ◽  
Suppression Of Combustion ◽  
Combustion Of Hydrogen

The results of investigation of combustion of hydrogen-air and methane-air mixtures in the presence of small additives of ethanol, isopropanol, propenol in horizontal tubes are presented. The additives reduce the upper limits of flame propagation and the rate of flame propagation. The difference of inhibiting efficiencies<br />of these alcohols corresponds to their ability to break the reaction chains of hydrogen and methane combustion processes. In the mixtures, containing less than 15% of hydrogen the suppression of combustion does not occur.

A Comparative Study of Methane Combustion Characteristics with Different Additions in an Optical SI Engine

2021 ◽  
Author(s):  
Lin Chen ◽  
Xiao Zhang ◽  
Ren Zhang ◽  
Wanhui Zhao
Keyword(s):  
Natural Gas ◽  
Flame Propagation ◽  
Power Output ◽  
High Speed ◽  
Propagation Speed ◽  
Pressure Oscillation ◽  
Methane Combustion ◽  
Natural Gas Engines ◽  
Auto Ignition ◽  
Flame Propagation Speed

Abstract Natural gas is a promising fuel for IC engines with minimal modification, whereas its low power output and slow flame propagation speed remain a challenge for automobile manufacturers. To find a method of improving the natural gas engines, methane combustion with different additions was comparatively studied. High-speed direct photography and simultaneous pressure were performed to capture detailed combustion evolutions. First, the results of pure methane combustion confirm its good anti-knock property, and no pressure oscillation occurs even there is an end-gas auto-ignition, indicating that high compression ratio and high boosting are effective ways to improve the performance of natural gas engines. Second, adding heavy hydrocarbons can greatly improve engines' power output, but engine knock should be considered if low anti-knock fuel was used. Third, as a carbon-free and gaseous fuel, hydrogen addition can not only increase methane flame propagation speed but reduce cyclic variations. However, a proper fraction is needed under different load conditions. Last, oxygen-enriched combustion is an effective way to promote methane combustion. The heat release becomes faster and more concentrated, specifically, the flame propagation speed can be increased by more than 2 times under 27% oxygen concentration condition. The current study shall give insights into improving natural gas engines' performance.

scholarly journals Residual Agroforestry Biomass–Thermochemical Properties

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1072 ◽  
Author(s):  
Teresa Enes ◽  
José Aranha ◽  
Teresa Fonseca ◽  
Carlos Matos ◽  
Ana Barros ◽  
...  
Keyword(s):  
Trace Elements ◽  
Elemental Analysis ◽  
Fossil Fuels ◽  
Chemical Properties ◽  
Mineral Elements ◽  
Agricultural Wastes ◽  
Heating Value ◽  
Corrosive Effect ◽  
The Difference ◽  
Combustion Processes

Research Highlights: Biomass from Mediterranean agroforestry vegetation may be a potential source of renewable energy. However, due to the high heterogeneity of this type of resource, the study of its characteristics becomes necessary for its efficient use. Objectives: The aim of this study was to evaluate the thermal and chemical properties of 14 different kinds of agroforestry biomass groups: shrubs, forest, and agricultural wastes. Materials and Methods: The higher heating value (HHV), the elemental analysis (C, H, O, N, S), ashes, mineral elements (Na, K, Ca, Mg, and P), trace elements (Mn, Fe, Zn, Ni, Cu, Cr, and Cd) and halogen elements (F and Cl) were quantified and compared with CEN/TS 147775 and CENS/TS 14961 standards, looking forward to future use for energy purposes, namely through combustion processes, as an alternative to fossil fuels. Results: The shrubs present the highest values of higher heating value (20.5 MJ kg−1), followed by the forest wastes (19.2 MJ kg−1) and the lowest in the agricultural wastes (18.5 MJ kg−1). Concerning the elemental analysis, the difference between groups C, H, and O are very small and not statistically significant, while for N, S and ashes values are higher in agricultural than shrubs and forestry wastes. The same tendency was found for the mineral nutrients. For the trace elements, the lowest content of Mn, Fe, and Zn is found in agricultural, Ni, and Cr content in the shrubs and Cu in the forest wastes. The halogen elements are present in greater amount in shrubs than agricultural and forest wastes. Conclusions: Although the high values of the halogen elements which may raise sintering problems and corrosive effect on metal parts in furnace and boiler, in general the shrubs biomass are those with better characteristics for energy uses, namely through combustion processes.

Gas penetration, flame propagation, and combustion processes in solid propellant cracks

1980 ◽  
Author(s):  
M. KUMAR ◽  
S. KOVACIC ◽  
K. KUO
Keyword(s):  
Flame Propagation ◽  
Solid Propellant ◽  
Combustion Processes ◽  
Gas Penetration

scholarly journals Studies on enzyme action. XXIV.—The oxidase effect and the phenomena of oxidation in general: Carbonic oxide

1925 ◽  
Vol 98 (688) ◽  
pp. 202-206
Keyword(s):  
Potassium Iodide ◽  
Stages Of Change ◽  
Linseed Oil ◽  
Chemical Society ◽  
Memorial Lecture ◽  
Platinum Surface ◽  
French Academy ◽  
Per Se ◽  
The Difference ◽  
Combustion Of Hydrogen

In 1904 I presented a brief communication to the Society on “ The Retardation of Combustion by Oxygen ” (‘ Proceedings,’ vol. 74, p. 86). Friends smiled at the title and no notice has been taken of my argument. Of late years, however, Moureu and his fellow-workers have brought before the French Academy a series of masterly studies of the inhibition of the oxidation of highly oxidisable materials, such as acrolein and linseed oil, by substances which are themselves oxidisable, including phenol and potassium iodide. The explanation they have put forward, involving the recognition of an active antagonism between peroxides, which constitute a reversing mechanism, is essentially that I have long held, the difference being mainly that I have gone more fully into the details of the process. In a recent fascinating brief communication to the Chemical Society (‘ Chem. Soc. Journ.,’ 1925, p. 1), Moureu and Dufraisse discuss the stoppage, by carbonic oxide, of the interaction of hydrogen and oxygen, at a platinum surface, contending that this also is an instance of inhibition owing to the antagonism of incompatible “ peroxides,” formed in the initial stages of change. I fully share their views and regard this communication as the settlement of a problem of prime importance which has been open to solution since early in last century (1833). I have discussed the peculiar “ indifferent ” behaviour of carbonic oxide on many occasions before the Society and elsewhere. I would now take one further and perhaps final step, and proclaim it to be per se an incombustible gas. If the process of combustion be, as I have frequently argued, one in which an electrolytic determinant is concerned (comp. First Messel Memorial Lecture, ‘ Soc. Chem. Ind.,’ 1922, pp. 253-270T), primarily as represented by the schematic equation it is one involving the electrolysis of water, and the “ energy ” developed in the interaction must be at least equal to that involved in the combustion of hydrogen. Actually, the heat of combustion of carbonic oxide is below that of hydrogen (67960 : 68360).

A Ceramic-Membrane-Based Methane Combustion Reactor With Tailored Function of Simultaneous Separation of Carbon Dioxide From Nitrogen

2014 ◽  
Author(s):  
Ryan Falkenstein-Smith ◽  
Kang Wang ◽  
Pingying Zeng ◽  
Jeongmin Ahn
Keyword(s):  
Membrane Reactor ◽  
Catalytic Combustion ◽  
Ceramic Membrane ◽  
Methane Combustion ◽  
Pure Oxygen ◽  
Conversion Rates ◽  
Dry Pressing ◽  
Catalytic Combustion Of Methane ◽  
Combustion Processes ◽  
Combustion Reactor

Today, industry has become more dependent on natural gases and combustion processes, creating a tremendous pressure to reduce their emissions. Although the current methods such as chemical looping combustion (CLC) and pure oxygen combustion have several advantages, there are still many limitations. A ceramic membrane based methane combustion reactor is an environmentally friendly technique for heat and power generation. This work investigates the performance of a perovskite-type SrSc0.1Co0.9O3-δ (SSC) membrane reactor for the catalytic combustion of methane. For this purpose, the mixed ionic and electronic conducting SSC oxygen-permeable planar membrane was prepared by a dry-pressing technique, and the SSC powder catalyst was spray coated on the permeation side of the membrane. Then, the prepared SSC membrane with the catalyst was used to perform the catalytic combustion of methane. The oxygen permeability of the membrane reactor was studied. Also, the methane conversion rates and CO2 selectivity at various test conditions were reported.

scholarly journals II. Ignition phenomena in mixtures of carbon monoxide and oxygen sensitized by hydrogen

1938 ◽  
Vol 167 (930) ◽  
pp. 292-318 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Chemical Reaction ◽  
Special Interest ◽  
Combustion Process ◽  
Proper Understanding ◽  
Factors Affecting ◽  
Chain Reactions ◽  
Gaseous Fuels ◽  
Combustion Processes ◽  
Combustion Of Hydrogen

Not the least important factors affecting the utilization of gaseous fuels are the remarkable effects of small quantities of catalytic substances, the presence of which may initiate or entirely change the nature of a combustion process. A proper understanding of these factors is therefore of great importance in the control of processes which are fundamental to many parts of applied chemistry. Such processes, however, are also intrinsically interesting for the insight they give into the ultimate mechanism of chemical reaction, and as a result of their study in the light of the theory of chain reactions, many empirical facts relating to combustion processes which previously were obscure now acquire a new significance. Of all these reactions the combustion of hydrogen and carbon monoxide stand in a unique position, for these substances more than any others occur as intermediaries in the burning of gaseous fuels; it is therefore of special interest to realize that the presence of traces of hydrogen may have a profound effect on the combustion of carbon monoxide, not only in lowering the temperature of ignition, but also in influencing the rate of propagation of the flame. This becomes of particular importance when it is remembered that carbon monoxide as used industrially nearly always contains traces of hydrogen.

Flashback in Prevaporizing/Premixing Combustion Systems

1983 ◽  
Author(s):  
A. G. Nein ◽  
A. M. Mellor
Keyword(s):  
Reaction Time ◽  
Flame Propagation ◽  
Chemical Reaction ◽  
Time Use ◽  
Characteristic Time ◽  
Fluid Mechanic ◽  
Pressure Oscillations ◽  
Combustion Systems ◽  
Combustion Processes ◽  
Test Fuel

Upstream flame propagation in prevaporizing/premixing continuous combustors was examined. Simplified axisymmetric burners used in this investigation were selected to simulate the same fundamental combustion processes in practical hardware. Straight cylindrical premixing tubes were used to reduce the possibility of upstream flame propagation mechanisms not associated with classical flashback. Combustor pressure oscillations were monitored and indicated that no flashback occurred due to these oscillations. Propane was selected as the test fuel because of its rapid vaporization characteristics. A characteristic time approach was used to analyze the data because the flashback process can be viewed as a competition between a fluid mechanic time and a chemical reaction time. Use of this technique revealed that stoichiometric contours existed in the premixing tubes of this system at most overall equivalence ratios tested, since the flashback limit was observed to be independent of overall stoichiometry.

Unexpected global patterns in plant vulnerability to climate change

2021 ◽  
Author(s):  
Alexander Tomas Sentinella ◽  
William B. Sherwin ◽  
Catherine A. Offord ◽  
Angela Moles
Keyword(s):  
Climate Change ◽  
At Risk ◽  
High Risk ◽  
Canopy Cover ◽  
Factors Associated ◽  
Tropical Environments ◽  
Vulnerability To Climate Change ◽  
Tropical Grasslands ◽  
Upper Limits ◽  
The Difference

Understanding how species will respond to climate change is critically important for managing our ecosystems into the future. However, surprisingly little is known about the distribution of risk based on the actual thermal tolerances of species, especially plants. We used germination records from 776 species to provide a global map of plant warming risk – the difference between maximum germination temperature and the predicted 2070 temperature. We then tested a series of hypotheses about factors associated with high risk. Many of our predictions were overturned. For example, although a great deal of attention has been paid to the risks faced by tropical forests, we found that the biomes most at risk were tropical grasslands, savannas and shrublands. Similarly, while we expected Australian species to have a lower warming risk due to its already variable conditions, our data showed that Australia had the highest average warming risk. Conversely, European species faced the lowest risk, with no plants examined in this study predicted to exceed their upper limits by 2070. Plants from regions with higher seasonality and higher canopy cover had lower warming risk, but the absolute range of annual temperature had no effect on risk. Therefore, the underlying factors contributing to warming risk warrant further examination. Overall, our results highlight that the regions most at risk from warming are not necessarily those with the most warming, but regions where species are closest to their upper limits. More attention needs to be given to high risk tropical environments, especially non-forest tropical environments which face the highest risk. In summary, while much of the world’s biota faces substantial threats from climate change, researchers may be surprised about where the effects are most acute.

Non-Newtonian Liquid-Gas Non-Uniform Stratified Flow With Interfacial Level Gradient Through Horizontal Tubes

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Haiwang Li ◽  
Teck Neng Wong ◽  
Martin Skote ◽  
Fei Duan
Keyword(s):  
Gas Flow ◽  
Energy Equation ◽  
Liquid Velocity ◽  
Stratified Flow ◽  
Newtonian Liquid ◽  
Published Data ◽  
Axial Distribution ◽  
Two Phase ◽  
Horizontal Tubes ◽  
The Difference

This paper presents the predictions of the axial distribution of liquid level and interfacial level gradient (ILG) for nonuniform non-Newtonian liquid-gas flow in horizontal tubes. The non-Newtonian liquid is described using power-law model, while the model of Heywood and Charles for uniform non-Newtonian liquid-gas two-phase flow, which was developed based on one dimensional energy equation, is extended to describe nonuniform stratified flow by incorporating the effect of interfacial level gradient. Two different critical liquid levels are found from the energy equation and are adopted as boundary condition to calculate the interfacial level distribution upstream of the channel exit. The results from the model are compared with the published numerical and experimental data. The results show that the model can predict the interfacial level distribution and interfacial level gradient for nonuniform stratified flow. Low liquid velocity, low gas velocity and high liquid viscosity are beneficial for forming a nonuniform flow with interfacial level gradient. The difference between the analytical model and the published data is smaller than 10%.

Combinations of CHCL and СHCL with propane and chladones 125, 227ea as prospective noncombustible refrigerants

2021 ◽  
pp. 54-59
Author(s):  
Илья Павлович Елтышев
Keyword(s):  
Energy Efficiency ◽  
Greenhouse Gases ◽  
International Agreements ◽  
Experimental Equipment ◽  
Atmospheric Lifetime ◽  
Combustion Properties ◽  
Combustion Processes ◽  
Suppression Of Combustion ◽  
Fluorinated Hydrocarbons

В данной работе рассмотрена проблема пожарной опасности применяемых в настоящее время хладагентов, предложено решение - создание негорючих смесевых композиций органических хлоридов с пропаном и хладонами 125, 227еа. Показана возможность увеличения доли короткоживущих компонентов в негорючих смесевых хладагентах, содержащих парниковые газы, с помощью создания тройных смесей. According to existing international agreements production of greenhouse gases must be drastically reduced in all sectors including refrigeration. It is known that refrigerants having short atmospheric lifetime are combustible. One of the methods to solve the problem of combustibility of refrigerants is to create noncombustible mixtures of combustible substance with an inhibitor of combustion. Such mixtures of organic chlorides with propane and CFH or CFH are investigated in this paper both theoretically and experimentally. Experimental equipment was specially adjusted to the combustion properties of the used chlorinated substances. It was obtained that CHCl и CНCl are strong inhibitors of combustion processes including self-inhibition of combustion of these substances themselves. Fluorinated hydrocarbons CFH and CFH are effective in suppression of combustion of dichloromethane and 1, 2-dichloroethane in air. As it follows from the obtained results, it is possible to reduce the content of the greenhouse component in the mixed refrigerant by 93% mass by creating noncombustible mixtures of dichlorides with CFH or CFH which are greenhouse gases. It was also revealed that CFH and CFH are stronger suppressants for combustion of CHCl and CНCl than for combustion of propane. Creation of triple noncombustible mixtures between CH, CHCl and CFH is advisable only when it is necessary to optimize energy efficiency of the refrigerant.

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