Conjugate transient flow and thermal analysis of non-isothermal rubber curing process in autoclave system

Abstract

Autoclave manufacturing under high pressure and elevated temperature was required to vulcanize the rubber compound applied in the aerospace industry. Nevertheless, few works have comprehensively explored the transient effect of flowing factors on curing efficiency, thermal uniformity, and exergy destruction in autoclave processing. In this study, the three-dimensional model and non-isothermal vulcanization of an autoclave with a built-in combustion chamber were solved by combining the finite volume method and the proposed mixed kinetic model, and exergy destruction was determined to estimate the energy consumption using a direct method. Variations in the Reynolds number (Re), gas pressure (P), temperature, rate of temperature change, and Prandtl number (Pr) were analyzed to improve the unstable thermo-vulcanization and reduce energy consumption in autoclave processing. The results demonstrate that increasing the inlet Re can significantly increase the curing rate while decreasing the temperature difference in the rubber area, and a reduction of 41.89 %−46.62 % for the complete vulcanization time is achieved by changing Re from 105 to 2 × 106; however, adjusting P and temperature has only a minor effect on the heat transfer under constant higher Re. Furthermore, changing the rate of temperature change and Pr is also advantageous for optimizing the curing process and reducing exergy destruction. A minimal non-dimensional exergy destruction rate arises for a given P, rate of temperature change, or Pr when the Re is raised. The knowledge gathered from this research could provide a theoretical foundation for reducing energy consumption and boosting productivity during autoclave curing.