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The main reasons for choosing L-foot tension for heat exchangers include its efficient heat transfer performance, structural characteristics and wide application scenarios.
L-Foot Tension Finned Tubes: Technical Specifications
1. Core Manufacturing Process
- Winding Technology: Pre-bent L-shaped metal strips (aluminum/steel/copper) are tension-wound onto the base tube surface, creating seamless contact.
- Contact Mechanics: Fin fixation relies on initial winding stress with average contact pressure ≤1.7 MPa. Thermal expansion mismatch between steel and aluminum limits continuous service temperature to ≤180°C.
2. Thermal Performance & Limitations
| Advantages | Constraints |
|---|---|
| ✓ Enhanced Surface Area: 15-25x bare tube surface expansion | ✗ High-Temp Degradation: Fin foot tension decays at >70°C tube wall temp, increasing contact resistance |
| ✓ Optimized Turbulence: L-profile disrupts boundary layers, improving convection | ✗ Structural Fatigue: Aluminum fin collapse under prolonged operation reduces lifespan (<5 years typical) |
| ✓ Thermal Gradient Matching: Trapezoidal fin cross-section aligns with heat flux distribution | ✗ Airflow Resistance: Fin deformation increases pressure drop by 18-35% |
3. Material Compatibility
- Base Tubes: Carbon steel (ASTM A179), Stainless steel (SAE 304/316), Copper (C12200)
- Fin Materials: Aluminum 1100/3003, Steel SPCC, Copper C11000
Note: Material pairs selected for CTE matching and corrosion resistance
4. Industrial Applications
- Energy Systems: Boiler economizers, air preheaters, solar thermal collectors (>75% market penetration)<sup>[4]
- Process Industries: Waste heat recovery in refineries, chemical plants, smelters
- Specialized Equipment: Spray dryers, HVAC heat exchangers, geothermal wellheads
5. Economic Advantages
- Cost Efficiency: 40-60% lower production cost vs. extruded/G-finned tubes
- Manufacturing Scalability: Automated CNC winding achieves ±0.1mm pitch accuracy at 15m/min production speed
Critical Design Consideration: While L-foot design enhances heat transfer area (validated by critical heat flux studies), its thermal cycling tolerance is limited. Selection requires evaluation of:
- Maximum continuous operating temperature
- Thermal shock frequency
- Acceptable maintenance intervals
Technical Clarifications
- Temperature Limit Consistency: The ≤180°C limit refers to bulk fluid temperature, while surface temperature exceeding 70°C causes fin tension loss.
- Lifespan Reference: 5-year lifespan applies to cyclical operations (>3 thermal cycles/day) at ≥150°C
L-foot tension significantly increases the heat dissipation area by tightly winding on the base tube, thereby improving the heat exchange efficiency. This design not only optimizes the heat conduction efficiency, but also enhances the heat transfer area, allowing heat to be transferred quickly and evenly.
L type fin tubes are manufactured through winding technology, ensuring seamless connection between the fins and the base tube, effectively preventing the generation of thermal resistance, and further improving the heat exchange efficiency.
In practical applications, L type fin tubes have a wide range of applicability. They are widely used in waste heat recovery, boiler energy-saving transformation and air preheating systems in many industries such as petroleum, chemical, electric power, metallurgy, etc. Its corrosion resistance and high strength characteristics enable these systems to maintain good heat dissipation performance and extend service life in harsh working environments.
L type fin tubes are also suitable for high temperature environments, such as solar thermal collection systems and geothermal energy utilization projects. They can efficiently collect and convert heat energy, providing strong support for the widespread application of renewable energy.
L-foot tension fin tubes are made by tightening the aluminum strip bent into an L shape and winding it around the core tube.
It is easy to manufacture and cheap. Însă, since the aluminum sheet is fastened to the surface of the steel tube by the initial stress of winding, the average contact pressure does not exceed 1.7Mpa. Due to the different thermal expansion coefficients of steel and aluminum, the operating temperature of L-shaped fin tubes is relatively low, generally ≤180℃.
Practice has shown that when the tube wall temperature exceeds 70℃, the fin tension is greatly reduced, the fin begins to loosen, and the contact resistance increases. În plus, due to the insufficient rigidity of the aluminum sheet, the fin’s anti-lodging performance is poor. Usually, large fins will fall over after a few years of use, which not only affects the heat transfer effect, but also increases the air flow resistance. The service life is short.
L-foot tension fin tubes have excellent heat transfer performance. L-type fin tubes adopt winding technology, with high production efficiency, uniform sheet spacing, good heat transfer, high fin ratio, and the base tube can be protected from air erosion. Its unique L-shaped design optimizes the heat transfer efficiency, increases the heat exchange area on the air side, promotes fluid turbulence, and further improves the heat exchange efficiency. L-type fin tube has compact structure and high production efficiency. L-type fin tube keeps the sheet bonding force in the best state through digital control, and the trapezoidal cross-section formed by calendering is consistent with the size of the heat flux density distribution. On the basis of saving materials, it greatly improves the thermal efficiency. L-type fin tubes are widely used. L-type fin tubes are widely used in many industries such as petrochemicals, electricity, papermaking, tobacco, and building heating. They are suitable for air coolers, air heaters, and spray drying systems in the food industry. În plus, it is also suitable for industrial and civil air heaters and radiators, as well as waste heat recovery systems in the petroleum and chemical industries. L-type fin tubes are available in a variety of materials
The base tube of the L-type fin tube can be made of steel tube, stainless steel tube or copper tube, while the fins can be made of steel strip, stainless steel strip, copper strip or aluminum strip. The selection of these materials ensures the durability and stability of the radiator and improves its ability to adapt to different environments and heat source conditions.
