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The flow characteristic of high pressure dense-phase pneumatic conveying of pulverized coal is essential to the safe and stable operation of the gasifier. In this paper, the effects of coal moisture content on conveying behavior and resistance characteristics of dense-phase pneumatic conveying were explored. Meanwhile, a model of the additional pressure drop of particles was proposed and compared with the experimental data. The results show that though the resistance and cohesiveness increase with increasing moisture content, its influence is different in dense and dilute phase. In the dense-phase region, the coal with lower moisture content shows a larger solid mass flow rate and solid concentration; while in the dilute-phase region, the moisture content has minor effect on conveying characteristics. For the coal with lower moisture content in dense-phase region, the solid mass flow rate and solid concentration are larger, and the gas velocity has a small effect on solid friction factor, due to its smaller cohesiveness and resistance, which is showed in our experiments and inferred from our model. The additional pressure drop model was proposed for straight pipes and bends, whose parameters are probably effective than the existing parameters in this kind of model, as the deviation in the vertical rise pipe, horizontal pipe and bend pipe is controlled within ±30%, and the corresponding vertical down pipe are controlled within ±40%.

Hot compression tests of Ti-6Cr-5Mo-5V-4Al alloy were carried out under the temperature range of 963–1113 K and strain rates of 0.001, 0.01, 0.1, 1 s−1 on a Gleeble-3500 isothermal simulator. The strain compensated Arrhenius model (SCAM) was developed after calculating the material constants including α, lnA, n and Q. Also, genetic algorithm (GA) was applied to optimize the material constants according to the acquired material constant ranges and the GA optimized Arrhenius model (GAOAM) was constructed for flow stress prediction. The prediction capabilities of the two models were assessed by correlation coefficient (R) and average absolute relative error (AARE). The results showed that GAOAM was better than SCAM in prediction precise. Two dynamic globularization mechanisms were proposed to describe the dynamic globularization behavior at different strain rate conditions according to the SEM observations. Extrusion type globularization (ETG) occurred at lower strain rate condition and cutting type globularization (CTG) occurred at higher strain rate condition. Also, dynamic globularization occurred easier at lower temperature and the α grain was squashed but not spherized at higher temperature. The processing map based on dynamic materials model was constructed for the microstructure identification. The instability region occurred at the area with high strain rate and low temperature and high η-value region was at the area with low strain rate and high temperature. According to the OM microstructure observations, flow localization occurred at the instability region and the dynamic recrystallization of β grain occurred at the high η-value region. Thus, the microstructure identification ability of the processing map was verified and this processing map could be referred to in the actual production.

The parallel hot wire technique has been widely used to measure the thermal conductivity of refractories. In this study, a non-linear fitting procedure based on the line heat source model (ideal model) is developed to obtain the thermal conductivity and thermal diffusivity of a sample from the measured temperature curve, whose accuracy is influenced by several factors. A semi-analytical method is proposed to evaluate the temperature change in the sample in parallel hot wire set-ups, considering the effects of the radii of the hot wire and thermocouple with their layers, their heat capacities and thermal contact resistances, and the outer boundary of the sample. The influence of these factors is analysed through comparisons of the temperatures calculated with the semi-analytical model and the line heat source model. Virtual measurements for samples with different thermal conductivities and thermal diffusivities in a parallel hot wire set-up are generated by the semi-analytical method. By fitting these virtual temperature curves with the line heat source model, it is found that the errors in the fitting results depend strongly on the length and position of the selected fitting time interval, and samples with high thermal conductivities and thermal diffusivities tend to exhibit larger errors. This study provides an efficient method to analyse the errors in line heat source fits for parallel transient hot wire measurements.

Hydrogen-enriched natural gas is a promising low-carbon fuel in combustion devices. To better assess its feasibility from the extinction prevention point of view, the extinction of near-limit premixed hydrogen-methane/air flames over a wide range of equivalence ratios was measured using the single-flame counterflow configuration. Results showed that the hydrogen addition resulted in a greater extinction stretch rate. Further analysis demonstrated that the extinction stretch rate of premixed hydrogen-methane/air flames linearly correlated with the corresponding reference flame speed. Thereby a combustion regime map diagram, separating the burning and extinction, was sketched. In addition, critical extinction Damkӧhlor number of premixed hydrogen-methane/air flames was investigated and it was found to be insensitive to the hydrogen addition and equivalence ratio. Finally, the hydrogen addition effect and the corresponding extinction response were assessed for two scenarios, 1) constant thermal load (gas turbine, gas-fired boilers, etc.), and 2) constant fuel injection pressure (gas stove, oven, etc.). The results indicated that H2 addition promoted the combustion safety by increasing the extinction stretch rates, but an allowable H2 variation window existed when considering the unexpected high-temperature damage of the burners. The allowable H2 variation window of Scenario 1 was found much broader than that of Scenario 2.

In this paper, experimental and numerical studies on the decomposition pyrene, a main component of tar, under the steam reforming condition were conducted. The effects of operational conditions of reaction temperature TR and steam to carbon molar ratio (S/C) on the yield of main light gases and soot are assessed. The associated global reaction rate and main reaction pathways were analyzed. The results revealed that pyrene was mostly converted into soot instead of light gases in the steam reforming. The yields of CO2 and H2 significantly increased with TR, whereas those of CO and CH4 remained relatively stable. The water shift reaction of exhaust gases at low temperature zone should be taken into account to accurately predicted the yield of light gases. The conversion of pyrene rapidly happened when S/C was

This paper is concerned with the open-circuit fault diagnosis of phase-controlled three-phase full-bridge rectifier by using a sparse autoencoder-based deep neural network (SAE-based DNN). Firstly, some preliminaries on SAE-based DNN are briefly introduced to automatically learn the representative fault features from the raw fault signals. Then, a novel strategy is developed to design the structure of the SAE-based DNN, by which the depth and hidden neurons of the SAE-based DNN could be regularly determined to extract the features of input signals. Furthermore, the fault model and system framework are presented to diagnose the open-circuit fault of the three-phase full-bridge rectifier. Finally, the effectiveness of the developed novel strategy is verified by the results of simulation experiments, and the superiority of the novel SAE-based DNN is evaluated by comparing with other frequently used approaches.

In this paper, the elimination of heavy tar by steam reforming at high temperature was studied with experiments and numerical simulation. The experiments were conducted in a tube reactor with five model compounds at temperatures of 1273–1673 K, steam of 0–40 vol% and sample weight of 3–20 mg with residence time of 2 s. The simulation was performed with the plug flow model in CHEMKIN program based on a kinetic model that consists of >200 chemical species and 2000 elementary step-like reactions. The results of experiments indicate that increasing temperature will accelerate the decomposition of heavy tar; moisture could significantly prompt the decomposition of heavy tars, but not so efficient above 20 vol%; less sample could help the decomposition of heavy tar; longer residence time can slightly increase the decomposition of heavy tar. At high temperature (1573 K or above), the heavy tar is mainly cracked into two parts: the one carbon molecules (CO and CO 2 ) and the soot at the beginning of reactor. Then the soot decomposes into CO, CO 2 and H 2 by steam reforming. The conversion and kinetic data of heavy tar can be divided by two temperature sections. The carbon conversion degrees of different model compounds from 1173 K to1473 K are close with similar trends, which may be represented by a universal kinetic model. Our results provide an insight in the understanding of the heavy tar decomposition and give the necessary information for the designation and operation of the tar cracker to eliminate heavy tar.

Crystallization is a significant challenge for the rheological properties of the liquid slag flowing down along the wall of entrained flow gasifier. Viscosity can increase sharply when certain crystals occur inside the slag. Chemical compositions are the intrinsic factors in determining the crystallization characteristics. In former studies, we have investigated the influence of major components such as SiO2, Al2O3, CaO, Fe2O3 as well as atmosphere based on synthetic coal slags. While for MgO, its ratio is less than the above four but higher than the other minors such as Na2O, TiO2. Therefore, in order to get a comprehensive understanding of crystallization characteristics of coal slag, the influence of MgO is investigated by four synthetic slags with different MgO ratios (0%, 4%, 8%, 12%). The experimental methods: differential scanning calorimetry (DSC), single high-temperature thermocouple system (SHTT), water quenching and calculation method -FactSage were combined to study the crystallization temperature, morphology of crystals as well as crystalline phases. The final state of slag with no MgO is almost glass with little crystals. The increase of MgO can lead to an enhancement of crystallization temperature and move the temperature–time transformation curve to high temperature region. Mg2+ ions acting as the network modifier participate actively into the crystallization process. At the temperature higher than 1200 °C, Mg2+ exists in spinel and the liquid. While as temperature decreases below 1200 °C, all the Mg2+ precipitates from the slag forming magnesium-silicate minerals such as diopside and melilite.

Crystallization inside the liquid slag can increase the viscosity, affecting flow down the wall which is associated with the temperature of critical viscosity ( T cv ). Four groups of synthetic slags with different Si/Al, Si + Al, CaO, Fe 2 O 3 ratios were sorted to study the crystallization characteristics including the crystallization tendency as well as crystallization temperature ( T crys ). Samples with base–acid ratio (R > 0.7) and Si/Al in the range of 1–4 are liable to crystallize with obvious crystallization peak on DSC curve, and the influence of R is more than that of Si/Al. The crystallization temperature ( T crys ) is found to display a linear relationship with the liquidus temperature ( T liq ). The deviation of real coal slag with synthetic slag is associated with the crystalline phases as well as the raw minerals present in the ash.

Large forming load at high temperature causes the occurrences of plastic deformation, wear, mechanical fatigue, and thermal fatigue in the large hot forging dies and resulted in their short service lives. In this study, temperature field, stress field, and wear condition of large hot forging die were predicted and evaluated by finite element modelling (FEM) analysis. Corroborated by the experimental results, analysis results demonstrated that failures mainly occurred in bridge, boss, and groove regions of the large hot forging dies. According to the analysis and experimental results, the failed large hot forging dies were refabricated by bimetal-layer weld surfacing technology with a cobalt-based superalloy (Co03) and a ferrous alloy (JXHC15). No failure was observed on these refabricated dies, after production of 25 pieces. In comparison with the conventional fabrication or prefabrication methods, this bimetal-layer weld surfacing technology reduced the fabrication cost, shortened the fabrication cycle, and elongated the service lives of large hot forging die effectively.

This study delivered a reassessment of the two-dimensional (2-D) velocity boundary effect on the determination of the extinction stretch rate and the laminar flame speed using the counterflow flame configuration. Experimental and numerical results showed that the extinction stretch rate was sensitive to the burner exit stretch rate, the burner separation distance, and the impinged flow temperature, but the reference flame speed is insensitive to these boundary conditions. A semi-quantitative analysis demonstrated that the boundary condition affected the computed function of the reference flame speed with respect to the stretch rate and thereby influence the extrapolated laminar flame speed using the computationally assisted nonlinear extrapolation. The experimental results over a broad range of equivalence ratios confirmed that the non-uniform velocity boundary would result in a considerable error in the determination of the laminar flame speed for the mixture with the non-unity Lewis number. This problem can be solved by applying the true measured velocity boundary in the extrapolation curve computation. The present study suggested the consideration of the 2-D velocity boundary condition effect in the determination of the laminar flame speed and the extinction stretch rate using the counterflow configuration.

The inhomogeneous quality of products manufactured by semisolid forming is mainly attributed from the phase segregation of semisolid metal slurry during forming. Phase segregation can be inhibited by lower forming temperature, higher strain rate, and lower stroke. However, the realization of net-shape forming with above parameters is quite difficult. In this study, a multi-stage thixoforging strategy including a partial melting, a fast first compression, a partial solidification, and a secondary compression was proposed to weaken phase segregation of thixoformed samples. A physical simulation of multi-stage thixoforging was conducted on commercial rolled Cr-V-Mo tool steel SKD11, using a multistage hot compression test machine. The microstructural evolution and forming behaviors of the SKD11 steel slurries in different stages of multi-stage thixoforging with various forming parameters were investigated experimentally. Out flow of liquid phase does not occur throughout the thixoforming, and can be inhibited effectively by partial solidification and subsequent secondary compression. SKD11 steel sample more homogenous microstructure and smoother surface was manufactured by multi-stage thixoforging including a fast first compression with a stroke of 4 mm and a strain rate of 2.0/s at 1280 °C, a partial solidification to 1240 °C with a cooling rate of 2 °C/s, and a secondary compression with a stroke of 2 mm and a strain rate of 0.1/s at 1240 °C.

Bimetal-layer surfacing intensifying the working area of die by welding materials with gradient mechanical properties is an effective fabrication and refabrication technology for hot forging dies with low cost and a short cycle. Owing to the extremely high operating temperature and large stress of large hot forging dies, the selection of welding materials is quite important. In consideration of the excellent high-temperature performance of cobalt-based superalloy, a cobalt-based superalloy welding material, Co03 was designed in this study to be combined with ferrous alloys with outstanding low-temperature mechanical properties and low price to realized effective refabrication of large hot forging dies by bimetal-layer surfacing. Refabrication of dies and subsequent hot forging processes were simulated physically by bimetal-layer welding conducted on 5CrNiMo blocks and heat treatments. Compared with the combination of two ferrous alloys (JXHC30 and JXHC15), the combination of Co03 and JXHC15 exhibited more stable microstructure and mechanical properties in extreme operating conditions. To verify the feasibility of the combination of JXHC15 and Co03 in refabrication of hot forging dies through bimetal-layer surfacing, a pair of large hot forging dies were refabricated and employed in forging production. The service lives of refabricated dies were improved by dozens of times, compared with the former homogeneous 5CrNiMo dies.

Crystallization inside the liquid slag of entrained flow gasifiers can increase the viscosity of the slag, affecting flow down the wall and resulting in operational problems. The chemical component of the slag is an intrinsic factor of crystallization characteristics. In the study presented here, Differential Scanning Calorimetry (DSC) and the Single Hot Thermocouple Technique (SHTT) were combined to investigate the influence of (SiO 2 + Al 2 O 3 ) ratios on crystallization temperature and crystalline morphology, and to construct temperature-time transformation (TTT) diagrams. Five synthetic slags with different amounts of silica and alumina (silica/alumina keeps constant) were prepared for their crystallization tendency. The mass ratio of (SiO 2 + Al 2 O 3 ) ranges from 30 to 70 wt.%. For the kinetics calculation, the Kissinger method was applied for activation energy under cooling conditions with DSC results and the JMA equation was used for crystallization mechanisms based on SHTT results under isothermal conditions. Bulk quenching samples were produced in a high temperature quenching furnace and analyzed by XRD to determine phases. The thermodynamic modeling program FactSage was also applied to predict the equilibrium composition and compared with experimental results. It turns out that crystallization of the slag with high amount of (SiO 2 + Al 2 O 3 ) was so weak that the crystals could hardly be observed. Higher basic oxides favored crystallization and led to higher crystallization temperature. When the proportion of (SiO 2 + Al 2 O 3 ) reduced to 30%, the crystallization tendency was extremely strong that the crystals formed at 1380 °C.

The temperature field and thermal cycling characteristics of a cast-steel matrix die of automobile crankshaft were predicted. The hot forging die was divided into three temperature regions, i.e., surfacing temperature fluctuation region (0–3 mm in thickness), near surfacing temperature gradient region (3–20 mm in thickness) and matrix temperature balanced region (above 20 mm in thickness), and their temperatures were distributed in high, medium and low-tempered temperature zones respectively. The influences of temperature distribution on the microstructure and mechanical properties of the forging die before and after service were studied. The tempered martensite of strengthened layer decomposed and the coarse grain appeared after service. The protruding part of the ribbed slab was easy to propagate fatigue crack, leading to significant decreasing of tensile strength and impact properties. The tempered martensite and lower banite increased in transition layer, the mechanical properties under high temperatures decreased obviously. The strengthening of hardened structure in weld zone was reduced and the coarse grain structure disappeared, this enabled the performance of the weld zone was more stable than the cast-steel matrix layer and the transition layer.

The thermal conduction behavior of slags affects the stable operation of entrained-flow gasifier. The thermal conduction behavior of five-element synthetic slag system with four series variable composition was systematically studied. The turning point of thermal conductivity changing with temperature is observed in each sample, where thermal conductivity is at peak value. The temperature of this point is defined as the transition temperature Tct, which is determined by the intersection point of two fitting lines based on two mechanisms. When T > Tct, the thermal conductivity is exponentially related to the reciprocal of temperature. With decrease of temperature, two different downward trends of thermal conductivity are observed, which is probably caused by the difference of crystal precipitating rate, and the effects of glassy and crystal state also cannot be neglected. When T

The generation of tar is the major draw back of biomass gasification, which is a barrier on the road to clean energy. Steam reforming is a promising method to eliminate tar in the biomass gasification process, which have been shown in our pilot tests. In this paper, the steam reforming of tar is investigated in a bench-scale horizontal tube reactor with Chemkin simulation, and in a pilot-scale tar reformer with CFD simulation. A set of simplified reaction paths and kinetic data is developed from bench-scale work, which is applied in the CFD simulation to predict the detail process in pilot-scale tar reformer. The prediction of CFD simulation is in a good agreement with the data from pilot test. The results revealed that the tar in the reformer is mainly eliminated by the steam, not the oxygen injected in the reformer, and the reaction place is within the first 1 m of the length of the reformer, where the intermediates of the reaction is decomposed quickly. Our CFD simulation indicated that the design of reformer can be optimized to a much shorter length, saving investment and heat. Our work demonstrated a complete cycle from the study of mechanism in bench-scale work to the investigation in pilot scale.

A comprehensive three-dimensional numerical model has been developed to for entrained flow coal hydrogasifier reactor. The kinetic model includes water evaporation, Johnson and Tran hydropyrolysis model, semichar reactions and secondary tar hydrocracking reactions. Numerical CFD(Computational Fluid Dynamics) simulation were performed using this model on a 6 t/d hydrogasifier reactor and the predictions are in good agreement with experimental results on coal conversion on a Dry Ash-Free (DAF) basis, overall carbon conversion, carbon conversions to the light hydrocarbon gases (LHGs, mainly methane) and the temperature at the outlet of the reactor. The performance of the reactor with different structural parameters (length-diameter draw ratio H / D , collision angle α , impinging distance h ) was compared, including the flow field, temperature distribution and carbon conversion to various products. The results show that larger H/D , smaller collision angle and impinging distance are favorable for higher carbon conversion and CH 4 production. But the influence of structural parameters on operating performance is not obvious.

In entrained flow gasifiers, crystallization inside the liquid slag can cause an increase of the slag viscosity, affecting flow along the wall and resulting in operational challenges. In the study reported here, a real Chinese ash was investigated for its crystallization behavior as well as the viscosity. Differential Scanning Calorimetry (DSC) and the Single Hot Thermocouple Technique (SHTT) were combined to measure the crystallization temperature and observe the crystallization process, constructing the temperature-time transformation (TTT) diagram. The ash was heated and then quenched to determine the crystalline phases. Unlike the synthetic slag mixed with oxides, the compositions of real ash had some variations after the long time heat treatment, which may attribute to the reducing minerals in the ash. Under inert atmosphere, gehlenite and spinel were the main crystals in cooling process. While under reduced atmosphere, the amount of crystals decreased especially gehlenite. Spinel was widely distributed inside the slag with irregular shape forming a network which caused the sharp increase of viscosity. The temperature of critical viscosity ( T cv ) was around 1310 °C corresponding to the spinel proportion calculated about 20%.

Colorectal cancer (CRC) is one leading contributor of cancer-related mortalities. Mammalian target of rapamycin (mTOR), existing in two complexes (mTORC1/2), is a valuable target for possible CRC interference. In the current study, we showed that WAY-600, a potent mTOR inhibitor, only exerted moderate activity against primary and HT-29 CRC cells. We proposed that DNA-dependent protein kinase catalytic subunit (DNA-PKcs) could be the major resistance factor of WAY-600 in CRC cells. DNA-PKcs inhibitors, including NU7026 and NU7441, dramatically enhanced WAY-600-induced cytotoxic and pro-apoptotic effect against the CRC cells. Further, WAY-600-exerted cytotoxicity was significantly increased in DNA-PKcs-silenced (by targeted siRNA/shRNA) CRC cells, but was attenuated with DNA-PKcs overexpression. Our evidence suggested that DNA-PKcs Thr-2609 phosphorylation might be critical for WAY-600's resistance. Mutation of this site through introducing a dominant negative DNA-PKcs (T2609A) dramatically potentiated WAY-600's sensitivity in HT-29 cells. Meanwhile, overexpression of protein phosphatase 5 (PP5) dephosphorylated DNA-PKcs at Thr-2609, and significantly increased WAY-600's sensitivity in HT-29 cells. In vivo, WAY-600-induced anti-HT-29 xenograft growth activity was significantly potentiated with NU7026 co-administration. These results suggest that DNA-PKcs could be the major resistance factor of WAY-600 in CRC cells.

A kinetic model of hydropyrolysis was developed based on the Chemical Percolation Devolatilization (CPD) network devolatilization model, considering the hydrogenation reactions of active species and fragments produced during the decomposition of the coal structure with hydrogen. Light gas compositions were calculated and the yields of oxygen-containing species were corrected. The calculation results show that the model well predicts the yields of volatile matter and methane for the coals that are in the scope of application of the correlation of the chemical structure parameters, with the value of β ranging from 0.0035 to 0.004 atm −1 , where β is a coefficient related to the ratio of the reaction rate of hydrogenation to that of crosslinking. The model successfully predicts the influence of coal type, final temperature and pressure on the hydropyrolysis yield and gas compositions. Further studies are needed to validate the model and determine the value and influencing factors of β .

A slag flow and heat transfer model coupled with a particle capture sub-model and 3-D gasifier model was developed to describe the slag characteristics and gasification process in entrained flow gasifier. A criterion for particle capture was used to evaluate the interaction of particles colliding with the wall. Two kinds of gasifiers were simulated using the developed model: the membrane wall gasifier and the refractory wall gasifier. The model was proved reliable by comparing the simulation with industrial results. Sensitivity of the model was analyzed. The model predicted the local thickness of the solid and liquid slag layers as well as the temperature distribution across the slag layer. Further study investigated the influence of particle behavior on slagging in the gasifier. In addition, a comparison was made between the membrane wall gasifier and the refractory wall gasifier. The results indicated that temperature of critical viscosity and the thermal conductivity of the slag were crucial factors in determining the accuracy of the combined model. The slag of the membrane wall consisted of both a solid and liquid slag layer. The internal surface temperature of the steel was lower than 540 K, which decreases the occurrence of thermal corrosion. The larger particle was beneficial to the capture efficiency and formation of slag layer, while the smaller one favors high carbon conversion. For the membrane wall gasifier, the thermal resistance of the solid slag layer contributed to the protection of the silicon carbide layer and membrane wall. For the refractory gasifier, thermal resistance of the refractory lining and environment convection were the major parts.

In entrained flow gasifiers, crystallization inside the liquid slag can increase the viscosity of the slag, affecting flow down the wall and resulting in operational challenges. Chemical composition of the slag is an intrinsic factor of crystallization characteristics. In the study reported here, five synthetic slags with different SiO 2 /Al 2 O 3 (S/A) ratios from 0.5 to 4.5 were investigated for their crystallization tendency. Differential Scanning Calorimetry (DSC) and the Single Hot Thermocouple Technique (SHTT) were combined to measure the influence of S/A on crystallization temperature and crystalline morphology, and to construct Temperature Time Transformation (TTT) diagrams, which can be an practical operation guide of temperature to a gasifier. For the kinetics calculation, the Kissinger method was used for activation energy based on DSC results under cooling conditions and the JMA equation was applied for crystallization mechanisms under isothermal conditions with SHTT results. Understanding the crystallization temperature is significant to the practically operation of gasifier when using a crystalline slag. It turns out that crystallization of the slag with low S/A (0.5) was so weak that the crystals could hardly be observed while the S/A range from 2.5 to 3.5 favored crystallization around 1100–1250 °C. As the S/A increased to 4.5, crystallization was retarded and shifted to a lower temperature range, below 1150 °C. Bulk quenching samples were produced in a high temperature quenching furnace and analyzed by XRD to determine phases. The thermodynamic modeling program Factsage was also applied to predict solids in equilibrium and compared with experimental results.

In slagging gasifiers, the crystallization ratio and crystal morphology are of great importance to fluidity of slag. Although increasing attention has been paid to the influence of crystallization on viscosity, few studies have investigated crystallization kinetics in slag melts due to challenges associated with high temperature and experimental complexity. In order to gain an understanding of crystallization characteristics, an in-situ observation Single Hot Thermocouple Technique (SHTT) system was set up and direct observation of the crystallization process was conducted. After completely melting, the slag would form a film as a result of its surface tension on the tip of the thermocouple. When the slag reached a certain degree of undercooling, crystals would precipitate from the homogenous melt. The crystallization ratio was quantitatively determined by taking advantage of the crystal color difference from the surroundings. A synthetic slag was produced from five oxides, with composition 38.4SiO2–14.8Al2O3–20.8CaO–19.1Fe2O3–6.9MgO, which is modeled on a real Chinese coal ash slag with low liquidus temperature and distinct crystallization characteristics. The crystallization characteristics of this synthetic slag were studied under isothermal temperatures and continuous cooling rates. Temperature Time Transformation (TTT) and Continuous Cooling Transformation (CCT) diagrams of the slag were constructed and a fundamental understanding of crystallization influenced by temperature and cooling rates was obtained. With decreasing temperature or increasing cooling rates, the crystals became finer and smaller. At lower temperatures with high degrees of undercooling the incubation time was shortened and the crystallization ratio increased. The influence of cooling rate was not significant until it exceeded 80 °C/min. Then the growth of crystals was greatly suppressed by high cooling rates, even appearing glassy when it surpassed the critical cooling rate. Based on the classic JMA equation, the crystallization kinetics and mechanism were determined. The Avrami parameter n indicates that at temperatures higher than 1200 °C, interfacial reaction mainly controlled the crystallization process, while at lower temperatures, diffusion was dominant. The crystals formed in different temperature regions may be different phases, which can also be predicted by Factsage Software, but needs further validation.

High-quality CdS/TiO 2 /FTO nanorod-array film photoelectrodes were fabricated by electrochemical atomic layer epitaxy method (ECALE). The detailed synthesis process and the surface morphology, structure, composition, optical absorbance property of the products were characterized by electrochemical voltammetry, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersion spectroscopy, ultraviolet and visible spectrophotometry, respectively. The results show that the ECALE method can significantly enhance the coverage of CdS quantum dots on TiO 2 surface and control the size of CdS quantum dot availably. In comparison with a pure TiO 2 nanorod array, the photovoltaic performance of the cell based on the ECALE deposited CdS/TiO 2 /FTO electrode achieves a maximum short circuit current density of 10.04 mA/cm 2 under one sun (AM 1.5G, 100 mW/cm 2 ), which is 5.7 times higher than that of the naked one.

Ternary oxide Zn 2 SnO 4 was successfully introduced to SnO 2 hierarchical microsphere photoanode for dye-sensitized solar cells by spin-coating method. Zn 2 SnO 4 nanoparticles with average size of 20 nm modified the SnO 2 hierarchical microsphere film uniformly and sufficiently. The shell of Zn 2 SnO 4 nanoparticles plays an important role in resisting acid etchant and suppressing the recombination of conduction band electrons with the oxidized dye. Benefiting from the advantages of both constituents, the composite photoanode exhibits an improved chemical stability and good photoelectric properties in contrast with bare SnO 2 nanostructures.

A double-layer (DL) film with a TiO2 nanosheet-layer on a layer of TiO2 nanorod-array, was synthesized on a transparent conductive fluorine-doped tin oxide substrate by a two-step hydrothermal method. Starting from the precursors of NaSeSO3, CdSO4 and the complex of N(CH2COOK)3, CdSe quantum dots (QDs) were grown on the DL-TiO2 substrate by chemical bath deposition method. The samples were characterized by X-ray diffraction, Scanning electron microscopy, Energy dispersion spectroscopy, and their optical scattering property was measured by light reflection spectrometry. Some CdSe QDs sensitized DL-TiO2 films serve as the photoanodes, were assembled into solar cell devices and their photovoltaic performance were also characterized. The short circuit current and open-circuit voltage of the solar cells range from 0.75 to 4.05 mA/cm2 and 0.20 − 0.42 V under the illumination of one sun (AM1.5, 100 mW/cm2), respectively. The photocurrent density of the DL-TiO2 film is five times higher than that of a bare TiO2 nanorod array photoelectrode cell.

An experimental study on the angle of repose (AoR) of pulverized coal with different particle sizes and different moisture contents (MC) was conducted. Three different measurement methods, free-base piling, fixed-base piling and sliding, were used. The data were analyzed by one-way and two-way analysis of variance. The results showed that the AoRs of pulverized coal with particle sizes smaller than 150 μm were in the range of 30–50°. The characterization of the flowability of pulverized coal was some cohesiveness or true cohesiveness. The increase of MC will increase AoR and thus decrease the flowability of the powder. However, the particle size effect is bifurcated. Below a critical size, the decrease of particle size decreases the flowability; while above the critical size, the decrease of particle size increases the flowability. It was found that the value of the critical size strongly depends on the powder density. Moreover, the AoR dependence on particle size could be linked with the Geldart's particle classification. The critical size at the turning point is on the boundary between Group A and Group B in Geldart's classification diagram. Based on the experimental results, there is no significant cross interaction between particle size and MC. The AoRs measured by free-base method and fixed-base method are close, but both remarkably smaller than that measured by the sliding method.

Starting from elemental powder mixtures of AgSn 18 SbTe 20 and Sn 50 Te 50 , P-type AgSn 18 SbTe 20 and Sn 50 Te 50 bulk thermoelectric materials were fabricated by a combined process of mechanical alloying (MA) and plasma activated sintering (PAS). It was found that SnTe compound could be easily synthesized after milling only for 1 h. Prolonging the milling time, Ag and Sb atoms diffused into the lattice of the primary SnTe compound gradually and SnTe-based solid solution was formed. The electrical resistivity and Seebeck coefficient of the as-PASed samples were measured from 323 K to 723 K. The maximum power factor of 1.98 × 10 −3 Wm −1 K −2 was obtained at 673 K for AgSn 18 SbTe 20 and it was higher than that of the material with similar composition from previous published literature.

Char―CO 2 gasification reactions in the presence of CO and char-steam gasification reactions in the presence of H 2 were studied at the atmospheric condition using a thermogravimetric apparatus (TGA) at various reactant partial pressures and within a temperature range of 1123 K-1223 K. The char was prepared from a lignite coal. The partial pressure of H 2 and CO varied from 0.05 to 0.3 atm. The experimental results showed that Langmuir-Hinshelwood (L-H) kinetic equation was applicable to describe the inhibition effects of CO and H 2 . The kinetic parameters in L-H equations were obtained. Interactions of char gasification by steam and CO 2 in the presence of H 2 and CO were discussed. It was found that the kinetic parameters determined from pure or binary gas mixtures can be used to predict multi-component gasification rates. The results confirmed that the char-steam and char―CO 2 reactions proceed on separate active sites rather than common active sites.

Bismuth selenide thin films were grown on Pt substrate via the route of electrochemical atomic layer epitaxy (ECALE) in this work for the first time. The electrochemical behaviors of Bi and Se on bare Pt, Se on Bi-covered Pt, and Bi on Se-covered Pt were studied by cyclic voltammetry and coulometry. A steady deposition of Bi 2 Se 3 could be attained after negatively stepped adjusting of underpotential deposition (UPD) potentials of Bi and Se on Pt in the first 40 deposition cycles. X-ray diffraction (XRD) analysis indicated that the films were single phase Bi 2 Se 3 compound with orthorhombic structure, and the 2:3 stoichiometric ratio of Bi to Se was verified by EDX quantitative analysis. The optical band gap of the as-deposited Bi 2 Se 3 film was determined as 0.35 eV by Fourier transform infrared spectroscopy (FTIR), which is consistent with that of bulk Bi 2 Se 3 compound.

Hydrogen formed in oxidative coupling of methane (OCM) over BaCO3 and MgO catalysts was measured since the data of H2 selectivity were missing almost in all articles published heretofore. It was found that H2 selectivity achieved about 18%, when C2 hydrocarbon's selectivity was maintained at 48%–45% over BaCO3 catalyst at the feed molar ratio of CH4/O2 = 4 in temperature range of 780 °C–820 °C. Under similar conditions, H2 selectivity was about 14%–16% over MgO catalyst, with C2 selectivity maintained at 41%–42%. Possible routes for hydrogen formation in OCM reaction were discussed. Effect of addition of alkali metallic ions was also investigated.

Measurement of temperature profiles of gas-solid two-phase flow at different heights in commercial-scale circulating fluidized bed (CFB) boilers was carried out. Experimental results showed that the thickness of thermal boundary layer was generally independent of the distance from the air distributor, except when close to the riser outlet. Through analysis of flow and combustion characteristics in the riser, it was found that the main reasons for the phenomena were: 1) the hydrodynamic boundary layer was thinner than the thermal layer and hardly changed along the CFB boiler height, and 2) both radial and axial mass and heat exchanges were strong in the CFB boiler. Numerical simulation of gas flow in the outlet zone confirmed that the distribution of the thermal boundary layer was dominated by the flow field characteristics.