Critical ignition conditions in exothermically reacting systems for arbitrary reaction kinetics

In this work, a universal method for determination of the critical ignition conditions taking into account the reactant consumption is proposed. Based on the analysis of the phase trajectories equation, the equation for maximal temperatures of exothermic reactions was obtained. In this case, the asymptotic criterion of ignition is determined by the impossibility of slow reaction mode realization with low value of maximum temperature. The method allows demarcating the regions of low- and high-temperature modes of exothermic reactions and to establish the criteria of transition to the region of high-temperature modes. The corresponding parametric diagrams can be characterized as the bifurcation ones (bistability). It was found that the region of thermal explosion (TE) existence is bounded by the classical TE conditions from below and by the degeneration conditions from above. The comparison of analytical calculation results with the results of numerical calculation gives a satisfactory agreement.

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Paper 12: Determination of the ‘Hot Spot’ Temperature Rise from P.V.C. Insulation Characteristics

Proceedings of the Institution of Mechanical Engineers Conference Proceedings ◽

10.1243/pime_conf_1969_184_355_02 ◽

1969 ◽

Vol 184 (11) ◽

pp. 117-130

Author(s):

S. W. Twaites ◽

R. F. Murray

Keyword(s):

High Temperature ◽

Temperature Rise ◽

Hot Spot ◽

Electrical Machines ◽

Maximum Temperature ◽

Spot Temperature ◽

Operational Service

It is normal practice when designing electrical machines to design for operation within the maximum temperature limits of the insulation. If part of the winding is not effectively cooled under these conditions, the resulting temperature rise can damage the insulation and seriously reduce the length of operational service of the machine. This paper discusses a method of detecting high-temperature regions within a winding and of estimating the ‘hot spot’ temperature. The investigation has been concentrated on the design associated with a direct water-cooled winding, although the results could be applied generally on other electrical machines.

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RESEARCH OF STRAW PYROLYSIS THERMAL EFFECTS FOR ESTIMATION OF POSSIBILITY ITS IMPLEMENTA-TION IN AUTOTHERMAL MODE

chemistry of plant raw material ◽

10.14258/jcprm.2019024535 ◽

2019 ◽

pp. 271-280 ◽

Cited By ~ 1

Author(s):

Aleksandr Vladimirovich Astafev ◽

Roman Borisovich Tabakaev ◽

Dias Erlanovich Musafirov ◽

Aleksandr Sergeyevich Zavorin ◽

Yuriy Vladimirovich Dubinin ◽

...

Keyword(s):

Thermal Analysis ◽

Differential Thermal Analysis ◽

Thermal Effect ◽

Thermal Effects ◽

Raw Materials ◽

Laser Flash ◽

Raw Material ◽

Exothermic Reactions ◽

Calculation Results

The aim of the work is research of straw pyrolysis in various modes, the determination of process thermal effects and estimation of straw thermal processing possibility in the autothermal mode. Physical experiment and differential thermal analysis were used as research methods. Thermotechnical characteristics of raw materials are determined by ISO 1171:2010, GOST R 55660-2013 and a bomb calorimeter; thermal and physical characteristic are determined by the analyzer of thermal diffusivity Discovery Laser Flash DLF-1200. In result of the work is established that thermal effects occur in the straw after heating to 200 °C. The first shows of exothermic reactions are observed when the reactor is heated to 303 °C – in this case the temperature of the straw reaches 308.8 °C. By differential thermal analysis is established that the temperature range of heat input was set from 235 to 575 °C and value of the thermal effect in this range was set 1475 kJ/kg. For this range, the heat costs for the organization of pyrolysis in the autothermal mode and the total thermal effect of the process are calculated. The calculation results showed that the maximum thermal effect (398.9 kJ/kg) can be obtained at a pyrolysis temperature of 460 °C. For these conditions, the influence of the initial straw moisture content on the autothermality of pyrolysis process was evaluated and it was established that process can be organized due to its own thermal effects when the raw material moisture is less than 30.5%.

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Determination of Fire Resistance of Ceiling Structure Variant Design on the Basis of Timber Using Numerical Calculation Methods

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.820.379 ◽

2016 ◽

Vol 820 ◽

pp. 379-384

Author(s):

Róbert Leško ◽

Martin Lopušniak

Keyword(s):

High Temperature ◽

Numerical Calculation ◽

Fire Resistance ◽

Building Materials ◽

Effective Alternative ◽

Fire Tests ◽

Calculation Methods ◽

Variant Design ◽

Temperature Impacts

Ability to resist of high temperature impacts during fire is not based exclusively on ignitability of building materials. At the present time, fire resistance is declared mainly through fire tests, but numerical procedures for the determination of fire resistance also represent an effective alternative in this field. Using calculation methods for the determination of ceiling structure fire resistance on the basis of timber is subject of the submitted paper. The main objective of this paper is to demonstrate the fact that timber, or products from it, are building materials capable to resist impacts of fully developed fire for the period of more than 60 minutes in spite of their flammability. Applicability of these results in selected countries of Europe can be seen from the list of requirements.

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