Fin Tubes----High-frequency welded finned tubes analysis
High-frequency welding spiral finned tubes (hereinafter referred to as finned tube) was developed in the early 1950s connecting pipes, profiles and materials such as a highly efficient welding method, based on the progressive development in the 1970s and 1980s came a mature kind of welding methods. Since the early 1980s, Maoming Petrochemical Machinery Factory on the development and production of finned tubes, finned tubes with production technology and production equipment and technology continues to improve, the production of more and more types of finned tubes. Whether from the product range, quality, or in the production capacity, have reached the leading domestic level. While the tensile strength of welded joints and welding the rates and other important quality indicators have reached or exceeded domestic "high-frequency electric resistance welded spiral fin tube technology" and foreign (API standard) professional standards, has become such equipment manufacturing base.
1.1 Basic principles of finned tubes are seamless steel pipe at a certain pitch on the outer wrapping strip (strip perpendicular to the pipe outer surface) to high-frequency current for welding heat source, the use of high frequency current skin effect and electric effect, local heating tube and the steel strip and the contact surface area to be welded, the contact surface can be welded plastically state, while the fin forging force is applied to the outside of the contact of the metal oxide, and the excess part of the melt plastic form metal extrusion, between the steel pipe and fin material to achieve a combination of solid atoms, in order to achieve the contact surface of the plastic welding, as shown in Figure 1. We can produce spiral finned tube can be welded steel pipe diameter (mm) Φ25 ~ Φ168 weldable steel Thickness (mm) 2 ~ 10 can be welded pipe length (m) 0.5 ~ 15 can be welded fin width (mm) 13 ~ 30 can be welding fin thickness (mm) 0.8 ~ 2.5 fin spacing (mm) 4 ~ 90 typical spiral fin tube welding equipment performance parameters: Φ25 steel finned tube thickness (mm) 2-3 weldable pipe length (m) 0.5 ~ 15 can be welded fin width (mm) 10 ~ 15 can be welded fin thickness (mm) 0.8 ~ 2.5 fin spacing (mm) 4 ~ 10
Frequency welded finned tubes disadvantages advantages:
1, due to the high frequency current generated heat, the fins and the material of the base pipe together at the contact, so that the fin - base tube connected, even lower than the thermal contact resistance and rolling fin-tube expander, far below the wound piece tube.
2, the overall strength, easy to clean, can withstand 100 kg pressure cleaning, no deformation.
3, can be achieved stainless steel base pipe - stainless steel fins, carbon steel base pipe - steel fins, carbon steel base pipe - stainless steel fins welded.
Frequency welded finned tubes' disadvantages:
1, due process limitations, fin spacing, minimum spacing 4mm, fin height up to 55mm, generally cooler aluminum fins fin spacing is 2.3mm, 57mm fin height, so the wings of the ratio is low, only the largest 13, the normal rolled sheet or film is bulge 23, meaning that the same area of the base pipe, finned aluminum fin small area only around 55% z, the heat transfer is limited.
2, the fins of steel or stainless steel sheet, thick sheet, the thinnest 0.8mm, and the aluminum is about 0.3 ~ 0.45mm, fin heat efficiency is poor, and if the stainless steel fins, stainless steel heat exchanger efficiency worse as (pass Thermal efficiency is only 65% of aluminum), the low heat transfer efficiency.
3, high-frequency welding finned, although the contact resistance is small, but the fin area is limited, poor heat transfer fin thickness, therefore, the overall thermal efficiency of the finned tube is not high. Except for some special process, in general, use less.
Frequency welded finned tubes' applications:
1, based on the above description, for use in high-frequency welding finned cooler is inappropriate, unless the temperature is higher than 500 ℃ situation.
2, but because of its antiseptic better, such as stainless steel fin - stainless steel base pipe, the methanol synthesis evaporative cooling applications can be used, however, the heat transfer efficiency is greatly reduced, and only about 45% of aluminum (area Only 60% of aluminum, the aluminum heat transfer efficiency is only 70% of the total effect of 0.6 × 0.7 = 0.45), so the water is poor. If you want a good antiseptic users, we can produce.
Key Words: Finned Tube, Fin Tubes, Extruded Fin Tubes, Embedded Fin Tube, L Fin tube, Tubos Aletados