Our coaxial heat exchangers (also known as double pipe heat exchangers) are designed for efficient heat transfer in HVAC, heat pump, chiller, and refrigeration applications. Built with an enhanced inner tube and a durable outer tube structure, they offer compact design, reliable thermal performance, and long service life under demanding operating conditions.
This design is commonly referred to as a tube-in-tube heat exchanger or coaxial tube heat exchanger, where one tube is positioned inside another to create a highly efficient heat transfer path. Depending on the application, it may also be described as a coil-type or spiral tube heat exchanger, especially when formed into helix or coiled configurations.
As a professional coaxial heat exchanger manufacturer, KAK offers customized solutions for OEMs, equipment manufacturers, and industrial buyers. Our products are widely used in residential and commercial air conditioning systems, heat pump water heaters, water chillers, geothermal heat pump systems, refrigeration equipment, marine cooling systems, and other industrial cooling or heating applications.
Product Overview
The coaxial tube-in-tube architecture is engineered for superior thermal management between two media. By optimizing the fluid velocity and surface area within the concentric tubes, this structure significantly enhances turbulence, which not only improves heat transfer efficiency but also provides a natural anti-fouling effect to reduce maintenance during long-term operation.
Compared with bulkier conventional designs such as shell and tube heat exchangers, KAK’s coaxial units offer a much more compact footprint and a lower refrigerant charge. This makes them the ideal choice for high-performance systems where space, efficiency, and reliability are critical. Our coaxial designs are optimized for series production and industrial-scale HVAC, chiller, and heat pump projects.
Our manufacturing flexibility allows for multiple coil profiles, including trombone shape, rectangular shape, helix (round) shape, spiral shape, and double-helix shape. To further maximize performance, we offer various inner tube enhancements such as spiral grooves or mesh-tooth surfaces to meet specific pressure drop and BTU requirements.
Key Features
- Space-Saving Design: Compact tube-in-tube structure ideal for restricted equipment cabinet spaces.
- High Thermal Efficiency: Corrugated or enhanced inner tube surfaces maximize heat exchange rates.
- System Stability: Engineered for Low Pressure Drop, ensuring stable performance in high-efficiency cycles.
- Custom Coil Profiles: Available in helix, spiral, and serpentine tube heat exchanger configurations to fit your specific layout.
- Self-Cleaning Effect: High internal turbulence prevents sediment buildup in water-side applications.
- Multi-Circuit Capability: Flexible circuiting options including 3, 4, 6, or 8 inner tube configurations.
- Corrosion Resistance: Wide range of material options suitable for marine and harsh industrial environments.
- High-Pressure Reliability: Optimized for modern refrigerants with working pressures up to 12 MPa.
Available Materials
Inner Tube Materials
- Corrugated Copper / Cupronickel (CuNi)
- Stainless Steel 304 / 316
- Titanium / Titanium Alloy
- Hastelloy (for extreme chemical corrosion)
Outer Tube Materials
- Copper / Steel / Stainless Steel
- Epoxy-coated Carbon Steel
Technical Specifications
| Parameter | Specification |
|---|---|
| Product Type | Coaxial / Double Pipe / Tube-in-Tube |
| Capacity Range | 1 kW – 200 kW (Customizable) |
| Max Working Pressure | 8MPa(Water Side) 12MPa(Refrigerant Side) |
| Refrigerant Compatibility | R410A, R32, R290, R134a, R407C, R404A, etc. |
| Certification | UL, CE, RoHS compliant options available |
Custom Manufacturing & OEM
As a leading coaxial heat exchanger manufacturer, we provide full engineering support from drawing-based manufacturing to custom coil layouts. Whether you need a titanium coil for a marine chiller or a high-pressure unit for a CO2 heat pump, KAK delivers reliable solutions with fast technical response.
Why Choose KAK
- Professional manufacturer focused on HVAC and refrigeration components
- Wide material and structure options for different operating environments
- Stable product quality and reliable thermal performance
- Support for OEM customization and engineering-based production
- Fast response for technical discussion, quotation, and project support
Request a Quote & Engineering Support
- Fast Support: Download Coaxial Selection Data Sheet
- Get precise thermal calculations and dimensions for your HVAC, Heat Pump, or Cryogenic project.
Ready for a Custom Solution? Send your specs (BTU, pressure drop, refrigerant) to sales@kakhvacr.com or [GET A QUOTE].
Typical Models for Reference
The models below are typical reference models. Custom dimensions, materials, capacities, and connection types are available upon request.
| Model | Inner Tube Material | Outer Tube Material | Capacity (kW) | Length (mm) | Outer Diameter (mm) | Typical Application |
|---|---|---|---|---|---|---|
| KAK-K-1.5 | Copper | Copper | 1.5 | 300 | Φ90 | Compact chillers |
| KAK-K-3 | Copper | Copper | 3.0 | 450 | Φ100 | Standard air conditioning units |
| KAK-K-5 | Copper | Copper | 5.0 | 600 | Φ120 | Heat pump systems |
| KAK-K-8 | Copper | Copper | 8.0 | 750 | Φ133 | Medium chillers |
| KAK-K-12 | Copper | Copper | 12.0 | 1000 | Φ159 | Large air conditioning or water chiller systems |
| KAK-KS-5 | Stainless Steel | Copper | 5.0 | 600 | Φ120 | Corrosive environments |
| KAK-KS-12 | Stainless Steel | Stainless Steel | 12.0 | 1000 | Φ159 | Industrial applications |
FAQ
Q1: What refrigerants are compatible with your coaxial heat exchangers?
Our coaxial heat exchangers are compatible with most common refrigerants used in HVAC and refrigeration systems, including R22, R134a, R407C, R410A, R32, R290, R404A, R454C, and others.
Q2: Can the coaxial heat exchanger be customized?
Yes. We provide OEM and custom manufacturing services. Tube material, coil shape, heat transfer capacity, tube diameter, circuit number, length, and connection type can all be customized according to your project requirements.
Q3: What is the typical service life of a coaxial heat exchanger?
The typical service life is approximately 5–10 years depending on operating conditions, water quality, system pressure, and maintenance. Proper installation and suitable materials can help extend the service life in demanding environments.
Q4: Can these heat exchangers be used in seawater or corrosive environments?
Yes. For corrosive environments such as seawater or industrial water systems, stainless steel 316, cupronickel, or titanium tube options are available depending on the corrosion resistance required by the application.
Q5: What certifications or compliance documents can you provide?
We can provide compliance documentation upon request, including PED (2014/68/EU) compliance documentation, CE-related support documents, RoHS compliance declaration, REACH SVHC statement, and UL-related documentation if required.
Q6: What capacity range do your coaxial heat exchangers cover?
Our coaxial heat exchangers typically cover a capacity range from 1 kW to 200 kW, depending on design and application. Custom capacities can also be developed for specific HVAC, heat pump, chiller, and refrigeration systems.
Q7: What information is needed to select a suitable coaxial heat exchanger?
To select a suitable model, we typically require the following information:
- Refrigerant type
- Required heat transfer capacity
- Water flow rate
- Water-side inlet and outlet temperature
- Operating pressure
- Installation space or dimensional limits
Our engineering team can assist with model selection based on your project requirements.
Related Products