Coupling of Wall Boiling with Discrete Population Balance Model

Abstract

A coupling between a polydisperse population balance method (Multiple Size Group Model – MUSIG) and the RPI wall boiling model for nucleate subcooled boiling has been implemented in ANSYS CFX. It allows more accurate prediction of the interfacial area density for mass, momentum and energy transfer between phases in comparison to the usual local-monodisperse bubble size assumption and underlying bulk bubble diameter correlations as they are commonly used in boiling flow applications like e.g. the prediction of subcooled nucleate boiling in rod bundles and fuel assemblies of PWR. The paper outlines the methodology of the coupled CFD model, which automatically avoids possible inconsistencies in the model formulation for the heated wall, when the generated steam bubbles on the heater surface are injected exactly in the bubble size class corresponding to the predicted bubble departure diameter. The coupling of the RPI wall boiling model and the MUSIG model has been implemented for both homogenous/inhomogeneous variants of the MUSIG model. The paper presents the validation of the coupled modeling approach for the well known test case of nucleate subcooled boiling of R113 refrigerant in a circular annulus with inner heated rod based on the experiments of Roy et al. [1]. ANSYS CFX results with the newly implemented approach as well as comparison to data and locally-monodisperse simulations are provided.

References

Roy

R.P.

Turbulent subcooled boiling flow -Experiments and simulations. February 2002,: ASME, 2002, Journal of Heat Transfer, Vol. 124, pp. 73–93.

Kurul

and Podowski

M.Z.

On the modeling of multidimensional effects in boiling channels. Minneapolis: 1991. 27th National Heat Transfer Conference.

Yeoh

G. H.

and Tu

J. Y.

Thermal-hydrodynamic modeling of bubbly flows with heat and mass transfer, 2005, AIChE Journal, Vol. 51, pp. 8–27.

Yeoh

G. H.

and Tu

J. Y.

Population balance modeling of bubbly flows with heat and mass transfer, 2004, Chemical Engineering Science, Vol. 59, pp. 3125–3139.

Frank

Th.

Validation of CFD models for mono- and polydisperse air-water two-phase flows in pipes. March 2008, J. Nuclear Engineering & Design (NED), Vol. 238, pp. 647–659.

Tolubisnki

V. I.

and Kostanchuk

D.M.

Vapour bubbles growth rate and heat transfer intensity at subcooled water boiling. Paris: 1970. 4th International Heat Transfer Conference.

Frank

Th.

Prediction of Subcooled Wall Boiling in a Heated Annulus Including Conjugate Heat Transfer in the Central Heated Rod. 2010. 7th International Conference on Multiphase Flow, ICMF 2010, May 30–June 4, 2010, Tampa, FL USA. pp. 1–14.

Lifante

Prediction of Polydisperse Steam Bubble Condensation in Sub-Cooled Water using the Inhomogeneous MUSIG Model. Tampa, FL: 2010. 7th International Conference on Multiphase Flow.

NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP): Version 9.0 [Online] http://www.nist.gov/srd/nist23.cfm.

10.

Menter

F.R.

Two-equation eddy-viscosity turbulence models for engineering applications. 8, 1994, AIAA Journal, Vol. 32, pp. 1598–1605.

11.

Krepper

Lucas

and Schmidtke

Modelling of Turbulence in Bubbly Flows. Tampa: 2010. 7th International Conference on Multiphase Flow.

12.

Tomiyama

Progress in computational bubble dynamics. Dresden: 2009. Workshop on Multiphase Flows 2009.

13.

Koncar

and Krepper

CFD simulation of convective flow boiling of refrigerant in a vertical annulus.: Elsevier, 2008, Nuclear Engineering and Design, Vol. 238, pp. 693–706.

14.

Menter

F.R.

CFD Best Practice Guidelines for CFD Code Validation for Reactor-Safety Applications.: ECORA, 2002.