Stainless Steel Coiltube for Internal-Melting Ice Thermal Energy Storage Systems
Product Code: 1456 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd
1. Product Overview
The Stainless Steel Coiltube (盘管, Coiltube) is a precision-engineered tubular product designed primarily for internal-melting ice thermal energy storage (TES) systems and other advanced heat exchanger applications. Unlike conventional external-melting ice storage configurations, internal-melting ice systems utilize coiltubes immersed within ice accumulators to facilitate direct heat exchange between the cooling medium and the stored ice matrix. This design eliminates the thermal resistance associated with ice encapsulation, resulting in significantly enhanced heat transfer coefficients and improved system efficiency.
Based on rigorous thermodynamic research into internal-melting ice coil tube cold storage tank heat transfer performance, this product line is optimized for maximum surface-to-volume ratio, uniform heat distribution, and long-term structural integrity under repeated freeze-thaw cycling. The coiltube geometry enables compact system integration while maintaining superior thermal performance in commercial and industrial cold energy storage installations.
2. Material and Properties
Wenzhou Jixing Metal Materials Co., Ltd offers this coiltube product in multiple stainless steel grades to accommodate diverse application requirements:
- Grade 304 (UNS S30408): The standard austenitic stainless steel offering excellent corrosion resistance, formability, and weldability. Suitable for general-purpose thermal energy storage and HVAC applications.
- Grade 316 (UNS S31608): Enhanced corrosion resistance through the addition of molybdenum (Mo 2.0–3.0%). Ideal for aggressive chemical environments and seawater-based cooling circuits.
- Grade 316L (UNS S31603): Low-carbon variant of Grade 316 with superior resistance to intergranular corrosion, recommended for welded assemblies exposed to chloride-containing media.
- Grade 321 (UNS S32103): Titanium-stabilized austenitic grade providing enhanced resistance to stress corrosion cracking at elevated temperatures.
Key Material Properties (Grade 304 Reference):
- Thermal Conductivity: 16.3 W/(m·K) at 300 K
- Specific Heat Capacity: 500 J/(kg·K)
- Density: 8,000 kg/m³
- Linear Thermal Expansion Coefficient: 17.3 × 10⁻⁶ /K (20–100 °C)
- Maximum Operating Temperature: −196 °C to +870 °C
- Yield Strength (Annealed): ≥ 205 MPa
- Tensile Strength: ≥ 515 MPa
3. Technical Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Form | Continuous Coiltube (盘管) | — |
| Outer Diameter (OD) | Φ6 mm – Φ50 mm (custom sizes available) | ASME B36.19M |
| Wall Thickness | 0.3 mm – 3.0 mm | ASME B36.19M |
| Coil Diameter | Φ200 mm – Φ2,000 mm | Custom per application |
| Coil Length (per bundle) | 5 m – 120 m | Custom per application |
| Surface Finish | No. 1, 2B, BA (Bright Annealed), or Polished (Ra ≤ 0.4 μm) | ASTM A240 |
| Pressure Rating | Up to 4.0 MPa (design dependent) | PV = π/4 × (OD² − ID²) × σ × t |
| Operating Temperature Range | −40 °C to +120 °C (standard); cryogenic capable to −196 °C | ASME BPVC Section VIII |
| Tolerance on OD | ±0.1 mm (precision grade); ±0.3 mm (standard grade) | ASTM A213 / A269 |
| Tolerance on Wall Thickness | ±10% of nominal | ASTM A213 / A269 |
| End Condition | Plain, threaded, flanged, or welded fittings | ASME B1.20.1 / B16.5 |
| Connection Method | Welded (TIG/Orbital), brazed, or mechanical coupling | ASME BPVC Section IX |
4. Manufacturing Process
The production of Wenzhou Jixing Coiltube products follows a tightly controlled multi-stage manufacturing workflow:
- Material Preparation: Cold-rolled stainless steel strip (coil) is inspected for chemical composition (via XRF or spectroscopic analysis) and mechanical properties in accordance with ASTM A240 specifications. Incoming material must conform to EN 10204 Type 3.1 certification requirements.
- Forming and Coiling: Precision CNC-controlled rolling machinery shapes the flat strip into tubular form at the specified OD and wall thickness. The formed tube is then coiled to the designated coil diameter using a hydraulic coiling head with real-time tension monitoring to prevent geometric distortion.
- Welding (if applicable): Longitudinal or spiral welds are produced using TIG (Tungsten Inert Gas) or orbital welding techniques with argon (Ar) internal purge gas to maintain a clean, oxide-free weld interior. Weld bead height is controlled to ≤ 0.1 mm to minimize flow resistance.
- Heat Treatment: Solution annealing is performed at 1,010–1,120 °C followed by rapid quenching to restore full austenitic microstructure and maximize corrosion resistance. Stress-relief annealing may be applied post-coiling to eliminate residual stresses.
- Surface Treatment: Pickling and passivation (acid wash with HNO₃/HF mixture) removes mill scale and surface contaminants, establishing a protective chromium oxide passive layer. Optional electropolishing achieves Ra ≤ 0.4 μm surface roughness for hygienic applications.
- Quality Inspection: Each coil undergoes 100% hydrostatic pressure testing (1.5× design pressure for 30 seconds), dimensional verification (OD, wall thickness, coil diameter), visual inspection of weld seams, and optional Eddy Current (ECT) testing for wall thickness and defect detection.
- Packaging and Dispatch: Coils are wrapped in moisture-barrier protective film, secured on wooden pallets, and shipped with accompanying mill test certificates (MTC) and dimensional inspection reports.
5. Applications
The internal-melting ice coil tube design is applicable across a broad spectrum of thermal energy management and heat exchange systems:
- Internal-Melting Ice Thermal Energy Storage (TES): Primary application — coiltubes serve as the heat transfer surface within ice accumulators, enabling off-peak electricity utilization for commercial building cooling. The internal-melting configuration achieves heat transfer coefficients 2–3× higher than external-melting systems.
- Commercial and Industrial HVAC Systems: Peak-shaving and load-shifting in large commercial facilities, data centers, hospitals, and manufacturing plants.
- Food and Beverage Processing: Rapid cooling of perishable products, refrigerated transport, and cold chain logistics where precise temperature control is critical.
- Pharmaceutical and Biotechnology: Temperature-controlled storage of vaccines, biologics, and laboratory samples requiring stable sub-zero environments.
- Industrial Process Cooling: Metalworking, chemical processing, and semiconductor fabrication facilities requiring high-temperature-difference heat rejection.
- Geothermal and Solar Thermal Systems: Heat collection and distribution in renewable energy integration projects.
- Cryogenic Applications: Liquid nitrogen (LN₂) transfer and storage systems leveraging the material's cryogenic toughness.
6. Quality Certifications and Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems ensuring full traceability and compliance with international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- ISO/TS 22163 — Quality management system for automotive series production (where applicable)
- ASME — American Society of Mechanical Engineers compliance for pressure-containing components
- EN 10204 — European certification for product inspection documents (Type 3.1)
- ASTM A213 / A269 / A240 — Material and product specifications
- GB/T 12771 — Chinese national standard for welded stainless steel tubes
- JIS G3459 — Japanese Industrial Standard for welded austenitic stainless steel tubes
Each production batch is accompanied by a comprehensive Mill Test Certificate (MTC) documenting chemical composition, mechanical properties, heat treatment parameters, and non-destructive testing (NDT) results. Customers may request supplementary testing including hardness testing (HV/HRB), impact testing (Charpy V-Notch), and intergranular corrosion testing (ASTM A923 Method A) at no additional cost.
7. Unique Selling Points
- Research-Validated Performance: Product design informed by peer-reviewed research on internal-melting ice coil tube heat transfer performance, ensuring optimal thermal efficiency in TES applications.
- Custom Geometric Configuration: Full customization of OD, wall thickness, coil diameter, and length to match specific system design requirements.
- Enhanced Heat Transfer Surface: Available with internal or external micro-fin configurations to further augment convective heat transfer coefficients.
- Full Traceability: Every coil is traceable to its raw material heat number with complete chemical and mechanical documentation.
- Multi-Grade Availability: Selection from Grades 304, 316, 316L, 321, and custom alloy compositions to address specific corrosion and mechanical requirements.
- Repeat-Cycle Durability: Engineered to withstand thousands of freeze-thaw cycles without fatigue failure, maintaining structural integrity over the system's operational lifetime.
Wenzhou Jixing Metal Materials Co., Ltd is committed to delivering precision-engineered stainless steel coiltube solutions that meet the most demanding thermal energy storage and heat exchange requirements. For detailed technical consultation, custom design support, or quotation inquiries, please contact our engineering team.