Prediction of swirling confined diffusion flame with a Monte Carlo and a presumed-PDF-model

This work aims to compare numerical results obtained by using the Monte Carlo composition-PDF method and a presumed-β-PDF in order to reveal their effects on the prediction of flow and scalar fields in swirling confined methane diffusion flame. Using the intrinsic low dimensional manifolds method for modelling the chemistry and a second moment closure for the turbulence, it is shown that both PDF-methods provide a similar accuracy level of the prediction of mean quantities. While the presumed-β-PDF performs using reasonable computational efforts, the Monte Carlo-PDF allows to capture well the turbulence-chemistry interaction and strong finite-chemistry effects such as local extinction.     

高镁边缘磷矿制取阻燃剂氢氧化镁的工艺

为解决大量的高镁低磷边缘磷矿废渣堆存对环境的影响,开发了以其为原料制取阻燃剂氢氧化镁工艺.该工艺主要包括酸解磷矿和镁沉淀过程,重点讨论了沉淀氢氧化镁过程中时间、温度、氨镁摩尔比n(NH3/MgO)等多种因素的影响,得到的最佳工艺条件是:反应温度65℃,反应时间80min,n(NH3/MgO)为5∶ 1,镁的沉淀效率为80%.     

Heterogeneous chain propagation in low-pressure flames

An analysis of papers on hydrogen combustion at low pressures is performed, which refines the contribution of the catalytic reactions on the reactor wall to the gas-phase part of the process. A new model for the heterogeneous loss of active reaction centers was proposed and tested experimentally to explain inconsistencies that occur in some papers. In this model, the diffusion region of chain termination is formed under standard experimental conditions in vacuum oxyhydrogen flames at a reactor gas pressure a thousand times lower than the boundary pressure postulated by the previous models as the pressure below which the diffusion region of chain termination cannot be formed. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 2, pp. 10–18, March–April, 2006.     

工业炉燃烧系统应用技术探讨

燃烧及其控制技术是各种火焰炉技术核心，强调高水平燃烧系统应对燃烧全过程进行控制，着重对燃烧系统点火、火焰监测、空燃比比例调节、燃烧过程各参数监控、炉温自动控制等各个方面内容进行了讨论介绍，最后用某天然气加热炉燃烧系统原理图及应用效果进行实例说明。     

关于彩色火焰蜡烛的研制

本文阐述了利用焰色反应的原理研制彩色火焰蜡烛，着重分析并解决了在研制工作中出现的几个技术关键，如主燃剂的选取、蜡烛成型和强度、发色剂的选择与用量等．     

磷－溴双元素阻燃涤纶切片的研制

分析了磷－溴（Ｐ－Ｂｒ）阻燃剂的特性及阻燃机理。应用Ｐ－Ｂｒ阻燃剂进行了阻燃涤纶切片的开发研制试验，结果表明：Ｐ－Ｂｒ阻燃剂阻燃效果好、能高度分散并有良好的热稳定性，其所制阻燃涤纶切片有良好的可纺性。     

高发泡聚乙烯阻燃初探

根据聚合物燃烧现象和一般阻燃机理寻求研究高发泡聚乙烯的阻燃方法和阻燃剂。研究结果表明:只有对添加型阻燃剂三元并用,方能不降低高发泡聚乙烯的物性,制得较为理想的高发泡聚乙烯自熄型制品。     

Heat transfer of a row of three butane/air flame jets impinging on a flat plate

Experiments were performed to investigate the heat transfer characteristics of a row of three premixed, laminar, butane/air flame jets impinging on a water-cooled flat plate. The between-jet interference was found to reduce the heat transfer rate in the jet-to-jet interacting zone due to the depressed combustion. The interference became stronger when the jet-to-jet spacing and/or the nozzle-to-plate distance were/was small. The positive pressure existed in the between-jet interacting zone caused the asymmetric flame and heat transfer distribution of the side jet. The meeting point of the spreading wall jets of the central and the side jets did not occur at the midpoint of the neighboring jets, but at a location shifted slightly outwards. The maximum local heat flux and the maximum area-averaged heat flux occurred at a moderate nozzle-to-plate distance of 5d with a moderate jet-to-jet spacing of 5d. The lowest area-averaged heat flux was produced when both the jet-to-jet spacing and the nozzle-to-plate distance were small. Comparing with a single jet under the same experimental conditions, the heat transfer rates in both the stagnation point and the maximum heat transfer point were shown to be enhanced in a row of three-jet-impingement system. The present study provided detailed information on the heat transfer characteristics of a row of three in-line impinging flame jets, which had rarely been reported in previous study.     

The flame retardant mechanism of polyolefins modified with chalk and silicone elastomer

This paper presents the current understanding of the flame retardant mechanism of Casico?. The study includes the flame retardant effect of each individual component: ethylene–acrylate copolymer, chalk and silicone elastomer, as well as the formation of an intumescent structure during heating. The flame retardant properties were investigated by cone calorimetry and oxygen index tests. To obtain insight into the flame retardant mechanism, heat treatment under different conditions has also been performed. The results indicate that the flame retardant mechanism of Casico is complex and is related to a number of reactions, e.g. ester pyrolysis of acrylate groups, formation of carbon dioxide by reaction between carboxylic acid and chalk, ionomer formation and formation of an intumescent structure stabilized by a protecting char. Special emphasis is given to the formation of the intumescent structure and its molecular structure as evaluated from ¹³C MAS‐NMR and ²⁹Si MAS‐NMR, ESCA and XRD analysis. After treatment at 500°C the intumescent structure consists mainly of silicon oxides and calcium carbonate and after treatment at 1000°C the intumescent structure consists of calcium silicate, calcium oxide and calcium hydroxide. Copyright © 2003 John Wiley & Sons, Ltd.