L-Finned Tubes (Wrapped / Helical Fins)
This is one of the most common and cost-effective types.
- Manufacturing: A strip of fin material (usually aluminum) with an “L”-shaped foot is wound tightly under tension in a helical pattern around the base tube. The foot sits securely against the tube.
- Bond: The bond is primarily mechanical. For better heat transfer and bond strength, the tube is often knurled or grooved before winding.
- Advantages:
- Low cost.
- High finning ratio (a lot of surface area).
- Good for low to moderate temperatures.