Pore-scale evaluation on hydrothermal performance in a microtube with homogeneous microporous media by lattice Boltzmann method

Abstract

This study investigates the heat transfer and flow behavior of Al2O3-water nanofluid in micro-scale systems, using the lattice Boltzmann method (LBM) for numerical simulations. To implement the LBM code, FORTRAN home-made programming is employed. The research focuses on a three-dimensional microtube (500 μm diameter and 6,000 μm length) subjected to a uniform wall heat flux, with Reynolds numbers between 40 and 100. Spherical particles of varying sizes and quantities are introduced into the flow path to investigate the impact of porosity on thermophysical properties. The study explores the relatively unexamined application of the LBM to curved boundaries. Results indicate that introducing 6–10 spherical objects at Re = 40 increases the average Nusselt number by about 23.61 % and 25.83 %, respectively, whereas larger spheres in smaller quantities exhibit minimal or negative effects on heat transfer. Although the lattice Boltzmann method is gaining traction in fluid dynamics, its application to curved boundaries remains limited. This study advances the field by analyzing flow dynamics in a microtube with spherical inserts, integrating curved boundaries, nanofluids, and porous structures, thereby providing valuable insights into thermophysical studies. HIGHLIGHTS • Heat transfer and laminar flow behavior of an Al2O3-water nanofluid are evaluated numerically in a microtube with homogeneous microporous media. • To implement the 3D lattice Boltzmann method code, FORTRAN home-made programming is used. • Spherical objects are inserted into the microtube as homogeneous microporous media. • Microporous structure enhances heat transfer performance in the microtubes. • The maximum increase in the average Nusselt number for the proposed microtube is approximately 31.01%.