Stainless Steel Coil Tube for Thermal Energy Storage Systems
Product Overview
The Stainless Steel Coil Tube (盘管Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product specifically designed for advanced thermal energy storage (TES) applications, particularly ice-storage-based cooling systems. This coil tube serves as the critical heat exchange medium within novel energy storage systems—ice storage tanks—where the coil tube is immersed in water to facilitate controlled freezing and thawing cycles for peak-shaving and load-shifting operations in commercial and industrial HVAC systems.
The product combines the inherent corrosion resistance and mechanical integrity of austenitic stainless steel with a tightly wound helical geometry that maximizes heat transfer surface area per unit volume. This design philosophy has been validated through rigorous numerical simulation and experimental analysis of heat accumulation processes in coil-based ice storage tanks, demonstrating superior thermal performance compared to conventional finned-tube or plate heat exchanger configurations.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional performance in cryogenic and sub-zero thermal cycling environments. Key material characteristics include:
- Material Grade: SUS304 (ASTM 304 / UNS S30400), SUS316L (ASTM 316L / UNS S31603), and SUS321 (ASTM 321 / UNS S32100) available upon specification
- Chemical Composition: Chromium (Cr) ≥ 18%, Nickel (Ni) ≥ 8%, with optional Molybdenum (Mo) ≥ 2% for enhanced pitting corrosion resistance
- Mechanical Properties: Tensile strength ≥ 520 MPa; Yield strength ≥ 205 MPa; Elongation ≥ 40%
- Thermal Conductivity: Approximately 16.3 W/(m·K) at 20°C, maintaining structural integrity across temperatures from −40°C to +450°C
- Corrosion Resistance: Excellent resistance to oxidation, chlorides, and de-icing brine solutions; suitable for potable water and refrigerant contact
- Cryogenic Performance: Retains ductility and impact resistance at temperatures below −196°C, making it ideal for ice accumulation and release cycles
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管Coiltube) |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. |
| Material Grade | SUS304 / SUS316L / SUS321 |
| Outer Diameter (OD) | Φ8 mm – Φ32 mm (customizable) |
| Wall Thickness | 0.5 mm – 2.0 mm |
| Coil Pitch (Helix Spacing) | 5 mm – 25 mm (adjustable per thermal load requirement) |
| Coil Diameter (Overall) | Φ100 mm – Φ2000 mm |
| Tube Length (Unwound) | Up to 500 m per coil assembly |
| Surface Finish | 2B / BA (Bright Annealed) / Electropolished |
| End Form | Plain end / Flanged / Threaded / Socket-weld |
| Maximum Working Pressure | 1.6 MPa – 4.0 MPa |
| Operating Temperature Range | −40°C to +200°C |
| Tolerance (OD) | ±0.05 mm |
| Tolerance (Wall Thickness) | ±10% |
| Heat Transfer Coefficient | 2000–4500 W/(m²·K) (internal flow, depending on geometry) |
Manufacturing Process
The production of high-performance stainless steel coil tubes follows a meticulously controlled multi-stage manufacturing process:
- Raw Material Selection: Premium-grade cold-rolled stainless steel strip is sourced from certified mills, with each batch subjected to spectroscopic analysis for chemical composition verification.
- Slitting & Surface Preparation: The strip is precision-slitted to the required width and cleaned through chemical pickling and passivation to remove surface oxides and contaminants.
- Tube Forming (Cold Roll Forming): The flat strip is fed through a series of progressively shaped forming rollers to create a seamless circular cross-section. This process maintains the metallurgical integrity and grain structure of the material.
- Welding (if applicable): Longitudinal seams, where present, are welded using high-frequency induction welding (HF-W) or orbital TIG welding to achieve full-penetration welds with minimal heat-affected zones (HAZ).
- Coil Winding: The formed tube is helically wound around precision mandrels using computer-controlled winding machines to achieve exact pitch, diameter, and concentricity tolerances.
- Post-Winding Heat Treatment: Stress-relief annealing is performed at controlled temperatures (typically 1050°C followed by controlled cooling) to eliminate residual stresses from forming and winding operations.
- Hydrostatic Testing: Each coil assembly undergoes 100% hydrostatic pressure testing at 1.5× the maximum working pressure to verify structural integrity and weld quality.
- Surface Finishing: Final electropolishing or passivation treatment enhances surface smoothness and corrosion resistance.
- Quality Inspection: Comprehensive inspection including dimensional verification, surface defect detection (magnetic particle or dye penetrant), and material certification.
Applications
The stainless steel coil tube from Wenzhou Jixing Metal Materials Co., Ltd. is deployed across multiple high-performance engineering sectors:
- Ice Storage Thermal Energy Systems: Primary application in novel ice-storage tanks where coil tubes serve as the heat transfer interface between refrigerant and the phase-change medium (water/ice). Numerical simulations confirm that helical coil configurations achieve uniform ice formation and controlled release, optimizing the heat accumulation and discharge processes.
- Commercial Building HVAC: Peak-shaving and load-shifting systems that store cooling capacity during off-peak hours and release it during peak demand periods, reducing operational costs by 20–40%.
- Industrial Process Cooling: Continuous or intermittent cooling applications in chemical processing, pharmaceutical manufacturing, and food processing where temperature control is critical.
- Geothermal Heat Exchange: Borehole heat exchangers and ground-source heat pump systems where corrosion resistance and long-term durability are paramount.
- Cryogenic Applications: Liquid nitrogen storage, cryogenic separation processes, and superconducting equipment cooling circuits.
- Marine & Offshore Systems: Seawater heat exchangers and marine HVAC systems benefiting from the chloride resistance of 316L-grade coil tubes.
- Distillation & Separation Processes: Condensers and reboilers in petrochemical and distillation columns.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and ensures full compliance with international standards:
- ISO 9001:2015 — Quality Management Systems certification
- ISO 14001:2015 — Environmental Management Systems certification
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes
- GB/T 12771 — Chinese national standard for welded stainless steel tubes
- ASTM A269 / A269M — Standard specification for seamless austenitic stainless steel tubing
- ASTM A312 / A312M — Standard specification for welded austenitic stainless steel tubing
- EN 10216-5 — European standard for stainless steel tubes and pipes
- JIS G3446 — Japanese Industrial Standard for seamless stainless steel tubes
- ASME B36.19M — Pressure vessel and piping components
Unique Selling Points: The coil tube product distinguishes itself through (1) optimized helical geometry validated by numerical simulation of thermal energy storage processes, ensuring uniform heat transfer and predictable ice formation patterns; (2) full traceability from raw material to finished product with mill test certificates (MTC) per EN 10204 Type 3.2; (3) custom engineering capability to tailor coil geometry, material grade, and dimensions to specific thermal load requirements; (4) superior fatigue resistance under repeated freeze-thaw cycling, extending service life beyond 20 years; and (5) environmentally sustainable manufacturing with closed-loop water recycling and zero hazardous discharge.