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Journal of Thermal Analysis and Calorimetry
Authors: Dumitru Oancea, Valentin Munteanu, Domnina Razus and Maria Mitu

Introduction The ignition and subsequent combustion of a fuel/air mixture by hot solid surfaces, either inert or catalytic, is a subject of great interest from both practical and theoretical points of view [ 1 ]. Several

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is in the initiation phase during the whole phase of pre-flashover. Therefore, determination and comparison of the substantial initiation parameters (ignition and flash ignition temperature, ignition and flash ignition induction period and critical

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usually used as fuels to enhance the energy characteristics and improve the ignition property of pyrotechnics [ 6 , 7 ]. The combination of KClO 4 and Mg are typically used for flare pyrotechnics and fireworks [ 8 , 9 ]. For some of these applications

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The “Ignition” criteria taken from the theory of combustion are suggested for the determination of various kinetic characteristics with the thermophysical parameters depending upon the temperature.

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The effects of the experimental conditions (sample size, heating rate, static and dynamic atmosphere) were studied on the value of the flash-ignition temperature (T i) obtained with a modified derivatograph able to measureT i simultaneously with the TG, DTG, DTA and T curves. The effects of various parameters are discussed and the optimum conditions determined.T i for bleached cotton fibre was found to be 270±1 °C.

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Abstract  

Combustion and pyrolysis experiments of Huadian oil shale have been conducted using a STA409 thermogravimetric analyzer. The effect of various factors on combustion of oil shale is studied. Particle size has little effect on combustion process of oil shale; starting temperature of combustion mass loss and ignition temperature of oil shale decrease with increasing O2 concentration of ambient gas; increase of heating rate can result in ignition temperature, burn-out temperature and maximum rate of combustion mass loss increasing. Homogeneous ignition mechanism of oil shale is ascertained using a hot state microscope. Activation energy was determined using Arrhenius model that is solved by Freeman–Carroll method. Calculation results show activation energy will increase with heating rate.

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Abstract  

A mathematical model of ignition and burning of organic polymers was used for evaluation and quantification of the tendency of polymers to ignition. The model permits investigation of the influence of one parameter of the polymer on the others. It was found that the model could be used for the verification of the ignitability method developed by Miller et al. [1]. Different steady states of combustion were found when using the model proposed. There is a characteristic steady state for normal flaming combustion, another for non-flaming combustion, and there are also unstable steady states that have no real physical meaning.

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Abstract  

Combustion experiments of three typical seaweeds (Gracilaria cacalia, Enteromorpha clathrata and Laminaria japonica) have been studied using a DTA-60H Thermal Analyzer and the combustion processes and characteristics are studied. Thermogravimetric experiments are carried out on the samples with 0.18 mm particle size at the heating rate of 20°C min−1. The results indicate that the ignition mode of seaweed is homogeneous and the combustion process is composed of dehydration, the pyrolysis and combustion of volatile, transition stage, the combustion of char as well as the reaction at high temperature. And the combustion characteristic parameters are obtained such as ignition temperature, maximum rate of combustion, burnout temperature etc. The combustion models of these seaweeds are also analyzed. The combustion characteristics and model differences between the seaweed and woody biomass are caused by the differences of volatile components. The combustibility indexes of seaweeds calculated are better than that of woody biomass, and the index of Gracilaria cacalia is the best. At last, activation energies are determined using Arrhenius model that is solved by binary linear regression method.

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The thermal ignition behaviour of various mixtures of organic fuels, magnesium and ammonium nitrate (AN) has been examined by differential thermal analysis technique. It has been observed that the thermal decomposition/ignition of organic fuel-AN mixtures is modified significantly in the presence of magnesium metal. The decomposition characteristics of the binary mixtures of AN with various metals indicate the specific action of magnesium and zinc in lowering the decomposition temperature. A possible explanation for the low temperature decomposition is given in terms of the solid state reaction causing the fusion of AN which further reacts with the metal resulting in a highly exothermic reaction.

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