Stainless Steel Coil Tube for Ice Storage Spray Pre-Cooling Systems
Product Overview
The Stainless Steel Coil Tube (Coil Tube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered heat exchange component specifically designed for ice storage spray pre-cooling systems (Ice Storage Spray Pre-Cooling Device). This product serves as the core thermal transfer element within advanced energy-efficient cooling architectures, enabling efficient latent heat storage and release cycles through ice accumulation and melting processes.
Unlike conventional straight-tube heat exchangers, the coil tube geometry provides a significantly larger surface-area-to-volume ratio, facilitating superior thermal exchange efficiency within compact installation footprints. The coiled configuration also promotes natural convection patterns that enhance ice formation uniformity and reduce flow maldistribution in spray pre-cooling circuits.
Material & Properties
Base Material Composition
- Primary Alloy: Austenitic Stainless Steel (奥氏体不锈钢)
- Standard Grades Available: AISI 304 (UNS S30408), AISI 316L (UNS S31603), AISI 321 (UNS S32100)
- Carbon Equivalent (Ceq): ≤ 0.030% for 316L grade to ensure maximum weldability and intergranular corrosion resistance
- Molybdenum Content: 2.0–2.5% (in 316L) for enhanced resistance to chloride-induced pitting and crevice corrosion in brine environments
Mechanical Properties
- Tensile Strength (UTS): ≥ 520 MPa (AISI 304), ≥ 485 MPa (AISI 316L)
- Yield Strength (0.2% offset): ≥ 205 MPa
- Elongation at Break: ≥ 40%
- Hardness: ≤ 200 HV (annealed condition)
- Operating Temperature Range: −196°C to +350°C
- Thermal Conductivity: 16.3 W/(m·K) at 20°C
- Specific Heat Capacity: 500 J/(kg·K)
Corrosion Resistance
- Excellent resistance to dilute organic and inorganic acids
- Superior performance in calcium chloride (CaCl₂) and ethylene glycol (EG) brine solutions
- Resistant to scaling and fouling under cryogenic operating conditions
- Long-term durability in humid, chemically aggressive pre-cooling environments
Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Outer Diameter (OD) | Φ12.7 / Φ15.9 / Φ19.1 / Φ25.4 / Φ31.8 | mm |
| Wall Thickness | 1.0 / 1.5 / 2.0 / 2.5 / 3.0 | mm |
| Coil Diameter (CD) | 100 – 800 | mm |
| Coil Length (per unit) | 3 – 30 | m |
| Total Surface Area (per coil) | 0.5 – 15.0 | m² |
| Max. Design Pressure | 1.6 – 4.0 | MPa |
| Min. Ice Storage Capacity | 5 – 50 | kWh |
| Surface Finish | No. 4 / Mirror / Electropolished | — |
| Surface Roughness (Ra) | ≤ 0.8 (standard) / ≤ 0.2 (mirror) | μm |
| End Preparation | Flat cut / Beveled / Threaded / Flanged | — |
| Heat Transfer Coefficient | ≥ 800 | W/(m²·K) |
| Design Life | ≥ 25 | Years |
Manufacturing Process
Process Flow
- Material Selection & Incoming Inspection: Cold-rolled stainless steel strip is verified against mill certificates for chemical composition (spectroscopic analysis) and mechanical properties (tensile testing).
- Slitting & Leveling: Precision slitting to target width with tension-controlled leveling to eliminate coil set and ensure dimensional uniformity.
- Coil Forming (Cold Bending): The flat strip is wound into the specified coil geometry using CNC-controlled bending machinery. The forming process maintains material integrity without inducing cold work hardening beyond acceptable limits (≤ 10% reduction in elongation).
- Welding: Continuous longitudinal welds are applied using TIG (Tungsten Inert Gas) or orbital automatic welding with argon (Ar) shielding. Weld parameters are optimized to achieve full penetration with minimal heat-affected zone (HAZ) distortion.
- Post-Weld Stress Relief (if required): Solution annealing at 1050–1150°C followed by rapid water quenching to restore full solution-treated condition and eliminate residual stresses.
- Surface Treatment: Pickling and passivation (acid pickling with nitric/hydrofluoric acid mixture) to remove oxide scale and establish a protective chromium oxide (Cr₂O₃) passive film.
- Hydrostatic Pressure Testing: Each coil is pressure-tested at 1.5× design pressure for a minimum dwell time of 30 minutes to verify weld integrity and leak-tightness.
- Dimensional Inspection & Final QA: Coordinate measuring machine (CMM) verification of coil geometry, wall thickness ultrasonic testing (UT), and visual inspection of surface finish.
Key Process Advantages
- Cold-forming process preserves the austenitic microstructure without phase transformation
- Orbital welding ensures consistent weld quality with minimal porosity and undercuts
- In-house passivation capability eliminates third-party handling and contamination risks
- 100% hydrostatic testing provides zero-defect confidence for cryogenic applications
Applications
Primary Application Domain: Ice Storage Spray Pre-Cooling Systems
The coil tube is integral to the Ice Storage Spray Pre-Cooling Device (盘管蓄冰式喷淋预冷装置), a next-generation energy management system that stores thermal energy as latent heat (ice) during off-peak electricity periods and releases it during peak demand. The heat storage and release characteristics (蓄放冷特性) of the system are directly governed by the coil tube's thermal performance.
Specific Application Scenarios
- Commercial HVAC Load Shifting: Peak-load management in shopping malls, office buildings, and hospitals by discharging stored ice during peak tariff periods.
- Industrial Process Cooling: Temperature-controlled cooling for pharmaceutical manufacturing, food processing, and semiconductor fabrication.
- Data Center Thermal Management: High-density cooling for server rooms requiring continuous 24/7 operation with backup cooling capacity.
- Agricultural Cold Storage: Refrigerated warehouses and cold-chain logistics requiring stable sub-zero temperatures.
- Marine & Offshore Cooling: Vessel and platform cooling systems where space is constrained and corrosion resistance is critical.
- Military & Emergency Power: Standalone cooling systems for field operations and disaster relief scenarios.
Performance in Ice Storage Cycles
In ice storage spray pre-cooling applications, the coil tube undergoes repeated freeze-thaw cycles (typically 300–500 cycles per year). The austenitic stainless steel construction ensures:
- No brittle fracture at temperatures as low as −25°C (brine ice point)
- Dimensional stability through thermal cycling (CTE: 17.3 × 10⁻⁶ /°C)
- No degradation of mechanical properties over 25+ year service life
- Uniform ice adhesion and controlled ice release during discharge cycles
Quality Certifications & Standards Compliance
Product Certifications
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health and Safety Management
- NACE MR0175 / ISO 15156 — Resistance to sulfide stress cracking (for oil & gas applications)
- EN 10204 3.1 — Material Test Reports per European standard
Applicable Standards
- ASTM A269 — Standard Specification for Seamless Austenitic Stainless Steel Tubing
- ASTM A312 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Pipe
- GB/T 12771 — Chinese National Standard for Stainless Steel Tubes for General Fluid Transport
- ASME B31.5 — Hydraulic and Pneumatic Piping Systems (design verification)
- ASME B31.9 — Building Services Piping (HVAC applications)
- EN 10217-7 — European Standard for Heat Exchanger Tubes
Testing & Verification
- Chemical composition verification via optical emission spectrometry (OES)
- Grain boundary segregation testing per ASTM A240 (ASTM A999/A999M for 316L)
- Intergranular corrosion (IGC) testing per ASTM A999 (acid copper test)
- Pitting resistance index (PREN) ≥ 24 for 316L grade
- Cryogenic impact testing (Charpy V-notch) at −40°C
- Full radiographic testing (RT) of weld joints upon request
Unique Selling Points
- Application-Specific Engineering: Coil geometry optimized through computational fluid dynamics (CFD) analysis for maximum ice nucleation efficiency in spray pre-cooling configurations.
- Superior Cryogenic Performance: Maintains full ductility and fracture toughness at sub-zero operating temperatures, eliminating brittle failure risk.
- Integrated Manufacturing: End-to-end production capability from raw strip to finished coil eliminates supply chain variability and ensures consistent quality.
- Custom Configuration Flexibility: Available in multiple OD, wall thickness, coil diameter, and surface finish options to match specific system design requirements.
- Extended Service Life: 25+ year design life with minimal maintenance, significantly reducing total cost of ownership (TCO) compared to carbon steel alternatives.
- Food-Grade & Hygienic Option: Electropolished surface finish (Ra ≤ 0.2 μm) available for pharmaceutical and food processing applications per 3-A Sanitary Standards.
Technical Summary
The Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. represents a state-of-the-art heat exchange component purpose-built for ice storage spray pre-cooling systems. Its austenitic stainless steel construction, precision coil geometry, and rigorous quality assurance program deliver exceptional thermal performance, corrosion resistance, and mechanical durability across demanding cryogenic operating environments. The product is engineered to maximize the heat storage and release efficiency (蓄放冷效率) of the integrated cooling system while minimizing lifecycle maintenance costs.