scholarly journals Effect of surface micromorphology and hydrophobicity on condensation efficiency of droplets using the lattice Boltzmann method

2021 ◽  
pp. 287-287
Author(s):  
Lijun Liu ◽  
Gaojie Liang ◽  
Haiqian Zhao ◽  
Xiaoyan Liu
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Hydrophobic Surface ◽  
Surface Hydrophobicity ◽  
Condensation Heat Transfer ◽  
Surface Microstructure ◽  
Condensation Process ◽  
Condensation Rate ◽  
Boltzmann Method

In the present study, the effects of the surface morphology and surface hydrophobicity on droplet dynamics and condensation efficiency are investigated using the lattice Boltzmann method (LBM). Different surface morphologies may have different condensation heat transfer efficiencies, resulting in diverse condensation rates under the same conditions. The obtained results show that among the studied morphologies, the highest condensation rate can be achieved for conical microstructures followed by the triangle microstructure, and the columnar microstructure has the lowest condensation rate. Moreover, it is found that when the surface microstructure spacing is smaller and the surface microstructure is denser, the condensation heat transfer between the surface structure and water vapor facilitates, thereby increasing the condensation efficiency of droplets. Furthermore, the condensation process of droplets is associated with the surface hydrophobicity. The more hydrophobic the surface, the more difficult the condensation heat transfer and the longer the required time for droplet nucleation. Meanwhile, a more hydrophobic surface means that it is harder for droplets to gather and merge, and the corresponding droplet condensation rate is also lower.

HEAT TRANSFER ENHANCEMENT IN A CHANNEL PARTIALLY FILLED WITH A POROUS BLOCK: LATTICE BOLTZMANN METHOD

2013 ◽  
Vol 24 (09) ◽  
pp. 1350060 ◽  
Author(s):  
M. NAZARI ◽  
M. H. KAYHANI ◽  
R. MOHEBBI
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Lattice Boltzmann Method ◽  
Heat Transfer Enhancement ◽  
Lattice Boltzmann ◽  
Block Size ◽  
Blockage Ratio ◽  
Transfer Enhancement ◽  
Porous Block ◽  
Boltzmann Method

The main goal of the present study is to investigate the heat transfer enhancement in a channel partially filled with an anisotropic porous block (Porous Foam) using the lattice Boltzmann method (LBM). Combined pore level simulation of flow and heat transfer is performed for a 2D channel which is partially filled with square obstacles in both ordered and random arrangements by LBM which is not studied completely in the literature. The effect of the Reynolds number, different arrangements of obstacles, blockage ratio and porosity on the velocity and temperature profiles inside the porous region are studied. The local and averaged Nusselt numbers on the channel walls along with the respective confidence interval and comparison between results of regular and random arrangements are presented for the first time. For constant porosity and block size, the maximum value of averaged Nusselt number in the porous block is obtained in the case of random arrangement of obstacles. Also, by decreasing the porosity, the value of averaged Nusselt number is increased. Heat transfer to the working fluids increases significantly by increasing the blockage ratio. Several blockage ratios with different arrangements are checked to obtain a correlation for the Nusselt number.

Numerical simulation of vapor bubble growth on a vertical superheated wall using lattice Boltzmann method

2015 ◽  
Vol 25 (5) ◽  
pp. 1214-1230 ◽  
Author(s):  
Tao Sun ◽  
Weizhong Li ◽  
Bo Dong
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Phase Change ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Nucleate Boiling ◽  
Numerical Results ◽  
Heat Transfer Mechanism ◽  
Content Type ◽  
Boltzmann Method

Purpose – The purpose of this paper is to test the feasibility of lattice Boltzmann method (LBM) for numerical simulation of nucleate boiling and transition boiling. In addition, the processes of nucleate and transition boiling on vertical wall are simulated. The heat transfer mechanism is discussed based on the evolution of temperature field. Design/methodology/approach – In this paper, nucleate boiling and transition boiling are numerically investigated by LBM. A lattice Boltzmann (LB) multiphase model combining with a LB thermal model is used to predict the phase-change process. Findings – Numerical results are in good agreement with existing experimental results. Numerical results confirm the feasibility of the hybrid LBM for direct simulations of nucleate and transition boiling. The data exhibit correct parametric dependencies of bubble departure diameter compared with experimental correlation and relevant references. Research limitations/implications – All the simulations are performed in two-dimensions in this paper. In the future work, the boiling process will be simulated in three-dimensional. Practical implications – This study demonstrated a potential model that can be applied to the investigation of phase change heat transfer, which is one of the effective techniques for enhance the heat transfer in engineering. The numerical results can be considered as a basic work or a reference for generalizing LB method in the practical application about nucleate boiling and transition boiling. Originality/value – The hybrid LBM is first used for simulation of nucleate and transition boiling on vertical surface. Heat transfer mechanism during boiling is discussed based on the numerical results.

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