Paper 10: Measurement of an Average Size and Number of Droplets during Spontaneous Condensation of Supersaturated Steam

Petr, Václav

doi:10.1243/pime_conf_1969_184_199_02

Cited by 7 publications

(8 citation statements)

References 4 publications

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“…Unfortunately, however, pressure distributions alone were insufficient to resolve the uncertainties associated with nucleation theory and in the 1960s and 1970s optical techniques were developed for measuring the droplet size (e.g. see Deych et al [28], Stein [29], Gyarmathy and Lesch [30], Petr [31], Kròl [32], and Walters [33]). These measurements provided additional data for comparison with the theoretical solutions.…”

Section: Introductionmentioning

confidence: 99%

Classical Nucleation Theory and Its Application to Condensing Steam Flow Calculations

Bakhtar

Young

White

et al. 2005

Proceedings of the Institution of Mechanical Engineers, Part C:

170

104

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The paper discusses the classical theory of the homogeneous nucleation of water droplets from supersaturated vapour and its application in predicting condensation in steam nozzles. The first part consists of a review of classical nucleation theory, focusing on the many modifications made to the original Becker-Döring theory and providing some new insights into recent developments. It is concluded that the predictive accuracy required for engineering calculations is not yet attainable with a theory derived from first principles. The areas that require most attention relate to the properties of small molecular clusters and the energy transfer processes in the non-isothermal theory. Experiments in converging-diverging nozzles provide the best means for validation at the very high nucleation rates of interest, but measurements of pressure distribution and the Sauter mean droplet radius are insufficient to provide independent checks on the separate theories of nucleation and droplet growth. Nevertheless, a judicious choice for the nucleation rate equation, in combination with a standard droplet growth model and a suitable equation of state for steam, can provide accurate predictions over a wide range of conditions. The exception is at very low pressures where there is evidence that the droplet growth rate in the nucleation zone is underestimated.

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Section: Introductionmentioning

confidence: 99%

Classical Nucleation Theory and Its Application to Condensing Steam Flow Calculations

Bakhtar

Young

White

et al. 2005

Proceedings of the Institution of Mechanical Engineers, Part C:

170

104

View full text Add to dashboard Cite

show abstract

“…Subsequently, Oswatitsch's treatment has been refined, developed further, and used in numerous investigations of one-dimensional high-speed flows of nucleating steam, e.g. see references [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. By the early 1970s, although some uncertainties associated with nucleation theory were still to be resolved, the state of progress was regarded as sufficient to justify the application of the theory to studies of wet steam in turbines.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Treatments of Two-Dimensional Two-Phase Flows of Steam and Comparison with Cascade Measurements

Bakhtar

White

Mashmoushy

2005

Proceedings of the Institution of Mechanical Engineers, Part C:

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During the course of expansion of steam in turbines, the state path crosses the saturation line and hence subsequent turbine stages operate with wet steam. These stages have lower thermodynamic efficiencies than those operating in the superheated region, and currently the phenomena contributing to the increased losses are not fully understood. The development of the nucleation theory has opened the way for the study of condensing flows in turbines. As, with the advances in numerical methods, the equations describing droplet nucleation and growth rates can be combined with the field conservation equations and the set treated numerically, which allows the behaviour of complex nucleating and wet steam flows in turbines to be analysed. This paper outlines and reviews wet steam calculation methods and discusses comparisons between numerical and experimental results. For the most part, the comparisons presented are based on work of the authors and their co-workers, but some more recent calculations by other investigators are also included.

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“…The introduction of optical methods has lead to a significant improvement in the detection of the size and concentration of the droplets. [8][9][10][11] The continuously increasing consumption of electricity has supported a number of researches on wetness effects both in fossil-fired and nuclear steam turbines. An extensive and fruitful review of the state of the subject was recently presented in a Special Issue on Wet Steam in which a number of review articles summarised the state of progress in theoretical and experimental studies of wetness effects Department of Energy Engineering, Czech Technical University in Prague, Czech Republic in steam turbines.…”

Section: Introductionmentioning

confidence: 99%

“…The introduction of optical methods has lead to a significant improvement in the detection of the size and concentration of the droplets. 8–11…”

Section: Introductionmentioning

confidence: 99%

Wet steam energy loss and related Baumann rule in low pressure steam turbines

Petr

Kolovratník

2013

Proceedings of the Institution of Mechanical Engineers, Part A:

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This paper presents the results of a computational analysis of the wet steam energy loss occurring in a 210 MW fossilfired and a 1000 MW nuclear LP steam turbine. The turbines operate under considerably different conditions as regards pressure level in the droplet nucleation zone, exit moisture level and droplet size spectra determined from optical extinction measurements. An evaluation of the basic wetness energy losses has been carried out including the thermodynamic loss, drag loss of the fine and coarse droplets, impact loss, collected water loss, centrifuging loss and exit loss. A statistical 2D evaluation method has been employed for the computational simulation of the loss. The objective of the analysis was to determine whether an equilibrium based Baumann factor of order 0.6 can be used for predicting the wet steam loss.

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Paper 10: Measurement of an Average Size and Number of Droplets during Spontaneous Condensation of Supersaturated Steam

Cited by 7 publications

References 4 publications

Classical Nucleation Theory and Its Application to Condensing Steam Flow Calculations

Classical Nucleation Theory and Its Application to Condensing Steam Flow Calculations

Theoretical Treatments of Two-Dimensional Two-Phase Flows of Steam and Comparison with Cascade Measurements

Wet steam energy loss and related Baumann rule in low pressure steam turbines

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