The Main Regularities of Ignition and Combustion of Coal-Water Fuels Produced from Brown, Flame and Gas Coals

2018 ◽  
Vol 37 ◽  
pp. 141-157 ◽  
Author(s):  
Valeriya Pinchuk
Keyword(s):  
Maximum Temperature ◽  
Time Interval ◽  
Power Type ◽  
Time Duration ◽  
Medium Temperature ◽  
Working Medium ◽  
Temperature Dependences ◽  
Ignition And Combustion ◽  
Coal Grade ◽  
Combustion Processes

An experimental investigation was carried out of coal-water fuel (CWF) drops ignition and combustion. CWF examples were produced by using of coal of different metamorphic stages, including brown coal, flame coal, and gas coal. The processes of combustion and ignition of CWF took place in the air. Time-temperature dependences of ignition and combustion processes were obtained; basic stages of CWF combustion were established and investigated; combustion completeness was defined and ash residue structure and properties were investigated during the experimental research. Influence of the working medium temperature on the time duration of each burning stage was defined. Generalization of results was carried out. It is shown, that duration of the volatiles combustion stage doesn’t depend on the medium temperature and stay constant for each of coal grade. Time interval before CWF ignition can be described with power-type dependence, which is identical for all metamorphic stages of coal. The maximum temperature of CWF combustion grows linearly in respect to the medium temperature in the oven.

Temperature Dependences in the O + OH → O2 + H Reaction. Quasiclassical Trajectory Calculation

1993 ◽  
Vol 58 (2) ◽  
pp. 234-243 ◽  
Author(s):  
Viliam Klimo ◽  
Martina Bittererová ◽  
Stanislav Biskupič ◽  
Ján Urban ◽  
Miroslav Micov
Keyword(s):  
Temperature Dependence ◽  
Energy Surface ◽  
Analytical Form ◽  
Mean Values ◽  
Quantum Numbers ◽  
Mean Lifetime ◽  
Temperature Dependences ◽  
Quasiclassical Trajectory Calculation ◽  
The Mean ◽  
Combustion Processes

The reaction O + OH → O2 + H in conditions of combustion of hydrocarbons and polymers was modelled by using the method of quasiclassical trajectories. The potential energy surface was determined by the multiconfiguration interaction method and fitted with the analytical form of the extended LEPS function. Attention was paid to the mean values of the vibrational and rotational quantum numbers of O2 molecules and their temperature dependence. The temperature dependence of the mean lifetime of the OOH collision complex was also examined. The calculated rate constants were analyzed and compared with the experimental data over the temperature region of the combustion processes.

scholarly journals Coupling Disease-Progress-Curve and Time-of-Infection Functions for Predicting Yield Loss of Crops

2000 ◽  
Vol 90 (8) ◽  
pp. 788-800 ◽  
Author(s):  
L. V. Madden ◽  
G. Hughes ◽  
M. E. Irwin
Keyword(s):  
Yield Loss ◽  
Numerical Solutions ◽  
Disease Incidence ◽  
Time Interval ◽  
Short Time Interval ◽  
Time Duration ◽  
Plant Yield ◽  
Disease Progress ◽  
Time Of Infection ◽  
Over Time

A general approach was developed to predict the yield loss of crops in relation to infection by systemic diseases. The approach was based on two premises: (i) disease incidence in a population of plants over time can be described by a nonlinear disease progress model, such as the logistic or monomolecular; and (ii) yield of a plant is a function of time of infection (t) that can be represented by the (negative) exponential or similar model (ζ(t)). Yield loss of a population of plants on a proportional scale (L) can be written as the product of the proportion of the plant population newly infected during a very short time interval (X′(t)dt) and ζ(t), integrated over the time duration of the epidemic. L in the model can be expressed in relation to directly interpretable parameters: maximum per-plant yield loss (α, typically occurring at t = 0); the decline in per-plant loss as time of infection is delayed (γ; units of time-1); and the parameters that characterize disease progress over time, namely, initial disease incidence (X0), rate of disease increase (r; units of time-1), and maximum (or asymptotic) value of disease incidence (K). Based on the model formulation, L ranges from αX0 to αK and increases with increasing X0, r, K, α, and γ-1. The exact effects of these parameters on L were determined with numerical solutions of the model. The model was expanded to predict L when there was spatial heterogeneity in disease incidence among sites within a field and when maximum per-plant yield loss occurred at a time other than the beginning of the epidemic (t > 0). However, the latter two situations had a major impact on L only at high values of r. The modeling approach was demonstrated by analyzing data on soybean yield loss in relation to infection by Soybean mosaic virus, a member of the genus Potyvirus. Based on model solutions, strategies to reduce or minimize yield losses from a given disease can be evaluated.

scholarly journals Analysis of the possibilities to achieve adiabatization process of combustion surrounded by inactive gases in Rapid Compression Machine

2017 ◽  
Vol 168 (1) ◽  
pp. 27-31
Author(s):  
Wojciech CIEŚLIK ◽  
Ireneusz PIELECHA
Keyword(s):  
Combustion Process ◽  
Combustible Mixture ◽  
Spark Ignition Engine ◽  
Rapid Compression Machine ◽  
Working Medium ◽  
Main Injection ◽  
Rapid Compression ◽  
Combustible Gases ◽  
Combustion Processes ◽  
Combustible Mixtures

In this work non-combustible gases impact on combustion processes studies is performed. Research was performed in a optically accessible rapid compression machine (RCM) under spark ignition engine conditions. The distribution of the swirl charge in the relation to adopted for analysis sequence of gas delivery to the chamber was varied with regard to the main injection. Authors investigate the influence of these sequence on the combustion and the ignition delay of the main injection and the overall combustion characteristics. The aim of this work is the experimental recognition of possibilities of creating combustible mixtures of light hydrocarbon fuels surrounded by non-combustible gases affecting the function of the inhibitor. Specifying the ability of preparation and combustion of mixtures in such systems enables the scientific analysis of adiabatization of the combustion process of fuel-air mixtures in the operating chambers. Theoretical analysis of the issues indicates possibility of obtaining such a stratification of the charge, that the inactive exhaust gases creating the outer ring surround the combustible mixture inside in such a way as to reduce the amount of heat exchanged between the working medium and the walls of the cylinder.

The Main Regularities of Ignition and Combustion of Coal-Water Fuels Produced from Fat, Non-Baking Coal and Anthracite

2018 ◽  
Vol 38 ◽  
pp. 67-78 ◽  
Author(s):  
Valeriya Pinchuk
Keyword(s):  
Experimental Data ◽  
Data Processing ◽  
Experimental Research ◽  
Combustion Process ◽  
Medium Temperature ◽  
Experimental Data Processing ◽  
Ignition And Combustion ◽  
Temperature Correlations

For the purpose of defining the regularities of CWF combustion in the air, we have conducted experimental research into ignition and combustion of the fuels produced from coal of different metamorphic ranks. The studies allowed to obtain time-temperature correlations describing CWF ignition and combustion, to determine the stages of the combustion process, to define the structure of the ash coating, and the degree of the fuel combustible mass burnout. The present paper analyses the results of experimental research into the regularities underlying the processes of ignition and combustion for CWF (fat coal), CWF (non-baking coal), and CWF (anthracite).It was established that the oven medium temperature affects the duration of every CWF combustion stage, which was substantiated by the relevant dependencies resulting from the experimental data processing.

scholarly journals Ignition of Slurry Fuel Droplets with Different Heating Conditions

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4553
Author(s):  
Timur Valiullin ◽  
Ksenia Vershinina ◽  
Pavel Strizhak
Keyword(s):  
Heat Fluxes ◽  
Radiative Heating ◽  
Convective Heating ◽  
Radiation Heating ◽  
Fuel Droplets ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Ignition And Combustion ◽  
Combustion Processes ◽  
Hot Surface

This paper describes modern research methods of the ignition and combustion processes of slurry fuel droplets. The experiments were carried out using a muffle furnace to ensure the conditions of radiation heating, the hot surface to reproduce the conditions of conductive heating, the high-temperature channel with convective heating, the chamber with the processes of soaring, i.e., a significant increase in the time of fuel residence in the combustion chamber. We identified the differences in combustion modes, threshold ignition temperatures, delay times and durations of combustion processes. We obtained the quantitative differences in the characteristics of the ignition and combustion processes for typical registration methods. It was found that for all heating schemes, the minimum ignition temperatures have comparable values. Minimum ignition delay times were recorded during convective heating. The maximum combustion temperatures were achieved with radiation heating. We determined the values of limiting heat fluxes, sufficient to initiate the combustion of slurries fuels during conductive, convective and radiative heating.

scholarly journals Modeling the Impact of High Temperature on Mortality in Pakistan

2021 ◽  
Vol 14 (1) ◽  
pp. 332
Author(s):  
Mushtaq Ahmad Khan Barakzai ◽  
S.M. Aqil Burney
Keyword(s):  
High Temperature ◽  
Geographical Location ◽  
Maximum Temperature ◽  
Climate Data ◽  
Medium Temperature ◽  
Average Rainfall ◽  
Medium Level ◽  
High Level ◽  
The Impact ◽  
Very High

The objective of this paper is to model and study the impact of high temperature on mortality in Pakistan. For this purpose, we have used mortality and climate data consisting of maximum temperature, variation in monthly temperature, average rainfall, humidity, dewpoint, as well as average air pressure in the country over the period from 2000 to 2019. We have used the Generalized Linear Model with Quasi-Poisson link function to model the number of deaths in the country and to assess the impact of maximum temperature on mortality. We have found that the maximum temperature in the country has a significant impact on mortality. The number of deaths in Pakistan increases as the maximum temperature increases. We found that, as the maximum temperature increase beyond 30 °C, mortality increases significantly. Our results indicate that mortality increases by 27% when the maximum temperature in the country increases from medium category to a very high level. Similarly, the number of deaths in the country increases by 11% when the temperature increases from medium temperature to high level. Furthermore, our study found that when the maximum temperature in the country decreases from a medium level to a low level, the number of deaths in the country decreases by 23%. This study does not consider the impact of other factors on mortality, such as age, medical conditions, gender, geographical location, as well as variability of temperature across the country.

scholarly journals Temperature Dependences of IR Spectra of Humic Substances of Brown Coal

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1822 ◽  
Author(s):  
Dmitry S. Volkov ◽  
Olga B. Rogova ◽  
Mikhail A. Proskurnin
Keyword(s):  
Organic Matter ◽  
Ir Spectra ◽  
Humic Substances ◽  
Brown Coal ◽  
Functional Dependence ◽  
Maximum Temperature ◽  
Experimental Conditions ◽  
Band Shift ◽  
Single Temperature ◽  
Temperature Dependences

The capabilities of temperature-monitored IR spectroscopy for studying the organic matter and mineral composition of humic substances (HS) were tested. Temperature dependences of the mid-IR spectra of humic substances heated in the air in the range 25–215 °C (298–488 K, with a step of 2.5 °C)—for three commercially available samples isolated from brown coal (leonardite)—were performed. The characteristic bands were identified, and their changes in band maxima positions and intensities were compared. From the viewpoint of interpretation of HS components, the spectra were divided into regions of quartz lattice region (800–260 cm−1), quartz overtone region (1270–800 cm−1), humic substance organic matter region (1780–1270 cm−1), quartz combination region (2800–1780 cm−1), CH-speciation region (3100–2800 cm−1), and hydrogen-speciation region (4000–3100 cm−1) thus selected to contain the dominating type of bands. For the first time, a reversible change in the frequencies of the band maxima in IR spectra upon heating was observed, which can be interpreted as forming structures with a particular order in the studied humic substances in the dry state. For a single sample, both the band-shift scale and the functional dependence of the various bands on temperature differ significantly. The approach differentiates crystalline quartz bands, amorphous silica, and HSOM/surface groups experiencing a different temperature behavior of the band maxima and their intensities. Band-maximum temperature dependence can be considered more stable to changes in experimental conditions than band maxima at a single temperature, thus providing a more detailed HS structure analysis without HS decomposition or destruction.

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