Japanese Patent Application Laid-open No. 58-48076 discloses a Rankine cycle system comprising a vane-type expander. This converts the pressure energy of high temperature high pressure vapor generated in a vaporizer employing a gas burner as a heat source into mechanical energy via a vane-type expander, and the vapor thereby generated, whose temperature and pressure have decreased, is condensed in a condenser and then returned to the vaporizer via a water supply pump.
As shown in FIGS. 9A to 9C, a condenser that condenses and coverts a gas phase medium into a liquid phase medium generally comprises a large number of cooling fins 01 that are stacked with gaps through which a cooling medium can pass, and a large number of cooling pipes 02 that run vertically through these cooling fins 01, the gas phase medium supplied from the upper end of the cooling pipe 02 being drained of heat by the cooling fins 01, so as to condense into the liquid phase medium while passing through the interior of the cooling pipe 02, and dripping from the lower end of the cooling pipe 02.
In order to reduce the dimensions of the condenser for condensing and converting a gas phase medium into a liquid phase medium and maintain a high level of heat exchange per unit volume with the gas phase medium, it is necessary to reduce the diameter of the cooling pipe 02, but when the cooling pipe 02 is narrow, it is easy for a droplet D that has been formed into a sphere from the liquid phase medium due to surface tension to reside in the lower end of the cooling pipe 02 under the influence of the surface tension and it becomes difficult for it to drop. When the lower end of the cooling pipe 02 is blocked in this way by the droplet D, it becomes difficult for the gas phase medium to flow through the interior of the cooling pipe 02, thus greatly degrading the performance of the condenser, and it is therefore necessary to remove by some means the droplet D residing in the lower end of the cooling pipe 02.