The coaxial economizer subcooler series is specially engineered for advanced refrigeration and HVAC systems to enable high-efficiency heat exchange between high-pressure liquid refrigerant and low-pressure suction vapor. Featuring a compact tube-in-tube design with a spirally corrugated inner tube, it substantially increases system energy efficiency (COP), provides essential subcooling to eliminate flash gas, and serves as a reliable pressure-rated containment barrier for next-generation refrigerants.
Key Features & Technical Advantages
- Optimized Counter-Flow Efficiency: Designed for low-pressure vapor flow in the inner tube and high-pressure liquid flow in the outer annulus, maximizing logarithmic mean temperature difference (LMTD) for this coaxial economizer subcooler.
- Spirally Corrugated Inner Tube: Creates high fluid turbulence to disrupt thermal boundary layers, increasing heat transfer performance by up to 2–3 times over smooth tubes while resisting fouling.
- High Pressure Durability: Constructed from premium ACR copper with silver-brazed joints, rated for working and inspection pressures up to 650 PSI (4.5 MPa).
- A2L Refrigerant & Corridor Safety Compliant: Straight tube-in-tube design serves as an ideal outer containment sleeve, fully meeting NYC LL77 and ASHRAE 15 safety requirements for A2L refrigerants (e.g., R32, R454B) running through public corridors.
- Compact Straight-Pipe Architecture: Requires minimal installation space and connects seamlessly into straight piping runs without complex bending or custom manifold setups.
Applications & Installation Guidelines
The coaxial economizer subcooler is widely utilized in commercial air conditioners, chillers, heat pumps, and transport refrigeration units. To achieve peak thermodynamic performance, the system should be plumbed in a counter-flow arrangement. Furthermore, its robust dual-wall construction ensures absolute safety and compliance when routing lines through public spaces.
Technical Specifications
| Model | Capacity (kW) | Length A (mm) | Connection B ID (mm) | Connection C ID (mm) |
|---|---|---|---|---|
| KAK-9005TT-Z | 0.5 | 160 | 12.7 | 9.52 |
| KAK-9010TT-Z | 1.0 | 260 | 12.7 | 9.52 |
| KAK-9015TT-Z | 1.5 | 330 | 12.7 | 9.52 |
| KAK-9020TT-Z | 2.0 | 415 | 12.7 | 9.52 |
| KAK-9025GT-Z | 2.5 | 500 | 12.7 | 9.52 |
| KAK-9030GT-Z | 3.0 | 560 | 12.7 | 9.52 |
General Frequently Asked Questions (FAQ)
Q1: What is the primary function of a coaxial subcooler/economizer in a refrigeration circuit?
It exchanges thermal energy between the high-pressure liquid leaving the condenser and the low-pressure suction gas returning to the compressor. This increases liquid subcooling to prevent flash gas at the expansion valve, boosts refrigeration capacity, and superheats suction gas to protect the compressor from liquid slugging.
Q2: What are the advantages of using a spirally corrugated inner tube over a smooth tube?
The spirally corrugated inner surface induces continuous multi-dimensional fluid turbulence. This disrupts the thermal boundary layer, enhances heat transfer coefficients by 200%–300% compared to smooth copper tubing, and significantly reduces internal fouling buildup.
Q3: Which refrigerants are compatible with this subcooler series?
Thanks to its heavy-duty copper construction and high-integrity silver brazing, the series is fully compatible with standard HFCs, HFOs, and Class A2L mildly flammable refrigerants, including R410A, R134a, R32, R454B, and R407C.
Q4: What is the operating pressure rating and leak testing standard?
Every unit undergoes 100% factory pressure and helium leak testing. Standard working pressure is rated up to 4.5 MPa (650 PSI), with burst pressure testing exceeding 15 MPa to ensure maximum reliability under demanding field conditions.
Q5: How do I determine the right model capacity for my system?
Selection depends on total system cooling tonnage, operating evaporating and condensing temperatures, refrigerant type, and desired subcooling degrees. Standard capacities range from 0.5 kW to 3.0 kW (Models KAK-9005TT-Z to KAK-9030GT-Z). Contact our engineering team for precise sizing assistance.
Q6: Are custom lengths, port sizes, or mounting configurations available?
Yes. While standard overall lengths range from 160 mm to 560 mm, full OEM/ODM customization is available for overall length, inner/outer tube diameters, connection fitting types (sweat, thread, press-fit), and custom bracket mounting positions.
Q7: What is the recommended orientation for installation?
For optimal thermodynamic performance, units should be installed in a counter-flow configuration (liquid refrigerant and vapor refrigerant flowing in opposite directions). Units can be mounted either horizontally or vertically to fit machine cabinet dimensions.