Project Overview

Project Overview

Specific project objectives

HiPerDry aimed to develop and implement a novel microwave-enhanced superheated steam process for high performance drying of hygroscopic polymers in order to improve the overall energy efficiency, thus facilitating economical production of hygroscopic polymers as well as substitution of imports from countries outside the EU. In order to achieve this objective, there were a number of challenges to be overcome. Therefore, new depths of scientific understanding necessary for the innovative technological developments were required.

HiPerDry resolved the current limitations in the state of the art for drying hygroscopic polymers by:

  • Reducing energy consumption through effective means to thermally remove moisture (bound water) from hygroscopic polymer granules;
  • Shortening drying and processing time with enhanced heat and mass transfer mechanisms; and
  • Improving product quality attributes by avoiding degradation due to oxidation and overheating


HiPerDry provided benefits to the European hygroscopic polymer processing industries by:

  • Strengthening the economic competitiveness of SME members of the SME-AG participants through an energy-efficient drying process
  • Enhancing the knowledge base of the hygroscopic polymers processing industry through SME-AGs and their members by publishing a best practice guideline on drying of hygroscopic polymers; and
  • Increasing eco- and resource-efficiency of European plastics processing industry by promoting the use of affordable bio-derived hygroscopic polymers.
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    Project status

    The HiPerDry project finished at the end of 2016. After 39 months of intensive research the Consortium could successfully develop a microwave enhanced superheated steam drying (MW-SHSD) system. The system is now stored at the University of Stuttgart, Institut für Kunststofftechnik. If you are interested in our unit and further individual material tests please contact the project coordinator.

    The Consortium would like to express its gratitude to the European Commission for the financial support of this research within the FP7 Framework Programme of the European Commission (Grant No. 606425).

    Principle of Combined MW-SHS Drying of Polymer Granules

    Principle of Combined MW-SHS Drying of Polymer Granules

    Through the simultaneous combination of microwave (MW) and superheated steam (SHS) in drying of hygroscopic polymers, not only can higher drying rates be achieved through enhanced mass transfer of evaporated moisture into superheated steam atmosphere (no diffusion resistance), but also the supply of latent heat for evaporation (heat transfer) can be done effectively and selectively to the water molecules by microwave. Thus, temperature gradients within the polymer granules will be reduced; leading to homogenous removal of bound water and avoiding local and surface overheating, while decreasing the drying retention time. Besides, as SHS is re-circulated and reheated in a closed loop; evaporated water becomes excess steam and is carried off along with volatile substances. The supplied latent heat (including thermal energy transformed from microwave) as well as condensable valuable compounds (e.g. solvent) can therefore be recovered as value-added products by means of condensation