HFW (High-Frequency Welding) finned tubes serve as core heat transfer components in waste heat recovery systems (WHRS), playing an irreplaceable role in capturing and recycling low-grade or high-temperature waste heat from industrial exhaust gases, flue gases, or process fluids.
The high-frequency welding process creates a metallurgical bond between the fins and the base tube, with minimal interface thermal resistance. Unlike mechanically attached fins, HFW fins do not have gaps that impede heat transfer. This ensures that the heat absorbed by the fins from the waste heat medium is rapidly and efficiently transferred to the base tube and then to the internal working medium, avoiding heat loss during the conduction process.
Waste heat recovery systems often operate in harsh environments, such as high-temperature flue gas (up to 800–1000℃), corrosive gas components, and frequent thermal cycling. HFW finned tubes exhibit excellent structural stability.
| Carbon % | Manganese % | Phosphorus % | Sulfur % | Silicon % | Nickel % | Chromium % |
|---|---|---|---|---|---|---|
| 0.04-0.10 | 2.00 | 0.045 | 0.030 | 0.75 | 9.0-13.0 | 17.0-19.0 |
The columbium content shall be not less than eight times the carbon content and not more than 1.10%.
| Tensile Strength, min | Yield Strength, min | Elongation in 2" or 50mm, min |
|---|---|---|
| 75ksi (515 MPa) | 30ksi (205 MPa) | Longitudinal:35%; Transverse:25% |
It possesses excellent corrosion resistance and oxidation resistance, making it suitable for medium- and low-temperature operating conditions containing slightly corrosive media, such as waste heat recovery from process exhaust gases in the chemical industry and drying equipment in the food and pharmaceutical industries. 316 stainless steel has even stronger resistance to chloride ion corrosion, making it suitable for applications in coastal or chlorine-containing environments.
It is inexpensive, has good processing performance, and is suitable for low-temperature, non-corrosive waste heat recovery applications, such as heating systems and ambient air cooling. Its disadvantages are poor corrosion resistance and high-temperature resistance; it is prone to oxidation and rusting with long-term use, typically requiring anti-corrosion treatments such as galvanizing and painting.
It has high thermal conductivity and is lightweight, making it suitable for low-temperature, high-efficiency heat exchange applications, such as central air conditioning units and cold storage evaporators. Its disadvantages include low high-temperature strength, poor resistance to strong alkali corrosion, and a generally limited operating temperature not exceeding 200℃.
It has excellent thermal conductivity and corrosion resistance (except in strong acid environments), and is often used in precision equipment with extremely high heat exchange efficiency requirements, such as the condensers of small heat pumps and refrigeration units. However, it is relatively expensive and heavy, making it unsuitable for large-scale industrial waste heat recovery systems.
