| 摘要 |
In a heat exchanger, the flowing fluid is caused to impinge vigorously against the heat conducting walls, for the purpose of improving heat transfer efficiency. Disclosed is an apparatus for and a method of making a twisted plastic ribbon that fits snugly in the tubes of the heat exchanger, and which imparts a helical swirling velocity to the fluid flowing through the tube. Efficiency is enhanced so economically that it becomes practical to make an automative radiator from round aluminum tubes, provided they are fitted with the twisted plastic ribbons; aluminum being a much cheaper material then the traditional copper. The apparatus includes two sets (55, 58) of traction rollers for conveying the ribbon from the extruder. One set of roller rotates to important the required helical twist. The ribbon is heated (56) to above its critical temperature so that the twist shaped becomes permanent. The ribbon is cooled (by quenching it in water (54, 57)) to give it the strength it needs to enter the respective sets of rollers. This apparatus allows the twisted ribbon to be produced on a continuous-production basis. |
