Design of equation relating boundary condition parameters and heat transfer coefficient in autoclave during curing of composite materials

In this study, carbon fiber-reinforced composites for aerospace applications were processed in an autoclave under high pressure and temperature. Similar to laboratory conditions, the loading arrangement in each cycle may vary, leading to differences in thermal mass, airflow, and non-uniform temperature distribution, which ultimately affect process stability and product quality. To address this, the heat transfer coefficient (HTC), a key factor in small-scale experimental autoclaves, was analyzed using calorimetric measurements and computational fluid dynamics (CFD) simulations. A turbulent flow model was applied, and HTC was evaluated under different boundary conditions and spatial locations. The results indicated that HTC remained relatively stable, enabling separate assessment of heat transfer and material curing. A design of experiments (DOE) approach was employed to establish an equation relating boundary conditions, spatial positioning, airflow characteristics, and HTC. This equation was validated through comparison with experimental data and Bohne’s simulations, confirming its reliability.