Stainless Steel Ice Storage Coil Tube (Coiltube)
Product Overview
The Stainless Steel Ice Storage Coil Tube (Coiltube) is a specialized thermal energy storage component manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is engineered for ice-based thermal energy storage systems (Ice Thermal Energy Storage, ITES), where the coil tube serves as the primary heat exchange surface through which refrigerant transfers thermal energy to form a controlled ice layer on the outer tube surface. The coiltube design enables efficient latent heat storage and retrieval, making it an integral component in peak-shaving air conditioning systems, district cooling networks, and industrial process cooling applications.
The product has been validated through rigorous experimental research, including ice layer thickness measurement studies and external ice storage performance characterization, confirming its reliability and thermal efficiency in practical applications.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its superior combination of thermal conductivity, corrosion resistance, and mechanical integrity under cryogenic conditions.
- Base Material: Austenitic Stainless Steel (Type 304 / 316L) conforming to ASTM A269 / ASME SA-213 standards
- Thermal Conductivity: 14–16 W/(m·K) at ambient temperature, ensuring efficient heat transfer to the surrounding water medium for ice formation
- Cryogenic Performance: Maintains mechanical strength and ductility at temperatures as low as −40°C, critical for ice storage cycling applications
- Corrosion Resistance: Excellent resistance to chloride-induced pitting and general corrosion in water-based thermal storage tanks
- Surface Finish: Electropolished or mechanically polished inner surface (Ra ≤ 0.4 μm) to minimize refrigerant flow resistance and prevent ice nucleation on the inner wall
Specifications
| Parameter | Specification |
|---|---|
| Tube Outer Diameter (OD) | 12 mm / 16 mm / 19 mm / 22 mm (customizable) |
| Tube Wall Thickness | 0.8 mm – 1.5 mm |
| Coil Pitch (Center-to-Center Spacing) | 20 mm – 50 mm (adjustable based on ice layer thickness requirement) |
| Coil Diameter | 300 mm – 1200 mm |
| Coil Length | Up to 50 m (continuous coil) |
| Refrigerant Flow Rate | 0.5 – 5.0 L/min (per coil circuit) |
| Operating Refrigerant Temperature | −15°C to −5°C (typical ice formation range) |
| Ice Layer Thickness (Designed) | 5 mm – 20 mm (controlled via coil pitch and flow parameters) |
| Operating Pressure (Tube Side) | ≤ 2.5 MPa (refrigerant side) |
| Design Life | ≥ 20 years (50,000+ freeze-thaw cycles) |
| Standards Compliance | ASTM A269 / ASME SA-213 / GB/T 12771 |
Manufacturing Process
- Material Selection & Inspection: Raw stainless steel tubes are procured from certified suppliers and subjected to spectroscopic analysis (PMI) to verify chemical composition, followed by hydrostatic pressure testing for wall integrity.
- Tube Straightening & Cutting: Precision straightening ensures uniform roundness (ovality ≤ 0.5%) prior to coil forming. Tubes are cut to specified lengths with burr-free end preparation.
- Coil Forming: Cold coiling is performed using a precision coil winding machine with controlled die geometry to achieve the specified coil diameter, pitch, and cross-sectional profile without work hardening or dimensional deviation.
- Welding & Brazing: Inlet and outlet headers are connected via orbital TIG welding (GTAW) or silver brazing, ensuring leak-tight joints rated for long-term pressure cycling.
- Surface Treatment: Optional electropolishing or passivation treatment is applied to enhance corrosion resistance and reduce frictional losses during refrigerant flow.
- Quality Inspection: Each coil assembly undergoes 100% hydrostatic pressure testing, dimensional verification (laser scanning for coil geometry), and visual inspection for weld quality.
Applications
- Ice Thermal Energy Storage (ITES) Systems: Primary heat exchanger in water-to-ice storage tanks for commercial and industrial HVAC peak-shaving applications
- District Cooling Networks: Distributed thermal storage units connected to centralized chilled water plants
- Industrial Process Cooling: Latent heat storage for high-demand intermittent cooling loads in food processing, pharmaceutical manufacturing, and chemical plants
- Cold Chain Logistics: Ice storage containers for temperature-controlled transportation and warehousing
- Research & Development: Experimental platforms for ice layer growth dynamics, heat transfer coefficient measurement, and thermal storage system optimization
Unique Selling Points
- Validated Ice Storage Performance: Backed by experimental research on ice layer thickness measurement and external heat transfer characteristics, ensuring predictable and repeatable thermal storage behavior
- Optimized Coil Geometry: Coil pitch and tube diameter are engineered to balance ice layer formation rate against refrigerant pressure drop, maximizing system COP (Coefficient of Performance)
- Cryogenic Durability: Full austenitic stainless steel construction eliminates risk of brittle fracture during repeated freeze-thaw cycling
- Modular Design: Available in multiple coil diameters and lengths to accommodate various tank configurations and storage capacity requirements
- Low Fouling Resistance: Smooth inner surface finish minimizes scale deposition and maintains long-term heat transfer efficiency
Quality Certifications
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ASME "S" Stamp — Pressure Vessel and Piping Components (where applicable)
- ASTM A269 / ASME SA-213 — Material Conformance Certification
- GB/T 12771 — Chinese National Standard for Stainless Steel Tubes (Hydronic Heating)
- Third-Party Hydrostatic Pressure Testing Reports (per batch)
- NACE MR0175 / ISO 15156 — Resistance to Sulfide Stress Cracking (for 316L grade, where specified)
Technical Notes
The ice storage coil tube operates on the principle of external surface freezing. As sub-cooled refrigerant flows through the coil, heat is extracted from the surrounding water in the storage tank, causing a controlled ice layer to form on the outer tube surface. The thickness of this ice layer is governed by the refrigerant flow velocity, coil pitch, tube wall thermal resistance, and the heat transfer coefficient at the ice-water interface. Proper design of these parameters—validated through experimental ice layer thickness measurement—ensures optimal thermal storage density and retrieval efficiency.