Performance Enhancement of Advanced Mechanical and Thermal Systems Using Phase Change Material-Based Heat Exchangers: A Combined Numerical and Experimental Investigation

Abstract

Advanced mechanical and thermal systems increasingly rely on efficient thermal energy storage to bridge the gap between intermittent heat generation and continuous energy demand. This paper reports a combined numerical and experimental investigation of a shell-and-tube latent heat thermal energy storage (LHTES) unit that uses paraffin-based phase change material (PCM) as the storage medium. A finned-tube configuration and a nano-enhanced PCM variant were evaluated against a plain-tube baseline to quantify improvements in charging rate and heat exchanger effectiveness. An enthalpy-porosity based numerical model was developed in ANSYS Fluent and validated against a laboratory-scale experimental rig instrumented with calibrated K-type thermocouples and a data acquisition system. Results indicate that annular fins reduce the full-charging time by approximately 28% relative to the plain-tube design, while dispersion of 2% Al2O3 nanoparticles in the PCM matrix further improves thermal conductivity and effectiveness by nearly 47% over baseline at a mass flow rate of 4 LPM. The findings provide quantitative design guidance for engineers developing compact thermal energy storage modules for solar-thermal plants, electric-vehicle battery thermal management, and industrial waste-heat recovery systems.

KEYWORDS: Phase Change Material, Thermal Energy Storage, Heat Exchanger Effectiveness, Nanoparticle Enhancement, Enthalpy-Porosity Method, Mechanical and Thermal Systems, CFD Simulation