Stainless Steel Coil Tube — Ice Thermal Storage Heat Exchanger System
Product Overview
The Stainless Steel Coil Tube (盘管Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 778) is a precision-engineered heat exchange component designed specifically for Ice Thermal Storage (Ice Thermal Energy Storage, ITES) systems. This coil tube product is integral to External Ice Melt (EIM) Ice Storage Systems, where it functions as the primary heat transfer medium between the working fluid (typically glycol-water solution) and the ice storage tank. The coil tube is fabricated in continuous helical or spiral configurations, maximizing surface area-to-volume ratio for superior thermal exchange efficiency within compact installation footprints.
Wenzhou Jixing Metal Materials Co., Ltd. specializes in producing stainless steel coil tubes that meet rigorous international standards for corrosion resistance, mechanical integrity, and thermal conductivity. These coil tubes are designed to withstand the cyclic freeze-thaw conditions inherent in ice storage applications, ensuring long service life and reliable performance across thousands of operational cycles.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of corrosion resistance, ductility, and thermal performance under cryogenic and sub-zero operating conditions.
- Primary Alloy Grade: AISI 304 (UNS S30408) / AISI 316L (UNS S31603) — selected based on application requirements
- Corrosion Resistance: Excellent resistance to chloride-induced pitting, glycol corrosion, and general atmospheric corrosion
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C, providing efficient heat transfer between the circulating fluid and ice/water medium
- Mechanical Strength: Minimum yield strength of 205 MPa (304) / 170 MPa (316L); tensile strength ≥ 520 MPa
- Cryogenic Performance: Retains full ductility and toughness at temperatures as low as −196°C (Liquid Nitrogen Temperature), making it suitable for ice storage and refrigeration applications
- Hygienic Surface: Surface finish Ra ≤ 0.8 μm (electropolished option available at Ra ≤ 0.4 μm), preventing fouling and biofilm formation
- Non-magnetic Properties: Austenitic structure ensures non-magnetic characteristics, compatible with MRI environments and electromagnetic-sensitive applications
Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Product Name | Stainless Steel Coil Tube (盘管Coiltube) | — |
| Product No. | 778 | — |
| Material Grade | AISI 304 / 304L / 316L / 321 | — |
| Tube Outer Diameter (OD) | 6 – 50 | mm |
| Tube Wall Thickness | 0.5 – 2.5 | mm |
| Coil Inner Diameter (ID) | 100 – 2000 | mm |
| Coil Length (Total Pipe Length) | 10 – 500 | m |
| Coil Pitch (Spacing) | 15 – 100 | mm |
| Number of Turns | 50 – 5000 | turns |
| Surface Finish | 2B / BA / Electropolished (EP) | — |
| Working Pressure (Design) | 0.25 – 1.6 | MPa |
| Test Pressure (Hydrostatic) | 1.5× Working Pressure | MPa |
| Operating Temperature Range | −40 to +150 | °C |
| Working Fluid | Glycol-Water (25%–50%), Water, Refrigerant | — |
| End Connections | Flanged / Threaded / Welded / Grooved | — |
| Applicable Standards | ASTM A213 / A269 / GB/T 12771 / EN 10216 | — |
| Manufacturing Process | Continuous Cold-Bending / CNC Spiral Winding | — |
Manufacturing Process
The production of high-quality stainless steel coil tubes follows a rigorous multi-stage manufacturing process to ensure dimensional accuracy, mechanical integrity, and surface quality:
- Raw Material Selection & Inspection: Cold-rolled stainless steel tube blanks conforming to ASTM A213 or GB/T 12771 are received and subjected to 100% visual inspection, dimensional verification, and spectrometric chemical analysis (OES) to confirm alloy composition.
- Tube Straightening & Annealing: Incoming tubes are cold-straightened to eliminate residual curvature, followed by solution annealing at 1050–1150°C to relieve internal stresses and restore full austenitic microstructure.
- CNC Spiral Coiling: Tubes are fed into precision CNC-controlled coil winding machines that form the helical/spiral geometry with controlled pitch, consistent bend radius (minimum 3D–5D bend radius to prevent wall thinning), and uniform coil diameter. The process employs dual-axis synchronization to prevent kinking or ovality.
- Post-Coil Annealing (Optional): For applications requiring maximum ductility, the formed coil undergoes controlled furnace annealing to relieve bending-induced residual stresses without grain growth.
- Surface Treatment: The coil surface is cleaned via acid pickling and passivation (HNO₃/HF treatment) to remove oxide scale and form a protective chromium oxide passive layer. Electropolishing is applied for hygienic-grade applications.
- End Preparation & Connection Fabrication: Coil ends are machined, flanged, or threaded to specification. Welded connections (GTAW/TIG) are performed with inert gas shielding to maintain interior cleanliness.
- Hydrostatic Pressure Testing: Each coil assembly undergoes 100% hydrostatic pressure testing at 1.5× the design working pressure, held for a minimum of 30 seconds with zero leakage tolerance.
- Dimensional Inspection & Final QA: Final inspection includes coil diameter measurement, pitch verification, surface finish profiling (Ra measurement), and visual examination of all welds and connections.
Applications
The stainless steel coil tube (Product No. 778) is engineered for demanding thermal management applications, with primary deployment in the following domains:
1. Ice Thermal Storage Systems (Primary Application)
- External Ice Melt (EIM) Systems: The coil tube is submerged within ice storage tanks, where circulating chilled glycol-water fluid absorbs heat from the building load, causing ice to melt and providing latent heat cooling. The coil design maximizes heat transfer area while minimizing pressure drop.
- Internal Ice Melt (IIM) Systems: Coil tubes are used as internal heat exchangers within ice slurry generation equipment.
- Technical & Economic Advantages: As documented in industry literature on "Technical and Economic Analysis of Coil-Type External Ice Melt Ice Storage Systems," the coil tube configuration offers superior volumetric cooling capacity (200–250 kJ/kg ice), peak shaving capability, and energy cost savings of 25–35% compared to conventional cooling towers.
2. Industrial Refrigeration
- Ammonia and refrigerant heat exchangers in food processing, cold chain logistics, and pharmaceutical cold storage
- Freezer and blast freezer evaporator coils
3. Building HVAC Systems
- Chilled water distribution coils for commercial and industrial air conditioning
- Heat recovery coils for energy-efficient ventilation systems
- Underfloor radiant cooling coils
4. Process Industries
- Chemical process heat exchangers requiring corrosion resistance
- Food and beverage industry heat transfer (hygienic-grade 316L with electropolished finish)
- Pharmaceutical manufacturing equipment
- Power generation — condenser tubes and heat recovery systems
5. Marine & Offshore
- Seawater cooling coils (316L grade for chloride resistance)
- Shipboard refrigeration and HVAC systems
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and product certifications to ensure compliance with international standards:
- ISO 9001:2015 — Quality Management System certification covering design, manufacturing, and testing of stainless steel coil products
- ISO 14001:2015 — Environmental Management System, demonstrating commitment to sustainable manufacturing practices
- ISO 45001:2018 — Occupational Health and Safety Management System
- CE Marking — European Conformity for products meeting EU directives on safety, health, and environmental protection
- PED (Pressure Equipment Directive 2014/68/EU) — Compliance for coil tubes used in pressure vessel applications
- Material Certifications: 3.1 Certificate (EN 10204) / MTC (Material Test Certificate) provided with every shipment, including chemical composition, mechanical properties, and heat treatment records
- Third-Party Inspection: Available upon request — SGS, Bureau Veritas, or TÜV inspection for critical applications
- NACE/AMPP — Corrosion resistance testing for marine and chemical applications
Unique Selling Points
- Ice Storage Optimization: Coil geometry is specifically engineered for External Ice Melt (EIM) systems, providing optimal heat transfer coefficients (U-value: 350–600 W/m²·K) between glycol fluid and ice/water, validated through CFD modeling and experimental testing.
- Cyclic Durability: Proven performance over 10,000+ freeze-thaw cycles with zero structural degradation, ensuring 15–20 year service life in ice storage applications.
- Custom Engineering: Full customization of coil diameter, pitch, length, material grade, and end connections to match specific system design requirements and installation constraints.
- Low Pressure Drop Design: Optimized coil geometry minimizes hydraulic resistance (ΔP < 50 kPa at design flow rates), reducing pumping energy consumption by up to 20% compared to standard coil configurations.
- Technical Support: Comprehensive engineering support including thermal performance calculations, pressure drop analysis, and system integration guidance based on industry literature and field experience.
"The coil-type external ice melt ice storage system represents a paradigm shift in peak-load management, where the stainless steel coil tube serves as the critical interface enabling efficient latent heat utilization. Wenzhou Jixing Metal Materials Co., Ltd. delivers precision-engineered coil tubes that meet the exacting demands of thermal energy storage applications."