薄型PMMA板一面与两面燃烧实验研究

对薄型材料一面与两面燃烧时火蔓延的不同特性进行理论分析,推导一面与两面燃烧时的热平衡方程。使用长300mm、宽50 mm、厚2 mm的PMMA薄板分别开展一面与两面燃烧实验,记录试样的火焰高度、热解高度和燃烬长度随时间的变化。实验结果表明:两面燃烧时的火焰高度、热解高度、燃烬高度是一面燃烧时的1.4倍。分析火焰高度与热解高度、火蔓延速度与有效加热长度之间的关系,得出拟合公式。

竖直条件下可燃织物燃烧特性实验研究

设计实验装置,对尺寸1.80m×1.35m,厚0.30、0.44mm的棉布进行实验,测量燃烧火焰的温度分布、质量损失速率、火焰高度以及热解高度,研究竖直条件下可燃织物的燃烧特性,得出拟合曲线。燃烧30s后,可燃织物被撕成左右两块。实验结果表明:竖向可燃织物的燃烧可分为两个阶段。火焰前锋到达材料顶端前,火焰为二维蔓延,且竖向蔓延为变加速的加速运动,质量损失呈幂函数变化;火焰高度、热解高度与时间均呈幂函数关系,且两者符合函数H_f=αH^n_p的增长趋势,其中增长系数α均在1.84左右,幂数n接近于1,说明火焰高度和热解高度基本呈线性关系,且其变化趋势与材料厚度无关。燃尽前锋到达材料顶端后,火焰为一维蔓延,且质量损失呈线性递减,即质量损失速率为定值,说明火焰水平蔓延速率基本为定值。

Production of carbon anodes by high-temperature mould pressing

Laboratory-scale carbon anodes were produced by a new method of high temperature mould pressing, and their physico-chemical properties were studied. The influence of mould pressing conditions and coal pitch addition on the bulk density, crushing strength, and oxidation resistance was analyzed. The mierostructure of carbon anodes was investigated by scanning electron microscopy （SEM）, and the mechanism of producing carbon anodes by high-temperature mould pressing was analyzed. The results show that when the anodes are produced by high-temperature mould pressing, coal pitch can expand into the coke particles and fill the pores inside the particles, which is beneficial for improving the quality of prebaked anodes. The bulk density of carbon anodes is 1.64-1.66 g/cm3, which is 0.08-0.12 g/cm3 higher than that of industrial anodes, and the oxidation resistance of carbon anodes is also significantly improved.

Preparation of Nano-MnFe2O4 and Its Catalytic Performance of Thermal Decomposition of Ammonium Perchlorate

Nano-MnFe2O4 particles were synthesized by co-precipitation phase inversion method and low-temperature combustion method respectively, using MnCl2, FeCl3, Mn（NO3）2, Fe（NO3）3, NaOH and C6H8O7. X-ray diffraction （XRD）, transmission electron microscope （TEM）, Fourier transform infrared spectroscopy （FT-IR）, thermogravim-etry-differential thermal analysis （TG-DTA） and differential scanning calorimetry （DSC） were used to characterize the structure, morphology, thermal stability of MnFe2O4 and its catalytic performance to ammonium perchlorate. Results showed that single-phased and uniform spinel MnFe2O4 was obtained. The average particle size was about 30 and 20 nm. The infrared absorption peaks appeared at about 420 and 574 cm-1, and the particles were stable below 524 ℃. Using the two prepared catalysts, the higher thermal decomposition temperature of ammonium perchlorate was decreased by 77.3 and 84.9 ℃ respectively, while the apparent decomposition heat was increased by 482.5 and 574.3 J？g？1. The catalytic mechanism could be explained by the favorable electron transfer space provided by outer d orbit of transition metal ions and the high specific surface absorption effect of MnFe2O4 particles.

Numerical simulation of coupled thermo-electrical field for 20 kA new rare earth reduction cell

To solve the problems of high energy consumption,low efficiency and short service life of conventional rare earth reduction cells,a 20 kA new rare earth reduction cell(NRERC)was presented.The effects of the anode-cathode distance(ACD)and electrolyte height(EH)on the thermo-electrical behavior of the NRERC were studied by ANSYS.The results illustrate that the cell voltage drop(CVD)and the temperature will rise with a similar tendency when the ACD increases.Also,the temperature rises gradually with EH,but the CVD decreases.Ultimately,when the ACD is 115 mm and the EH is 380 mm,the CVD is 4.61 V and the temperature is 1109.8℃.Under these conditions,the thermal field distribution is more reasonable and the CVD is lower,which is beneficial to the long service life and low energy consumption of the NRERC.