Stainless Steel Coil Tube — HVAC Dry Coil System Application Grade
Product Overview
The Stainless Steel Coil Tube (Product No. 902) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product designed for integration into direct evaporative fresh air dehumidification systems coupled with dry coil air conditioning architectures. This coil tube serves as the critical heat exchange conduit within dry coil units, enabling efficient sensible heat removal from conditioned air streams without introducing latent moisture into the indoor environment. The product represents a high-performance solution for advanced HVAC (Heating, Ventilation, and Air Conditioning) systems where precise thermal management and moisture control are paramount.
Unlike conventional water-cooled coil tubes that rely on latent heat transfer through condensation, the dry coil tube operates by circulating chilled water or refrigerant through tightly wound stainless steel tubing, achieving superior dehumidification efficiency when paired with direct evaporative cooling technology. This synergistic system architecture delivers enhanced indoor air quality (IAQ) while optimizing energy consumption.
Material & Properties
The coil tube is fabricated from high-purity austenitic stainless steel, selected for its exceptional corrosion resistance, thermal conductivity, and mechanical durability in demanding HVAC operating environments.
- Primary Material Grade: SUS304 / AISI 304 (18Cr-8Ni austenitic stainless steel) or SUS316 / AISI 316L (18Cr-10Ni-2Mo) for enhanced chloride resistance
- Surface Finish: Electropolished interior with Ra ≤ 0.4 μm to minimize flow resistance and prevent fouling
- Thermal Conductivity: 16.3 W/(m·K) at 20°C
- Operating Temperature Range: −40°C to +150°C
- Maximum Operating Pressure: 1.6 MPa (design pressure); 2.5 MPa (burst pressure)
- Corrosion Resistance: Superior resistance to condensation water, refrigerant, and humid air environments
- Hygienic Properties: Non-toxic, non-flavor-transferring, compliant with potable water contact standards
- Weldability: Excellent; suitable for TIG (Tungsten Inert Gas) and orbital welding
Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Outer Diameter (OD) | 6.35 / 9.52 / 12.7 / 15.88 (customizable) | mm |
| Wall Thickness | 0.5 / 0.8 / 1.0 / 1.2 | mm |
| Coil Pitch (Center-to-Center) | 12 / 15 / 18 / 20 | mm |
| Coil Diameter | 100 – 500 | mm |
| Tube Length per Coil | 3 – 50 | m |
| Reel/Coil Weight | 50 – 500 | kg |
| Surface Roughness (ID) | ≤ 0.4 | μm (Ra) |
| Surface Roughness (OD) | ≤ 0.8 | μm (Ra) |
| Dimensional Tolerance (OD) | ±0.05 | mm |
| Dimensional Tolerance (Wall) | ±10% | % |
| Helix Angle | 0° – 2° | degrees |
| Applicable Fluids | Chilled water, glycol-water mixture, refrigerant (R-410A, R-32, R-134a) | — |
| Standard Reference | GB/T 12771, ASTM A269, EN 10217-7 | — |
Manufacturing Process
The production of this stainless steel coil tube follows a rigorous multi-stage manufacturing workflow to ensure dimensional precision, material integrity, and performance reliability:
- Raw Material Selection & Inspection: Certified stainless steel strip from accredited mills undergoes spectroscopic analysis (PMI — Positive Material Identification) to verify chemical composition compliance.
- Cold Forming / Roll Forming: Precision roll-forming equipment shapes the strip into seamless tubular profiles with controlled wall thickness and roundness.
- Welding (if applicable):strong> High-frequency induction welding or TIG welding with 100%氩气 (argon) internal shielding ensures full-penetration weld integrity.
- Heat Treatment: Solution annealing at 1050–1100°C followed by controlled cooling to eliminate residual stresses and restore full austenitic microstructure.
- Coil Winding: Computer-controlled winding machines form the tube into precise helical coils with exact pitch and diameter specifications.
- Electropolishing: Electrochemical polishing of the interior surface achieves hygienic smoothness (Ra ≤ 0.4 μm), removing micro-roughness that could impede fluid flow or promote biofilm formation.
- Pressure Testing & Leak Detection: Every coil undergoes hydrostatic pressure testing at 1.5× design pressure with automated leak detection systems.
- Final Inspection & Packaging: Dimensional verification, visual inspection, and protective packaging with moisture barriers for shipment.
Applications
The stainless steel coil tube is engineered for a broad spectrum of high-performance thermal management applications:
- Direct Evaporative Fresh Air Dehumidification Systems: Serves as the core component in dry coil units that work in tandem with direct evaporative coolers to achieve efficient total heat removal from ventilation air.
- Hospital & Cleanroom HVAC: Critical applications requiring hygienic, corrosion-resistant heat exchange surfaces in operating theaters, pharmaceutical manufacturing, and semiconductor fabrication facilities.
- Commercial Building Air Conditioning: High-end commercial complexes, data centers, and server rooms requiring precise temperature and humidity control.
- Food & Beverage Processing: Refrigeration and cooling systems in food processing plants where sanitary standards are mandatory.
- Marine & Coastal Environments: HVAC systems on vessels and coastal facilities exposed to high-chloride, corrosive atmospheres.
- Industrial Process Cooling: Precision temperature control in chemical processing, electronics manufacturing, and laboratory environments.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and product certifications to ensure international market compliance:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- CE Marking — European Conformity for mechanical and pressure equipment directives
- EN 10204 3.1 — Material Test Reports (third-party inspection)
- GB/T 19001 — Chinese National Quality Management Standard
- PED (Pressure Equipment Directive) 2014/68/EU — Compliance for pressure vessel and piping components
- NSF/ANSI 61 — Drinking water system components (where applicable for potable water circuits)
Unique Selling Points
1. Superior Dehumidification Efficiency: Optimized coil geometry and high-thermal-conductivity stainless steel construction maximize sensible heat transfer coefficient, reducing energy consumption by up to 30% compared to conventional copper tube dry coils when integrated with direct evaporative systems.
2. Elimination of Corrosion & Scaling: Unlike carbon steel or copper alternatives, austenitic stainless steel coil tubes resist internal scaling and external corrosion, ensuring stable performance over extended service life exceeding 20 years without degradation of heat transfer capability.
3. Hygienic Interior Surface: Electropolished Ra ≤ 0.4 μm interior surface prevents biofilm accumulation and ensures compliance with pharmaceutical and food-grade sanitary requirements.
4. Precision Manufacturing: CNC-controlled winding ensures coil pitch uniformity within ±0.1 mm, guaranteeing consistent airflow distribution across the entire coil face and eliminating performance hotspots.
5. Full Traceability: Each coil batch is accompanied by complete material traceability documentation, mill certificates, and process test records in accordance with EN 10204 3.1 requirements.
Research Context
This product specification incorporates findings from the academic study "Performance Research on Direct Evaporative Fresh Air Dehumidification and Dry Coil Air Conditioning System" (Direct Evaporative Fresh Air Dehumidification Combined with Dry Coil Air Conditioning System — Performance Investigation). The research demonstrates that the integration of stainless steel dry coil tubes with direct evaporative coolers achieves a combined system COP (Coefficient of Performance) improvement of 15–25% over standalone conventional air conditioning systems, while simultaneously providing superior humidity control and enhanced ventilation air quality. The coil tube geometry parameters specified herein have been validated through computational fluid dynamics (CFD) simulation and experimental testing under representative operating conditions (dry-bulb temperature: 35°C, relative humidity: 70%, air velocity: 2–3 m/s).