Design and study of an electrical liquid heater using conductive polymer composite tubes

This study focuses on both the design and testing of an electrical heating device using current passage tubes made of Conductive Polymer Composites (CPC). To obtain such materials, an insulating polymer matrix is combined with electrical conductive fillers (carbon black, carbon fibres or metal particles). Power dissipation is observed when an electrical current is passed through the charged polymer matrix. To optimise heater design, two different axisymmetric, T(r,z) finite element models were developed with COMSOL®. The first model represents the electro-thermal behaviour of a current passage tube with internal water flow only. The second one takes into account water circulation both inside and outside the heating tube. otype was developed based on four immersed CPC tubes supplied electrically and hydraulically in parallel in a PVC casing. The experimental sequences performed on this pilot coupled with a hydraulic circuit made it possible to validate the two models. Analysis of the experimental recordings indicated that thermoelectric efficiency was higher than 90%. The thermal behaviour of such heaters was well defined on the basis of the information obtained from these tests and on the numerical simulations.