Thermally conductive polypropylene composites as corrosion‐resistant materials for plate heat exchangers

Abstract The suitability of polypropylene‐graphite composites as materials for corrugated heat exchanger plates is investigated, as the associated materials have low density (<2.3 g/cm³) and excellent corrosion resistance at a comparatively low price. Therefore, custom‐made polymer composite plates with a thickness of 1–2 mm and a filling degree of up to 80 wt% were evaluated for their thermal and mechanical suitability with regard to their use in plate heat exchangers. Three‐point flexural tests show that the loading of polypropylene with graphite leads to mechanical properties that are suitable for the application of heat exchanger plates. The simulated maximum overpressure is greater than 7 bar. The thermal conductivity of the composites was increased by a factor of 20 compared to pure polypropylene, resulting in thermal conductivities of up to 2.74 W/mK. Considering the density differences between the developed composites and stainless steel, similar thermal performances over a wide range of process conditions are obtained. Moreover, the composites investigated have lower crystallization fouling susceptibility compared to stainless steel, which is attributed to the low surface free energies of approximately 25 mN/m. For calcium sulfate fouling, the fouling resistance on stainless steel exceeds that on the composite by 1.5 m²K/kW after 60 h.