Influence of CF<Subscript>3</Subscript>I and CBrF<Subscript>3</Subscript> on Methanol–Air and Methane–Air Premixed Flames

The suppression of CH₄ and CH₃OH premixed flames with CBrF₃ and CF₃I is examined, using computational techniques. By combining sensitivity analysis, reaction pathway analysis (based on carbon, hydrogen, bromine and iodine atom fluxes) and heat release estimation, we develop an explanation for the difference of suppression efficiencies which is qualitatively consistent with experimental cup burner data. The key reaction steps and channels responsible for the (apparent) higher inhibition efficiency of CF₃I compared to CBrF₃ in CH₃OH premixed flames are disclosed, by combining reaction pathway and heat release contribution analysis. The reaction of bromine atom dominates the decomposition channel for CH₃OH but plays a relatively minor role in the activation of CH₄, while I atom plays a minor role in CH₃OH or CH₄ activation. Accordingly, the rate of production of flame propagating radicals CH₂O and OH is higher in a CH₃OH–air–CBrF₃ system than in a CH₃OH–air–CF₃I system. The overall conclusion is that CBrF₃ contributes significantly to flame propagation for CH₃OH fuel reactions and consequently more CBrF₃ is required to extinguish a CH₃OH flame than CF₃I. Finally the explanation is validated by applying the reaction “switching-off” test.     

三氟碘甲烷气相合成催化剂分析

三氟碘甲烷是新型环保灭火剂和制冷剂的重要组分。通过对气相催化合成三氟碘甲烷催化剂的研究,发现碱金属盐的催化活性较高,对三氟碘甲烷转化率达到27%以上,在碱金属盐中,硝酸铷和硝酸铯催化的转化率可达39%,高于相应的氟化物催化活性。通过对反应前后催化剂的EDS和XPS分析发现,硝酸铷在活化过程中受热分解为亚硝酸铷,反应过程中主要生成氟氧化铷,表面约85%的Rb以氟氧化铷的形式存在;反应后催化剂的热解实验表明,表面的氟元素来自中间体二氟卡宾与活性炭的化学结合。     

全卤代烃CF3I和CF4的阻燃能力实验

实验测量了多组含CF3I或CF4的制冷剂混合物的爆炸极限,绘制了爆炸极限数据曲线和数据表格,确定了不同摩尔比例制冷剂混合物的爆炸三角区和临界爆炸比.参照文献中已得出的部分实验结论,通过分析比较得出全卤代烃CF3I和CF4比N2、CO2等"惰性气体"以及含氢卤代烃R134、R134a、R125等更能有效抑制可燃制冷剂的燃...     

Vapor pressure of pentafluoroethane and trifluoroiodomethane

nwtctionAeeording to the revision of the MOntred ProtOcol,Ws was SCheduled tO be Phased out befor 2030.There is no single-COInPOnent retheeran tO rePlaceHCFC-22 at thes momen althongh some binny andtw hawts have been mpsed; e.g., theHFC-32ll25 binare and THR3 temny systeInS areconot the Prondsing substitutes tO mplace HCFC-22.W-l25 and CFJ are inW in most of these InixwtW, and it is W tha these thennPhysicalPrOW be for to op accuravms pp reportS the exPerimental results Of v…     

第三代ODS替代品FIC-1311

介绍了三氟碘甲烷(FIC-1311)的各种性质、合成方法和用途.三氟碘甲烷具有良好的环境性能和安全性能,在灭火、制冷、发泡、医药等领域有着广阔的应用前景.     

Thermophysical Properties of a New Environment Friendly Alternative—Trifluoroiodomethane

Trifluoroiodomethane (CF₃I) is considered as a promising refrigerant alternative, especially as a component in mixtures, to replace CFC-12. But reliable thermophysical property data for CF₃I are still limited. The investigations on thermophysical properties of CF₃I developed by us are summarized in this paper. Experimental data of critical parameters, and the correlations of saturated liquid and vapor density, enthalpy of vaporization, vapor pressure, PVT properties, second virial coefficient, ideal-gas heat capacity, surface tension, viscosity and thermal conductivity are given in the present paper.     

Thermodynamic Properties of Trifluoroiodomethane (CF13I)1

Studies of the thermodynamic properties of trifluoroiodomethane (CF₃I) are presented in this paper. The vapor–liquid coexistence curve of CF₃I was measured by visual observation of the meniscus. The critical temperature and the critical density of CF₃I were determined by considering not only the level where the meniscus disappeared but also the intensity of the critical opalescence. The correlation of the saturated density in the critical region was developed, and the exponent of the power law was determined. Correlations of the saturated vapor and liquid densities and the enthalpy of vaporization for CF₃I were also developed. The vapor pressure of CF₃I was measured at temperatures ranging from below the normal boiling point to the critical point, and a vapor pressure equation for CF₃I was developed, from which the normal boiling point of CF₃I was determined. The gaseous PVT properties of CF₃I were measured with a Burnett/isochoric method, and a gaseous equation of state for CF₃I was developed. The speed of sound of gaseous CF₃I was measured with a cylindrical, variable-path acoustic interferometer operating at 156.252 kHz, and the ideal-gas heat capacity and second acoustic virial coefficient were calculated. A correlation of the second virial coefficient for CF₃I was obtained by a semiempirical method using the square-well potential for the intermolecular force and was compared with the result based on PVT measurements. The surface tension of CF₃I was measured with a differential capillary rise method (DCRM), and the temperature dependence of the results was successfully represented to within ±0.13 mN·m^–1 using a van der Waals correlation.