.ThermoPower.Water.Flow1D2phDB

Information

This model extends Flow1D2ph by computing the distribution of the heat transfer coefficient gamma and making it available through an extended version of the wall connector.

This simplified model can be used for one-phase or two-phase water/steam flow. The heat transfer coefficient is computed according to the following hypotheses:

• If the fluid is subcooled liquid or superheated steam, Dittus-Boelter's correlation [1] is used.
• If the fluid is a two-phase mixture with a steam fraction less than the (constant) critical value xCHF, boiling heat transfer is assumed with a heat transfer coefficient equal to gamma_b.
• If the fluid is wet steam with a steam fraction greater than the (constant) critical value xCHF, the heat transfer coefficient is computed according to Dittus-Boelter's correlation, by considering only the steam fraction of the mixture.

A smoothing algorithm is applied to the nodes which are in the neighbourhood of a transition boundary between non-boiling and boiling conditions, to avoid non-physical sudden changes of the nodal values of the heat transfer coefficient when the transition boundary passes through a node. The computed values of the heat transfer coefficient are thus a continuous function of the nodal enthalpies and pressures, so that it is not necessary to generate events in order to handle discontinuities

References

1. J. C. Collier: Convective Boiling and Condensation, 2nd ed.,McGraw Hill, 1981, pp. 146.

Revisions

• 24 Mar 2005 by Francesco Casella:
  FFtypes package and NoFriction option added.
• 16 Dec 2004 by Francesco Casella:
  Standard medium definition added.
• 1 Nov 2004 by Francesco Casella:
  Equations revisited.
• 24 Sep 2004 by Francesco Casella:
  Adapted to Modelica.Media.
• 11 Feb 2004 by Francesco Casella:
  Computation of the h.t.c. extended to all the thermodynamic conditions of the fluid.
• 1 Oct 2003 by Francesco Casella:
  First release.