BUG 4391 in Flownex involves using the incorrect heat flux when determining wall temperature at critical heat flux, causing errors in boiling heat transfer calculations. The issue arises because the nucleate boiling coefficient scaling uses the current heat flux instead of the critical heat flux from Groeneveld tables. Fixed in version 8.14.0.4675, the workaround is to override heat transfer coefficients via a script with user-defined two-phase heat transfer regimes.
ERROR INFORMATION
Bugzilla Error Number | BUG 4391 |
Description of Error | The incorrect heat flux is used when determining the wall temperature associated with critical heat flux. |
Comments | The Flownex calculation procedure relies on the critical heat flux value determined from the Groeneveld lookup tables. Then based on the prevailing conditions the wall temperature that is calculated would correspond to the wall temperature at the critical heat flux. To do so, a nucleate boiling coefficient is required based on the correlation of Steiner and Taborek. Flownex used the currently calculated heat flux for the scaling of the nucleate boiling coefficient in the Steiner and Taborek correlation, whereas the critical heat flux should be used instead. Since the wall temperature at critical heat flux is used to determine the boiling regime, this can introduce large errors when determining the boiling heat transfer since the heat transfer coefficients vary significantly between the different boiling regimes. |
| Corrected Version | 8.14.0.4675 |
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Workaround Description: The script defined heat transfer option can be used to override the Flownex calculated heat transfer coefficients. With this workaround the user will have to provide a complete implementation of the two-phase heat transfer coefficients for all the heat transfer regimes. |