Stainless Steel Coiltube for Closed Cooling Tower Systems
Product Overview
The Stainless Steel Coiltube (Product No. 1013) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coil tube product specifically designed for closed-loop cooling tower applications. This product integrates both dry and wet coiltube configurations into a hybrid closed cooling tower system, offering superior heat transfer efficiency, corrosion resistance, and long-term operational reliability. The coiltube serves as the primary heat exchange medium within the cooling tower, facilitating thermal energy dissipation through both evaporative (wet) and sensible (dry) cooling mechanisms.
This product line has been extensively validated through academic research on the structural design and performance analysis of hybrid dry-wet coiltube closed cooling towers, establishing its position as a state-of-the-art solution in industrial thermal management systems.
Material Composition & Properties
The coiltube is fabricated from high-grade austenitic stainless steel, typically conforming to AISI 304 (UNS S30408), AISI 316L (UNS S31603), or duplex stainless steel grades (e.g., UNS S31803), depending on the specific service environment and corrosion requirements.
- Chemical Composition: Carbon (C) < 0.08%, Chromium (Cr) 18–20%, Nickel (Ni) 8–10.5%, Molybdenum (Mo) 2–3% (for 316L grade)
- Tensile Strength: ≥ 520 MPa (AISI 304), ≥ 550 MPa (AISI 316L)
- Yield Strength: ≥ 205 MPa
- Elongation at Break: ≥ 40%
- Corrosion Resistance: Excellent resistance to pitting, crevice corrosion, and intergranular corrosion in chloride-containing environments
- Operating Temperature Range: −196°C to +400°C
- Thermal Conductivity: 16.3 W/(m·K) (at 20°C for AISI 304)
Technical Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Tube Outer Diameter (OD) | Φ 12 / Φ 15 / Φ 19 / Φ 25 / Φ 32 (customizable) | mm |
| Tube Wall Thickness | 0.5 / 0.6 / 0.8 / 1.0 / 1.2 | mm |
| Coil Pitch (Spacing) | 12 – 50 (adjustable based on heat load) | mm |
| Coil Diameter | Φ 300 – Φ 2000 (customizable) | mm |
| Tube Length per Coil | 5 – 50 (continuous forming) | m |
| Surface Finish | Ba < 0.5 μm (electropolished) / Ra ≤ 0.8 μm (passivated) | — |
| Pressure Rating | 0.6 / 1.0 / 1.6 / 2.5 (design pressure) | MPa |
| Heat Transfer Coefficient | 2,500 – 4,500 (wet section) / 1,500 – 3,000 (dry section) | W/(m²·K) |
| Applicable Fluids | Water, glycol-water mixtures, process fluids | — |
| Standards Compliance | ASTM A269, ASME B36.19M, EN 10217-7 | — |
Manufacturing Process
The production of the stainless steel coiltube involves a multi-stage precision manufacturing process to ensure dimensional accuracy, mechanical integrity, and surface quality:
- Material Preparation: Cold-rolled stainless steel strip is supplied from certified mills, undergoing incoming inspection for chemical composition, mechanical properties, and surface defects.
- Coil Forming: The flat strip is fed through a multi-roll progressive die forming system, gradually bending the strip into the desired coil geometry with controlled springback compensation.
- Welding: Where continuous-length coils are required, longitudinal welds are produced using Automatic Tungsten Inert Gas (ATIG) welding or Laser Welding (LW) technology, achieving weld strength equivalent to the parent material.
- Heat Treatment: Solution annealing (1050–1150°C followed by rapid water quenching) is performed to restore full austenitic structure and maximize corrosion resistance.
- Pickling & Passivation: The surface is treated with a mixed acid pickling solution (HNO₃/HF) followed by passivation to remove oxidation scale and form a protective chromium oxide layer.
- Quality Inspection: Each coil undergoes hydrostatic pressure testing, eddy current testing (ECT) for wall thickness uniformity, and dimensional verification per ASTM E165.
Applications
The hybrid dry-wet coiltube closed cooling tower system is applicable across a wide range of industrial and commercial sectors:
- Power Generation: Condenser cooling in combined cycle power plants, reducing water consumption by up to 90% compared to conventional open cooling towers.
- Chemical & Petrochemical Industry: Heat rejection for process streams in environments with aggressive chemical exposure.
- Pharmaceutical & Food Processing: Sanitary-grade heat exchange where fluid purity and contamination prevention are critical.
- Building Services (HVAC): Chilled water condenser heat rejection for commercial and institutional buildings.
- Oil & Gas: Separator cooling and wellhead back-pressure control systems in offshore and onshore installations.
- Renewable Energy: Thermal management for solar thermal power plants and geothermal systems.
Quality Certifications & Standards
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring adherence to international standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO 45001:2018 — Occupational Health and Safety Management
- ASME — American Society of Mechanical Engineers (pressure vessel components)
- API 5L / API 5CT — American Petroleum Institute standards (for oil and gas applications)
- CE Marking — Conformity with European directives
- TÜV / SGS Inspection — Third-party verification of product quality
Unique Selling Points
- Hybrid Dry-Wet Configuration: The combination of dry and wet coiltube sections enables optimized heat transfer across varying ambient conditions, achieving up to 95% thermal efficiency while significantly reducing water consumption and chemical treatment requirements.
- Superior Corrosion Resistance: The use of premium austenitic and duplex stainless steel grades ensures exceptional durability in aggressive environments, extending service life beyond 25 years with minimal maintenance.
- Precision Coil Geometry: Advanced progressive forming technology delivers uniform coil pitch and diameter tolerances within ±0.5 mm, ensuring optimal airflow distribution and heat transfer performance.
- Scalable & Customizable Design: Product dimensions, tube diameters, and coil configurations are fully customizable to match specific thermal load requirements and installation constraints.
- Academic Validation: Product performance has been validated through rigorous structural design and thermodynamic performance analysis published in peer-reviewed engineering literature, providing documented evidence of reliability and efficiency.
- Reduced Total Cost of Ownership (TCO): Lower water usage, reduced chemical consumption, minimal fouling, and extended service intervals translate to substantially lower lifecycle costs compared to conventional cooling tower alternatives.
Performance Analysis Summary
Based on comprehensive structural design analysis and performance evaluation of the hybrid dry-wet coiltube closed cooling tower system, the following key performance indicators have been established:
- Approach temperature (difference between outlet water temperature and wet-bulb air temperature): 3–5°C
- Range (inlet minus outlet water temperature): 5–10°C
- Heat rejection capacity: 100 – 5,000 kW per module (scalable)
- Water savings: 85–95% reduction compared to open cooling towers
- Energy consumption (fan power): 0.3 – 0.6 kW per 100 kW heat rejection
- Performance ratio (heat rejected per unit fan power): ≥ 1,200 kW/kW
Conclusion
The Stainless Steel Coiltube (No. 1013) from Wenzhou Jixing Metal Materials Co., Ltd. represents a cutting-edge solution for closed-loop thermal management. Backed by rigorous academic research, international quality certifications, and advanced manufacturing capabilities, this product delivers exceptional heat transfer performance, environmental sustainability, and long-term economic value across diverse industrial applications. The integration of dry and wet cooling sections within a single coiltube-based system marks a significant advancement in cooling tower technology, addressing the dual challenges of thermal efficiency and water resource conservation.