Fin Tube

Increase Heat Transfer Rate:

A finned tube exchanger typically has tubes with fins attached to the outside. Usually, there will be some liquid flowing through the inside of the tubes and air or some other gas flowing outside the tubes, where the additional heat transfer surface area due to the finned tube increases the heat transfer rate. In a crossflow fin tube exchanger, the fins will typically be radial fins and they’ll either be circular or square in shape.

Improve Heat Transfer Coefficient:

By not using a finned tube, the outside surface area is not significantly greater than the inside surface area. Because of this, the fluid with the lowest heat transfer coefficient will dictate the overall heat transfer rate. When the heat transfer coefficient of the fluid inside the tube is several times larger than that of the fluid outside the tube, the overall heat transfer rate can be greatly improved by increasing the outside surface area of the tube.

Increase Outside Surface Area:

By having a finned tube in place, it increases the overall heat transfer rate. Finned tubes increase the outside surface area. This decreases the total number of tubes required for a given application which then also reduces overall equipment size and can in the long-run decrease the cost of the project.

Finned tube heat exchangers are used in a variety of applications, and more so as industrial heat exchangers. An air heat exchanger like the evaporator coil in an air conditioning unit is typically a fin tube exchanger. Another common fin tube air heat exchanger is the car radiator. The purpose of the car radiator is to cool the hot water in the tubes with the air passing through the crossflow. On the contrary, the air conditioner evaporator coil has the purpose of cooling the air passing through it. The finned tubes that are manufactured at Kainon Boilers, use high grade carbon steel, stainless steel, copper, brass, and aluminum. Our finned tube exchangers are designed to meet the specific duty condition, temperature and pressure of the fluids.

Carbon steel fins are available on carbon, stainless steel, or copper tube. Please call for a specific size if not listed

Type	Description	Base tube	Fin specification (mm)
		O.D. (mm)	Fin pitch	Fin height	Fin thick
Embedded	G-type fin tueb	16-63	2.1-5	<17	~0.4
Extruded	Single metal combined metal	8-51	1.6-10	<17	0.2-0.4
	Low fin tube t-type fin tube	10-38	0.6-2	<1.6	~0.3
	Bamboo tube corrugated tube	16-51	8-30	<2.5	/
Wound	l/kl/ll type fin tube	16-63	2.1-5	<17	~0.4
String	String fin tube	25-38	2.1-3.5	<20	0.2-0.5
U-type	U-type tube	16-38	/	/	/
Welding	HF-welding fin tube	16-219	3-25	5-30	0.8-3
	H/HH type fin tube	25-63	8-30	<200	1.5-3.5
	Studed fin tube	25-219	8-30	5-35	φ5-20

Carbon steel fins are available on carbon, stainless steel, or copper tube. Please call for a specific size if not listed

Classification

Specific classification of finned tubes, there are lot of types of finned tubes, meanwhile also lot of new species comes up.

According to the classification process

1. rolling forming finned tubes (extruded fin tube);
2. welded finned tubes ( high frequency welded finned tubessubmerged arc welded finned tubes,
3. roll forming finned tube
4. set forming finned tube
5. casting finned tube
6. the tension wound finned tubes
7. inserts the tube .

According to the fin shape classification

1. square fin tube (Square finned tube);
2. round finned tube
3. spiral finned tube (spiral finned tube);
4. the vertical fin tube (Longitudinal Finned Tube)
5. corrugated fin tube
6. serrated spiral finned tubes (Helical Serrated Finned Tubes);
7. the needle finned tube
8. the overall plate- fin tube ( plate-fin,
9. the finned tube (inner finned tube).

And so on.

Depending on whether the finned tubes finned tube material and the same material can be divided into groups :

1. a single metal finned tube
2. bi-metal composite finned tube

A single metal finned tube Material Classification

1. copper finned tubes
2. aluminum finned tube
3. carbon steel finned tube
4. stainless steel finned tube
5. iron ( steel, finned tube etc. .

By use classification

1. air conditioning with finned tubes
2. air-cooled with finned tubes
3. the boiler : finned water wall economizerair preheater tubes were used
4. industrial waste heat recovery with finned tubes
5. other special purpose finned tube etc.

The material certificate including all the tests can be provided, and also with EN10204 3.1standard.

Technology

It is fabricated with a batch of single fins that were processed by the punch press and then manually or mechanically, with a certain distance (wingspan) on the base tube.

This is the earliest fin tube fabrication with low cost and simple production process/ technology, easy to maintain. Divides into manual set and mechanical set. Manual set uses a tool that relies on the power of man to press the fins one by one. This method is limited by the pressure of the fin, so it is easy to get loose. The machine – set fin is carried on the wing piece machine. Due to the mechanical impact or liquid pressure, the pressure of the fin is high, so it can be used in a larger volume. The bonding strength between fin and tube is high and not easy to loosen. Mechanical transmission has high productivity, but the noise is large, the safety is poor, and the working conditions of the workers are not good. Although the hydraulic transmission does not have the above problem, but the equipment price is more expensive, the technical requirement to use maintenance personnel is higher, its productivity is also lower.

Currently HF Fin Tube is one of the most widely used helical fin tubes, you can see it as waste heat recovery in power, metallurgy, concrete, oil and gas, petrochemical, etc. When winding the steel strip around steel tube, the use of high frequency current skin effect and proximity effect on steel strip and steel pipe surface heating, until the plastic state or melt, the coil steel belt must be under pressure to complete welding. Comparing with embedded type and spot welding spiral crimped type, it is more advanced either on fin tube quality or production efficiency or automation degree.

The extruded fin is formed from an outer aluminum tube with a large wall thickness (muff), which is aligned over an inner base tube. The two tubes are pushed through three arbors with rotating discs that literally squeeze or extrude the aluminum fins up and out of the muff material in a spiral shape in one operation. Comparing with welding fin tube, dr extruded fin has higher production efficiency with low cost on material and high heat transfer. At present, it divides into copper or aluminum single metal fin tube and bi-metal composited fin tube.

Fin tube manufacturers produce a wide range of fin tubes. They are used in heat exchangers (air, water and chemically cooled) for various industries such as petroleum, petrochemical, steel, power generation and many more.

Corrosion protection processes are performed during fin tube manufacturing and the material used is corrosion resistant. Some fin tube types are:

Helical high fins

Helical high finned tubes are used to repair air-cooled heat exchangers and are available in 5 variations

Helical high fins

Helical high finned tubes are used to repair air-cooled heat exchangers and are available in 5 variations

Type	Photo	Descriptions	Properties
"KL" fin tubes		After application the fin foot is knurled into the corresponding knurling on the base tube thereby enhancing the bond between the fin and tube resulting in improved heat transfer characteristics. Max. operating. temp. 260ºC	Max working temperature – 260 °C (500 °F) Atmospheric corrosion resistance – acceptable Mechanical resistance – acceptable Fin material – aluminum, copper
"G" fin tubes		Fin strip is wound & embedded on a groove and securely locked by closing the groove with the base tube metal. This ensures maximum heat transfer at high temperatures. Max. operating temp. 450ºC	Max working temperature – 400 °C (752 °F) Atmospheric corrosion resistance – poor Mechanical resistance – acceptable Fin material – aluminum, copper, carbon steel
"LL" fin tubes		Manufactured in the same way as the ‘L’ fin type except that the fin foot is overlapped to completely enclose the base tube thereby giving excellent corrosion resistance. This type of tube is often used as an alternative to the more expensive extruded type fin in corrosive environments. Max. operating. temp. 180ºC	Max working temperature – 180 °C (356 °F) Atmospheric corrosion resistance – acceptable Mechanical resistance – poor Fin material – aluminum, copper
“L” fin tubes		The strip material is subjected to controlled deformation under tension giving the optimum contact pressure of the foot of the fin onto the base tube thus maximizing the heat transfer properties. The foot of the fin considerably enhances the corrosion protection of the base tube. Max. operating. temp. 150ºC	Max working temperature – 150 °C (302 °F) Atmospheric corrosion resistance – acceptable Mechanical resistance – poor Fin material – aluminum, copper
Extruded fin tubes		This fin type is formed from a bi-metallic tube consisting of an aluminium outer tube and an inner tube of almost any material. The fin is formed by rolling material from the outside of the exterior tube to give an integral fin with excellent heat transfer properties and longevity. Extruded fin offers excellent corrosion protection of the base tube. Max. operating. temp. 280ºC.	Max working temperature – 285 °C (545 °F) Atmospheric corrosion resistance – excellent Mechanical resistance – excellent Fin material – aluminum