Convective dropwise condensation out of humid air inside a horizontal channel - Experimental investigation of the condensate heat transfer resistance

摘要

A new facility feasible for the investigation of dropwise condensation at a vertical polymer surface (9 x 6 mm, L x H) is described in detail. The droplets are liquefied out of humid air, which flows through a rectangular channel (12 x 32 mm, W x H) and passes the sub-cooled surface of a sensor. The latter one is flush mounted into one of the vertical channel walls beyond a hydrodynamic entry length of 550 mm determining perpendicular heat fluxes by measuring temperature differences. Furthermore the droplet covered surface is observed through the opposite channel wall by an infrared camera. The variable experimental parameters include temperature, water content and flow velocity of the humid air, as well as the surface temperature of the sensor.