High frequency welded finned tube and integral finned tube are one kind of finned tube. Although their functions are similar, they are different in appearance and performance characteristics. So they are suitable for different occasions. Today, China finned tube network will introduce the shortcomings of high frequency welded finned tube and the advantages of integral finned tube. As follows.
1. disadvantages of high frequency welded finned tubes
(1) Due to technological limitations, the fin spacing is large, the minimum spacing is 4 mm, the fin height is the highest 55 mm, the general air cooler aluminum fin is 2.3 mm, the fin spacing is 57 mm, so the finning ratio is low, the maximum is only about 13, the normal rolled or expanded fin is about 23, that is to say, the same base tube area, the fin area is only 55% smaller than the aluminum fin. The heat transfer effect is limited.
(2) The fins are made of steel or stainless steel. The fins are thicker and the thinnest is 0.8mm, while the aluminium fins are about 0.3-0.45mm. The thermal efficiency of the fins is poor. If the fins are made of stainless steel, the heat transfer efficiency of stainless steel fins is lower because the heat transfer efficiency of stainless steel fins is worse.
(3) Although the contact thermal resistance of high frequency welded fins is small, the fin area is limited and the fin thickness and heat transfer are poor. Therefore, the overall thermal efficiency of finned tubes is not high. In addition to some special processes, they are generally used less.
(4) Based on the above introduction, it is inappropriate for high frequency welded finned tubes to be used in air coolers unless the temperature is higher than 500 C. However, based on its good anti-corrosion, such as stainless steel fin-stainless steel base tube, it can be used in methanol synthesis evaporative cooling. However, its heat transfer efficiency is greatly reduced, only about 45% of the aluminium sheet, so its water-saving effect is poor.
2. advantages of integral fin tube
(1) the heat transfer effect can be expanded.
(2) wear resistance
Because the integral fin tube fin and the tube are formed as one body, the crystal structure is consistent, the performance is stable, and the fin is dune-shaped, which is consistent with the temperature gradient shape when heated. When heated, the outer surface temperature of the fin is the same, the thermal stress is uniform, there will be no concentration, and there will be no strength weakness. In addition, the fin is similar to the temperature gradient shape when heated. It can divert the flue gas. At the same time, it can make the flue gas index more uniform. It will not produce flue gas deviation, and it will not cause the flue gas to concentrate on scouring a certain area or a certain part, so it is more wear-resistant.
(3) not accumulating ash
The reason of ash accumulation is caused by Carmen eddy current: when the smoke flows through the pipe, a negative pressure zone will be formed on the back of the pipe. In this area, the smoke velocity is zero or even reflux, where the smoke accumulates and the ash is attached to the surface of the pipe. Greater thermal resistance of ash, thicker ash accumulation, greater thermal resistance, less heat transfer, higher exhaust temperature, and lower boiler efficiency. The finned tube's diversion to the flue gas overcomes the Karman eddy current, and combs the ash distribution to make it distribute evenly in the flue gas.
(4) stable heat transfer performance
As a heating surface, the flue gas temperature fluctuates little during many years of operation, and no tube burst of economizer occurs.
(5) long service life
Under the same running condition, the life of the finned tube is 2 times higher than that of the light tube. Generally speaking, the life span of light tube is 3 to 4 years, and the life of finned tube is at least 7 to 8 years. 辛苦整理.转载请注明http://www.wxsxsjx.com
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