Efficient Porous‐Medium Framework for Compact Heat Pipe Heat Exchanger

Waste heat recovery is one of the most effective strategies for improving global energy efficiency. However, accurately modeling of compact heat pipe heat exchangers (HPHXs) remains computationally challenging due to their intricate fin geometries and complex phase‐change processes. This work introduces a porous‐medium modeling framework that combines anisotropic flow resistance coefficients with a local thermal nonequilibrium (LTNE) formulation. The approach enables precise resolution of thermal gradients and interfacial heat transfer while significantly reducing computational costs. Experimental validation was conducted on a representative compact HPHX and benchmarked against both a conventional local thermal equilibrium (LTE) porous‐medium model and a fully resolved fin‐geometry simulation. The LTNE model predicted heat transfer and pressure drop with errors within 5%, while reducing hot‐ and cold‐side pressure drop errors by ~45% and 60%, respectively, compared to LTE. It also eliminated the systematic overprediction of heat transfer observed in LTE. Matching the accuracy of the fully resolved fin model, the LTNE framework achieved a ~97% reduction in computational time, offering an accurate and efficient alternative for large‐scale simulations. These results establish the anisotropic‐LTNE porous‐medium framework as a robust and scalable tool for the design and optimization of next‐generation compact heat recovery systems.