水、丙酮混合工质振荡热管传热性能

采用水、丙酮以及其二元混合工质对振荡热管进行实验研究,选取35%～70%充液率,10～100 W加热功率以及水/丙酮13：1、4：1、1：1、1：4、1：13配比,将实验数据与混合工质物性、相变特点结合以研究其振荡热管传热性能。结果表明：混合溶液振荡热管启动所需功率小于水;小充液率时,除较低丙酮比例配比（如水/丙酮13：1混合工质）以外,混合工质比纯工质振荡热管不容易烧干,纯工质振荡热管在50 W时热阻就已经上升到较高数值,而混合工质振荡热管在同样的功率则维持着较低的热阻。在丙酮中加入少量水（如水/丙酮1：13混合工质）能有效改善振荡热管烧干情况,然而,少量丙酮与水混合而成的工质（如水/丙酮13：1混合工质）对振荡热管烧干情况的改善不明显;大充液率时,混合工质振荡热管的传热性能要弱于纯工质,在35～50 W,纯工质振荡热管热阻都低于混合工质,而在较大加热功率（50～100 W）,水与混合工质振荡热管仍保持着较明显的热阻差。对混合工质振荡热管的传热性能的分析可为今后更深入研究其工作机理以及传热特性理论模型的建立提供参考。     

Combustion products from polydiallylamine

Crosslinked polydiallylamine (Sirorez Au¹) was prepared by the redox-initiated (K₂S₂O₈/TiCl₃) polymerization of freshly distilled diallylamine [containing 2% 1,6-bis(N,N-diallylamino)hexane] as a 30% solution in 80% phosphoric acid at 0°C. The resulting crosslinked resin is thoroughly washed with water and then sodium hydroxide solution (10%) before a final distilled water washing and air drying. Polydiallylamine resin containing ? 50% by weight gold was prepared by soaking the above resin in a three fold molar excess of gold cyanide solution (2 g/L at pH 8.5) overnight and then filtering the resin, washing with distilled water, and air drying. The samples were dried for 24 h over P₂O₅ before combustion.     

两组元乙醇基混合工质振荡热管的传热性能

通过实验研究乙醇中分别加入少量水、丙酮、甲醇,体积比分别为2：1、4：1,加热功率从10 W到100 W,充液率为45%、55%、62%、70%、90%时振荡热管的热阻特性,并与纯乙醇工质振荡热管相比较。结果表明,45%充液率时,乙醇中加入水可以改善烧干,混合工质较乙醇、水纯工质振荡热管热阻小;55%充液率时,乙醇-丙酮混合工质较乙醇、丙酮纯工质振荡热管热阻小;大充液率62%～90%时,两组元乙醇基混合工质振荡热管传热性能略不如各纯工质振荡热管。混合工质对振荡热管的影响主要与物性、分子间相互作用、溶液汽液相平衡及相变特性、传质阻力有关。     

Absorption of a multicomponenet gaseous mixtures in the presence of instantaneous surface reaction

The rate of absorption from a multicomponent gaseous mixture into a flowing stream in the presence of instantaneous surface reaction is investigated. This is effected by using the generalized Fick's Law for multicomponent diffusion and also by applying the approximate approach based on the assumption that the concentrations of the reactive species are small. Constant properties are assumed for the mixture which are taken at a reference state. As an example, the absorption of C0₂-H₂S and C0₂-H₂ from air are considered. The results show that when the binary diffusion coefficients of the species in the inert gas are greatly different, the error introduced in calculations based on the “Low Concentration” approach is quite appreciable.     

水平螺旋扁管内载气汽油蒸气的凝结换热

采用实验的方法,研究了空气质量含量在2%～13%范围内,汽油蒸气在水平螺旋扁管内的凝结换热,并与同样条件下水平光管内的凝结换热进行了对比分析。实验结果表明,随着不凝气体质量含量的增加,螺旋扁管内的凝结换热减弱,在相同条件下,螺旋扁管的平均换热系数高于光管。同时,提出了水平螺旋扁管内凝结换热的实验关联式。     

On turbulent pipe flow with heat transfer and chemical reaction

A theoretical model has been developed to describe heat transfer to a fluid which is flowing turbulently in a pipe and within which a first-order endothermic irreversible chemical reaction is taking place. It is based on the penetration model for the fluid boundary layer close to the pipe wall and enables the calculation of the effect of chemical reaction on the heat transfer coefficient of turbulent pipe flow.The model has been checked against experimental results for flow distribution and heat transfer in turbulent pipe flow without chemical reaction. Good agreement between the calculated and experimental results was found. The measured heat transfer coefficients for turbulent pipe flow with a uniformly distributed heat source within the fluid were also well predicted. Unfortunately no accurate experimental data on the effect of a first-order chemical reaction on the heat transfer coefficient of turbulent pipe flow are available. However, calculations made with the model show that this effect can be considerable and thus may not always be neglected in practice.     

Combustion products from burning wool fabric

A Preliminary study of the thermal degradation of wool fabric was carried out under a wide range of oxidative degradation conditions including flaming combustion. Product collection methods and analysis conditions were designed to minimize secondary reactions. The degradation products obtained included a variety of organic nitriles and heterocyclic compounds as well as the usual aromatic and oxygenated products. Variations in moisture content and fire retardant level in the wool had little effect on the organic volatiles produced form the fabrics.     

载气汽油在水平螺旋扁管管束外的沸腾换热

以汽油-空气为介质,在不凝性气体质量含量不超过5%时,分别对导程为200mm、300mm和400mm的螺旋扁管管束外的沸腾换热进行了实验研究,分析了沸腾换热系数随两相质量流量和导程的变化规律。结果表明在一定的汽油质量流量下,沸腾换热系数随质量含气率的增大而降低,而随汽油质量流量的不同,沸腾换热系数的主要影响因素有所不同。并且拟合得到了相关条件下,载气汽油在3种不同导程的螺旋扁管管束外的沸腾强化换热实验关联式。     

Development of pyrotechnic compounds for heat treating welded joints

Results are provided for a study of heating annular welded joints in steel pipes where the temperature gradient in the weld is provided by heating the pipe with various types of pyrotechnic compounds. An estimate is made of the nature of burning of compounds and their heat emission. It is shown that the level of residual stresses in a pipe after pyrotechnic treatment of a welded joint may be considerably reduced compared with the original condition.Chelyabinsk. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 4, pp. 73–79, July–August, 1991.     

Pressure measurements at the combustion front of gas-free pyrotechnic mixtures with low gas permeability

It is shown that the method of continuous measurement of pressure at the combustion front using an axial-force gauge is applicable to gas-free pyrotechnic systems producing solid reaction products and characterized by low gas permeability of specimens in the initial state. Small inclusions of a high-energy material producing gas combustion products are placed in the specimens to check the reliability of the result. These inclusions are located near the inlet to the main line going to the pressure gauge. The results of experiments on Ti+C+20% TiC specimens containing inclusions of pyroxylin powder are given. Institute of Experimental Physics, Sarov 607190. Translated from Fizika Goreniya i Vzryva, Vol. 33, No. 2, pp. 76–80, March–April, 1997.     

Separation of gaseous mixtures with asymmetric dense polymeric membranes

The advantages of using asymmetric polymeric membranes with a dense skin and a microporous backing for separation of permanent gas mixtures have been p     

Possibility of continuous measurement of the pressure in the combustion front of pyrotechnic compositions producing solid reaction products

Moscow. Translated from Fizkika Goreniya i Vzryva, Vol. 27, No. 1, pp. 67–70, January–February, 1991.     

Combustion of aluminum-based mixtures

The enthalpy approach was used to analyze experimental data on the burning rate of various aluminum-based systems. The thermal parameters of the combustion wave have been determined for these systems. It has been established that the temperature of ignition of these systems in a steady-state combustion wave is close to the melting point of aluminum.Scientific-Research Institute of Applied Chemistry, Sergiev Posad 141300. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 6, pp. 71–75, November–December, 1994.     

Low-velocity detonation limits of gaseous mixtures

Low-velocity detonation regimes in acetylene-oxygen mixtures are studied experimentally. Data are obtained on the kinematics of detonation waves and on the boundaries of the high-velocity, galloping, and low-velocity detonation regions. In lean mixtures, the lower pressure limit for the detonation regimes in narrow channels is found to be an order of magnitude lower than assumed previously under the assumption that the limiting detonation is always spin detonation. The major structural characteristics of low-velocity detonations are calculated. The boundary between low-velocity and galloping detonation is found to correspond almost exactly to equality between the induction time in a particle and the time for it to move from shock wave to flame. Nearly harmonic oscillations of the flame are observed with periods that are related to the longitudinal size of low-velocity detonation waves. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 3, pp. 89–96, May–June 1999.