Experimental study of regimes of low-velocity motion of a subheated liquid in horizontal annular channels with a heat-transfer crisis

The range of existence of different regimes of flow of a two-phase mixture during initiation of a heat-transfer crisis is determined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 2, pp. 214–218, February, 1986.     

Hydraulic resistance of annular,and disperse-annular flow conditions of a two-phase mixture

Results of experimental research on hydraulic resistance in the case of annular and disperse-annular systems of movement of a two-phase mixture are given.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 18, No. 3, pp. 409–413, March, 1970.     

The influence of film structure on the interfacial friction in annular two-phase flow under microgravity and normal gravity conditions

Results for the interfacial friction factor and relative interfacial roughness on the gas-liquid interface are reported for an air-water annular flow in a small inner diameter tube (9.53 mm i.d.). The film structure was obtained through processing the time trace signal of film thickness measurements using conductance probes. The interfacial friction factor and the wave height were altered through changing the gravity level and gas Reynolds number. It was found that the wave height decreased with increasing the gas Reynolds number. The wave height in microgravity is less than half of that in normal gravity, while the friction factor was about 10% smaller in microgravity than that in normal gravity. It was shown that the annular two-phase flow friction factor decreased less dramatically as the relative interfacial roughness decreased compared to the single-phase case. It is interesting to note that the interfacial shear stress values at microgravity were very close (or even larger than) those at normal gravity. This was attributed to the thicker substrate at microgravity.     

Measuring the parameters of a dispersed-annular flow

We present certain experimental data on the parameters of the dispersed-annular flow of a vapor-water mixture; these data have been derived with a tube 18 mm in diameter, 3 m in length, and for the following range of variations in the basic parameters: the weight velocities varied from 145 to 400 kg/m²·sec; the pressures varied from 9.8 to 49 N/cm²; and finally, the vapor content varied from 0 to 0.5. We derived results on film thickness, the boundaries of existence for a dispersed-annular flow regime, the pressure gradient, and the volumetric vapor content.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 1, pp. 5–12, July, 1969.     

Experimental study of the drag of a two-phase helium flow in channels

Results are presented from an experimental study of the drag of a turbulent twophase helium flow in a horizontal channel under adiabatic conditions.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 43, No. 2, pp. 195–201, August, 1982.     

Propagation of disturbances of pressure in a porous medium under conditions of filtration of a two-phase flow

The paper deals with the results of experimental investigation of unsteady-state processes in a channel with a porous medium under conditions of filtration of liquid-vapor flow and pressure disturbances initiated by injection of steam or noncondensing gases from an outside source. Singular features are studied of the propagation of pressure waves in a porous medium compared to dynamic processes occurring in an unfilled round pipe. The experimentally measured values of the propagation velocity of low-amplitude pressure waves in a channel with a pebble bed correspond to the calculated values of the equilibrium sound velocity of a liquid-vapor medium. It is for the first time that this result is obtained.Translated from Teplofizika Vysokikh Temperatur, Vol. 42, No. 6, 2004, pp. 947–953.Original Russian Text Copyright © 2004 by B. G. Pokusaev, E. G. Tairov, and M. Yu. Gritsenko.     

Experimental study of the heat-transfer mechanism for a single bubble-generating center

It is shown that in the development of boiling the main quantity of heat is transferred from the surface into the vapor volumes due to the latent heat of vaporization.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 18, No. 5, pp. 910–915, May, 1970.     

Experimental and numerical study of a horizontal-vertical gas-solid two-phase system with self-excited oscillatory flow

To better explore the energy-saving mechanism and flow characteristics of the self-excited oscillatory flow, the experiment is performed by a new self-excited oscillatory flow generator that the 45° oblique sheet is mounted through the pipe axis in a horizontal-vertical closed pneumatic conveying system. The experimental study focuses on the optimum air-velocity and power consumption, and results shows the maximum reduction of the optimum air-velocity and the coefficient of power consumption are approximately 8.2% and 16.4%, respectively. In addition, the CFD-DEM coupled approach is first developed to investigate the interaction of gas-solid flow in terms of the gas turbulent kinetic energy and spatial particle flow characteristics. Compared with the conventional pneumatic conveying, it is found that the optimum air-velocity and power consumption are reduced by the new self-excited oscillatory flow at lower air-velocities. The numerical results show that the approximately symmetric distribution of axial velocity and the intensive tangential velocity is emerged in the self-excited oscillatory flow at upstream. Particles is efficiently dispersed and suspended by the self-exited oscillatory flow reflecting in the smaller particle variation coefficient and the lager particle suspension coefficient. And since the airflow kinetic energy is utilized more fully to promote particles flowing, the spatial particle axial velocity is accelerated and reached early steady state. As a result, the developed numerical model is further explained the mechanism of energy saving with the self-excited oscillatory flow.     

Intensification of heat-transfer processes in disperse system flow with solid phase deposition

The influence of the thickness of particle deposits and surface roughness on the heat-transfer and resistance coefficients is examined. It is shown that for high degrees of roughness resulting from the deposition of coarse particles, the efficiency decreases with increase in the thickness of the layer deposited, even at large Re numbers.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 52, No. 2, pp. 252–255, February, 1987.     

Hydrodynamic characteristics of a horizontal channel with the motion of a two-phase helium flow

Experimental data is presented on the pressure drop in the motion of a two-phase helium flow in a horizontal pipe under adiabatic conditions and with a supply of heat.     

Experimental study of heat transfer in the boiling of liquids at low pressures under conditions of free motion

The results of an experimental investigation into the boiling of water, ethyl alcohol (96% aqueous solution), and 13% NaCl solution under conditions of free motion at pressures of 0.036–1 bar are presented. The experimentally observed characteristics of the boiling mechanism at low pressures are discussed.Translated from Inzhenerno-Fizichenskii Zhurnal, Vol. 18, No. 4, pp. 624–630, April, 1970.     

Random motion of solid particles and energy dissipation in two-phase flow

We obtain equations describing the fluctuations and energy loss of particle collisions in two-phase flow from the experimental velocity distribution functions.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 58, No. 2, pp. 207–213, February, 1990.     

On the motion of two-phase systems in a porous medium taking account of heat- and mass-transport processes

The essential influence of the process of mass transport of the condensate on the filtration resistance is shown. It is explained that mass transport of residual water occurs in the isothermal filtration of gas-liquid systems.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 18, No. 6, pp. 1025–1031, June, 1970.     

Investigation of local heat-transfer coefficients under conditions of the resonance oscillations of a gas in channels

A physical model of the process of heat transfer during resonance oscillation of a gas in channels is proposed. The results of experiments are generalized by a criterial dependence.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 31, No. 2, pp. 197–201, August, 1976.     

Role of internal unsteady processes in problems of the motion of two-phase streams

A model of a two-phase stream is developed which allows one to calculate the basic hydraulic and continuity characteristics of the stream as well as the mode of flow on the basis of the allowance for the unsteadiness of the motion of the separate phases.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 2, pp. 211–220, February, 1976.     

The effects of gravity on the features of the interfacial waves in annular two-phase flow

A physical model of interfacial waves in annular two-phase flow was studied in both microgravity and normal gravity. The wave structure was obtained for local film thickness and velocity measurements using a conductance probe technique. It was found that the wave height, and not its width, is strongly affected by changing the gravity level. In fact, the wave height in normal gravity is more than twice that in microgravity. Using an analogous approach to a turbulent, single-phase flow in a rough tube, a preliminary mathematical model was proposed to calculate the wave amplitude. The model fits well with the experimental data and shows that the wave height in normal gravity is approximately 1.7 times the combined thickness of the viscous sublayer and transition zones in the turbulent gas stream. The wave height in microgravity was estimated to be approximately 80% of the total thickness.     

Effect of pressure on heat exchange in nitrogen boiling under conditions of free motion in an annular channel

Heat transfer and the boiling crisis are studied in nitrogen in annular channels with various gap sizes at pressures from 1.25·10⁴ to 9·10⁵ Pa.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 3, September, 1985.     

Convective heat-transfer equation in the entrance section of an annular channel

The authors present results of experimental investigations of convective heat transfer in annular drying channels, and examine their possible practical use.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 1, pp. 22–28, July, 1985.     

Thermodynamic analysis of a diabatic two-phase flow for a pure refrigerant and a refrigerant/oil mixture under equilibrium conditions

Two different definitions of the vapor quality during a diabatic two-phase flow with and without the presence of oil are presented in this paper: the well-known vapor flow quality and the thermodynamic vapor quality. The vapor flow quality is based on the mass flow rates whereas the thermodynamic vapor quality is based on the mass. Two-phase thermodynamic diagrams for pure R-134a and R-134a/oil mixture are plotted for different slip ratios. It is shown that the iso-flow quality lines are moved to lower enthalpies for larger slip ratios. In addition, the maximum vapor flow quality of a fluid/oil mixture is shown to increase when increasing the slip ratio whereas the maximum thermodynamic vapor quality remains constant. In addition, the correct expression of the elementary derivative of the vapor quality is also proposed, highlighting the role of the heat capacity at constant vapor quality.