Tens of millions of car radiators are produced annually in Europe alone. They are usually made of metal, but experts from the Faculty of Mechanical Engineering at BUT have been working for several years on the development of a completely new type of a radiator made of hollow polymer fibres. The first-generation prototype has already been tested in a car, but the new type of an exchanger could also be used in air conditioning units, in battery cooling or in places where a metal radiator is not suitable, for example, due to corrosion.
At first glance, it looks like an ordinary radiator. In fact, it is a completely new generation of heat exchangers, on which BUT has been working at the Faculty of Mechanical Engineering since 2007. The exchanger forms a network of hollow polymer fibres interwoven with textile fibre to keep the polymer where it should be and allow the air to flow around it. “The fibres have an outer diameter of about 1 millimetre. It is possible to produce a fibre with a diameter of up to 0.4 millimetres, but although smaller fibres transfer heat better, they have other limits, so it is necessary to look for the golden mean,” Tereza Kroulíková, who is working on the research, explains.
At the beginning of the development, experts from the Laboratory of Heat Transfer and Convection were inspired by an idea from abroad, namely to use polymers for heat exchange. However, since the polymers themselves do not conduct heat very well, carbon is added to them or they are used in the form of hollow fibres with the thinnest possible wall. The impetus for the development of these radiators came from industry. “For example, you cannot put a metal radiator in a chemically active environment because it corrodes very quickly, while many plastics resist better. Another advantage is the lower weight of the polymer exchanger. And also the fact that plastics are cheaper, easier to machine and recycled plastics could be used for the production, which reduces the environmental burden,” Kroulíková describes.
In their research, the group led by Tereza Kůdelová is deciding how to use the heat exchanger for the automotive industry. They have completed their first test drive, where a polymer fibre exchanger was installed instead of a conventional radiator. It was cooled by air outside, and by a mixture of circulated water and antifreeze, which is commonly used in cars, inside. “It’s the so-called first-generation prototype, which we will now test in the test room. In the next two years, an improved prototype of the second generation should be created, and if it goes well, we should also go through tests with the car on the circuit,” Kroulíková believes.
Companies also cooperate in the development
The engineers from Brno are not alone in developing new radiators. They cooperate with the Technical University of Liberec in the production of prototypes, which can weave a heat exchange surface from polymer fibres. Three companies from the automotive industry and plastics processing are also involved in the development.
Researchers are now working on how to deal with some of the limitations of the new technology. One of them is how the current relatively complex experimental production could become simpler, or even serial. In addition to the development of the car radiator, they are also interested in other uses in the automotive industry. “The potential is in air conditioning units, cooling of electronics or batteries, which is a current issue, for example, in the case of electric cars. This material has the advantage that it is non-conductive, so no additional insulation is needed, the exchanger is an insulator in itself,” Kroulíková concludes and hopes that the new type of heat exchangers could find wide use in practice.
Source: Brno University of Technology