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Steady-state critical two-phase flashing flow with possible multiple choking phenomenon: Part 1: Physical modelling and numerical procedure
A Attou,Jean-Marie Seynhaeve +1 more
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In this article, the modeling of pure fluid steady-state adiabatic flashing flow through a pipe involving an abrupt enlargement is presented, where the thermal non-equilibrium two-phase flow model DEM has been adjusted for subcooled inlet conditions close to saturation and/or for inlet 2-phase mixture state.Abstract:
In this paper, the modelling of pure fluid steady-state adiabatic flashing flow through a pipe involving an abrupt enlargement is presented. The thermal non-equilibrium two-phase flow model DEM has been adjusted for subcooled inlet conditions close to saturation and/or for inlet two-phase mixture state. The multichoking flow phenomenon occurs when two basic criteria are simultaneously fulfilled. A general procedure taking into account this possible occurrence is developed on the basis of two iterative algorithms. The first algorithm is applied to the mass flow rate upstream from the enlargement and the second algorithm is based on the length of the pipe downstream from the enlargement. The proposed methodology involves the improved physical one-dimensional two-phase flow model DEM and the global non-equilibrium model through the abrupt enlargement. (C) 1999 Elsevier Science Ltd. All rights reserved.read more
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Study of ejector efficiencies in refrigeration cycles
Fang Liu,Eckhard A. Groll +1 more
TL;DR: In this paper, a two-phase flow ejector model was used to determine the internal ejector component efficiencies using measured performance data external to the ejector in conjunction with the model.
Journal ArticleDOI
Investigation on performance of variable geometry ejectors for CO₂ refrigeration cycles
TL;DR: In this paper, a two-phase flow ejector expansion model was developed and experimentally validated, and a method of determining the efficiencies of ejector motive nozzle, suction nozzle, and mixing section based on the measured performance data external to the ejector was developed.
Journal ArticleDOI
1D Computational model of a two-phase R744 ejector for expansion work recovery.
Krzysztof Banasiak,Armin Hafner +1 more
TL;DR: In this paper, a one-dimensional mathematical model of the R744 two-phase ejector for expansion work recovery is presented, where governing equations were formulated for all passages of the ejector based on the differential equations for mass, momentum, and energy balance as well as a differential representation for the equation of state.
Journal ArticleDOI
Current Advances in Ejector Modeling, Experimentation and Applications for Refrigeration and Heat Pumps. Part 1: Single-Phase Ejectors
TL;DR: A review of the main developments in ejectors over the last few years can be found in this article, where the main findings and trends in the area of heat-driven ejectors and ejector-based machines using low boiling point working fluids are summarized.
Journal ArticleDOI
Application range of the HEM approach for CO2 expansion inside two-phase ejectors for supermarket refrigeration systems
Michal Palacz,Jacek Smolka,Adam Fic,Zbigniew Buliński,Andrzej J. Nowak,Krzysztof Banasiak,Armin Hafner +6 more
TL;DR: In this paper, the accuracy of the homogeneous equilibrium (HEM) applied to 3D CFD-based simulations of CO2 expansion inside two-phase ejectors is presented.
References
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Journal ArticleDOI
A unified model for predicting flow-pattern transitions for the whole range of pipe inclinations
TL;DR: In this article, models for predicting flow-pattern transitions in steady gas-liquid flow in pipes are summarized and presented, incorporating the effect of fluid properties, pipe size and the angle of inclination in a unified way.
Journal ArticleDOI
The two-phase critical discharge of initially saturated or subcooled liquid
TL;DR: In this paper, a nonequilibrium model was developed to describe the two-phase critical discharge of initially saturated and subcooled liquid through sharp edged inlet, constant area ducts with L/D ≥ 12.
Journal ArticleDOI
A Model for Choked Flow-through Cracks With Inlet Subcooling
TL;DR: In this article, a model to predict the mass flow rate has been developed and has been successfully validated, taking into account the persistence of some metastable liquid in the crack and the special flow pattern which appears in such particular geometry.
Journal ArticleDOI
Highlights of two-phase critical flow: On the links between maximum flow rates, sonic velocities, propagation and transfer phenomena in single and two-phase flows
TL;DR: In this article, a necessary critical flow criterion is obtained by equating to zero the determinant of the set of equations describing the steady-state flow, and this criterion must be complemented by the compatibility conditions of a set.
Critical flow of saturated and subcooled water at high pressure. [PWR; BWR]
G.L. Sozzi,W.A. Sutherland +1 more
TL;DR: In this paper, critical flow rate measurements have been made with saturated and subcooled water to determine the effect of fluid enthalpy, flow geometry and size, and flow length.
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