Molecular Insights into the Mechanism Underlying the Influence of Insulating Liquid Molecular Structure on Thermal Conductivity

Investigating the relationship between molecular structure and thermal conductivity in insulating liquids provides crucial insights for enhancing their heat transfer performance. This study systematically examines how the molecular configurations of three major insulating oils, including mineral oil, ester-based oil, and hybrid oil, affect thermal conductivity through microscopic parameters. Molecular dynamics simulations reveal temperature-dependent variations in density, free volume, intermolecular forces, radius of gyration, and isobaric heat capacity. Experimental validation establishes a strong structure-property correlation, showing that optimal thermal conductivity arises from a balanced molecular density that enables tight packing, minimized free volume that ensures efficient molecular alignment, moderate intermolecular interaction energy that facilitates energy transfer, and appropriate molecular dimensions. In addition, a higher isobaric heat capacity enhances heat energy transport per unit volume. As temperature increases, density decreases and intermolecular forces weaken. However, the rise in molecular kinetic energy and vibrational frequency offsets these effects, leading to an overall improvement in thermal conductivity. These findings provide fundamental guidelines for designing high-performance insulating oils through molecular engineering.