Visualization experiment and numerical analysis of supercritical CO2 flow inside porous chip: Effect of heat transfer and porous structures

Carbon dioxide (CO₂) geological sequestration is one of the key methods to reduce atmospheric carbon emissions, yet the migration mechanisms of CO₂ within reservoirs remain unclear. This study systematically investigates the flow and heat transfer characteristics of supercritical CO₂ (sCO₂) in porous media through integrated optical visualization experiments and numerical simulations. Experimental results show that under supercritical conditions (pressure: 8.2–8.6 MPa, temperature: 32–34 °C), increasing the outlet pressure enhances momentum exchange but reduces flow uniformity, whereas raising the inlet temperature reduces fluid viscosity and smoothens density gradients, thereby improving flow homogeneity. Numerical simulations further reveal that under supercritical conditions (8.5 MPa, 305.15–318.15 K), boundary parameters including the inlet Reynolds number, inlet temperature, and wall heat flux exhibit non-monotonic influence patterns on the heat transfer coefficient (HTC), with an optimal range identified for each parameter. Exceeding this range leads to a significant reduction in HTC by 75–94 %. Under transcritical conditions (7.5–9.0 MPa, 303.15 K), the structure of the porous media effectively suppresses disturbances caused by thermophysical nonlinearities of sCO₂ through flow inertia, enabling the local heat transfer coefficient to maintain strong robustness against variations in outlet pressure and heat flux.