Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
BOUNDARY CONDITIONS EFFECTS ON THE BOILING HEAT TRANSFER PROBLEM IN CHANNELS USING THE LATTICE BOLTZMANN METHOD
Submission Author:
Luiz Czelusniak , SP
Co-Authors:
Luiz Czelusniak, Alfredo Jaramillo, Luben Cabezas Gómez
Presenter: Luiz Czelusniak
doi://10.26678/ABCM.COBEM2021.COB2021-1365
Abstract
Processes involving phase change in liquid-vapor mixtures inside channels are of great interest in mechanical engineering due to the advantages that this phenomenon provides in refrigeration systems in terms of heat transfer efficiency. Systems of this type are found in different applications such as domestic refrigeration, nuclear reactors and electronics cooling. There is a high scientific interest in the development of numerical tools capable of simulating this type of systems. A promising tool in this regard is the lattice Boltzmann method (LBM). One LBM extension to simulate multi-phase flows is the pseudopotential method which consists in the addition of a fluid-fluid interaction force. This additional term naturally induces and allows coexistence of different fluid phases. In this work, the pseudopotential LBM is applied to the study of boiling heat transfer in channel flows. The Multi-relaxation time (MRT) collision operator will be used in the lattice Boltzmann equation in order to increase simulation stability. The Peng-Robinson equation of state (EOS) will be used and its parameters will be selected in order to approximate the fluid behavior to that of water. The LBM is employed along a suitable energy conservation equation. Also, bubble nucleation is induced by applying temperature perturbations at the walls. In this work, two discrete outflow boundary conditions (convective and Neumann null conditions) are tested and their impact on stability and bubble nucleation is assessed. This work will contribute to a better understanding about current strengths and limitations of the pseudopotential method in the simulation of boiling in channel flows. From these results, improvements of the method may be devised in order to improve its accuracy.
Keywords
Boiling Heat Transfer, Lattice Boltzmann method, Outflow Boundary Conditions, channel flow
