Impact of thermal boundary configuration on phase transition heat transfer characteristics of carbon dioxide in confined geometries

Abstract

This study investigates the impact of varying heat source configurations on the multiphase flow dynamics and phase-change heat transfer characteristics of carbon dioxide within a sealed cavity. Comprehensive numerical simulations were performed to analyze the temporal evolution of temperature, pressure, and vapor volume fraction over a 0.04 s duration for three distinct heat source arrangements: (1) a cylindrical enclosure with a fully immersed heating element (model one), (2) an axial heat source configuration (model two), and (3) a circumferential heat source arrangement (model three). The findings reveal that continuous heating of the carbon dioxide by the heat source induces progressive increases in temperature, pressure, and vapor volume fraction. While pressure exhibits a gradual and spatially homogeneous distribution over time, both temperature and gas-phase volume fractions demonstrate non-uniform spatial distributions. The heat source arrangement significantly influences these thermodynamic and phase-change parameters, with the axial configuration showing the least deviation from the baseline model. Notably, the circumferential arrangement enhances heat transfer efficiency by increasing the contact area with liquid carbon dioxide, thereby accelerating vaporization. At 0.04 s, model three attained a peak pressure of 112.86 MPa, surpassing model one (104.5 MPa) and model two (100.654 MPa). These results underscore the superior performance of the circumferential heat source configuration in terms of pressure buildup rate, pressure distribution uniformity, and vapor volume fraction change dynamics.