Evaporator and condenser performance is directly related to our aluminium tubes and products. Hydro supplies individual aluminium components and "all-in-one" HYVAC™ packages for two primary designs of heat exchangers (learn more on HYVAC™ packages):
- Mechanically expanded tube and fin heat exchanger
- Controlled atmosphere brazed (CAB) heat exchanger
Mechanically assembled heat exchanger
Click on the product pictures to learn more about the individual components:
The most common design today is the mechanically expanded tube and fin heat exchanger, with fins made of thin aluminium sheet and tubes of copper. Hydro can provide precision drawn tubes with or without internal enhancements to manufacture an all-aluminium heat exchanger.
The tubes are first inserted into a stack of fins. The tubes are pre-bended in hair pin shape. After insertion, the tubes are expanded. The expansion secures the thermal contact between tube and fin. Afterwards, U-bends are brazed to the tubes.
Change to all-aluminium design and save weight, space and cost
Savings, from an index 100, for standard copper tube and aluminium fin design to level:
• 80 on heat exchanger weight
• 40 on the cost (visit the comparison table)
The all-aluminium heat exchanger utilizes the same processes as used in traditional fin and tube heat exchanger manufacture. The tube expansion and brazing processes have to be tailored to the all-aluminium design.
Controlled atmosphere brazed heat exchanger
Click on the product pictures to learn more about the individual components:
Change to all-aluminium and brazed design releases the full potential of aluminium.
With an identical front surface on the airside, the brazed heat exchanger provides up to 10 percent added efficiency compared to a conventional fin and tube design. A lower thickness gives up to 50 percent lower pressure drop on the air side. This creates potential for lower energy consumption of the fan or, if desired, increased airflow. (Sensitivity to fouling can be expected to be lower.)
On the refrigerant side, the lower internal volume in the heat exchanger decreases the refrigerant charge.
Savings from index 100:
• 30 on required space
• 40 on heat exchanger weight
• 30 on the cost (visit the comparison table)
This compact design based on multi-port extrusions (MPEs) demands controlled atmosphere brazing (CAB), an oven-based process. Hydro supplies all parts needed to manufacture brazed heat exchangers. The parts can be delivered with Hybraz coating, ready for assembly and oven brazing. Hybraz is a combined flux and filler material. For more information, visit the Hybraz page.
- Increased Corrosion Resistance
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| Conventional coil vs All-aluminium brazed heat exchanger after 5000h salt mist / amonium sulphate test |
Unlike conventional coils, the brazed heat exchanger is made entirely of aluminium. This one-metal concept eliminates galvanic currents that are generated when different metals touch in conventional coils. Many comparative tests, including the salt mist and ammonium sulphate test, provide proof of the increased corrosion resistance of the all-aluminium brazed heat exchanger. Brazed heat exchangers offer three-and-a-half times higher corrosion resistance than traditional copper/ aluminium coils.
Brazed heat exchangers have lower internal volume and a smaller refrigerant charge is needed. The smaller charges imply decreased use of refrigerants.
- Condensation of water on evaporator fins.
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| Examples of fins designed for water drain-ability |
Operation in subfreezing conditions: Very high fin density (small distance between fins) can be achieved with MPE heat exchanger design. The cold surface of the fin will normally create condensation of water. If the fin density is too high, then the condensed water cannot drain by gravity or airflow. The fin density shall also be balanced with the speed of frost formation and drainability under defrosting. Hydro has performed wind tunnel tests of condensation, drainability, frost formation and defrosting. Based on its in-house knowledge, Hydro supports customers in brazed heat exchanger design. Fin design is the key.
Many internal flow concepts can be realized with all-aluminium brazed heat exchangers. In a condenser design, it is easy to tailor the internal port cross section to the specific volume of the refrigerant. As shown above, there is a reduction of port section downstream alongside the condensation process in the condenser.
