| 摘要 |
<p>Heat exchanger tubes have fins shaped from the tube body on opposing sides along its axis, the whole forming an integral appts. component. Fins are approximately tongue shaped with their base remaining part of the tube body, from which they are bent up at approximately right angles. Their surfaces facing into the bending direction have a thickened portion below their tips, and are rougher than those opposite, so representing a larger heat exchanging area. These faces are made to front the gaseous medium stream by twisting uniformly along their axis their upper portions and tips w.r.t. their base by up to 90 degrees. A long rectangular block pierced by a series of parallel channels may be used with the fins shaped upon it side by side in line with the channels and sepd. by rectangular grooves, the whole resembling a (double-sided) harrow in external appearance. Working from one tube ends towards the other, such fins are formed one at a time by limited length cuts, first at a relatively steep, then at a shallower angle into the tube body. This operation together with the bending over produces automatically the inner "rougher" surface with its thickened ridge.</p> |
