Three-dimensional condensation in a vertical channel filled with metal foam using a pseudo-potential lattice Boltzmann model

Abstract

In this study, three-dimensional condensation in a domain filled with metal foam is investigated using the lattice Boltzmann method for the first time. A recently proposed two-phase pseudo-potential lattice Boltzmann model is extended to 3D phase-change problems by adding the energy equation with the Peng–Robinson equation of state. The phase-change model is validated using the thermodynamic consistency test, Laplace law, contact angle test, and D2-law. To provide accurate pore-scale analysis, both the flow and energy equations are discretized with the D3Q27 model. Moreover, the metal foam cell structure is reconstructed by implementing the Lord Kelvin model on the mesh nodes. The results are reported in terms of condensation modes, droplet nucleation, growth and removal, heat flux on the walls and mass flow rate of the discharged condensate. Furthermore, the effects of the Jakob number (in range of Ja=0.06 to 0.24) and cell size (S=16,32, and 64) are investigated regarding the condensation process, average heat flux, and mass flow rate. The condensation curve under constant temperature boundary condition is presented for different configurations. It is shown that the model is capable of simulating convection heat transfer along with different condensation modes, including dropwise and filmwise modes. Our results revealed that the onset of nucleation and mode transition occurs at lower Jakob values as the metal foam cell size is increased. Also, it is shown that at a fixed configuration, increasing the Jakob number affects the condensate mass flow rate more than heat flux. The results of this study could be useful in the design of phase-change heat exchangers with metal foam construction.