Fin Tube Radiator Applications，Duties and Characteristic

The Finned Tube for air cooler is commonly used in industry. Finned tube is the key element of air cooler, and its cost for more than 60% of the total cost of tube bundle. 

           Fin Tube Radiator generally use air to cool or heat fluids such as air, water, oil or gas, or they can be used to capture or recover waste heat. These radiator can used in a broad range of industries including oil & gas, power generation, marine and HVAC&R.

Fin Tube Radiators have a wide range of applications, a few of which are:

· diesel charge air coolers;

· oil coolers;

· hydrogen coolers;

· waste heat recovery;

· driers;

· air conditioning;

· air heaters;

· steam condensers;

· generator coolers

Fin Tube Radiator are often used in circumstances where air is the preferred medium for the cooling or heating, particularly where there is limited or poor quality water.

In a Fin Tube Radiator , heat is exchanged between a thermally efficient fluid that transports heat efficiently, such as a liquid which has some viscosity, and a fluid that does not, such as air or gas with little density. On the ‘air side’, the tube surface is enhanced by the addition of fins or other elements such as looped wires, designed to increase the surface area of the tube and improve its thermal performance.

Fins can range in height (high-fin to low-fin) and the fins can be either pressure connected to the outer surface of the tube or formed into the tube surface.

Depending on the intended duty and the environment in which they are to operate, finned tubes can be manufactured in numerous designs and incorporate a combination of differing materials for both the tubes and the fins. The types and combinations of tubes and fins is significant, but in this article, we will explore only the more common types.

Fig. 2: Finned tube radiators for air cooling for customers in Saudi Arabia

Fin Profile

The profile of the fins has significant effect of the performance of a Fin Tube Radiator .  It is important to ensure each fin has a tight connection on the tube surface to provide maximum thermal conductivity.

The larger the fins and the tighter the fin pitch, the more thermal conductivity is achieved. The trade-off may be an increase in pressure drop which may, in turn, adversely affect performance. A balance between the two opposing functions is vital for effective and optimal thermal performance and equipment function.

Fig. 3: Typical Finned tube schematic with annular fins.
A = fin height; B = fin pitch, C = fin thickness and D = Diameter of

1. Elliptical finned tube

  Elliptical finned tubes are a specialized type of heat exchanger tube with elliptical-shaped fins attached to the outer surface. These fins significantly increase the surface area of the tube, allowing for more efficient heat transfer between the fluid flowing inside the tube and the surrounding environment. Here are some key points about elliptical finned tubes:

1. **Shape:** The fins attached to elliptical finned tubes have an elliptical cross-section, which provides a larger surface area compared to traditional circular or rectangular fins. This increased surface area enhances heat transfer efficiency.

2. **High Efficiency:** Due to their larger surface area, elliptical finned tubes offer improved heat transfer performance, making them suitable for applications where maximizing heat exchange is crucial.

Fig. 4: Fin tube radiators for food drying for customers in the Middle East

3. **Compact Design:** Despite their larger surface area, elliptical finned tubes can often be designed to fit within the space constraints of various heat exchanger systems. This compact design is beneficial for applications where space is limited.

4. **Strength and Durability:** Elliptical finned tubes are typically manufactured using materials such as carbon steel, stainless steel, or copper, which provide strength and durability, ensuring long-term reliability in harsh operating conditions.

 Fig. 5: Elliptical finned tubes manufactured for customers in Italy

5. **Versatility:** Elliptical finned tubes can be customized to meet specific heat transfer requirements, including variations in fin density, fin height, tube diameter, and material composition. This versatility allows for optimal performance in a wide range of industrial applications.

6. **Applications:** Elliptical finned tubes are used in various industries, including HVAC systems, power generation, oil and gas processing, chemical processing, and refrigeration. They are particularly well-suited for applications where high efficiency, compact design, and durability are essential.

2. ‘L’ Finned Tubes

One common type of finned tube is the ‘L’ fin. Receiving its name from the letter it creates from the cross-sectional view, the ‘L’ fin relies on maximum surface contact between fin and tube which is ensured by tension-forming a fin strip helically around the base tube.

Fig. 9: Finned tube radiators for oil cooling manufactured for customers in Dubai

This type of connection maximizes the heat transfer capacity and enhances the corrosion protection of the tube. The ‘L’ fin accommodates temperatures between 150 to 170 °C and comes in mainly ductile metals such as aluminum or copper which are capable of withstanding the compression around the base of the fin and allow stretching on the outside during installation.

Fig. 10: L Foot Fin Tube manufactured for customers in Egypt

Fig. 11: Cross-sectional schematic of L fin

3.‘LL’ Finned Tube

1. **Enhanced Heat Transfer:** The primary feature of LL finned tubes is their enhanced heat transfer capability. The external fins increase the surface area available for heat exchange, allowing for more efficient transfer of heat between the fluid inside the tube and the surrounding environment.

Fig. 12:  L Foot Fin Tube manufactured for customers in Saudi Arabia

2. **Low Fins:** LL finned tubes are characterized by low fins, which means that the fins have a relatively shallow profile compared to other types of finned tubes. Despite their low height, these fins effectively increase the surface area and improve heat transfer performance.

Fig. 13: Cross-sectional schematic of ‘LL’ fin

3. **Increased Turbulence:** The presence of fins on the surface of LL finned tubes disrupts the flow of fluid passing over them, creating turbulence. This turbulence enhances heat transfer by promoting better mixing and distribution of the fluid, further improving the overall efficiency of the heat exchanger.

4. **Compact Design:** Despite their enhanced heat transfer capabilities, LL finned tubes maintain a compact design. This makes them suitable for applications where space is limited or where a smaller footprint is desired, such as in air-cooled heat exchangers or compact heat exchanger units.

4.‘KL’ Finned Tube

'KL' Finned Tubes are a specific type of heat exchanger tube with a unique fin design. Here are the features and characteristics of 'KL' Finned Tubes:

1. **Finned Surface:** 'KL' Finned Tubes have fins that are knurled or crimped along their length, forming a distinctive pattern on the outer surface of the tube. This design increases the surface area available for heat transfer, enhancing the overall efficiency of the heat exchanger.

Fig. 14: ‘KL’ finned tube manufactured for customers in Iraq National Oil Company

2. **Enhanced Heat Transfer:** The knurled or crimped fins disrupt the flow of air or fluid passing over them, creating turbulence and promoting better heat transfer between the tube and the surrounding medium. This results in improved heat transfer performance compared to smooth tubes.

Fig. 15: Cross-sectional schematic of ‘KL’ fin

5. ‘G’ Embedded Finned Tube

'G' Embedded Finned Tubes are a type of heat exchanger tube where fins are embedded into the walls of the tube itself. Here are the features and characteristics of 'G' Embedded Finned Tubes:

1. **Embedded Fins:** The fins in 'G' Embedded Finned Tubes are formed by cutting grooves into the outer surface of the tube and then pressing or folding the material to create the fin shape. These fins are embedded directly into the tube wall, providing a strong mechanical bond and ensuring durability.

2. **G-Shaped Cross-Section:** The fins in 'G' Embedded Finned Tubes typically have a G-shaped cross-section, which gives them their name. This shape increases the surface area of the tube, allowing for more efficient heat transfer between the fluid inside the tube and the surrounding environment.

Fig. 16: Copper ‘G’ finned carbon steel tube manufactured for customers in Qatar

3.**High Heat Transfer Efficiency:** The embedded fins in 'G' Embedded Finned Tubes significantly increase the surface area available for heat transfer, resulting in improved heat transfer efficiency compared to smooth tubes. This makes them suitable for applications where maximizing thermal performance is essential.

4. **Compact Design:** Despite their enhanced heat transfer capabilities, 'G' Embedded Finned Tubes maintain a compact design. This makes them suitable for applications where space is limited or where a smaller footprint is desired, such as in air-cooled heat exchangers or compact heat exchanger units.

Fig. 17: Cross-sectional schematic of ‘G’ fin

5. **Versatility:** 'G' Embedded Finned Tubes can be manufactured from various materials, including carbon steel, stainless steel, copper, and aluminum, to suit different application requirements. They are commonly used in industries such as HVAC systems, refrigeration, power generation, oil and gas processing, and chemical processing.

6.Extruded Finned Tube

This fin type is formed from a bi-metallic tube consisting of an aluminum 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 produce an integral fin with excellent heat transfer properties and longevity. Extruded fin offers excellent corrosion protection of the base tube and excludes virtually all exposure to any outside fluid.

Fig. 19: Extruded Finned Tube manufactured for customers in Pakistan

Fig. 20: Cross-sectional schematic of extruded fin

Extruded finned tubes are used in high temperature conditions and corrosive atmospheric conditions such as:

· operating temperatures up to 300°C;

· offshore or other remote applications;

· heat pipes;

· dry air coolers for air, gas or oil;

· air to air heat exchangers for HVAC applications;

· air dehumidification in air treatment plants and

· energy recovery in air exhaust system.

What next?

There are many variables  to be considered to successfully select and design a Fin Tube Radiator  including:

· the duty to be performed;

· type, style and number of tubes required;

· metals best suited for the tubes and the fins;

· type of tube enhancement – fins or wire;

· thickness of the tube walls;

· I/D and O/D of the tubes;

· pitch of the fins;

· type and number of fans to provide air flow;

· the environment in which the heat exchanger is to be used and

· the duty it is required to perform

To ensure you get the best Fin Tube Radiator for your needs requires high-end software calculations, experience and technical know-how to bring it all together into a reliable unit that will provide years of efficient and reliable service. We have many decades of expertise in the design, manufacture and maintenance of Fin Tube Radiators.