A Nonequilibrium Vapor Generation Model for Flashing Flows

Saha, Pradip Kumar; Abuaf, N.; Wu, B.J.C.

doi:10.1115/1.3246634

Cited by 18 publications

(3 citation statements)

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“…All of these models ignore the effect of neighboring bubbles, and thus they are limited to very low void fractions. Saha et al [92] have modeled the vapor phase growth and calculated this rate for every flow regime (estimating interfacial area density and net interfacial heat flux). However, they varied the nucleation rate (bubble number density) to obtain an optimum fit of the experimental results of the flow through the vertical converging-diverging nozzle.…”

Section: Article In Pressmentioning

confidence: 99%

Flash-boiling atomization

Sher

Bar-Kohany

Rashkovan

2008

Progress in Energy and Combustion Science

305

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Section: Article In Pressmentioning

confidence: 99%

Flash-boiling atomization

Sher

Bar-Kohany

Rashkovan

2008

Progress in Energy and Combustion Science

305

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“…For the reported experiments, the number density of bubbles varies between 3xl0 9 and8x!0 10 ni 3 . Saha et al (1984) developed a model for the net evaporation rate for each flow regime downstream the throat. The bubble number density and initial void fraction at the flashing inception point were varied to best match the measured void fraction data.…”

mentioning

confidence: 99%

Modeling of Flashing Two-Phase Flow

Pinhasi¹,

Ullmann²,

Dayan³

2005

Reviews in Chemical Engineering

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A review of the published work on the flashing of a two-phase flow system, owing to a sudden depressurization of a compressed liquid, is presented. Of concern is the two-phase flow transient occurring during a failure of a pressurized tube or vessel-blowdown. Abrupt depressurization of a confined liquid can bring the liquid to a superheated state. If this occurs, an intense nucleation process is triggered. The level of superheating at which the nucleation process begins is referred to as the "flashing inception" point. The rapidity of the bubble nucleation and growth processes substantial influence the mixture blowdown scenario that sometimes can be in the form of a Boiling Expanding Vapor Explosion (BLEVE).The current review deals with flashing of a single pure substance. First, the models of bubble formation and growth are presented. This is followed by a description on the incorporation of these models into two-phase flow transport models. The two-phase models are used for analysis of the blowdown scenario. This subject is of critical importance for the investigation of the safety of compressed liquid systems.

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“…Considerations of the thermodynamic modeling issues associated with flashing are beyond the scope of this dissertation; however, work exists in the literature that suggests that this issue is being considered by the academic community [119,120]. It would be valuable at some future point in time to conduct CFD simulations to gain greater insight into the thermodynamic behavior of the system.…”

Section: Nondimensionalmentioning

confidence: 99%

Dynamic and efficiency characteristics of an inlet metering valve controlled fixed displacement pump

Wisch¹

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This project developed the inlet metering system. An inlet metering system represents a new option in hydraulic pump design. Traditional pressure controlled hydraulic pumps rely on either swashplate displacement (for variable displacement pumps) or bleed off valves (for fixed displacement pumps). Variable displacement pumps require mechanically complex parts which are expensive to machine and prone to break down. Bleed off valves represent a significant loss in system efficiency. In contrast, the inlet metering system is able to make use of a fixed displacement pump (which is relatively inexpensive and mechanically robust) and a two-way spool valve. This dissertation goes through the process of designing the valve and pump dimensions, presents a theoretical dynamic analysis, studies the control law associated with this pump, and examines the energy requirements associated with inlet metering system operation. A prototype of the design was constructed and experimental data was used to validate the efficiency analysis. The major finding associated with this work was that the inlet metering system can be designed to display a first order pressure response. This means that when the inlet metering system is operated, the actual pressure in the system will never exceed the desired pressure. In contrast, traditional hydraulic systems will display up to 60% pressure overshoot, meaning the systems must be designed to handle pressures significantly greater than operating pressures. Additionally it was found that the inlet metering system is more efficient than using a bleed off valve, but less efficient than using a variable displacement pump.

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A Nonequilibrium Vapor Generation Model for Flashing Flows

Cited by 18 publications

References 0 publications

Flash-boiling atomization

Flash-boiling atomization

Modeling of Flashing Two-Phase Flow

Dynamic and efficiency characteristics of an inlet metering valve controlled fixed displacement pump

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