In this paper, the development of a new mass transfer model to simulate the thermal and phase change characteristics encountered by binary mixtures during flow boiling process is discussed. A new boiling mass transfer model based on detailed bubble dynamic effects, inclusive of local bubble shear, drag and buoyancy dynamics, has been developed and full implemented within the commercial CFD code AVL FIRE v2010. In the present study the phasic mass, momentum and energy equations are solved in a segregated fashion in conjunction with an interfacial area transport and a number density equation to study the heat and mass transfer characteristics of binary flow boiling inside a rectangular duct. Turbulence in the fluidic system and those generated by the bubbly flow are treated using an advanced k-ζ-f model. The simulation results comprising of flow variables such as volume fraction, fluidic velocities and temperature and the resultant heat flux generated on the heated wall section clearly monitors the suppression in heat transfer coefficients with enhancement in flow convection. Competing mechanisms such as phase change process and turbulent convection are identified to influence the heat transfer characteristics. In particular, the varying influence of the mass transfer effects on the heat flux characteristics with alteration in wall temperature is well demonstrated. Comparisons of the predicted heat transfer coefficients for varying wall superheat and varying fluidic velocity indicates a very good agreement with experimental data, wherever available. Description of the flow field inclusive of interfacial area and number density distribution is provided. The current model can be easily extended to simulate multiphase flow in complex systems such as a cooling water jacket for automotive applications.
Numerical Simulation of Flow Boiling of Binary Mixtures Using Multi-Fluid Modeling Approach
Srinivasan, V. "Numerical Simulation of Flow Boiling of Binary Mixtures Using Multi-Fluid Modeling Approach." Proceedings of the ASME 2011 International Mechanical Engineering Congress and Exposition. Volume 10: Heat and Mass Transport Processes, Parts A and B. Denver, Colorado, USA. November 11–17, 2011. pp. 565-575. ASME. https://doi.org/10.1115/IMECE2011-63848
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