Lord Fin Tube- Extruded Bimetallic Finned Tubes
1. Extruded Bimetallic Finned Tubes
Bimetallic Finned Tubes represent an advanced heat transfer technology where extruded bimetallic finned tubes are specialized heat exchange elements engineered for optimal thermal performance in demanding applications. These tubes feature a composite structure with two distinct metal layers permanently bonded through an extrusion process.
Technical Characteristics
Thermal Conductivity: 180-400 W/m·K (depending on material combination)
Operating Temperature Range: -200°C to +400°C
Pressure Rating: Up to 300 bar (depending on base tube specification)
Fin Efficiency: 85-95% (significantly higher than welded fins)
2. Extruded Bimetallic Finned Tubes Materials
The structural integrity of extruded bimetallic finned tubes derives from the metallurgical bond between the base tube and fin material. This bond ensures optimal heat transfer and mechanical stability under thermal cycling conditions.
Material Combinations and Specifications
| Base Tube Material | Fin Material | Thermal Conductivity (W/m·K) | Max Service Temp (°C) | Typical Applications |
|---|---|---|---|---|
| Carbon Steel (SA179, SA210) | Aluminum 1100/3003 | 180-200 | 280 | Air Coolers, HVAC |
| Stainless Steel 304/316 | Aluminum 1100/3003 | 190-210 | 260 | Chemical Processing, Marine |
| Carbon Steel | Copper C12200 | 380-400 | 200 | High Performance Heat Exchangers |
| Stainless Steel 304/316 | Copper C12200 | 390-410 | 180 | Corrosive Environments |
| Alloy Steel (T11, T22) | Aluminum 1100/3003 | 185-195 | 400 | High Temperature Applications |
Base Tube Specifications
OD Range: 12.7mm - 50.8mm
Wall Thickness: 1.2mm - 4.0mm
Length: Up to 24 meters
Materials: Carbon steel, stainless steel, alloy steels
Fin Specifications
Fin Height: 6mm - 16mm
Fin Thickness: 0.8mm - 2.0mm
Fins per Meter: 200 - 500
Surface Area Ratio: 10:1 - 25:1
Extruded Bimetallic Finned Tubes - Advanced Heat Transfer Solution
3. Extruded Bimetallic Finned Tubes Manufacturing Process
The extrusion manufacturing process creates a permanent metallurgical bond between the base tube and fin material, ensuring superior heat transfer characteristics and mechanical integrity.
Step-by-Step Manufacturing Sequence
| Process Step | Technical Parameters | Quality Control Measures |
|---|---|---|
| Material Preparation | Base tube cleaning to SA2.5 standard Aluminum sleeve thickness: 2-4mm |
Visual inspection, dimensional verification |
| Extrusion Process | Temperature: 400-450°C Pressure: 100-200 MPa Speed: 0.5-2.0 m/min |
Temperature monitoring, pressure control |
| Fin Formation | Die temperature: 200-250°C Fin height tolerance: ±0.2mm |
Optical measurement, sample testing |
| Bond Verification | Bond strength: >70 MPa Thermal cycling: 1000 cycles |
Ultrasonic testing, peel tests |
| Final Inspection | Surface finish check Dimensional accuracy |
Helium leak test, hydrostatic test |
Technical Insight: Metallurgical Bond Formation
The extrusion process creates a true metallurgical bond through controlled intermetallic diffusion. At the optimal temperature range of 400-450°C, aluminum atoms diffuse into the steel surface, forming a thin intermetallic layer (typically 2-5μm) that provides exceptional bond strength while maintaining thermal conductivity.
4. Extruded Bimetallic Finned Tubes Comparison
Understanding the performance differences between various finned tube technologies is crucial for proper selection in heat exchanger design.
| Parameter | Extruded Bimetallic | Welded Fins | Integral Low-Fin | Embedded Fins |
|---|---|---|---|---|
| Thermal Resistance | Lowest (0.001-0.003 m²K/W) | Medium (0.005-0.015 m²K/W) | Low (0.002-0.004 m²K/W) | High (0.010-0.025 m²K/W) |
| Corrosion Resistance | Excellent | Good (weld dependent) | Excellent | Fair |
| Fin Efficiency | 90-95% | 70-85% | 85-92% | 60-75% |
| Maximum Temperature | 400°C | 350°C | 450°C | 300°C |
| Cost Factor | 1.0x (Reference) | 0.8x | 1.2x | 0.7x |
| Typical Applications | Corrosive environments, high efficiency | General purpose, moderate conditions | High temperature, high pressure | Light duty, cost-sensitive |
Performance
Heat Transfer Performance Comparison
Extended Surface Efficiency: Extruded bimetallic tubes achieve 10-25% higher heat transfer coefficients compared to welded fin alternatives due to the continuous metallurgical bond eliminating contact resistance.
Pressure Drop Characteristics: Optimized fin geometry results in 15-30% lower pressure drop for equivalent heat transfer duty compared to other fin types.
Long-term Performance: After 5 years of service, extruded bimetallic tubes maintain 95-98% of original heat transfer capacity, versus 80-90% for welded fin tubes.
5. Extruded Bimetallic Finned Tubes Application
Extruded bimetallic finned tubes excel in applications requiring superior thermal performance, corrosion resistance, and long-term reliability.
- Power Generation - Feedwater heaters, air-cooled condensers, turbine oil coolers
- Petrochemical Industry - Process gas coolers, overhead condensers, reactor feed/effluent exchangers
- Chemical Processing - Acid coolers, solvent condensers, polymerization reactors
- Refrigeration & HVAC - Ammonia evaporators, refrigerant condensers, chiller bundles
- Marine Applications - Seawater coolers, lube oil coolers, central cooling systems
- Natural Gas Processing - Gas dehydration units, amine contactors, glycol coolers
- Waste Heat Recovery - Economizers, waste heat boilers, process gas cooling
- Food & Beverage - Pasteurizers, sterilization systems, process cooling
Industry-Specific Technical Requirements
| Industry | Typical Service Conditions | Recommended Material Combination | Design Considerations |
|---|---|---|---|
| Power Plant Air Coolers | Steam condensation, ambient air cooling Pressure: 5-50 bar, Temperature: 80-200°C |
Carbon Steel / Aluminum | High fin density for maximum surface area, corrosion protection for coastal environments |
| Chemical Process Coolers | Corrosive media, frequent thermal cycling Pressure: 10-100 bar, Temperature: 50-300°C |
Stainless Steel 316 / Aluminum | Enhanced fin thickness for corrosion allowance, optimized for cleaning access |
| Refrigeration Systems | Ammonia or halocarbon refrigerants Pressure: 15-25 bar, Temperature: -40 to +40°C |
Carbon Steel / Aluminum | Optimized for two-phase flow, defrost cycle compatibility |
| Marine Heat Exchangers | Seawater cooling, high corrosion potential Pressure: 5-20 bar, Temperature: 10-90°C |
CuNi 90/10 or 316L SS / Aluminum | Cathodic protection compatibility, enhanced fouling resistance |
Application Engineering
For optimal performance in specific applications, consider the following design parameters:
Air-Cooled Applications: Select fin densities of 394-472 fins/meter (10-12 FPI) with fin heights of 12-16mm for maximum heat transfer efficiency.
Liquid Service: Use lower fin densities of 236-315 fins/meter (6-8 FPI) with optimized fin geometry to minimize fouling and facilitate cleaning.
Corrosive Environments: Specify protective coatings or select appropriate material combinations to ensure 20+ year service life in aggressive chemical services.
The advanced manufacturing process of extruded bimetallic finned tubes ensures a permanent metallurgical bond that provides superior heat transfer efficiency, exceptional corrosion resistance, and long-term reliability in demanding industrial applications.