A hybrid immersed boundary-lattice Boltzmann method for flow and heat transfer within a fluid heat exchanger.

This article focuses on extending a hybrid immersed boundary-lattice Boltzmann method (IB-LBM) to analyze the hydrodynamic and thermodynamic behaviors of a fluid heat exchanger (FHE) with an asymptotic tube configuration. The study investigates the effects of Reynolds number (Re), superheat levels, porosity, and cylinder arrangements on temperature, flow velocity, pressure drop, and heat transfer efficiency. Results indicate that increasing Re raises pressure drops and heat transfer rates but lowers outlet temperature and thermal performance due to reduced fluid contact time with heated surfaces. Higher superheat levels increase outlet temperature without significantly affecting flow velocity fluctuations or pressure drops. Among five porosity and cylinder arrangement cases analyzed, the configuration with the highest porosity and optimized cylinder layout achieved substantially improved heat transfer rates and thermal performance, alongside more uniform temperature and velocity distributions, suggesting enhanced stability and efficiency for practical FHE applications.