1. Introduction

Heat transfer equipment must have adequate surface area for the thermal transfer duty.

But tubes on their own offer limited surface area on the outside of the tube.

An L Type Finned Tube features continuous fins that are wrapped around the outside diameter of the tube.

The fins create additional surface area that can participate in heat transfer.

As a result, engineers can use L type finned tubes to greatly increase heat transfer without needing a much larger tube.

The fin base will wrap around the tube in an L shaped pattern.

This design creates a practical mechanical attachment between the tube and the fin.

In addition, L type finned tubes allow for different tube and fin materials.

L type finned tubes see use in heat exchangers, air coolers, HVAC equipment, refrigeration applications, and many industrial thermal systems.

2. What Is an L Type Finned Tube?

An L type finned tube is a finned tube heat exchanger tube that uses a continuous L shaped fin.

The fin wraps continuously around the outside of the tube.

The base of the fin creates an L contact area against the surface of the tube.

As a result, the fin is mechanically attached to the tube surface.

Fins allow greater heat transfer surface area on the outside of the tube.

With more surface area available on the outside of the tube, more heat can be transferred to or from the surrounding fluid.

A common fin material is aluminum.

The tube can be comprised of carbon steel, stainless steel, copper, or another material.

Ultimately the material choice will depend on the specific temperature, corrosion, pressure, and thermal considerations.

L Type Fin Tube

3. How Does an L Type Finned Tube Work?

The heat transfer enhancement principle is the same as with other finned tubes.

Fluid enters the tube.

Heat is conducted through the tube wall.

Heat is transferred to the outside of the tube and into the fin.

Finally, heat is either taken in or dissipated by the surrounding air or fluid.

The fins add additional surface area.

As a result, the heat exchanger can achieve a greater amount of external heat transfer compared to an unfinned tube.

The contact area formed by the L- shaped fin also supports heat conduction from the tube to the fin.

Also, because the fin spirals continuously around the tube, the tube achieves a large and continuous heat transfer surface.

4. L Type Finned Tube Structure

Several characteristics define the construction of an L type finned tube.

4.1 Base Tube

The base tube is what carries the fluid inside the tube.

The material used for construction can vary. Some common options include:

• Carbon steel
• Stainless steel
• Copper
• Aluminum
• Nickel alloys

As a result, there are many options that allow designers to choose a material suitable for their application’s specific conditions.

4.2 L- Shaped Fin

The fin that is applied to the outside of the tube has a base that is L- shaped.

As the fin wraps around the tube, a continuous spiral fin is formed.

Therefore, the tube features increased surface area for the entire length.

4.3 Fin Pitch

Fin pitch refers to the distance between each individual turn of the fin.

Smaller pitches create more surface area.

However, if the fin density is too high, it can cause issues with flow resistance.

Therefore, the fin pitch must be optimized to provide the greatest benefit.

4.4 Fin Height

Fin height is how tall the fin is from the surface of the tube.

Taller fins create more surface area but they also increase the outside diameter of the finned tube.

As a result, the ideal fin height varies on a case by case basis depending on the equipment’s design.

4.5 Fin- to-Tube Contact

With an L- shaped base, the fin has actual mechanical contact with the tube.

This allows for the finned tube to both efficiently transfer heat and have structural stability.

5. L Type Finned Tube Manufacturing Process

Fin consistency and tube quality are determined by the manufacturing process.

As a result, proper equipment is necessary to ensure precision and consistency.

5.1 Tube Preparation

The base tube must first be prepared before finning begins.

Cleaning and dimension inspection of the tube surface must be conducted.

Doing so provides a stable surface to form the fins onto.

5.2 Fin Strip Preparation

Once the tube is prepared, the fin strip is fed into the production system.

While aluminum fins are commonly used, other materials can be used for specific applications.

5.3 Fin Strip Feeding

The fin strip is fed through the machine towards the tube by a fin feeding system.

The feeding system controls the speed at which the aluminum moves as well as the tension of the strip.

Consistent feeding allows for consistent fin pitch.

5.4 L Fin Forming

After feeding, the strip is formed into an L shape by forming tools.

Once formed, it will begin to wrap around the surface of the tube.

During this process, the machine controls the pitch of the fins and the tension of the feed fin strip.

5.5 Fin- to- Tube Attachment

Because the base of the fin is attached to the tube in an L- shape.

Not only does this create greater surface area, but it allows for heat conduction between the fin and tube.

Depending on the machine design, different methods can be used to create this mechanical attachment.

5.6 Final Inspection

The final step of the process is a dimensional inspection of the finished product.

Some key items that are checked during this process include:

• Fin height

• Fin pitch

• Fin thickness

• Tube diameter

• Fin outside diameter

• Tube length

• Fin attachment

By inspecting dimensions, manufacturers can ensure consistent quality from piece-to-piece.

Internal Link: Fin Tube Manufacturing Machine

6. Advantages of L Type Finned Tubes

Similar to all finned tubes, L type finned tubes have many benefits when compared to bare tubes.

6.1 Increased Heat Transfer Area

A continuous fin adds substantial surface area to the outside of the tube.

As a result, more heat can be transferred compared to a tube without fins.

6.2 Compact Design

Since L fins do not need to be extremely tall to create surface area enhancement.

Finned tubes can have a more compact design.

6.3 Good Fin Stability

The fin provides a mechanical stability on the wrapped portion due to its attachment to the tube.

Finned tubes should therefore have no issues with the fins falling off during normal operation.

6.4 Flexible Material Selection

Since the tube and fin can be made from different materials, there are many possible material combinations.

For instance, many industrial applications use aluminum fins with steel tubes.

As a result, designers have a lot of flexibility in their choice of materials.

6.5 Lightweight Fin Material

Typically, aluminum fins will be used.

Since aluminum is a light material, this allows finned tubes to have a lower weight.

As a result, the overall weight of heat exchanger equipment can be reduced.

6.6 Good Air- Side Performance

Since more surface area is added to the tube, heat transfer effectiveness is increased on the air side.

As a result, L type finned tubes are ideal for air cooled thermal equipment.

6.7 Practical Manufacturing

Due to the fact that mechanical finning is a well established method of adding fins to tubes.

Manufacturers are able to quickly produce long continuous sections of L type finned tubes.

7. L Type Finned Tube Materials

Like any thermally conducting tube, material selection is based off of the operating conditions.

As a result, it is important to evaluate what materials are used for both the tube and the fin separately.

7.1 Aluminum Fin

Aluminum fins are common due to their thermal conductivity and light weight.

Another benefit of aluminum fins is their corrosion resistance.

7.2 Carbon Steel Tube

Carbon steel offers good strength and affordability.

As a result, it works well for many heat transfer applications.

Bear in mind that some corrosion protection will be needed.

7.3 Stainless Steel Tube

Stainless steel offers excellent corrosion resistance.

As such, it can be used in chemical processing applications and other harsh environments.

7.4 Copper Tube

Due to copper’s thermal conductivity, it can be used for HVAC applications, refrigeration, and more heat transfer applications.

7.5 Steel Fin

Steel fins offer high mechanical performance.

As such, they can be used in applications with high temperature or mechanical requirements.

8 L Type Finned Tube Applications

L type finned tubes can be used for a variety of heat transfer applications.

Its fins connect continuously around the tube, increasing its outside surface area.

As a result, these finned tubes can enhance the performance of many air-side heat transfer applications.

8.1 Air Cooled Heat Exchangers

Heat rejection from air cooled heat exchangers relies on surface area.

L type finned tubes add surface area for air-side heat transfer to occur.

As a result, they can facilitate effective heat rejection.

Air Cooled Heat Exchanger

8.2 HVAC Systems

HVAC systems require heat transfer components that don’t take up too much space.

Not only can L type finned tubes be used in heating or cooling coils, but they can also benefit systems that use air as their heat transfer medium outside of the tubes.

8.3 Refrigeration Equipment

Refrigeration systems need to transfer heat quickly and effectively.

L type finned tubes allow for additional surface area to be applied to condenser and evaporator designs.

Keep in mind that material selection will play a key role due to the refrigerant and operating conditions.

8.4 Industrial Cooling

Industrial processes may require heat to continuously be removed from the system.

Both selected industrial cooling systems and compact equipment designs can benefit from the installation of L type finned tubes.

8.5 Oil and Gas

Heat exchangers are installed in oil and gas facilities to provide cooling or heat recovery from a process.

When the application calls for it, L type finned tubes can be used in these air-side applications.

Note that engineers should pay close attention to corrosion and temperature requirements.

8.6 Petrochemical Systems

Petrochemical applications typically face extreme conditions.

Because of this, proper tube material can play a role in reliability.

8.7 Power Generation

Heat exchangers are found throughout power generation in many stages of the process.

Like previous examples, L type finned tubes can be used where suitable in cooling and heat recovery applications.

9 L Type Finned Tube vs Other Finned Tubes

Fin type dictates many characteristics of the finned tube.

With that said, engineers should review their options before deciding on what fin tube to use.

As shown in the table above, L type finned tubes work best when engineers need a simple fin structure that is continuous and lightweight.

G finned tubes offer a fin that is connected to the tube via an embedded groove.

KL finned tubes offer an alternative fin that is mechanically attached to the base tube.

Lastly, extruded fin tubes use a unique method of attaching the fin to the tube by extruding them together.

10 How to Choose an L Type Finned Tube

Selecting the correct L type finned tube involves analyzing the application.

10.1 Determine Heat Duty

Engineers should first know how much heat needs to be transferred.

This will determine the tube dimensions and fin shape among other things.

10.2 Check Operating Temperature

The expected temperature range should be identified early on.

This will ensure that the materials of the tube and fin can handle the conditions.

10.3 Evaluate Pressure

Pressure inside the tube dictates wall thickness and material.

As such, knowing the pressure requirements is important before choosing the product.

10.4 Analyze Corrosion

Internal and external environments should be considered.

Salt, chemicals, moisture, and more can play a factor when deciding on material.

10.5 Select Fin Pitch

Fin pitch will affect overall surface area and airflow.

Smaller fin pitch creates more surface area but can increase the pressure drop.

As such, engineers must balance the fin pitch to create an optimal thermal and hydraulic design.

10.6 Select Fin Height

Taller fins create more surface area.

However, they will increase the overall diameter of the tube.

As such, fin height should be chosen based on available space for the equipment.

10.7 Consider Maintenance

Particles can get caught in between fins if the air is dirty.

As such, certain applications will require a proper fin pitch to allow for cleaning.

Also, keeping the heat exchanger clean can improve performance and longevity.

11 L Type Finned Tube for Heat Exchangers

L type finned tubes can be used in heat exchangers to provide supplemental surface area on the outside of the tubes.

Fluid travels through the base tube while air flows over the fins attached to the outside of the tube.

As a result, there is effective heat transfer between the internal fluid and the external air.

Air cooled heat exchangers can take advantage of this feature to provide heat rejection to the air.

Industrial cooling systems can use them as well provided the operating conditions match up with the finned tube design.

However, a detailed design process is needed to calculate and finalize heat exchanger specifications.

Some of these specs include:

• Heat duty

• Fluid Temperature

• Air Temperature

• Flow Rate

• Operating Pressure

• Tube Diameter

• Fin Height

• Fin Pitch

• Tube Material

• Fin Material

• Corrosion / Environments

Because of this, L type finned tubes should be considered during the heat exchanger design process.

12 Why Choose Bangwin Thermal?

Picking the right fin tube starts with a company that has the manufacturing technology and knowledge to produce them according to your application.

Bangwin Thermal specializes in industrial heat transfer and finned tube solutions.

The company offers multiple types of fin tubes to satisfy various heat exchanger designs.

These can include L type finned tubes, G finned tubes, KL fin tubes, extruded fin tubes, high frequency welded fin tubes, and laser welded fin tubes.

As such, customers have the ability to compare different fin configurations to meet their project’s needs.

Not only can they account for thermal performance and operating conditions, but material and production requirements along with equipment configuration can play a role in the decision process.

Looking for industrial fin tube and heat exchanger solutions?

Check out Bangwin Thermal.

Home

13 FAQ About L Type Finned Tubes

13.1 What is an L type finned tube?

An L type finned tube is a fin tube that has a continuous L-shaped fin wrapped around the outside of the tube.

13.2 Why is it called an L type finned tube?

The fin creates an L shaped connection where it meets the base tube.

For this reason, it is called an L type finned tube.

13.3 What materials are used to make L type finned tubes?

Aluminum fins are commonly used on L type finned tubes.

Typical tube materials include carbon steel, stainless steel, copper, aluminum, and more alloys.

13.4 What are some applications for L type finned tubes?

Applications for L type finned tubes include air cooled heat exchangers, HVAC systems, refrigeration equipment, industrial cooling, oil and gas, and heat recovery equipment.

13.5 What are the advantages of L type finned tubes?

L type finned tubes provide a larger surface area while maintaining a relatively compact design.

The way the fin attaches to the tube also provides a mechanically strong connection.

13.6 Are L type finned tubes good for air cooled heat exchangers?

Yes! Since these finned tubes provide extra surface area on the outside of the tube, they can easily be used for air cooled heat exchangers.

13.7 How are L type finned tubes different from G type finned tubes?

L type finned tubes have fins that are wrapped around the tube and create an L shape where it meets the tube.

G type fins have a groove cut into the tube for the fin to sit.

13.8 Can L type finned tubes be customized?

Yes! L type finned tubes can be customized by varying the diameter, fin height, fin pitch, fin thickness, material, and length.

Tube length will be dependent on the machinery used at the manufacturer’s facility.

13.9 How does fin pitch impact performance?

Fin pitch can impact the heat transfer surface area and airflow around the finned tube.

A smaller fin pitch will create more surface area but will also increase the pressure drop.

Engineers should design to what works best for their application.

13.10 Can I use aluminum fins with steel tubes?

Yes! This combination is very common due to aluminum’s low weight and steel’s high strength.

Just make sure to consider thermal contact and whether or not galvanic corrosion can occur.

14 Conclusion

An L Type Finned Tube is capable of increasing the surface area on the outside of the tube.

It does this by having a continuous L- shaped fin that wraps around the outside of the tube.

Because L type finned tubes have a wrapped fin, they can be used in air cooled heat exchangers, HVAC systems, refrigeration equipment, industrial cooling applications, oil and gas, and heat recovery equipment.

Not only can a variety of fin materials be used, but several tube materials can be used.

As a result, engineers are able to properly match their application’s temperature, pressure, corrosion, and thermal requirements.

Keep in mind that fin height, fin pitch, tube diameters, and material choice will affect heat transfer rates, pressure drop, size of the heat exchanger, and maintenance.

Customers seeking L type finned tubes and custom industrial heat exchangers can visit Bangwin Thermal.