Design Of U-Air Duct Combined Condenser With Air Inducing And Experiment On Heat Transfer Outside Evaporation Tube

The current study proposed a new U- air duct combined condenser. The fan and its electric machinery inside the device was below the finned-tube bundle, and it induced air for water evaporation while blasting air for cooling fin, thus forming a U air duct. The flowing direction of air in water evaporation was similar to leached water in that they both flew from top to bottom in which way the flow of water film could be enhanced, the thickness of water film would be reduced, and the heat transfer of water film shall be strengthened. Moreover, this design also avoided the dry points resulting from the the up flow of air in the bottom of the tube.The fan below the finned tube bundle could eluded the inefficiency of lubrication heating of the electric machinery deriving from the excessively high air temperature when the fan was on the top, and omitted the air short cut or leak when the belt went through the air duct. Based on the field observation of U- air duct condenser, a new U- air duct blast combined condenser was designed under given technical conditions. Air quantity and sprinkling rate were two major operational parameters of combined air cooler and water film evaporation air cooler. Therefore, the present study also experimented on the impact of air quantity on water film evaporation heat transfer and the changes of thickness of out-tube water film under small density of sprinkling rate.On the water evaporation air cooling test bed, 5 head-on air speed was chosen to investigate the impact of head-on sir speed on heat transfer of water evaporation. It was demonstrated that head-on air speed significantly influenced extra-tubal average coefficient of heat transfer, and that the change of extra-tubal average coefficient of heat transfer was relatively complicated depending on the combined functions of sensible heat and latent heat in this working situation.On the test bed of measuring the thickness of horizontal pipe water film, regulations on the changes of thickness of extra-tubal water film as the variations of the pipe diameter, sprinkle density and toroidal angle were researched. The experiment indicated that when the pipe diameter and sprinkle density were certain, water film would turned thin first and become thick later as water film flowing toroidal angle enlarged; and that the most thin part of water film occurred after the 90° toroidal angle; and that when sprinkle density and toroidal angle are certain, the lager the pipe diameter was, the thicker of the water film would become.