L Type Finned Tube is a finned tube made of aluminum fin tape or copper fin tape folded into an L-shaped spiral under tension and wrapped tightly around the outer surface of the base tube.

L Type Finned Tube is a finned tube made of aluminum fin tape or copper fin tape folded into an L-shaped spiral under tension and wrapped tightly around the outer surface of the base tube.

The tension in the fin strips of the L Type Finned Tube wraps around the tube, causing the fin feet to press forcefully against the tube, holding the fins firmly in place. L Type Finned Tube is usually used in air coolers in petrochemical, power, paper, tobacco, building heating and other industries as well as heat exchangers in power plants (electricity, nuclear, thermal and geothermal power plants), the maximum operating temperature can reach 230°C.

L Type Finned Tube for Heat Exchanger Quick Details:

Fin type: Solid plain
Fin Tube Type:L Type
Outer diameter (OD): 16mm Min~50.8mm max.
Tube length: up to 18,000 mm.
Fin height: 16.5mm max.
Fin thickness: generally 0.4mm~0.6mm
Fin pitch: 2.1mm minimum (12FPI)
Surface Protection: Both bare ends shall be zinc or aluminum metallized by electrospray arc system coating.
Accessories: Tube support boxes, clamps or spacer boxes (materials: aluminium, zinc and stainless steel).

Features of L Type Finned Tube

1. The trapezoidal section formed by the calendering of L Type Finned Tube for heat exchanger is consistent with the distribution of heat flow density, the tubes are tightly combined, and the thermal efficiency is high, which eliminates the contact heat caused by the gap between the tubes and the finned tube. resistance, the fin spacing is uniform, and the heat transfer performance is good.
2. The tube can withstand temperatures up to 150°C and there is no risk of atmospheric corrosion or thermal stress.
3. The L-type finned tube provides the contact area between the fin strip and the surface of the tube to protect the tube wall from atmospheric corrosion.
4. This L TYPE design is much more economical than LL, KL or even G-embedded types.
5. Maximum operating temperature: 230°C

Application of L Type Finned Tube

1. Highly corrosive systems (condenser, evaporator, desalination, fertilization, urea system, ammonia, gas, corrosive acid);
2. Air coolers in petrochemical, electric power, paper, tobacco, building heating and other industries;
3. Air heaters and air heaters for spray drying systems such as vegetable protein powder and starch in the food industry;
4. Heat exchanger installations in power plants (electrical, nuclear, thermal and geothermal power plants).

Struction

Why L-Type Finned tubes?

L-Type finned tubes are one of specific types of finned tubes that feature a unique L-shaped fin design. The fins are attached to the outer surface of the tube, forming a series of continuous L-shaped profiles along the length of the tube.

The L-Type finned tubes find application in various industries, including power generation, petrochemical, and HVAC systems. They are commonly used in heat exchangers, air coolers, and condensers, where efficient heat transfer is essential.

The specific design and dimensions of L-Type finned tubes can vary based on the requirements of the application. Factors such as the fluid characteristics, operating temperature, and pressure conditions influence the selection of materials, fin geometry, and fin spacing to optimize heat transfer performance.

Advantages

Transferring heat from a hot fluid into a colder fluid through a tube wall is the reason many of us use finned tubes.

But you may ask, what is the major advantage of using a finned tube? Why can’t you just use a regular tube to make this transfer? Well you can but the rate will be much slower.

By not using a finned tube the outside surface area is not significantly greater than the inside surface area. Because of that, 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.

Finned tubes increase outside the surface area. By having a finned tube in place, it increases the overall heat transfer rate. This then 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. In many application cases, one finned tube replaces six or more bare tubes at less than 1/3 the cost and 1/4 the volume.

For applications that involve the transfer of heat from a hot fluid to a colder fluid through a tube wall, fin tubes are used. Usually, for an air heat exchanger, where one of the fluids is air or some other gas, the air side heat transfer coefficient will be much lower, so additional heat transfer surface area or a fin tube exchanger is very useful. The overall pattern flow of a finned tube exchanger is often crossflow, however, it can also be parallel flow or counterflow.

Fins are used to increase the effective surface area of heat exchanger tubing. Furthermore, finned tubes are used when the heat transfer coefficient on the outside of the tubes is appreciably lower than that on the inside. In other words, heat transferred from liquid to gas, vapor to gas, such as steam to air heat exchanger, and thermic fluid to air heat exchanger.

The rate at which such heat transfer can occur depends on three factors – [1] the temperature difference between the two fluids; [2] the heat transfer coefficient between each of the fluids and the tube wall; and [3] the surface area to which each fluid is exposed.

Finned tubes are used because they help

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.

Reference

What are fin tubes for boiler?

Fin tube boilers represent one of a number of pressurized equipment options used to heat water or convert water into steam under controlled conditions. As in a water tube boiler, water passes through boiler tubes while combustion gases remain in the shell side, passing over the tube surfaces.

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

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

Uncovered tube area between the fins

Fin foot is pre-formed into an LL shape (overlapped LL) and applied to base tube under tension. However, foot is pre-shaped to give overlap of one foot onto another, thereby improving base tube protection and thermal contact area Fin materials: Aluminum Base tube materials: Any metallic material. The smooth flat fins perpendicular to the tube surface give rise to very low resistance to air /gas flow and ensure that fouling is kept to a minimum. The foot of the fin is in contact with base tube and provides a complete sheathing over the finned length.

The Overlapped “L” fin design has interlocking fins that are wound together to prevent movement and separation. The fin protects the entire tubes, so the designation works well for the applications where corrosion is a factor.This type of finned tube is often used as an alternative to the more expensive extruded type fin in corrosive environments.

• Common Applications: Steam Coils, Air Pre-heaters.
• Max. Working Temperature: 180 °C
• Atmospheric Corrosion Resistance: OK
• Mechanical Resistance: Poor
• Fin Material: Copper, Aluminum
• Base Tube materials: Any material available, such as Carbon steel Tube, A179, A192, A210, stainless tube A269/A213 T5 T11 T22 304 316

What are fin tubes?

Fin tubes are a type of heat exchanger that is used in many different industries. These tubes have a finned surface, which increases their surface area and allows them to transfer heat more efficiently. This makes them ideal for applications where high heat transfer rates are required, such as in power plants and refrigeration systems.

Fin tubes are made from a variety of materials, including copper, aluminum, and stainless steel. They are available in a range of sizes and shapes and can be customized to meet the specific needs of each application.

One of the key benefits of fin tubes is their ability to operate efficiently at high temperatures and pressures. This makes them suitable for use in a wide range of applications, including air conditioning, heat exchangers, and radiators.

In addition to their high thermal performance, fin tubes are also durable and long-lasting. They are resistant to corrosion and can withstand the harsh environments often found in industrial settings. This makes them a cost-effective solution for many different industries.

Delivery

Inspection

The first actual inspection work on the fin tube heat exchanger is the raw materials inspection. Based on the ASME Code, providing material test reports for fin tube heat exchanger plates is mandatory. For other components, the marking inspection will be enough.

Packing

The Finned Tube is exposed to the outside to prevent rainwater from falling, try to keep it dry, and it should not be too close to the ground to prevent the irrigation in the greenhouse from corroding the finned tube. After the maintenance of the finned tube, the service life of the finned tube will be greatly increased.

Wooden cases

Well packing