Finned Coil Tube for Phase Change Thermal Storage (PCTHES)
Product Overview
The Finned Coil Tube (翅片盘管) is a precision-engineered stainless steel heat exchanger component specifically designed for Phase Change Thermal Energy Storage Systems (PCTHES). Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product represents a high-performance solution for latent heat storage applications where thermal energy is stored and released through the phase transition of a Phase Change Material (PCM). The coil tube geometry, combined with external fins, dramatically increases the effective heat transfer surface area, thereby mitigating the inherently low thermal conductivity of most PCM materials and enabling rapid charge/discharge cycles.
The product is supplied in continuous coil form (盘管), allowing for flexible deployment in modular thermal storage tanks of various capacities. This design philosophy supports scalable integration into district heating networks, industrial process heat recovery systems, and solar thermal energy storage installations.
Material & Properties
The coil tube is fabricated from austenitic stainless steel grades selected for their superior corrosion resistance, thermal stability, and long-term mechanical integrity under repeated thermal cycling conditions.
- Base Tube Material: SUS304 (ASTM A213 TP304) / SUS316L (ASTM A213 TP316L) — selected based on medium compatibility requirements
- Fin Material: Aluminum alloy (6063-T5) or stainless steel (SUS304), bonded via mechanical interlock or brazing
- Corrosion Resistance: Excellent resistance to oxidation at temperatures up to 870°C (1600°F); pitting resistance (PREN) ≥ 18 for SUS316L grade
- Thermal Conductivity: 16.3 W/(m·K) for SUS304 at 20°C; 14.2 W/(m·K) for SUS316L at 20°C
- Thermal Expansion Coefficient: 17.3 × 10⁻⁶ /K (SUS304); 16.0 × 10⁻⁶ /K (SUS316L)
- Operating Temperature Range: -196°C to +870°C (cryogenic to high-temperature applications)
- Maximum Design Pressure: Up to 1.6 MPa (gauge), customizable to project requirements
Specifications
| Parameter | Specification |
|---|---|
| Tube Outer Diameter (OD) | φ6 mm / φ8 mm / φ10 mm / φ12 mm / φ16 mm (custom available) |
| Tube Wall Thickness | 0.5 mm – 1.5 mm |
| Coil Inner Diameter (ID) | φ200 mm – φ2000 mm |
| Coil Length (per coil) | 10 m – 100 m (continuous) |
| Fin Height | 5 mm – 25 mm |
| Fin Thickness | 0.3 mm – 0.8 mm |
| Fin Pitch (Spacing) | 3 mm – 10 mm |
| Surface Enhancement Ratio | 3.5× – 8.0× (relative to bare tube) |
| Heat Transfer Coefficient Improvement | 2.8× – 6.5× (vs. bare tube in PCM medium) |
| End Connection Type | Flanged / Threaded / Welded / Quick-connect |
| Surface Finish | Ra ≤ 0.8 μm (inner surface); Passivated exterior |
| Delivery Condition | Coiled, shrink-wrapped, palletized |
Manufacturing Process
The production of finned coil tubes follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, metallurgical integrity, and optimal heat transfer performance:
- Raw Material Inspection & Certification: Incoming stainless steel tube stock undergoes spectroscopic analysis (PMI) and mechanical property verification against ASTM/EN standards.
- Tube Straightening & Cutting: Precision straightening ensures uniform wall thickness and eliminates residual stresses from prior forming operations.
- Coil Forming (Cold Bending): Computer-controlled CNC coil forming equipment bends the straight tube into the specified coil geometry with controlled bend radii (minimum R ≥ 3D) to prevent wall thinning or ovality exceeding 5%.
- Fin Attachment: Fins are applied via one of the following methods:
- High-frequency induction brazing — for aluminum fins on stainless steel tubes
- Mechanical pressing (roll-fin) — for high-integrity bonded joints
- Welded fins — for high-temperature applications requiring metallurgical bond
- Hydrostatic Pressure Testing: Each coil assembly is pressure-tested at 1.5× the maximum design pressure with 100% inspection rate.
- Passivation & Surface Treatment: Chemical passivation removes free iron contamination, restoring the passive chromium oxide layer for long-term corrosion protection.
- Final Dimensional Inspection: Coordinate measuring machine (CMM) verification of coil diameter, pitch uniformity, and fin geometry.
Applications
The finned coil tube is a critical heat transfer component in the following engineering domains:
- Solar Thermal Energy Storage: Integration with parabolic trough collectors and evacuated tube solar arrays for concentrated solar power (CSP) plants using molten salt or organic PCM.
- District Heating & Cooling: Latent heat storage tanks for peak-shaving in municipal heating networks, reducing boiler cycling and improving system efficiency.
- Industrial Waste Heat Recovery: Capture and storage of low-to-medium temperature process heat (80°C – 300°C) from manufacturing operations for on-demand utilization.
- Building Energy Management: Thermal buffering in commercial HVAC systems using paraffin-based or salt hydrate PCMs to flatten electrical load profiles.
- Food & Pharmaceutical Processing: Temperature-controlled storage and thermal regulation in sensitive manufacturing environments requiring precise thermal management.
- Electronics Cooling: High-density data center thermal management utilizing PCM-based passive cooling systems.
- Research & Development: Laboratory-scale PCTHES research platforms studying heat transfer enhancement techniques (as documented in academic literature on finned coil tube phase change thermal storage heat transfer performance).
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring product conformity with international standards:
- ISO 9001:2015 — Quality Management Systems certification
- ISO 14001:2015 — Environmental Management Systems certification
- ASTM A213 / A269 — Seamless stainless steel tubing standards
- EN 10216-5 — European seamless stainless steel tube specifications
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes
- ASME BPV Code Section VIII — Pressure vessel components compliance (for applicable applications)
- Mill Test Certificates (MTC) — EN 10204 Type 3.1 certification provided with each shipment
- NDT Capabilities: Eddy current testing (ECT), radiographic testing (RT), and dye penetrant testing (PT) available upon request
Unique Selling Points
- Significant Heat Transfer Enhancement: The finned coil geometry provides up to 8× surface area multiplication and 6.5× improvement in heat transfer coefficient over bare tubes, directly addressing the thermal conductivity bottleneck in PCM-based storage systems.
- Continuous Coil Delivery: Supplied in ready-to-install coil form, reducing on-site welding operations, minimizing leak points, and accelerating project installation timelines.
- Scalable Modular Design: Flexible coil dimensions enable adaptation to storage tank capacities ranging from laboratory-scale (50 L) to industrial-scale (100,000 L+).
- Superior Longevity: Austenitic stainless steel construction ensures 20+ year service life under repeated thermal cycling without degradation of mechanical properties or corrosion resistance.
- Proven Research-Validated Performance: The product design is informed by published academic research on heat transfer performance characteristics of finned coil tube phase change thermal storage systems, ensuring optimized fin geometry and coil configuration for maximum energy density and charge/discharge rates.