Abstract
This thesis focuses on the development of the twofluid
model of the APROS simulation program. The system of
constitutive equations and how equations are related to
basic equations have been presented and discussed. The
new noncondensable gas model, which was implemented to
the twofluid model, has been described in detail. The
extension of the noncondensable gas model to the
twofluid system and the validation of the model have
also been presented. The changes made to the sixequation
model when the model has been applied to supercritical
pressure calculation have been depicted. Finally, the
author describes how the whole complicated system is
verified and validated. Through the simulations, the
applicability of the twophase model for the analyses of
real plant applications is substantiated and verified.
In addition to this summary, the thesis consists of four
publications. The first paper deals with how the CCFL
(Counter Current Flow Limitation) correlations have been
implemented to the code and how these correlations have
been verified. In the second paper, the noncondensable
gas model and its implementation to the twofluid model
have been presented. The third paper describes how the
sharp temperature distribution can be maintained in the
liquid flow through the aid of simple higher order
discretization. In the fourth paper, the modifications
carried out to the twofluid model when applied to the
calculation of the supercritical pressure flow are
described and discussed.
Original language  English 

Qualification  Doctor Degree 
Awarding Institution 

Supervisors/Advisors 

Award date  27 Nov 2009 
Place of Publication  Espoo 
Publisher  
Print ISBNs  9789513873677 
Electronic ISBNs  9789513873684 
Publication status  Published  2009 
MoE publication type  G5 Doctoral dissertation (article) 
Keywords
 twofluid model
 twophase flow
 interface heat transfer
 interface friction
 wall heat transfer
 boiling crisis
 noncondensable gas
 dissolved gas
 counter current flow limitation
 discreatization
 validation
 supercritical pressure
 nuclear power plant
 APROS
Fingerprint Dive into the research topics of 'Phenomenological extensions to APROS sixequation model. Noncondensable gas, supercritical pressure, improved CCFL and reduced numerical diffusion for scalar transport calculation: Dissertation'. Together they form a unique fingerprint.
Cite this
Hänninen, M. (2009). Phenomenological extensions to APROS sixequation model. Noncondensable gas, supercritical pressure, improved CCFL and reduced numerical diffusion for scalar transport calculation: Dissertation. VTT Technical Research Centre of Finland. http://www.vtt.fi/inf/pdf/publications/2009/P720.pdf