Finned tube is a kind of heat exchange element. In order to improve the heat exchange efficiency, fins are usually added to the surface of the heat exchange tube to increase the external surface area (or internal surface area) of the heat exchange tube to achieve the purpose of improving the heat exchange efficiency. Such a heat exchange tube.
The outer surface of the fin tube is covered with small fins. The role of these fins is to act as a transfer process and filter. Heat transfer is usually from the inside to the outside and then in the reverse direction.
G type fin tube, also known as embedded finned tube, where g means slotted. It is formed by screwing fin strips made of copper or aluminum into machined grooves and backfilling to secure the lock. Fill the base tube material. Compared with other finned tubes, G type fin tubes are firmer. Therefore, it is widely used in places where high-temperature heat transfer is required.
The G type fin tube is a circumferential finned tube in which the fin is mechanically embedded in the groove, the groove is plowed into the tube, and the roller is locked in place, thereby forcing the groove to tightly surround the fin base.
The aluminum fin strip is wound and embedded in the groove, and is firmly locked by closing the groove with the bottom tube metal. This ensures maximum heat transfer at high temperatures.
The maximum operating temperature of G fins is 450 degrees Celsius. Commonly used heat sink materials are aluminum (or) copper, pipes-carbon steel, stainless steel, copper, copper alloys, etc.
G type fin tube manufactruring process
Specifically, the G type fin tube is a spiral groove with a certain width and depth that is pre-processed on the steel tube, and then the aluminum strip is inlaid on the steel tube on the equipment. During the winding process, due to a certain pre-tightening force, the steel strip will be tightly pinched in the spiral groove, thus ensuring a certain contact area between the steel strip and the steel pipe.
In order to prevent the steel strip from rebounding and falling off, both ends of the steel strip should be welded to the steel pipe. In order to facilitate the inlay, there should be a certain backlash between the steel strip and the spiral groove. If the backlash is too small to form an interference, the inlay process is difficult to proceed smoothly.
In addition, the wound steel belt will always have a certain rebound, as a result, the steel belt and the bottom surface of the spiral groove cannot be well joined. Inlay fins can be carried out on general equipment, and the cost is not high.
G type fin tube processing requirements
Embedded depth and stability
1.1 Pull-off force test: more than 8kg or the aluminum strip is torn
1.2 Mosaic depth: 0.35~0.5 according to the wall thickness of the furnace tube
1.3 Mounting stability: the first pull-off test specimen of each class meets the requirements of 1.1
1.4 The embedded tube is made of stainless steel and carbon steel, and the wall thickness of the pipe shall not be less than 2mm
1.5 The diameter of the inlaid pipe is dn20~38 (the British American standard is based on 1.5 requirements)
1.6 No cracks or cracks on the surface of the pipe after inlay
1.7 The height of the inlaid piece is calculated based on the diameter of the pipe-generally half of the diameter of the pipe, but not higher than 57 plus or minus
G type fin tube product size accuracy
2.1 The overall length of the wing segment -5mm ~ +5mm, segmental motion accuracy -0.3mm ~ +0.4mm
2.2 Film pitch +0.21mm or more
2.3 Verticality of fin and steel pipe -1 degree ~ +1 degree
2.4 Mounting flatness -0.1mm ~ +0.1mm except for the height difference caused by the thickness tolerance of the fin itself
2.5 Mounting height difference -0.1mm ~ +0.1mm Except for height difference caused by fin size tolerance
2.6 Under the same steel tube material, the same spacing and number of fins, the length of the different fin tubes after inlaying is the same.
