An aluminium or plastic counterflow heat exchanger?

To find the answer, we need to remind ourselves of the basic physical and mechanical properties of both materials. As we conclude, we’ll run once more through a summary of the issues.

Aluminium

Specific weight (density): 2,7 kg/dm³
Strength: 100 Mpa
Thermal conductivity: 221 W⋅m^-1⋅K^-1
Elongation (ductility): 15%

Plastic

Specific weight (density): 1,05 kg/dm³
Strength: 43 Mpa
Thermal conductivity: 0,043 W⋅m^-1⋅K^-1
Elongation (ductility): 125%

How individual parameters affect the heat exchanger

1. Specific weight

This parameter shows that the same amount of plastic will be 2.5 times lighter than aluminium. Plastic wins the first point… but the second parameter levels the match straight away.

2. Strength

Plastic has approximately 2.5 less strength, meaning a greater material thickness must be used to ensure the heat exchanger’s plate can resist pressure ratios inside the unit. So far, a tie.

3. Heat transfer coefficient

The winner here is definitely aluminium. By far. But because the thickness of both materials starts at zero, this parameter is not as influential as one might, at first glance, imagine.

If the material thickness were theoretically zero, the effect of the parameter would be none at all. Thus, aluminium moves in front.

4. Elongation (ductility)

This parameter significantly affects the plate shape and enables plastic to catch up.

Plastic’s substantially greater ductility allows for more waves in the counterflow part, resulting in a larger heat-transfer area (essential for efficiency) and, therefore, allowing for relatively larger spacing between plates (in comparison with aluminium).

5. Price

Price is the last, but not least, parameter. The price of one kilogram of plastic is lower; however, the plastic’s thickness is three times greater with a 2.5 times smaller specific weight, which means the material price of one plate is very similar to aluminium.

Nevertheless, fewer plates can be used in plastic heat exchangers due to the larger heat-transfer area. Therefore, the price of plastic heat exchangers is usually slightly lower than the price of aluminium heat exchangers.

Practical comparison

REK+27-300-22 – Aluminium

Input: 5°C, Humidity: 72%
Output: 25°C, Humidity: 28%
Flow rate: 300 m³/h
Heat exchanger height: 300 mm
Plate spacing: 2.2 mm

Output

Efficiency: 80.2%
Pressure drop: 114 Pa
Approximate price: more expensive by 10%
than the plastic version

REP+27-300-32 – Plastic

Input: 5°C, Humidity: 72%
Output: 25°C, Humidity: 28%
Flow rate: 300 m³/h
Heat exchanger height: 300 mm
Plate spacing: 3.2 mm

Output

Efficiency: 75.2%
Pressure drop: 118,8 Pa
Approximate price: cheaper by 10%
than the aluminium version

The comparison shows that the winner in technical parameters is the aluminium heat exchanger. But pricewise the plastic heat exchanger come out on top. So it’s up to you to choose the version which best suits your need 🙂.

Choose your favourite!

In conclusion, let’s summarize the pros and cons of both solutions.

Aluminium heat exchanger

Greater pressure resistance
More resistant to higher temperatures
No cracks or fragility at lower temperatures
Low flammability

Plastic heat exchanger

Lower weight
Compact dimensions
Corrosion resistance
Lower price

View our products

We believe you’ll find your optimal solution somewhere in our wide product range. Many of our customers prefer plastic heat exchangers for residential applications and aluminium heat exchangers for commercial applications. Whichever you choose, you can rely on the superior quality and excellent processing of RECUTECH heat exchangers.

Aluminium Heat Exchangers

Plastic Heat Exchangers

Calculate your own parameters