| 摘要 |
PURPOSE:To make a quite large cooperative area multiplicity through bags and fins by a method wherein non-continous and fine fins are formed longitudinally or angularly of the bags at either one of inner and outer surfaces of the bags or one of the inner and outer surfaces. CONSTITUTION:Saw-teeth are formed at inner and outer surfaces of a pipe having fins, the area of either one of the inner and outer fins of each of layers is enlarged by several multiplicity, the total thermal conducting area is made to have about ten times of a cylindrical surface equal to the outer diameter of an outer pipe 1 under an accumulative effect with an enlarged area of fins so as to improve performance and reduce cost. Longitudinal directions of fins F having saw-teeth therein may be in parallel with an axis of the pipe and a slight angle may be applied to the pipe. In any way, the length of these fins is made short, thereby an interface layer is prevented from being formed at the surfaces of the blades so as to improve the thermal conductivity. Means for forming saw-teeth is not varied more as compared with that of a file and so they may be strike cut with a blade, etc. In order to improve the efficiency of fins, the material is preferably aluminum, copper or copper alloy or titanium.
|
