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1.
Flame structure and NO emission characteristics in counterflow diffusion flame of blended fuel of H2/CO2/Ar have been numerically simulated with detailed chemistry. The combination of H2, CO2 and Ar as fuel is selected to clearly display the contribution of hydrocarbon products to flame structure and NO emission characteristics due to the breakdown of CO2. A radiative heat loss term is involved to correctly describe the flame dynamics especially at low strain rates. The detailed chemistry adopts the reaction mechanism of GRI 2.11, which consists of 49 species and 279 elementary reactions. All mechanisms including thermal, NO2, N2O and Fenimore are taken into account to separately evaluate the effects of CO2 addition on NO emission characteristics. The increase of added CO2 quantity causes flame temperature to fall since at high strain rates a diluent effect is prevailing and at low strain rates the breakdown of CO2 produces relatively populous hydrocarbon products and thus the existence of hydrocarbon products inhibits chain branching. It is also found that the contribution of NO production by N2O and NO2 mechanisms are negligible and that thermal mechanism is concentrated on only the reaction zone. As strain rate and CO2 quantity increase, NO production is remarkably augmented. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
2.
结合大同铁路分局中心医院直线加速器室工程实际,介绍了大体积防射线混凝土的特点及施工中应注意的事项,并阐述了具体的施工技术。 相似文献
3.
高温炉内的辐射传热是工业生产中常遇到的问题。过去,人们在应用热流法计算辐射传热时遇到了一定的困难,使计算结果与实际有一定的偏差。本文运用文献[1]中给出的新热流数学模型,开发出由新热流方程与能量方程相耦合的计算机程序,其中的比热流参数由线加热热源情况下计算得到。用该程序计算了实验室用马弗炉内的温度场,并且用热电偶实测了炉内的一些温度值,理论计算与实测值符合很好。 相似文献
4.
5.
Thermal Radiative Properties of Xonotlite Insulation Material 总被引:1,自引:0,他引:1
X inxin ZHANG Gaosheng WEI Fan YU Department of Thermal Engineering University of Science & Technology Beijing Beijing China Professor 《热科学学报(英文版)》2005,14(3):281-283,253
Introduction Xonotlite-type calcium silicate (6CaO?6SiO2?H2O) is synthesized porous insulation material by hydrothermal processing with quartz powder and limestone as the raw material (with CaO/ SiO2≈1:1). Compared with fire- retardant fibre, xonotlite has more excellent insulating performance, such as low thermal conductivity, environment friendly, high intension, and wide applying temperature range, which has been emphasized in recent years by many scholars and widely used in many indu… 相似文献
6.
Radiation is usually the dominant mode of heat transfer in furnace enclosures. The imaginary planes method is one of the new methods for calculating the radiative heat transfer in such systems. In this study, a general procedure was developed for its application in furnace modelling. Various case studies were carried out for a number of furnaces, and the results were compared with those of the zone method. It was found that the new method combines good accuracy with low computation time and appears to be a promising method for the determination of heat flux and temperature distributions within furnace enclosures. 相似文献
7.
被动日间辐射制冷(PDRC)技术由于不需要外部能源、绿色清洁无污染而受到广泛关注。该文通过将聚二甲基硅氧烷(PDMS)和二氧化锆(ZrO2)颗粒进行复合形成分散液,将其浇铸成膜后得到PDMS/ZrO2辐射制冷薄膜材料,然后通过喷涂PDMS/SiO2分散液对其进行疏水化处理制备了一种超疏水辐射制冷薄膜材料。通过优化ZrO2粒径和喷涂液中SiO2用量,薄膜表面接触角可达156.6 ° ± 2 °,滚动角为0.3 ° ± 0.1 °,呈现优异的自清洁性能。其太阳光反射率高达95.3%,红外发射率大于90%。在太阳光直射下,薄膜可实现平均9.99 ℃的降温效果。薄膜的自清洁性能使其表面不受泥土污染从而具有稳定持久的辐射降温功能。除此之外,薄膜具有优异的机械性能、耐摩擦性能以及耐酸/碱溶液和紫外光照稳定性。 相似文献
8.
郑跃伟 《上海冶金高等专科学校学报》1995,(2)
由于水的选择性吸收特性,辐射换热中水份波长匹配一直是一个有分歧的问题。文章通过理论与计算论证了这个问题,得出的结论否定了波长匹配的重要性。 相似文献
9.
Jing Wang Dengsen Yuan Peiying Hu Yongjiang Wang Jin Wang Qingwen Li 《Advanced functional materials》2023,33(32):2300441
Silica aerogels, a type of porous material featuring extra low density and thermal conductivity, have drawn increasing interest from both academia and industry owing to their excellent thermal insulation performance. However, thermal insulation is always the single consideration when silica aerogels are used for thermal management. In this study, the on-demand thermal management (ODTM) of silica aerogel with either passive thermal insulation, passive heating, or passive cooling in different environments is revealed. The ODTM behavior of silica aerogels can be simply fulfilled through their optical property variations such as solar light transparency and infrared emissivity, which are controllable via the microstructures of the building blocks and surface composition design. Robust solar heating of 25 °C higher than the ambient in the daytime and sub-ambient cooling of 7 °C at night is achieved with the traditional transparent silica aerogel. Interestingly, sub-ambient cooling of 5 °C in the daytime and a warmer state on cold nights is achieved by modifying its solar transmittance and infrared emissivity. This study guides a comprehensive understanding of the thermal management behavior of silica aerogels and leads to ODTM applications of silica aerogels by tailoring their optical and thermal conductivity properties. 相似文献
10.
Yuan Deng Yihai Yang Yuanhang Xiao He-Lou Xie Ruochen Lan Lanying Zhang Huai Yang 《Advanced functional materials》2023,33(35):2301319
Switchable passive radiative cooling (PRC) smart windows can modulate sunlight transmission and spontaneously emit heat to outer space through atmospheric transparent window, presenting great potential in building energy conservation. However, realizing stable and on-demand control of the cooling efficiency for PRC materials is still challenging. Herein, an electro-controlled polymer-dispersed liquid crystal (PDLC) smart window showing PRC property is designed and prepared by adding mid-infrared emitting reactive monomers into the conventional PDLC matrix. It is found that not only the electro-optical properties but also the PRC efficiency of PRC PDLC film are tunable by regulating the content of the mid-infrared emitting components, film thickness, and micromorphology. This advanced PRC PDLC material achieves a near/sub-ambient temperature when the solar irradiance is below 400 W m−2 and can dynamically manage daytime cooling efficiency. Importantly, its PRC efficiency is capable of being tuned in an on-demand and ultrafast millisecond-scale way, whose controllable transparency enables multistage heat regulation. This study is hoped to provide new inspiration in the preparation of advanced optical devices and energy-efficient equipment. 相似文献