The role of turbulent fluctuations on radiative emission in hydrogen and hydrogen-enriched methane flames

A theoretical analysis is reported in the present work to quantify the increase of radiative emission due to turbulence for hydrogen and hydrogen-enriched methane diffusion flames burning in air. The instantaneous thermochemical state of the reactive mixture is described by a flamelet model along with a detailed chemical mechanism. The shape of the probability density function (pdf) of mixture fraction is assumed. The results show that turbulent fluctuations generally contribute to reduce the Planck mean absorption coefficient of the medium, in contrast with the blackbody emissive power, which is significantly increased by turbulence. If the turbulence level is relatively small, the influence of turbulence on the absorption coefficient is marginal. Otherwise, fluctuations of the absorption coefficient of the medium should be taken into account. The scalar dissipation rate and the fraction of radiative heat loss have a much lower importance than the turbulence intensity on the mean radiative emission.     

Impacts of CO2 emission constraints on technology selection and energy resources for power generation in Bangladesh

This paper examines the impacts of CO₂ emission reduction target and carbon tax on future technologies selection and energy use in Bangladesh power sector during 2005–2035. The analyses are based on a long-term energy system model of Bangladesh using the MARKAL framework. The analysis shows that Bangladesh will not be able to meet the future energy demand without importing energy. However, alternative policies on CO₂ emission constraints reduce the burden of imported fuel, improve energy security and reduce environmental impacts. The results show that the introduction of the CO₂ emission reduction targets and carbon taxes directly affect the shift of technologies from high carbon content fossil-based to low carbon content fossil-based and clean renewable energy-based technologies compared to the base scenario. With the cumulative CO₂ emission reduction target of 10–20% and carbon tax of 2500 Taka/ton, the cumulative net energy imports during 2005–2035 would be reduced in the range of 39–65% and 37%, respectively, compared to the base scenario emission level. The total primary energy requirement would be reduced in the range of 4.5–22.3% in the CO₂ emission reduction targets and carbon tax 2500 Taka/ton scenarios and the primary energy supply system would be diversified compared to the base scenario.     

Examining the driving forces for improving China’s CO2 emission intensity using the decomposing method

This paper examines the driving forces for reducing China’s CO₂ emission intensity between 1998 and 2008, utilizing the logarithmic mean divisia index (LMDI) technique. By first grouping the CO₂ emissions into two categories, those arising from activities related to the electric power industry and those from other sources, emission intensity is further broken down into the effects of the CO₂ emission coefficient, energy intensity of power generation, power generation and consumption ratio, electricity intensity of the gross domestic product (GDP), provincial structural change, and the energy intensity of the GDP for other activities. The decomposition results show that improvements in the energy intensity of power generation, electricity intensity of GDP, and energy intensity of GDP for other activities were mainly responsible for the success in reducing China’s CO₂ emission intensity and that activities related to the electric power industry played a key role. It is also revealed that performance varied significantly at the individual province level. The provinces with higher emission levels contributed the most to China’s improvements in CO₂ emission intensity.     

稻壳混合贫煤燃烧对SO2排放的影响

本文利用循环流化床实验平台,分析稻壳混煤燃烧对SO2排放的影响.将稻壳与贫煤按不同质量比制成混合燃料,在流化床锅炉中燃烧,采集炉温及烟气中SO2浓度等数据进行分析.结果表明,当燃烧温度恒定时,SO2的排放量随着燃料中稻壳所占比重增加而降低;当燃料中稻壳所占比重恒定时,SO2的排放量随着燃烧温度的升高而增加.     

微型燃气轮机燃烧室性能影响因素的探讨

针对微型燃气轮机燃烧室性能的各种影响因素(进气条件、燃料热值、燃烧室结构等)对燃烧稳定性和燃烧效率的影响,介绍了国内外相关实验和数值模拟研究现状,分析了燃烧室主要污染物的生成机理和影响因素,以及降低氮氧化物排放浓度的技术措施。     

低低温电除尘及高效电源协同烟气处理技术的应用

为研究低低温电除尘及高效电源协同烟气处理技术的应用效果,以一循环流化床锅炉为研究对象,通过试验方法,对协同烟气处理技术投运前后烟气中的粉尘颗粒特性及排放质量浓度进行了测量及对比,并对该技术投运后的经济性进行了分析.结果表明:协同烟气处理技术投运后,机组排放的粉尘质量浓度由49.5 mg/m3降低至10.7 mg/m3,...     

内河船舶LNG发动机-蓄电池混合动力系统性能仿真

为改善船舶天然气发动机动力系统调速性能,提高内河液化天然气（LNG）燃料动力船舶的操纵性及安全性,提出构建天然气发动机-蓄电池混合动力系统。分别针对LNG发动机动力系统及混合动力系统建立Matlab/Simulink仿真模型,并实现了船舶起动和变负荷过程。对两种仿真系统的仿真结果进行分析,结果表明：采用该混合动力系统的船舶变负荷过程航速变化区间变大,系统达到稳定时间缩短;采用设计的控制策略,天然气的消耗最多降低19.6%;NOx、CO、HC排放分别最多降低22.1%、18.5%、23.6%。     

基于声学有限元的柴油机增压器压气机气动噪声研究

为研究船用低速柴油机增压器压气机气动噪声,采用计算流体动力学和声学有限元的混合计算方法进行了数值预测。通过试验对压气机计算模型进行了验证。在3个工况下对压气机非定常流场进行了计算,其中压力脉动被用作声学计算中的声源信息;采用声学有限元方法对压气机气动噪声进行了预测。结果表明:计算流体力学和声学有限元的混合计算方法具有较高的计算精度,可以用于压气机气动噪声数值预测;压气机进口气动噪声主要谱成分为离散单音噪声和宽频噪声;离散单音噪声在叶片通过频率处有明显的指向性,存在两个突出峰值。     

电子调速器控制器的电磁兼容分析与试验验证

基于辐射发射的形成机理,以某型号电子调速器控制器为目标,利用EMSCAN电磁干扰扫描系统对控制器进行近场辐射测试,总结出一套切实可行的辐射发射分析与试验验证方法.在此基础上,对该型号电子调速器控制器进行了整改设计,并进行了试验验证.结果 表明:基于EM-SCAN系统的分析及整改方法效果明显,缩短了电子产品电磁兼容问题的整改设计周期,并节约了测试成本.     

丙酮-丁醇-乙醇(ABE)/汽油混合燃料对高速发动机性能影响的试验研究

以发动机4000r/min、节气门开度35%为试验工况,对纯汽油及不同掺混体积分数丙酮-丁醇-乙醇(acetone-butanol-ethanol,ABE)与汽油混合物开展了不同点火提前角和喷油量的试验研究。分析了不同ABE混合比、点火提前角和过量空气系数对发动机性能的影响,并对每种燃料发动机最大功率工况的性能参数进行了比较。结果表明：点火提前角和过量空气系数相同时,混合燃料中ABE含量越高,燃油流量越大,发动机功率越大,有效热效率越高;燃油流量的总热量增大和热-功转换效率提高是促使发动机功率增大的主要原因;随ABE掺混比增加,NO比排放明显降低,CO比排放略有增加,碳氢化合物比排放先增后减。浓混合气工况增加ABE含量比在当量空燃比状态下增加ABE含量,发动机的有效热效率增大更明显,发动机的NO比排放降低更加明显。研究表明高速汽油机掺混ABE燃料具有较好的应用前景。