PIP-based numerical modeling of mixed convection, heat and mass transfer in NEPCM composite structures within porous solar thermal flow domains

Purpose Enhancing heat and mass transfer in porous solar thermal systems incorporating phase change materials remains a significant challenge due to the complex coupled thermal–solutal transport within heterogeneous composite structures. This study aims to develop an advanced numerical framework to accurately analyze these coupled transport mechanisms and to assess the influence of material and geometric parameters on system performance. Design/methodology/approach An advanced numerical modeling framework, based on a novel Point-in-Polygon (PIP) identification approach, is developed to investigate thermal and solutal transport in composite-structure nano-encapsulated phase change materials (NEPCM) composed of a nonadecane core and a polyurethane shell. The analysis is performed in a vented cavity containing a hollow cylinder saturated with non-Darcy porous media. Four hollow-cylinder materials with different thermal conductivities – plastic tiles (Ks = 0.5), clay tiles (Ks = 0.84), concrete tiles (Ks = 0.1) and slate tiles (Ks = 2) – are examined. The effects of varying inlet and outlet lengths are also investigated. Furthermore, novel third-order polynomial correlations are proposed to predict heat and solutal transfer as functions of key governing parameters, including the conductive cylinder radius and inlet/outlet dimensions. Findings The results demonstrate that both material selection and geometric configuration strongly influence heat and mass transfer characteristics. Increasing the inlet/outlet dimensions from 0.05 to 0.2 enhances heat and mass transfer rates by up to 4.43% and 10.14%, respectively. Moreover, employing slate tiles as the conductive inner cylinder increases the average Nusselt number by 52.99% compared to plastic tiles. Originality/value This study introduces a novel PIP-based numerical framework for accurately modeling coupled thermal–solutal transport in complex composite porous domains containing NEPCM. The proposed third-order polynomial correlations provide practical predictive tools for system design and optimization, offering valuable insights to improve the thermal performance of porous solar thermal systems with composite phase change materials.