Semi-analytical model for the prediction of the Wilson point for homogeneously condensing steam flows

Lucia Azzini, Matteo Pini, Piero Colonna

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Abstract

An investigation on non-equilibrium condensing steam flow is conducted to attain a semi-analytical model for the prediction of the Wilson point up to the critical point. The database for the analysis includes experimental observations in various nozzles and conditions (ranging from 20 to 150 bar) taken from the literature as well as additional data at lower and higher reduced pressures, generated by means of a calibrated quasi-1D model based on the method of moments.

The simplified model is based on a reformulation of the Wilson point in terms of activation time, defined as the temporal interval between the instant at which the flow is at saturation conditions and the inception stable of condensation. This allows to incorporate the dependency of the Wilson point on the cooling rate and dew-point temperature, which are found the key parameters affecting the delay of condensation.

The accuracy of the approach is proved by predicting the degree of subcooling on four different test cases, with deviations against experiments in the range of 1−10%. As demonstrated, the same approach can be exploited to design nozzles free of condensation.
Original languageEnglish
Pages (from-to)1-14
JournalInternational Journal of Heat and Fluid Flow
Volume70
DOIs
Publication statusPublished - 2018

Keywords

  • Non-equilibrium condensation
  • Supersonic nozzles
  • steam expansion
  • Wilson point

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