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Knowledge about fin tube fins

Why use aluminum fins?

There are various materials according to the application and operation of the heat exchange.

Common ones are aluminum, alloys, copper, brass, nickel, titanium, stainless steel, carbon steel, etc. Among them, aluminum and alloys are the most commonly used.

The basic performance of finned tube heat exchange should have good welding ability and forming ability, high mechanical strength, good corrosion resistance and thermal conductivity. Nevertheless, aluminum and alloys are also ductile, and their tensile strength increases at lower temperatures. They are widely used all over the world, especially in low temperature and compact heat exchange.

Let’s take a look at the characteristics of aluminum

1. Low density

Through alloying and heat treatment, the structure of building steel can be achieved. It is suitable for all kinds of transportation, especially small vehicles, which reduces weight and consumption.

2. Good corrosion resistance

Under harsh conditions, aluminum oxides are non-toxic. Using aluminum for heat exchange, there is no need to worry about oxides destroying the air or liquid inside for a long time.

3. Good thermal conductivity,

Especially suitable for heat sinks, heat transfer evaporators and condensers. To

4. High yield and die cutting resistance.

It is easy to process and shape.

As a professional finned tube manufacturer, our leading product is aluminum finned tube. If you have any interest, please contact us for more information.

The ratio of fin tube is affected by fin height, fin thickness and fin spacing.

When the root of the fin is exposed on the base bare tube, if heat is transferred from the inside to the outside, the heat will be transferred from the root of the fin along the height of the fin. It is also continuously transferred to the surrounding fluid through convective heat transfer. 

As a result, the temperature of the fin gradually decreases along the height. This also shows that the difference between the temperature of the fin and the temperature of the ambient fluid is gradually decreasing, and the change in heat per unit is shrinking. Therefore, the effect of the fin surface area on the enhanced heat transfer is diminishing. The higher the fin, the smaller the contribution of the increased area to the heat exchange.

Murphy G type fin tube

Fin height

Generally speaking, for high-frequency welded finned tubes used in engineering projects, when the fin height is 15mm, the fin efficiency is about 0.8. When the fin height is 20mm, the fin efficiency drops to 0.7. 

 

Based on this, the optimal height is 15mm. If the fin height exceeds 20mm, the fin efficiency will be poor, so it is generally not used. However, for the aluminum fins on the air cooler, since the thermal conductivity of aluminum is much better than that of carbon steel, the height of 22-25mm is always used.

 

How will the fin spacing affect the fin ratio?

 

Usually a smaller pitch can effectively increase the fin ratio. When considering the nature of the flowing gas and the ash deposition, the following factors should be noted.

 

A. Severe heavy ash deposition

 

For example, the exhaust of electric furnaces and converters in steel plants and industrial kilns has high ash content. If finned tubes are used for heat exchange, a larger fin pitch is recommended. For example, if the pitch is greater than 10mm, you need to increase the air discharge and choose a blower.

 

B. Attention should be paid to occasions with little ash.

 

Take the exhaust of factory boilers and industrial boilers as an example. A fin pitch of 8mm is appropriate, but it should be designed to have self-blowing capability.

 

C. Dust-free or lightly dusty occasions.

 

For example, the exhaust from natural gas burning equipment or air cooler, the fin spacing is 4-6mm. For aluminum air coolers, 3mm is also selected as the fin pitch.

 

Fin thickness

The choice of the thickness of the heat sink depends on the corrosion and wear of the fluid gas. Under normal circumstances, thicker heat sinks will be used in severely corroded sites.

 

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