Theoretical Model for Predicting Steam-Ejector Performance

1976 ◽  
Vol 98 (2) ◽  
pp. 645-651 ◽  
Author(s):  
E. F. Kurtz
Keyword(s):  
Theoretical Model ◽  
Volume Fraction ◽  
Liquid Fraction ◽  
Isothermal Flow ◽  
Two Phase ◽  
Potential Flows ◽  
Steam Ejector ◽  
Secondary Steam ◽  
Phase Liquid ◽  
Mass Transfers

A simple theoretical model has been developed as an aid to designing steam ejectors. The ejector flow is modeled as comprising a number of continuum components such as potential flows and shear flows. Velocity profiles are approximated by stepped profiles, each flow component having a uniform velocity. Compressibility effects are accounted for by assuming isothermal flow in the mixing section. The differential equations governing momentum and mass transfers are integrated numerically, yielding pressure distribution predictions in the ejector mixing section, as a function of primary- and secondary-steam inlet states, and of mixing-section shape, in good agreement with published steam-ejector data. The model exhibits compound choking and compound supersonic flow in agreement with the data. While the isothermal-flow model has been tested only with steam-ejector data, it should be applicable for designing any ejector wherein the primary stream is a two-phase liquid-vapor mixture with the liquid fraction in small droplets occupying a negligible volume fraction. The model has been implemented via a FORTRAN computer program.

scholarly journals Collisions of Two-Phase Liquid Droplets in a Heated Gas Medium

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1476
Author(s):  
Pavel Tkachenko ◽  
Nikita Shlegel ◽  
Pavel Strizhak
Keyword(s):  
Volume Fraction ◽  
Industrial Applications ◽  
Droplet Breakup ◽  
Liquid Volume ◽  
Liquid Droplets ◽  
Vapor Bubbles ◽  
Two Phase ◽  
Relative Volume Fraction ◽  
Phase Liquid ◽  
Gas Medium

The paper presents the experimental research findings for the integral characteristics of processes developing when two-phase liquid droplets collide in a heated gas medium. The experiments were conducted in a closed heat exchange chamber space filled with air. The gas medium was heated to 400–500 °C by an induction system. In the experiments, the size of initial droplets, their velocities and impact angles were varied in the ranges typical of industrial applications. The main varied parameter was the percentage of vapor (volume of bubbles) in the droplet (up to 90% of the liquid volume). The droplet collision regimes (coalescence, bounce, breakup, disruption), size and number of secondary fragments, as well as the relative volume fraction of vapor bubbles in them were recorded. Differences in the collision regimes and in the distribution of secondary fragments by size were identified. The areas of liquid surface before and after the initial droplet breakup were determined. Conditions were outlined in which vapor bubbles had a significant and, on the contrary, fairly weak effect on the interaction regimes of two-phase droplets.

scholarly journals The Results of Numerical Simulation of Two-Phase Liquid-Gas Flow with Constant and Real Thermodynamics Properties of the Liquid in a Shock-Jet Nozzle

2019 ◽  
pp. 51-60
Author(s):  
A.D. Khlopov ◽  
M.S. Frantsuzov
Keyword(s):  
Liquid Phase ◽  
Thermophysical Properties ◽  
Gas Flow ◽  
Volume Fraction ◽  
Temperature Dependent ◽  
Two Phase ◽  
Dispersion Process ◽  
Commercial Software Package ◽  
Phase Liquid ◽  
Jet Nozzle

In this paper, the outflow of liquid in the coflowing airstream from a shock-jet nozzle is examined using a commercial software package with varying initial and boundary conditions. Gas-dynamic characteristics and distribution fields for pressure, velocity, temperature and volume fraction of the two-phase flow are obtained. The influence of thermophysical properties of the liquid on the process of jet dispersion is determined. The results of simulation of the liquid outflow from the shock-jet nozzle at constant and real (temperature dependent) thermophysical properties of the liquid phase are compared. The qualitative and quantitative influence of the input pressure in the nozzle on the jet dispersion process is determined. As a result of a series of calculations, the minimum required characteristics of temporal and spatial resolution for the correct solution of the problem are identified. It is established that the volume content of the liquid phase is higher with real thermophysical properties compared to the constant ones.

Phase Inversion in Two-Phase Liquid Systems

1992 ◽  
Vol 57 (7) ◽  
pp. 1419-1423
Author(s):  
Jindřich Weiss
Keyword(s):  
Interfacial Tension ◽  
Phase Inversion ◽  
Continuous Phase ◽  
Considerable Effect ◽  
Weak Dependence ◽  
Dispersed Phase ◽  
Two Phase ◽  
Liquid Systems ◽  
Phase Liquid

New data on critical holdups of dispersed phase were measured at which the phase inversion took place. The systems studied differed in the ratio of phase viscosities and interfacial tension. A weak dependence was found of critical holdups on the impeller revolutions and on the material contactor; on the contrary, a considerable effect of viscosity was found out as far as the viscosity of continuous phase exceeded that of dispersed phase.

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