Knowledge base
The finned coil of a radiator or dry cooler can be built from copper, aluminium or a combination of the two, and the choice decides more than the price: it decides how the coil behaves with the coolant, in the site's atmosphere and after twenty years. This guide compares the common constructions - copper tube with aluminium fins, all-aluminium, and copper tube with copper fins - on the points that matter.
Copper Tube, Aluminium Fins: The Standard
Most industrial radiators and dry coolers use copper tubes with aluminium fins. Copper conducts heat well, resists the inhibited water-glycol coolants of engines, is easy to braze and repair, and tolerates the pressure and vibration of an engine circuit. Aluminium makes a light, cheap and efficient fin. The tubes are mechanically expanded into the fin collars, and the quality of that contact is the quality of the coil.
Its weak point is the contact between the two metals: in salty or polluted air the aluminium fin corrodes galvanically at the copper tube. For coastal and industrial sites the answer is an aluminium-magnesium fin alloy such as AlMg2.5, an epoxy coating over the whole coil, or both.
All-Aluminium Coils
All-aluminium coils - aluminium tubes, or flat microchannel tubes brazed to aluminium fins - avoid the copper-aluminium couple, weigh less and use less material. They are widespread in automotive radiators and air-conditioning condensers. For engine and process coolants they need care: aluminium is sensitive to coolant chemistry, to pH and to contact with other metals in the circuit, and a leak in a brazed microchannel coil is generally not repairable on site. For heavy-duty engine cooling, copper tubes remain the common choice.
Copper Fins And Other Options
Copper tube with copper fins gives the best corrosion resistance against salt air and the highest conductivity, at the price of a much heavier and more expensive coil; it is chosen for some marine and offshore duties. Steel and stainless steel tubes are used where the pressure, the temperature or the fluid rules out copper. Whatever the construction, the casing, the collectors and the fasteners follow the same corrosion class as the coil.
TECS builds its coils with copper tubes and aluminium fins as standard, with AlMg2.5 fins and epoxy coatings for aggressive sites, and selects the construction with the coolant, the site and the life the customer expects. Send the duty and the site conditions, and the proposal states the coil construction and the corrosion protection.
In Short
- Copper tube, aluminium fin: the standard for engine and process coolants
- Galvanic corrosion at the copper-aluminium contact in salty air: AlMg2.5 fins or epoxy coating
- All-aluminium: lighter, sensitive to coolant chemistry, hard to repair
- Copper fins: best corrosion resistance, heavier and dearer
- Steel and stainless tubes for high pressure and aggressive fluids
- TECS standard: Cu/Al, with AlMg2.5 and epoxy for aggressive sites
What To Send With An Enquiry
- Coolant and its chemistry, or the engine maker's coolant specification
- Site atmosphere: distance to the sea, industry nearby, corrosion class
- Design pressure and temperature
- Expected service life
- The usual thermal data: heat, flows, temperatures, ambient
- Any owner's material specification
Questions We Are Often Asked
Is copper or aluminium better for a radiator?
For heavy-duty engine and process cooling, copper tubes with aluminium fins give the best balance of heat transfer, durability, repairability and cost. All-aluminium coils are lighter and cheaper but more sensitive to coolant chemistry.
Why do aluminium fins corrode at the coast?
Salt air turns the contact between copper tube and aluminium fin into a galvanic cell that dissolves the aluminium. AlMg2.5 fins corrode much more slowly, and an epoxy coating seals the contact.
Can an aluminium radiator be repaired?
Brazed aluminium and microchannel coils are generally not repairable on site; copper-tube coils can be brazed and plugged.
Does the fin material change the capacity?
Slightly: aluminium alloys and coatings conduct a little less, which the design compensates with surface. The datasheet capacity includes the chosen construction.
What does TECS use?
Copper tubes with aluminium fins as standard, AlMg2.5 fins and epoxy coating for coastal, offshore and industrial sites.
Contact Us
Send us the heat duty, the fluid temperatures and flow rates, the ambient conditions and the installation limits. We answer with a design proposal - or write to us on WhatsApp.
