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Abstract: Serious mine fire disasters have occurred in Northwest China where there are abundant coal resources. For the shortage of water and loess, a large cost of conventional grouting slurry is needed. However, plenty of sand and fly ash resources have been found there. In order to improve the quality of sand injection and reduce the wastage of water during grouting, a kind of new compound material of sand-suspended colloid, which is composed of mineral inorganic gel and organic polymer, was developed in this paper. And the inhibition performance experiments of the sand-suspended colloid were carried out. The results show that the sand-suspended colloid efficaciously affected the oxidation characteristics above the critical temperature during the acceleration oxidation of the lignite and fat-gas coal samples and restrained the oxidation course by increasing the activation energy, so that it reduced the contents of CO and C2H4 and depressed the oxidation rate during the coal spontaneous combustion, and finally inhibited the coal spontaneous combustion. [Copyright &y& Elsevier]

Abstract: In order to understand the characteristic of coal-oxygen reaction, oxygen consumption of coal at low temperatures is tested. The results show that the change of oxygen consumption with the rise of temperature is a non-liner process. Oxygen consumption decreases with the rising of coal temperature from 30 °C to 50 °C and reaches the minimum at 50 °C. Then, it increases steadily and rapidly upon 50 °C. This characteristic is more obvious for high rank coals. The difference of oxygen consumption at the same temperature is significant for different rank coals. The test shows the difference of the coal samples tested in the paper reaches 78.6% at 100 °C. Based on the theory of coal-oxygen reaction, the phenomenon above is analyzed in the physical and chemical character, and the appearance of coal-oxygen is complex. [Copyright &y& Elsevier]

Abstract: The propensity of coal to spontaneous combustion demonstrates the inherent character of the oxidation capacity at normal temperature. Currently, based on simulating spontaneous combustion of coal using adiabatic oxidation and temperature-programmed experiment, many overseas countries test characteristic parameters of spontaneous combustion of coal, such as SHT, HR, R70, CPT, high-temperature activation energy, and so on. Oxygen adsorption method is used to test the absorbed oxygen at 30 °C in China. According to the deficiency of the present research using partial stage parameters to demonstrate the whole process, Oxidation Kinetics which reflects the entire dynamic process is put forward, through testing the concentration of oxygen in the outlet of sample vessel at 70 °C and CPT later. With results repeated well and simple manipulation, the method can reflect the self-heating character very well and thus has a vital significance for the prevention and control of the mine fire. [Copyright &y& Elsevier]

The study of a Late Devonian arborescent lycopsid, Sublepidodendron songziense Chen 1977, from the Hsiehchingssu (Xiejingsi) Formation of Hubei Province and the Wutung (Wutong) Formation of Anhui Province, PR China, provides new insight into its holistic architecture and taxonomic affinity. The study allows several interrelated organ species to be integrated into a conceptual whole-plant species, Sublepidodendron songziense Chen emend. Wang Q., Hao, Wang D.-M., Wang Y. et Thomas Denk. The plant consists of a monocaulous trunk growing from a stigmarian rhizomorph, the trunk bearing biseriate, sub-opposite to possibly alternate lateral branches that expand by means of isotomous to slightly anisotomous dichotomies, forming an excurrent canopy. Lateral branches bear terminal Lepidostrobus-like strobili. These strobili are dimorphic, implying separate mega- and microsporangiate strobili considered with the associated organ assemblage, including Triletes-type megaspores, Lepidocarpopsis-like sporophylls, and Lepidophloios-like cauline anatomy. Moreover, lateral branches are caducous, and ulodendroid scars mark the attachment sites of former branches onto the trunk. The plant diagnostically possesses spirally arranged, small, vertically elongated leaf cushions, which have false leaf scars. The presence of ligule cannot be excluded definitely. The characteristics of leaf cushions show considerable variation corresponding to different taphonomic processes, preservational modes and ontogenetic stages so that this plant megafossil has been classified in various ways previously. Based on organic connection and cauline anatomy, a reconstruction of the whole-plant species is tentatively given. We compare this whole-plant species to the type species S. mirabile (Nathorst) Hirmer, and revise Sublepidodendron (Nathorst) Hirmer 1927, suggesting that the genus and its own family Sublepidodendraceae sensu Kra¨usel et Weyland 1949 should be separated from the order Protolepidodendrales sensu Pichi-Sermolli 1958 and referred to the order Isoe¨tales sensu lato and the suborder Dichostrobiles sensu DiMichele et Bateman 1996. Present Ulodendron specimens are the earliest record in the Late Palaeozoic strata, demonstrating that the pseudomonopodial branching architectural form in the arboresent lycopsids had evolved by the Late Devonian (Famennian). Such a woody trunk together with lateral branches (or cauline peduncles), separate mega- and microsporangiate strobili, and rootlet-bearing rhizomorph epitomize the major structural units (or architectural modules) of a true arborescent lycopsid, and S. songziense appears to be the oldest arborescent lycopsid showing an apparently centralized rhizomorph. We suggest that phylogenetically more advanced arborescent lycopsids did not precipitately occur in the Carboniferous, rather they had already evolved by the Late Devonian (Famennian). The widespread genus Sublepidodendron (Nathorst) Hirmer 1927 emend., especially abundant in China, among the Late Devonian–Early Carboniferous floras may represent one of the progenitors of the phylogenetically advanced arborescent lycopsids. [Copyright &y& Elsevier]

Coal fire is the major hazard to energy security and the environment in the world. Liquid CO 2 and liquid N 2 are widely used in coal mines. However, the spontaneous combustion tendency and re-ignition of coal which is dealt with liquid CO 2 and liquid N 2 remain unclear. To solve the problem, this paper studied the pore and oxidation property changes in coal treated by liquid carbon dioxide and liquid nitrogen, applying SEM, isothermal adsorption and thermogravimetric experiments. The results showed that the matrix of coal soaked by liquid CO 2 and liquid N 2 is shrunk due to cold condition in the context of low temperature (236 K, 77 K). The pore and crack are grown with the increase of total pore volume and specific surface area, which result in increased the oxygen absorption capacity, especially when being soaked by liquid N 2. It can be explained liquid CO 2 mainly promotes the increase of mesopores in 3.5 nm – 4 nm. Because of the low temperature of liquid N 2 , new micropores are formed in 0.45 nm–0.55 nm and mesopores in 2 nm–4 nm are increased. After coal is soaked by liquid CO 2 and liquid N 2 , the pore surface becomes rougher and the pore structure for liquid N 2 tends to be more complex. Pore evolution promotes oxygen absorption by the coal, which results in the decrease of characteristic temperatures in coal oxidation and combustion stages. After coal is soaked in liquid CO 2 and liquid N 2, the oxidation and combustion intensity of coal has increased and the average apparent activation energy of oxidation has dropped by 9.65%–11.33% and 15.10%–17.62% respectively, which indicates that their tendency of spontaneous combustion and reignition increases. In all, this study reveals the evolution of pore structure and changes in oxidation property of coal soaked by liquid CO 2 and liquid N 2 , focusing on providing more information for effectively controlling coal spontaneous combustion after using liquid CO 2 and liquid N 2. • The coal mesopores between 3.5 nm and 4 nm increase treated by liquid CO 2. • The coal micropores formation and mesopores increase treated by liquid N 2. • The oxidation activation energy decreases after soaking liquid CO 2 and liquid N 2. • The coal oxidation active is enhanced after soaking liquid CO 2 and liquid N 2. • The liquid N 2 have more significant effect on pore development and oxidation. [ABSTRACT FROM AUTHOR]

• Mechanism functions of CO, CO 2 generation in isothermal smoldering combustion of coal. • Reactive group conversion in isothermal smoldering combustion of coal. • The relationship between CO and CO 2 production and the consumption and conversion of reactive groups. The process of coal smoldering combustion will produce a significant number of CO and CO 2 gases, causing environmental pollution and casualties. It is important to elucidate the law and mechanism of CO and CO 2 generation during coal smoldering combustion. In this paper, the CO and CO 2 production patterns and the relationship of reactive group conversion during isothermal smoldering combustion were investigated by TG-MS and FT-IR. Results reveal that the CO and CO 2 generation curves with time during isothermal smoldering combustion of coal in the first stage conform to the polynomial function Y 1 = A 1 + B 1 t + C 1 t 2 + D 1 t 3 + E 1 t 4 , in the second stage accord with the complex exponential function Y 2 = A 2 + B 2 e kt (k < 0), as well as the CO + CO 2 production curve. The consumption rate function of functional groups during isothermal smoldering combustion is calculated from the CO + CO 2 production curve as v = L · Y CO + CO 2 1000000 V m . As the isothermal temperature rises, the rate of coal combustion in smoldering combustion accelerates, causing an exponential increase in CO + CO 2 emissions and reactive group consumption. The CO and CO 2 emissions vary considerably at different isothermal temperatures, which is due to the increase in the number and type of reactive groups involved in the reaction with rising temperature. During isothermal smoldering combustion of coal, in exception to the direct generation of CO and CO 2 from carboxyl and carbonyl groups, aliphatic hydrocarbons are key groups for the continuous generation of CO and CO 2 , and are also important mediators for the formation of carboxyl and carbonyl groups. The hydroxyl group acts as a reactant at relatively low temperatures and plays an essential role in driving the reaction. The aromatic hydrocarbon is the principal source of CO and CO 2 at higher temperatures. This study will help to forecast the degree of coal smoldering combustion and to control coal smoldering combustion. [ABSTRACT FROM AUTHOR]

Abstract: In this article, we present the numerical simulations of a real cylinder head quench cooling process employing a newly developed boiling phase change model using the commercial CFD code AVL-FIRE v8.5. Separate computational domains constructed for the solid and liquid regions are numerically coupled at the interface of the solid–liquid boundaries using the AVL-Code-Coupling-Interface (ACCI) feature. The boiling phase change process triggered by the dipping hot metal and the ensuing two-phase flow is handled using an Eulerian two-fluid method. Multitude of flow features such as vapor pocket generation, bubble clustering and their disposition, are captured very effectively during the computation, in addition to the variation of the temperature pattern within the solid region. A comparison of the registered temperature readings at different monitoring locations with the numerical results generates an overall very good agreement and indicates the presence of intense non-uniformity in the temperature distribution within the solid. Overall, the predictive capability of the new boiling model is well demonstrated for real-time quenching applications. [Copyright &y& Elsevier]