Working with heating fabrics based on conductive nanoparticles

The overall concept of the heating and cooling system being developed in JOSPEL is to reduce energy consumption. To achieve this goal, various different technologies are being applied, each with their own characteristics and benefits when it comes to performance and placement options. 

The reason for developing a heating fabric based on conductive nanoparticles is that its characteristics allows it to be integrated in strategic parts of the vehicle interior, such as floor mats, roof, seats and headrests.  Here, the radiant heat produced by the fabric helps maintain an adequate body temperature for the driver and the passengers, while also reducing the energy required to obtain a good thermal comfort inside the vehicle cabin.

The concept of a heating device based on textile is interesting because of the flexibility and weightlessness of the material. In addition, the use of electrically conductive nanoparticles offers excellent electrical properties that can be transferred to the fabric via a coating process with a specially designed colloidal dispersion.

Manufacturing a heating fabric

Essentially, the process of manufacturing a heating fabric based on nanoparticles is very simple, when you look at it from a manufacturing and industrialisation point of view. First you coat the fabric with an electrically conductive dispersion of nanoparticles which is specially developed to ensure flexibility as well as good adherence to the substrate. During the trials, it has been confirmed that almost any non-elastic fabric could likely become a heating fabric using this technology.

Once the textile has been coated, flexible electrodes are implemented. In this process, neither adhesives nor laminated parts are needed to fix the electrodes on the coated textile surface, thus ensuring the stability of the electrodes’ electrical properties – even in high flexural stress conditions where the fabric is twisted or turned. Finally, the heating fabric is coated with a protective resin.

Using this method, the heating textile maintains the flexibility of the initial fabric, and it is even possible to achieve diverse geometries.

The challenge of vehicle integration

To ensure a proper integration of the heating fabrics in the interior parts of the vehicle, several issues had to be taken into account. Here, the interconnection b

etween the heating fabric and the power line of the vehicle proved to be one of the biggest challenges, and various different methods for connecting the electrodes and the power supply wires were explored before coming up with a solution.

So far, two different prototypes have been developed –  a heating floor mat and a heating bar for the upper part of the vehicle cabin. The main reason for developing these prototypes was to have an initial validation of the selected materials’ technical properties and the thermal and endurance properties of the heating devices. Consequently, two simple tests –  a continuous working test and a working cycle test – have been carried out in order to validate the heating devices.

Obviously, further validation is needed before integrating these devices into a commercial vehicle, and both testing and further development will be carried out in the coming period of the project.