Stainless Steel Coil Tube for Ice Storage Thermal Energy Systems

Product Series: Coiltube — Ice Storage Heat Transfer Coil Tube
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Code: 1046

1. Product Overview

The Stainless Steel Coil Tube for Ice Storage Thermal Energy Systems is a precision-engineered heat exchange component designed specifically for ice storage (Ice Accumulation) systems in commercial and industrial HVAC applications. This coil tube serves as the primary heat transfer medium within ice storage tanks, facilitating the phase-change process between water and ice during off-peak energy periods and enabling efficient cooling load delivery during peak demand periods.

Unlike conventional shell-and-tube heat exchangers, the coil tube configuration offers superior thermal conductivity, compact volumetric efficiency, and enhanced natural convection characteristics that are critical for the reliable operation of ice storage systems. The product is manufactured in accordance with rigorous international standards and is backed by extensive research into heat transfer performance optimization and system-level economic viability.

2. Material & Properties

2.1 Base Material

The coil tube is fabricated from high-purity austenitic stainless steel, primarily utilizing the following alloy grades:

• SUS304 / AISI 304: General-purpose grade offering excellent corrosion resistance, formability, and weldability. Suitable for standard ice storage applications with fresh water or glycol-based brine solutions.
• SUS316 / AISI 316: Enhanced molybdenum-containing grade providing superior resistance to chloride-induced pitting and crevice corrosion. Recommended for applications involving saltwater brine, coastal environments, or chemically aggressive heat transfer fluids.
• SUS316L / AISI 316L: Low-carbon variant of 316 grade, offering improved resistance to intergranular corrosion during welding and fabrication processes.

2.2 Key Physical and Mechanical Properties

• Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C — ensuring efficient heat transfer during both ice formation and melt-down cycles.
• Specific Heat Capacity: 500 J/(kg·K) — contributing to thermal mass stability during transient operating conditions.
• Density: 7,900–8,000 kg/m³ — providing structural rigidity without excessive weight penalty.
• Yield Strength (R_p0.2): ≥ 205 MPa (SUS304), ≥ 275 MPa (SUS316L) — ensuring resistance to mechanical deformation under hydrostatic pressure and thermal cycling.
• Tensile Strength (R_m): 520–750 MPa — guaranteeing long-term structural integrity under cyclic loading.
• Corrosion Resistance: Excellent resistance to oxidation, general corrosion, and stress corrosion cracking (SCC) in aqueous environments at temperatures ranging from −40°C to +200°C.
• Cold Work Formability: High ductility enabling precise coiling and bending without cracking or surface degradation.

3. Specifications

Parameter	Specification	Standard / Reference
Outer Diameter (OD)	6.35 mm – 25.4 mm (¼" – 1")	ASTM A213 / GB/T 14976
Wall Thickness	0.5 mm – 2.0 mm	ASTM A269 / EN 10217
Coil Diameter	150 mm – 600 mm (customizable)	Manufacturer Specification
Coil Length	5 m – 50 m per coil (customizable)	Manufacturer Specification
Surface Finish	No. 1 (Industrial), 2B (Bright Annealed), BA (Bright Annealed & Pickled)	ASTM A480
Surface Roughness (Ra)	≤ 0.8 μm (polished); ≤ 1.6 μm (standard)	ISO 4287
Operating Temperature Range	−40°C to +200°C	—
Maximum Operating Pressure	≤ 1.6 MPa (standard); ≤ 4.0 MPa (reinforced)	EN 10217-2
Heat Transfer Fluid Compatibility	Water, Ethylene Glycol (EG), Propylene Glycol (PG), Calcium Chloride Brine	—
End Connections	Flanged, Threaded, Soldered, or Welded (customizable)	ASME B1.20.1
Dimensional Tolerance	±0.05 mm (OD); ±10% (wall thickness)	ASTM A213
Coiling Pitch	1.5 × OD to 3.0 × OD (optimized for heat transfer)	Manufacturer Specification
Weight (Approximate)	0.12 – 0.85 kg/m (depending on OD and wall thickness)	—

4. Manufacturing Process

The production of high-performance ice storage coil tubes follows a rigorous multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and optimal heat transfer performance:

1. Material Selection and Inspection: Raw stainless steel wire or seamless pipe stock is sourced from certified mills. Each batch undergoes spectroscopic analysis (OES) to verify chemical composition, ultrasonic testing (UT) for internal defects, and visual inspection for surface imperfections.
2. Heat Treatment (Solution Annealing): The material is subjected to solution annealing at 1,050–1,150°C followed by rapid water quenching to achieve a fully austenitic microstructure with maximum ductility and corrosion resistance.
3. Precision Drawing: The pipe stock is cold-drawn through calibrated tungsten carbide dies to achieve the required outer diameter and wall thickness with tight dimensional tolerances. This process also introduces beneficial work hardening to enhance mechanical strength.
4. Precision Coiling: Using CNC-controlled coiling machinery, the drawn tube is wound into the specified coil geometry. The coiling process is carefully controlled to avoid excessive bending strain, surface scratches, or geometric deviations. The coil pitch and diameter are optimized through computational fluid dynamics (CFD) analysis to maximize heat transfer efficiency in the ice storage tank configuration.
5. Post-Coil Annealing (Optional): For applications requiring maximum ductility or where cold work hardening is undesirable, a stress-relief annealing cycle is performed at 850–900°C to restore full austenitic properties.
6. Surface Finishing: Depending on the specification, the coil tube undergoes pickling and passivation (to remove scale and form a protective chromium oxide layer), mechanical polishing, or electropolishing to achieve the required surface finish and surface roughness.
7. End Processing and Connection Fabrication: Coil ends are cut, deburred, and fitted with the specified connection types (flanges, threads, or welding preparation). Flanged connections are machined to ASME B16.5 standards.
8. Hydrostatic Pressure Testing: Each coil assembly is subjected to hydrostatic pressure testing at 1.5× the maximum operating pressure for a minimum dwell time of 10 minutes to verify leak-tightness and structural integrity.
9. Final Quality Inspection: Comprehensive dimensional measurement, visual inspection, and (where applicable) dye penetrant testing (PT) or magnetic particle inspection (MT) are performed prior to packaging and shipment.

5. Applications

5.1 Primary Application — Ice Storage Cooling Systems

The coil tube is the core heat exchange element in ice storage thermal energy storage (TES) systems, which are increasingly deployed in commercial buildings, hospitals, data centers, and industrial facilities for the following purposes:

• Peak-Shaving: Ice is formed during off-peak electricity hours (typically nighttime) using the coil tube as the refrigerant-to-ice heat transfer interface. During peak demand periods, the stored ice is melted to provide cooling, reducing peak electrical load and associated demand charges.
• Base-Loading: In systems with limited peak cooling capacity, the coil tube enables continuous ice formation to supplement the mechanical chiller output, effectively doubling the system's thermal capacity.
• Emergency Backup Cooling: Stored ice provides a reliable cooling reserve during chiller failures, power outages, or extreme weather events, ensuring occupant comfort and protection of sensitive equipment.

5.2 Secondary Applications

• Commercial Refrigeration: Ice storage for commercial ice makers, fish markets, and cold chain logistics facilities.
• Process Cooling: Temperature-controlled cooling loops in pharmaceutical manufacturing, food processing, and chemical production where precise thermal regulation is critical.
• Geothermal Heat Exchange: Coil tubes deployed in borehole heat exchanger arrays for ground-source heat pump (GSHP) systems, leveraging the corrosion resistance and thermal conductivity of stainless steel in subsurface environments.
• Marine and Offshore Systems: Ice-making and thermal management systems on vessels and offshore platforms where chloride resistance is paramount (SUS316/316L grades).
• Research and Development: Custom coil configurations for thermal energy storage research, including novel ice formation enhancement studies and system-level economic optimization research.

6. Quality Certifications and Standards Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring that all coil tube products meet or exceed international standards:

• ISO 9001:2015 — Quality Management System certification covering all aspects of design, manufacturing, inspection, and delivery.
• ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices.
• EN 10204 Type 3.1 — Third-party inspection certificates verifying material composition, mechanical properties, and dimensional compliance.
• ASTM A213 / A269 — Compliance with American Society for Testing and Materials standards for austenitic stainless steel seamless and welded tubing.
• GB/T 14976 — Compliance with Chinese national standards for seamless stainless steel tubes.
• EN 10217-2 — Compliance with European standards for seamless stainless steel tubes for pressure purposes.
• ASME B31.5 — Design and construction compliance for process piping, where applicable.
• Material Test Reports (MTR): Provided with every shipment, including chemical analysis, mechanical test results, and heat treatment documentation.

7. Unique Selling Points

Research-Validated Performance: This product line is developed and continuously optimized based on rigorous academic research into ice storage coil tube heat transfer performance and system-level economic analysis. The coiling geometry, material selection, and surface finish are informed by experimental data and computational modeling, ensuring that each coil tube delivers verified thermal performance in real-world ice storage applications.

• Superior Corrosion Resistance: The use of high-grade austenitic stainless steel (SUS304/316/316L) ensures decades of service life even in aggressive brine environments, eliminating the need for costly replacement or maintenance associated with carbon steel or copper alternatives.
• Optimized Heat Transfer Geometry: Coil pitch and diameter are engineered through CFD simulation and validated through experimental heat transfer testing, maximizing the heat transfer coefficient (U-value) and minimizing ice formation time — directly reducing operational energy costs.
• Customization Capability: Full customization of coil diameter, pitch, length, OD, wall thickness, surface finish, and end connections to meet specific system design requirements and tank geometries.
• Economic Efficiency: The coil tube design enables significant reduction in peak electricity demand charges (typically 30–50% reduction in peak load) through strategic ice storage and discharge, delivering rapid return on investment (ROI) for commercial building operators.
• Hygienic and Food-Safe: The stainless steel surface is non-toxic, non-porous, and easily sanitized, making the coil tube suitable for food-grade and pharmaceutical cooling applications without risk of contamination.
• Thermal Cycling Durability: Engineered to withstand thousands of freeze-thaw cycles without degradation of mechanical properties, dimensional stability, or heat transfer efficiency — ensuring consistent performance throughout the system's operational lifespan.
• Full Traceability: Every coil tube is traceable to its mill heat number, with complete documentation of material certification, manufacturing parameters, and inspection records provided to the end user.

8. Technical Support and Customization

Wenzhou Jixing Metal Materials Co., Ltd. offers comprehensive technical support for coil tube selection, system integration, and performance optimization. Engineering consultation is available for custom coil configurations, including CFD-based heat transfer analysis, structural stress evaluation, and system-level energy economic modeling to ensure optimal performance and cost-effectiveness for each specific application.

For detailed quotations, custom specifications, or technical inquiries, please contact the manufacturer directly with your application parameters, operating conditions, and system design requirements.