Abstract: A lattice Boltzmann (LB) method is presented for solving the energy conservation equation in two phases when the phase change effects are included in the model. This approach employs multiple distribution functions, one for a pseudotemperature scalar variable and the rest for the various species. A nonideal equation of state (EOS) is introduced by using a pseudopotential LB model. The evolution equation for the pseudotemperature variable is constructed in such a manner that in the continuum limit one recovers the well known macroscopic energy conservation equation for the mixtures. Heats of reaction, the enthalpy change associated with the phase change, and the diffusive transport of enthalpy are all taken into account; but the dependence of enthalpy on pressure, which is usually a small effect in most nonisothermal flows encountered in chemical reaction systems, is ignored. The energy equation is coupled to the LB equations for species transport and pseudopotential interaction forces through the EOS by using the filtered local pseudotemperature field. The proposed scheme is validated against simple test problems for which analytical solutions can readily be obtained.@en

Abstract: Dispersed gas (vapor) liquid flow through an inclined microchannel with bends has successfully been simulated, that is, without numerical difficulties, by means of a two-phase Lattice Boltzmann method. Combining in this method the Shan-Chen(1) pseudopotential interaction model with the Yuan and Schaefer(2) proposal for dealing with nonideal equations of state makes high density ratios achievable. This approach also allows simulation of gas liquid flows without explicitly having to track the phase interfaces. Rather, a potential function related to the equation of state for vapor liquid equilibrium, a coupling strength representing attraction or repulsion between species, and a relaxation time scale take care of microscale and mesoscale phenomena such as phase separation and interfacial tension as well as interphase transport and multiphase flow. In addition, fluid wall interaction (contact angle) is taken into account by selecting proper potential functions and coupling strengths. As far as the phase behavior is concerned, we assessed our method by studying the phase separation process and by validating against Maxwell's equilibrium rule. Qualitative validation of our approach of gas liquid flow has been done with a comparison against experimental data on a single bubble rise. Detailed simulations were carried out for an individual Taylor bubble in a channel, the results of which compared favorably to literature data@en

Chemical Engineering Journal Volumes 207¿208, 1 October 2012, Pages 587¿595 22nd International Symposium on Chemical Reaction Engineering (ISCRE 22)@en