Experimental Investigation of Heat Conduction and of a Temperature Jump in Binary Mixtures of Nonreacting Gases with One Condensing Component

Experimental data on heat conduction and a temperature jump in binary mixtures of nonreacting gases with one condensing component in a low-pressure region are presented. The results have been processed with account for modern concepts of interaction of differently structured gases with a surface during energy transfer. It is shown that it is possible to obtain data on the thermal conductivity of the vapor of high-boiling substances in a low-pressure region in the presence of a foreign noncondensing impurity when its evacuation from a measuring cell is difficult or impossible.     

混合气体的安全生产与管理

对混合气体在充装设计、制备过程中气瓶及阀门的选择、气体成分及材料的相容性、气瓶标识及压力等涉及气体在制备和使用过程中应该注意的安全问题进行了概述。     

Simulation of a Flow of Spontaneously Condensing Moist Steam in Laval Nozzles

A method is suggested for the simulation of the evolution of the size distribution of droplets as a result of simultaneous processes of nucleation (spontaneous condensation), heterogeneous condensation/evaporation, and coagulation. The results of analysis of the effect of initial moisture on spontaneous condensation of steam in transonic nozzles are given.     

Propagation of Substance in an Axisymmetric Filtration Flow

Journal of Engineering Physics and Thermophysics - The article considers the propagation of a substance in a cylindrical coordinate system in filtration flow. A common assumption is made that the...     

Two Variants of Calculation of the Parameters of Bubbling Processes in Axisymmetric Channels with a Variable Flow Area

Consideration is given to the formulations of the primal and inverse problems of calculation of bubbling processes in axisymmetric channels with a variable flow area. A physico-mathematical model of motion of a bubble gas-liquid mixture and results of numerical calculations are presented.     

Axisymmetric crack with a slightly non-flat surface

A three-dimensional axisymmetric crack with a slightly non-flat surface in an isotropic linear solid under axisymmetric loading is analyzed. The problem is formulated by using the Hankel transform and a perturbation solution is obtained, which is accurate to the first order of the parameter representing the non-flatness. The stress intensity factor for the problem is evaluated. In particular, the stress intensity factor at the onset of axisymmetric kinking from a penny-shaped crack is obtained. It is also shown that the two-dimensional Cotterell-Rice theory for the effect of tensile stress acting parallel to the crack surface on the stability of crack path is valid for the axisymmetric crack.     

Wide-Range Model of Mixture for Chemically Reacting Nonideal Gases and Composite Plasma

A mixture model is constructed for dense chemically reacting gases and dense chemically active nonideal composite plasma. Investigations are performed of the contribution made by the interactions of free heavy particles (charged and neutral) into the thermodynamic functions of gases and plasma in different regions of the phase diagram, where bound states may arise. The excluded phase volume, accessible for classical motion of free atoms, is included by introducing the Hill pseudopotential. A wide-range calculation is performed of the thermodynamic parameters of various substances and mixtures, and a comparison is made with the experimental data and the theoretical results of other researchers.     

Axisymmetric crack problem of a thick-walled Cylinder with cladding

The paper considers the elastostatic axisymmetric problem for a long thick-walled cylinder containing an axisymmetric circumferential internal or edge crack with cladding. The cladding is assumed to be bonded to inner wall of the hollow cylinder. Using the standard transform technique, the problem is formulated in terms of an integral equation of the first kind which has a generalized Cauchy kernel as the dominant part. The integral equation is solved numerically by using appropriate quadrature formulas. The related stress-intensity factors are calculated for the hollow cylinder with cladding under axial load. The influence of the geometrical configuration and the cladding on the stress-intensity factors is shown graphically.     

Numerical Simulations of Thermocapillary Flow of a Binary Mixture with the Soret Effect in a Shallow Annular Pool

In order to understand the characteristics of thermocapillary flow of a toluene/n-hexane mixture with the Soret effect in a shallow annular pool, a series of three-dimensional numerical simulations were carried out. The shallow annular pool was heated from the outer cylinder and cooled at the inner cylinder. The initial toluene concentration in the toluene/n-hexane mixture varied from 0 to 0.4467. Results indicate that the flow undergoes two transitions from the axisymmetric steady flow to the hydrothermal waves, and then to chaos with the increase of the thermocapillary Reynolds number. The critical thermocapillary Reynolds number for the incipience of the oscillatory flow decreases with the increase of the initial solute concentration. When the thermocapillary flow transits to a three-dimensional oscillatory flow, a concentration fluctuation is observed on the free surface, which is similar to the hydrothermal waves. However, compared with that of the temperature, the dimensionless fluctuation amplitude of the concentration is relatively weak. Furthermore, the fundamental oscillation frequency increases linearly with the initial solute concentration, but the wave number of the hydrothermal waves is almost unchangeable.     

Hydrodynamic Drag under Conditions of Flow of a Two-Phase Mixture in a Pebble Bed

An experimental investigation is performed of the hydrodynamic drag under conditions of motion of water, air, and steam–water mixture in a pipe 34 mm in diameter with a bed of pebbles 2 mm in diameter. The experiments with air and water are performed for Reynolds number values from 100 to 1770. Experimental data are obtained for the first time on the resistance of a two-phase mixture in the ranges of pressure from 0.9 to 3.0 MPa, mass flow rate in the pebble bed from 108 to 238 kg/(m² s), and steam quality from zero to 0.21. Theoretical relations are suggested, which generalize the measurement results. Tables of experimental data are given.     

Steady Free Surface Flow of a Fluid-Solid Mixture Down an Inclined Plane

The present work is an extension of the investigations performed by Massoudi and Anand (2001) Massoudi, M. 2001. On the flow of granular materials with variable material properties. Inl. J. Non-linear Mech., 36: 25–37.  [Google Scholar]. The free surface flow problem is studied here. Numerical solutions for steady free surface flow of a solid-fluid mixture down an inclined plane are presented. The problem is formulated using the mixture theory framework. The resulting set of three coupled nonlinear differential equations is nondimensionalized. A parametric study is conducted to understand the influence of the dimensionless numbers on the velocity and volume fraction. The maximum fluid velocity is found to decrease with increase in the ratio of the drag force to the viscous forces within the fluid phase (D₁). The fluid phase velocity was found to decrease with increase in the ratio of the drag force to viscous force within the solid component (D₂), and the corresponding solid phase velocity was found to increase.     

Steady Free Surface Flow of a Fluid-Solid Mixture Down an Inclined Plane

The present work is an extension of the investigations performed by Massoudi and Anand (2001). The free surface flow problem is studied here. Numerical solutions for steady free surface flow of a solid-fluid mixture down an inclined plane are presented. The problem is formulated using the mixture theory framework. The resulting set of three coupled nonlinear differential equations is nondimensionalized. A parametric study is conducted to understand the influence of the dimensionless numbers on the velocity and volume fraction. The maximum fluid velocity is found to decrease with increase in the ratio of the drag force to the viscous forces within the fluid phase (D₁). The fluid phase velocity was found to decrease with increase in the ratio of the drag force to viscous force within the solid component (D₂), and the corresponding solid phase velocity was found to increase.     

回收冷凝热的冷热双温型风幕陈列柜的仿真

食品冷链设备中的风幕式陈列柜能耗大,尤其是双温型风幕陈列柜可满足冷、热双温储存的需求,其独立的制冷、制热设备具有更高的能耗。采用冷凝热回收技术可以有效降低双温型风幕陈列柜用于制热的能耗,进而降低总耗电量。本文对可回收冷凝热的冷热双温型风幕陈列柜进行了仿真分析,以COP和有效制热功率为指标,确定了制冷系统中各部件的优化方向,给出了具体的模型,将并将其与传统电加热型陈列柜进行了对比,然后结合具体的实验数据验证了模型的有效性,对其节能潜力进行了研究,结果发现:冷凝热回收的双温陈列柜具有显著的节能优势,其系统配置的核心是冷凝侧的风量,推荐配置变频风机,可在15、20、25、32℃的环境温度下分别采用0.018、0.03、0.045/、0.095 m3/s的最优风量;当冷凝器风量保持0.06 m3/s时,冷凝热回收型双温陈列柜在高温工况有较好的节能效果,而在标准工况25℃环温时节能的效果最好,可以使耗电量下降约52%。