Studies on condensation heat transfer in two-phase closed thermosyphons

The effects of shear stress acting on liquid vapor interface at the condenser of two phase closed thermosyphons were studied. An analysis based on Nusselt's theory of filmwise condensation and heat transfer experiments was conducted. The analysis shows that interfacial shear stress caused by rising vapor makes condensate film thicker and condensation heat transfer coefficient and heat transfer rate decreased. Heat transfer rates increase and became large than analytical results. Flow situations inside the thermosyphon are observed using a glass thermosyphon.