Improving the performance of fluoroprotein foam in extinguishing gasoline pool fires with addition of bromofluoropropene

The fluoroprotein foam is one of the most widely used fire suppressants for its low cost, low toxicity and biodegradability. However, its fire extinguishing performance is limited. In this article, fluoroprotein foam was combined with a clean and degradable fire suppressant of 2‐bromo‐3,3,3‐trifluoropropene (BTP) to improve its fire extinguishing efficiency. Laboratory scale suppression experiments on gasoline pool fires were conducted in a 27 m³ confined space. An optimized volume flow ratio of air to foam solution was found out first to acquire fluoroprotein foam with best fire extinguishing efficiency; then varied amounts of BTP were added to the foam at the optimal flow ratio for performance examination. Results demonstrated: at the optimized volume flow ratio of air to foam solution of 9 and the volume flow ratio of BTP to foam solution of 3.75%, a superior fire extinguishing performance was achieved with the fire extinguishing time reduced by 43% in comparison to that without any BTP added. The fire suppression mechanism of the foam with BTP additive was discussed based on established fire suppression theories and experimental results. Copyright © 2014 John Wiley & Sons, Ltd.     

水喷雾灭火系统管网布置优化

通过分析水喷雾灭火系统干管的布置方式对系统的压力和流量的影响,优化了水喷雾灭火系统管网的布置,从而降低了水喷雾灭火系统的流量和压力,避免了对已有消防泵房的改造,达到了减少投资、缩短工期的目的。     

涂装线喷漆室排风管路的自动消防装置

设计了一种用于涂装线喷漆室排风管路的自动消防装置,主要包括排风组件和自动喷淋系统.详细介绍了它的结构.该装置在监测到排风管道内的火势时,能通过阀门自动将排风管道与外界空气隔绝,同时启动喷淋系统.该装置结构简单,设计合理,使用方便.     

煤矸石山深孔注浆灭火的研究

煤矸石山自燃释放出大量有毒有害气体,污染环境。在灭火治理过程中易发生中毒、烧烫伤、灭火后易自燃等问题。为了保证煤矸石山灭火施工过程中的安全,并确保灭火效果,笔者对事故发生的原因进行了分析研究。提出了以深孔注浆为主,覆盖为辅的施工工艺。针对煤矸石山自燃时的特点,对注浆灭火材料的选择进行了研究。结果表明,凝胶类、碱性、触变性或初凝时间可控的灭火材料灭火性能较好;最后提出了通过改进钻孔冲洗液的方式,提高矸石山钻孔成孔率。     

液化石油气储罐的水喷雾灭火系统设计

通过工程实例,介绍了液化石油气卧式储罐的水喷雾灭火系统的组成、设计计算、设备选型、水雾喷头的布置及环保措施。     

液氮防灭火系统在煤矿中的应用

液氮防灭火系统是煤矿行业近年来研究及应用的一种新技术,具有综合防灭火效果。针对其在煤矿中的应用,从系统选型、工艺流程、设备选用等方面进行了详细地介绍,同时对设计和运行方面需要注意的问题进行了分析和探讨。     

The initial stage of fuel spray penetration

Effects of droplet evaporation, break-up and air entrainment on diesel fuel spray penetration have been studied theoretically at the initial stage of spray penetration when the influence of air entrainment is small (up to 0.1-0.2 ms after the start of injection). Theoretical plots of spray penetration versus time are compared with experimental results obtained using an optical single cylinder rapid compression test rig based on a Ricardo Proteus engine. Three models of spray penetration have been compared. In the first, neither break-up nor air entrainment are taken into account. The break-up processes (bag and stripping) are taken into account in the second model, while in the third model both bag break-up and air entrainment processes are considered. It has been found that the agreement between the predictions of the third model with experimental measurements is better than that for the first two models.     

A model for fuel spray penetration

A new model for fuel spray penetration (location of spray tip) is suggested and validated against available experimental data. Simple analytical expressions for fuel spray penetration are derived in two limiting cases: the initial stage and the two-phase flow regime. At the initial stage, the effects of droplet drag and entrainment of air are accounted for. In the case of the two-phase flow, it is assumed that the spray droplets have the same velocities as the entrained air. The characteristic time of droplet break-up in the spray is estimated for both bag and stripping break-up mechanisms. For realistic diesel spray parameters, the droplet break-up takes place almost immediately after the droplets leave the nozzle. This leads to a considerable shortening of the initial stage and a rapid conversion of the flow to the two-phase stage. This allows the analysis to be restricted to the two-phase flow approximation for this type of spray. The expressions for spray penetration derived in this paper give more accurate predictions compared with those suggested earlier.     

Mass transfer into/from nanofluid drops in a spray liquid‐liquid extraction column

The performance of a spray liquid‐liquid extraction column at two mass‐transfer directions was experimentally studied in the presence of silica nanoparticles. Toluene‐based nanofluid drops containing 0.0005–0.01 vol % silica nanoparticles were dispersed in aqueous phase and acetic acid (AA) transfer between phases was investigated. The experiments were performed at fixed volumetric flow rates of dispersed and continuous phases. Maximum enhancement of 47.4% and 107.5% in overall mass‐transfer coefficient, respectively, for mass‐transfer direction of dispersed to continuous phase and vice versa were achieved for drops with 0.001 vol % silica nanoparticles. These enhancements can be referred to Brownian motion of nanoparticles and induced microconvection. The results showed that nanoparticles are more effective in augmenting AA transfer from continuous to dispersed phase. Probable reason is that smaller diameter and lower internal turbulence of drops in this transfer direction increase dispersed phase resistance potential to be manipulated by Brownian motion of nanoparticles. © 2015 American Institute of Chemical Engineers AIChE J, 62: 852–860, 2016     

立体传质塔板板上液相流场的三维数值模拟

针对立体传质塔板(CTST)操作时的特点,对1 000 mm的CTST板上液相流场进行了三维计算流体力学(CFD)数值模拟.计算得出了板上液相流场的三维分布特征;实验测量和模拟结果对比,结果吻合较好,说明文中模型有较好的准确度,可以用于CTST板上液相流场的预测.对相同条件下筛板和CTST板上的液相流场分别进行模拟,...     

Experimental study of liquid fuel boilover behavior in normal and low pressures

To elucidate the effect of pressure on liquid fuel boilover, a series of field experiments were carried out using a portable measuring setup at Hefei (Alt.: 0 m, P: 101 kPa) and Lhasa (Alt.: 3650 m, P: 64 kPa). It is found that for a given size of pan, the boilover premonitory onset time t_p and the boilover onset time t_b are delayed; the intensity of boilover is weaker in low pressure. For a given pressure, t_p and t_b in larger pan are shorter. In addition, the boiling point of water is still the critical of boilover premonitory period in low pressure, and the critical temperature at the interface is reduced as pressure drops when boilover occurs. Then a prediction equation was made to explain the effect of atmospheric pressure on t_p and t_b, which proves that the pan diameter has a negative correlation against with t_p and t_b, and there is a negative correlation between the boilover premonitory onset time t_p and the low pressure P_L when P_L > 10 kPa.     

Combustion of sprayed liquid fuel in a swirling flow

A physicomathematical model and results of numerical studies of aerodynamics and combustion of liquid fuel in a coaxial swirling flow of a gaseous oxidizer are presented. The characteristics of liquid-fuel spraying by a centrifugal injector were determined on the basis of experimental data obtained under isothermal conditions. The influence of flow swirling on the burner characteristics is analyzed.__________Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 2, pp. 26–37, March–April, 2005.     

生物液体燃料

对全球生物液体燃料的发展现状进行了概述。叙述了目前我国发展燃料乙醇的主要原料以及秸杆乙醇技术。对我国生物柴油产业的发展、生物柴油标准以及影响我国生物柴油发展的因素进行了探讨。并结合我国国情,对如何发展生物液体燃料提出了建议。     

双溢流立体传质塔板上液相流场CFD研究

采用计算流体力学方法对直径为2 600 mm的工业规模双溢流立体传质塔板板上气液二相流动进行了模拟研究。计算了不同工况下收缩流和扩张流2种流型的液相流场分布,得到了双溢流塔板收缩流和扩张流2种流型的板上气液二相流场分布规律。通过将清液层高度的CFD结果和经验公式的计算结果进行对比,验证了所建模型的正确性。模拟计算结果表明:边降液管收缩流板面液相流动较均匀,近似于均匀的收缩流,不存在回流区;中降液管扩张流板面液相流动不均匀,靠近塔板中心流速较快,塔板弓形区存在着回流现象;板孔处的帽罩区液层较其他地方小,液相体积分数较其他地方低,扩张流受气相的影响较收缩流大。     

喷雾冷却装置在电石渣浆上清液回用工艺上的应用

详细介绍了喷雾冷却的原理及在电石渣浆上清液回用工艺上的应用。     

空心喷嘴喷淋特性实验研究

为使大型水平管降膜多效蒸发海水淡化装置的横管降膜蒸发器均匀布液,自主设计并搭建了一套离心喷嘴喷淋特性实验台及径向喷淋密度测量装置,通过高速摄影仪拍摄的喷淋照片对喷淋外缘进行标注测量,得到喷嘴各喷淋锥角,对旋流式空心喷嘴的流量、喷淋锥角和径向喷淋密度等喷淋参数随入口压力、喷淋高度的变化规律进行实验探究分析。结果表明,流量随入口压力增加而增加,但入口压力越大,流量增长速度越缓慢;正常工况下,喷淋锥角由喷嘴出口扩张段角度决定,与喷嘴扩张角保持一致,在重力作用下出现向内的收缩圆弧液膜边;喷淋形状为规则的环形喷淋,入口压力增加使有效喷淋区域整体向中心压缩,喷淋密度峰值变大,两波峰的对称性得到改善,压力为349 kPa时,喷淋密度基本完全对称,增加喷淋高度则情况相反。根据此喷淋密度分布特点,在设计横管蒸发布液器时合理控制工况压强,根据峰谷叠加原理可有效消除无效喷淋区域。     

Investigation of fuel spray atomization in a DI heavy-duty diesel engine and comparison of various spray breakup models

In the last decade 3D-CFD has been successfully established for the simulation of IC-engine fuel spray formation and propagation processes. The accuracy of the calculation results, however, strongly depends on the models adopted for simulation of the primary and secondary atomization processes. Hence, careful validations of the individual models serve as major prerequisites for the successful analysis and optimization of high-pressure sprays in diesel engines. In the present work, a CFD code has been used to study the detailed modeling of spray and mixture formation in a caterpillar heavy-duty diesel engine. With respect to the liquid-phase, spray calculations are based on a statistical method referred to as the Discrete Droplet Method (DDM). This paper presents a comparison of four Lagrangian fuel spray breakup models that are in use with commercial softwares in diesel engine simulation. In this paper, we tried to highlight this models prediction difference for sample case, compare their result and explain some possible reasons for differences. The predicted results are validated by comparing with existing experimental data. A good agreement between the predicted and experimental values ensures the accuracy of the numerical predictions collected with the present work.     

Diesel nozzle geometry influence on spray liquid-phase fuel penetration in evaporative conditions

An experimental study of real multi-hole Diesel nozzles is performed under current DI Diesel engines operating conditions. The aim of the investigation is to study the influence of orifice geometry on the flow at the nozzle exit and to analyse its effect on the spray in evaporative conditions. Special attention is taken in the study of the influence of cavitation on the orifice internal flow and spray development. The spray liquid-phase fuel penetration has been characterized. The visualization was made in a wide optical access engine for different operating conditions. From the measurements, the dependencies of nozzle geometry, injection conditions and ambient conditions on liquid-phase length were studied and analyzed. A model for liquid-phase fuel penetration in diesel sprays based on nozzle flow parameters has been proposed and validated.     

Remote extinguishing of large fires with powder aerosols

A new method for distant extinguishing of fire spreading in an extended closed volume such as a mine working, storehouse, subway tunnel, electric cable channels, etc. is proposed. A novel extinguishing agent based on a stable mixture of superfine ammonium phosphate [NH₄H₂PO₄] and modified fumed silica [SiO₂–CH₃] is supplied to the fire by a powerful ventilator. The properties of the extinguishing agent (average particle size, airborne residence time, distance of transfer by the air stream) have been studied in an experimental chamber (100 m³). A test extinguishing of a large‐scale fire has been performed in an experimental tunnel 180 m in length. Extinguishing agent consumption, dynamics of temperature change over the tunnel length and composition of fire gases were recorded in this test. The influence of foam concentration, addition of nitrogen and halons to aerosol, were also studied. Copyright © 2006 John Wiley & Sons, Ltd.