Vacuum Web Coating Drum with Phase-Change Cooling

The patent applies phase transitions of a working fluid within the drum structure to achieve cooling. The fluid undergoes phase changes (liquid to vapor and back) to absorb and release heat, providing an efficient cooling mechanism without requiring complex external cooling systems. This resolves the contradiction by achieving high cooling efficiency through a self-contained phase change mechanism rather than complex external heat transfer systems.

The patent utilizes pneumatic principles by introducing a gas phase working fluid into the drum to facilitate heat transfer. The gas flow dynamics and pressure variations created by phase changes enable efficient heat removal from the web, achieving high heat transfer coefficients through fluid dynamics rather than complex mechanical cooling structures.

The patent introduces a working fluid as an intermediary heat transfer medium between the web and the cooling system. This fluid mediates heat transfer through phase changes, enabling efficient cooling in vacuum conditions where conventional convection and radiation are ineffective. The intermediary fluid bridge gaps the thermal coupling between the web and cooling mechanism.

The patent exploits phase transitions of the working fluid to achieve efficient heat transfer in vacuum. During evaporation, the fluid absorbs heat from the web; during condensation, it releases heat to the cooling system. This phase change mechanism provides high cooling efficiency without relying on vacuum-impaired convection or radiation processes.