基于可调谐二极管激光吸收光谱分析技术的燃烧烟气组分浓度和温度的测量分析

针对目前燃烧测量中的不足,结合国内外燃烧检测技术的发展趋势,提出采用可调谐二极管激光吸收光谱技术测量燃烧组分和温度的方法并概述了该技术的特点。首先分别详细推导了该测量技术的浓度和温度测量的原理,并分别介绍直接吸收测量方法和二次谐波测量方法的特性以及两者之间的差异。在实验室中,运用二次谐波测量方法标定了从600℃～1000℃的标定曲线。通过应用实例的介绍和该项测量技术的特点分析,指出该测量技术将在燃烧的烟气组分浓度和烟气温度的测量中得到广泛的应用。     

超细水雾熄灭甲烷火焰的临界灭火质量浓度

利用发展的临界灭火质量浓度预测模型,分别在1600K和1700K两种燃烧极限温度下对超细水雾和水蒸气的临界灭火质量浓度进行计算,并采用FLUENT软件开展具有详细化学反应的数值模拟.模型采用1600K得出的理论结果与模拟结果、前人实验结果均较为接近;通过对比理论结果与模拟结果,发现超细水雾冷却在灭火作用中的效果稍高于水蒸气,但却远低于水;模拟发现在火焰温度降低到1600K以下时,才可实现稳定灭火,这对于消防工程中火焰熄灭温度的选取具有一定理论指导作用.     

温度法测量煤粉浓度的研究

介绍了温度法测量煤粉浓度的原理和方法,并指出以往在测量煤粉浓度的过程中,由于温度测量滞后,会引起粉量波动动态误差的问题。提出了温度测量的数值补偿模型,给采集的时间序列温度数据进行动态补偿,对热风送粉的燃烧调整具有积极意义。     

基于灰色关联和ABC-BP神经网络的叶绿素a浓度预测

为预测太湖梅梁湾叶绿素a浓度,建立了基于灰色关联和ABC-BP神经网络的叶绿素a浓度预测模型,即通过灰色关联分析选取总磷、CODMn、水温、pH值、悬浮质为BP神经网络的输入变量,采用人工蜂群(ABC)算法优化网络权值与阈值,构造基于ABC算法优化的BP(ABC-BP)神经网络模型,预测出2014年1月?2015年12...     

预混合气浓度和温度对DMCC发动机运行边界的影响

以大柴DEUTZ-BM6F1013发动机的燃烧室为原型,采用FORTé程序包建立了缸内燃烧的三维CFD模型.通过不同条件下模型计算值与试验值的对比验证了模型的正确性.基于纯柴油模式(1,000,r/min、100,N·m)工况点,计算了不同初始温度、初始甲醇混合气浓度下缸压的变化情况,结果表明:柴油/甲醇组合燃烧(DMCC)模式随预混合气浓度和温度变化的运行边界可分为失火、爆燃和早燃3个区域.在失火和早燃区域,预混合气浓度的极限值均较低,热效率不高,且存在停转的风险,不利于发动机安全可靠的运行;在爆燃区域,预混合气浓度的极限值受最大爆发压力的限制,可以维持较高的数值,且该阶段燃烧稳定,发动机热效率高.因此,进一步提高DMCC模式的掺醇比,应考虑使发动机运行在进气的中高温范围.     

转化气余热锅炉管板结构的温度耦合分析

转化气余热锅炉入口温度达到860℃,管壳程温差载荷较大,管板承受内压和温差载荷的双重作用,在管板管程侧、换热管管板部位和旁通管内部设计了防热材料,管板的管壳程的连接结构采用H型锻件,在温差载荷和管壳程设计压力相互作用的三种工况条件下,依据JB4732对设备相应部位进行应力评定,评定结果合格,为工程设计人员提供可参考的数据。     

强烟尘水滴干扰下DOAS法在线测量NO质量浓度的研究

在高浓度烟尘、水汽液滴和NO共存的工况下,采用差分吸收光谱法研究和分析了不同质量浓度NO的吸收光谱特性,提出了一种基于差分吸收光谱法的NO质量浓度反演算法;同时,利用信噪比对小波分解时小波母函数的选取进行了比较.结果表明：在对NO吸收光谱进行小波分解后,即使在干扰颗粒质量浓度较大时,某些特征波长点处的小波系数高频细节分量与未受干扰的NO吸收光谱的小波系数高频细节分量有较好的重合;通过对小波分解时小波母函数选取的比较,可以获得适用于此反演算法的最优小波母函数sym10,它可以有效消除烟尘、水汽液滴的干扰影响,而且测量误差在允许范围内,能够满足烟尘排放监测要求.     

机车组合式活塞温度应力耦合场有限元分析

本文以280机车组合式活塞为研究对象，利用Pro／E进行了实体建模，然后导入有限元分析软件中，采用间接耦合法对活塞原设计及其改进方案在各工况下的温度场以及热载荷和外加载荷综合作用下的应力场进行了分析对比，结果表明改进后在易失效的部位温度值稍有降低，应力值则有明显下降，且对比计算出了危险点的应力降幅。计算结果证明了改进设计的有效性，为活塞的改进方案提供了有力依据。     

液态排渣煤粉燃烧器燃烧温度影响因素分析

针对液态排渣煤粉燃烧器,基于方程求解法建立燃烧温度计算模型,采用控制变量的方法设计计算方案,研究分析了热风温度、过量空气系数、冷却水带走热量比例、热负荷、煤低位发热量各单因素对燃烧温度的影响规律。计算了20种不同影响因素情况下的煤粉燃烧器燃烧温度,在此基础上,利用灰色关联分析探讨了各因素对燃烧温度的影响程度。     

阀控式密封铅酸蓄电池的容量与温度关系分析

研究了阀控式密封铅酸蓄电池在工作时容量与温度关系,分析了温度对蓄电池寿命的影响,提出了这种电池在制造及使用过程中应注意的一些问题.     

Experimental study on the temperature dependence of ultraviolet absorption cross-sections of sulfur dioxide

The photoabsorption cross-sections of sulfur dioxide were measured in the spectral regions of 200–230 nm and 275–315 nm at 298–415 K, using a grating monochromator with a resolution of 0.2 nm. The discrete absorption cross-section is directly correlated with the number of quantum excited from the base state. The absorption cross-sections at the peaks of discrete bands decreased linearly with the increase of temperature, which corresponded to the decrease in the population of vibrational and rotational transitions from the base level to higher excitation levels. The absorption cross-section peaks decreased linearly when the temperature increased from 298 to 415 K, with relative drops of 74.0% and 75.8% at 200–230 nm and 275–315 nm, respectively. Another distinctive feature of sulfur dioxide absorption spectra in the above two spectral regions was the quasiperiodic structure of the absorption peaks, whose equal wavelength intervals were 1.53 nm and 1.95 nm, respectively. Red and blue shifts were not found at the absorption peak positions. __________ Translated from Journal of Zhejiang University (Engineering Science), 2007, 41(2): 329–332 [译自: 浙江大学学报(工学版)]     

Effect of temperature and iron concentration on the growth and hydrogen production of mixed bacteria

Anaerobic mixed culture acclimated with sucrose was used as inoculum in batch experiments to investigate the effects of various parameters on biological hydrogen production from sucrose. In particular, the effect of the culture temperature has been investigated in detail. The optimum of the iron concentration in the external environment on hydrogen production was also studied at different temperatures. Experimental results show that the hydrogen production ability of the anaerobic bacteria was deeply affected by both culture temperature and iron concentration. Increasing the culture temperature favored the production of hydrogen when it was in the range of 25–40 °C, and high sucrose conversion efficiencies (ca. 98%) were consistently obtained with the mixed bacteria at the same time. While the temperature went on increasing to 45 °C, the hydrogen production was almost inhibited. The optimum concentrations of iron for hydrogen production decreased obviously along with increasing the reactor's temperature. For 25, 35, and 40 °C, the maximum production yield of hydrogen were 356.0, 371.7, and 351.1 ml obtained at the iron concentration of 800, 200, and 25 mg FeSO₄l^-1${\mathrm{l}}^{-1}$, respectively.     

Experimental and principal component analysis studies on minimum oxygen concentration of methane explosion

Gas explosion has always been one of the leading disasters in chemical and mining industries, causing tremendous considerable casualties and property damage. It is very effective to control ignition parameters to prevent explosion accidents. To intensively investigate the impacts of C₂H₆/C₂H₄/CO/H₂ mixtures on CH₄ explosion, we added C₂H₆/C₂H₄/CO/H₂ mixtures with different ratios (samples 1–4) and different volume fractions ([mixture] = 0–2.0 vol%) to CH₄/air([CH₄] = 7.0, 9.5 and 11.0 vol%) for measurement of the flammability limit and minimum oxygen concentration (MOC) for CH₄ explosion in a 20-L spherical vessel. Changes of flammability limits of CH₄ were obtained with the addition of C₂H₆/C₂H₄/CO/H₂ mixtures at room temperature (18–22 °C) and pressure (1 atm). The experimental data about MOC of CH₄ explosion were examined by principal component analysis (PCA). On the basis of experimental results, multiple regression models were established to determine the influences of principal components on MOC of CH₄ explosion. The results clearly indicated that the impacts of organic and inorganic combustible gases on flammability limits of CH₄ were significantly different. The involvement of sample 1 and sample 2 (main component is organic flammable gas) increased the explosive hazard degree (F value) of CH₄ by 43.18% and 45.45%, respectively. However, it was increased by 15.91% and 4.55%, respectively after adding sample 3 or sample 4 (main component is inorganic flammable gas). Additionally, the required MOC for CH₄ explosion was increased with the increase of C₂H₆/C₂H₄/CO/H₂ mixtures, and they showed a quadratic parabola relationship. Moreover, the linear expressions between the concentrations of C₂H₆, C₂H₄, CO and H₂ and the MOC of CH₄ explosion were achieved by PCA. Based on these analyses, it is indicated that the effects of C₂H₆, C₂H₄ and CO were increasingly significant on MOC while H₂ was just the opposite from the oxygen-rich state to the stoichiometric state and fuel-rich state for CH₄/air mixture. The results presented in this paper can provide theoretical reference for the prevention and control of multiple flammable gas explosion.     

The effect of total solids concentration and temperature on biogas production by anaerobic digestion

This paper analyzed the effect of total solids (TS) concentration and temperature on biogas production from anaerobic digestion with dairy manure. Batch experiments were carried out for TS concentrations of 6%, 8%, and 10%, respectively, at five different temperatures (31, 34, 37, 40, and 43°C). Results showed that two factors both had significant effect on biogas production. The optimal condition for anaerobic digestion was 8% TS concentration at the temperature of 40°C. Under such condition, the biogas production is much better than the others and the yield peaked higher. Daily biogas production of 8% was more than those test groups which are 6% and 10% under the same temperature. When TS concentration was 8%, the rank of total biogas production of different digestion temperature test was 40 ＞ 37 ＞ 34 ＞ 43 ＞ 31°C, the biogas production of the 31, 34, 37, 40, and 43°C was 0.123, 0.159, 0.171, 0.205, and 0.153 L/g, respectively.     

基于空间统计模型的区域风电消纳风险聚类分析

弃风问题严重制约风电场的可持续开发与建设,急须开展区域风电消纳风险的评估方法。为计算消纳风险,文章基于风险理论构建了风电消纳风险计量模型,并对蒙西地区87家风电场2012-2018年消纳风险数据进行空间相关性分析,应用ArcGIS工具研究内蒙古电网风电消纳风险区域的动态变化趋势和特征。研究结果能够直观反映区域的风险水平及其演化趋势,为区域风电场科学规划提供参考。     

温度参数对升温型溴化锂吸收式热泵性能系数影响程度分析

通过对升温型溴化锂吸收式热泵进行理论分析,得到在相同工况条件下,发生温度变化对系统性能系数的影响程度最大,但小于吸收温度和冷凝温度影响程度之和.并利用焓浓度图,结合前人数据对理论分析进行了验证.     

Measurement of concentrator solar cell efficiency at high concentration and narrow-band spectrum

High efficiency of solar cells may be obtained at high concentration and narrow-band spectrum system. Difficulties are encountered in determination of the cell efficiency using narrow-band-artificial-light sources at high concentration. A method is proposed in this article for determination of the solar cell efficiency at high concentration and narrow-band spectrum. This method is based on measurement of the solar cell fill factor and the open-circuit voltage at moderate concentration and full spectrum, and based on a calculation procedure.     

Two-dimensional modeling of a salt-gradient solar pond with wall shading effect and thermo-physical properties dependent on temperature and concentration

In this paper,the behavior of a salt-gradient solar pond with the square cross-section has been studied experimentally and numerically.A small-scale solar pond were designed and built to provide quantitative data.A two-dimensional,transient heat and mass transfer model has been solved numerically by using finite-control-volume method.In this study,all the thermo-physical properties are variable as the function of temperature and salt concentration.Numerical results as obtained for the experimental pond have been satisfactorily compared and validated against measured data.Furthermore,the wall shading effect has been elaborated to improve the agreement between two sets of results.The temperature of the storage zone is predicted well by the model.It also can be observed that the initial concentration profile is preserved with time.The stability of the pond in time has been investigated in order to distinguish the critical zones.Finally,the application of an energy analysis gives an efficiency of about 12%for the pond.     

Effectively extending visible light absorption with a broad spectrum sensitizer for improving the H2 evolution of in-situ Cu/g-C3N4 nanocomponents

Photocatalysts with broad spectrum absorption have been desired for a long time due to their ability to absorb more visible light. Herein, we developed an in-situ approach to specifically fabricate Cu nanoparticles onto the exterior surface of g-C₃N₄, followed by sensitization with Erythrosin B, to improve the photocatalytic H₂ evolution of g-C₃N₄ and extend the spectrum absorption. The photocatalytic H₂ evolution rate was significantly promoted, to more than 26 times that of pure g-C₃N₄, and the photocatalytic ability was maintained until reaching a wavelength of 700 nm. The origin of the improved activity was attributed to an in-situ Cu nanoparticle modification, which acts as an electron reservoir, and dye sensitization, which could extend the range of the visible light absorption, preventing charge recombination and enhancing the visible light utilization efficiency. In addition, the photocatalytic stability was investigated, and no significant attenuation was detected after six recycles.