Drying as preservation method can be used on everything from fruits or berries to medical powders and to pet food. At NTNU we have designed and built a single stage heat pump dryer with carbon dioxide that is more efficient and more environmentally friendly than any other dryer.

I work with development of advanced drying technologies contributing to a better and sustainable world. Among the current green technologies are the modern heat pump dryers and superheated steam dryers. Heat pump dryers were developed at NTNU and have been built in pilot and industrial scales.

Heat pump dryer design based on green technology

tørket mat

Dried food. Photo: Odilio Alves-Filho

It is important that we perform research in possible layouts of new heat pump dryers operating in single and multi stage vapor compression (just compression of gas) and multiple drying chambers. The main drying modes are atmospheric sublimation and evaporation that are applied in combination to improve capacity and to manufacture dried sensitive products with superior quality.

The future trend is to adopt natural fluids in the heat pump dryer to comply with recent regulations and to minimize existing environmental problems such as global warming and climate change. The refinements of pilot plants resulted in the currently designed heat pump dryers. This new green drying technology is now ready for modern industries willing higher efficiency, enhanced quality and wishing to contribute to a sustainable society and better world.

single stage heat pump dryer with carbon dioxide

The NTNU single stage heat pump dryer with carbon dioxide is located in Varmeteknisk, Gløshaugen in Trondheim. Photo: Odilio Alves-Filho

To the right is a photo of the NTNU single stage heat pump dryer with carbon dioxide:

  1. Cyclone
  2. Drying chamber
  3. Gas cooler
  4. Evaporator
  5. Gas subcooler
  6. Control panel
  7. Compressor
  8. Cleaning in place system

What is new on the international drying scene

In June I organized a new conference on drying in Gdańsk, Poland: the Nordic Baltic Drying Conference. The NBDC 2015 is the first dewatering and drying conference organized by the Nordic and Baltic countries. It is the expanded event from the previously Nordic Drying Conferences that successfully took place in Norway, Denmark, Sweden, Finland and Iceland.

The Nordic Baltic Drying Conferences confirms the previous Nordic tradition of excellence by bringing together the academia and industry. It is a forum for knowledge and scientific exchange between induPolenadstrialists, professors and researchers representing companies, universities and R&D centers. The topics include dewatering, drying and related processing of foods, aquaculture and pharmaceuticals while focusing sustainable, green and energy efficient drying technologies.

About sixty participants from 20 countries and most continents attended the conference, including Central, Western and Eastern Europe, Asia, Oceania as well as North, Central and South America. World recognized authors and industry experts working in dewatering and drying process and products gave keynote lectures and oral presentations on current technologies and future R&D in the field.

The NBDC uniquely promoted an industrial roundtable organized to provide the audience, composed of academia and researchers, with realistic topics originated in the industry. The objective is that the discussions lead to joint projects contributing to effective cooperation between universities and industries.


Cells may also be dried.

The seven sessions in the conference illustrates the variety of subjects within heat pump drying:

  • Keynote lectures on major topics of dewatering, drying and related processes
  • Modeling, simulation and mass-heat transport
  • Spray drying: modeling, simulation and kinetics
  • Heat pump drying, energy efficiency and environmental aspects in drying processes
  • Drying of fruits, vegetables and bio-organic compounds
  • Drying quality, intensification and use of MW, ultrasound and infra-red radiation
  • Industrial session

Awards given in the NBDC 2015

Finally, I would like to bring the attention to awards granted to researchers and professors during the conference:

  • Distinguished contribution to the development of drying technology in the Nordic and Baltic regions
  • Outstanding achievement and excellence in drying R&D
  • Novelty and advanced R&D among the keynote papers presented at the NBDC 2015
  • Distinguished contribution & support to the Nordic Baltic Drying Conference
  • Best international scientific presentation
  • Outstanding leadership and promotion of R&D in the Nordic and Baltic region.

The NBDC 2015 was jointly organized by the Norwegian University of Science and Technology (NTNU) and Lodz University of Technology. The conference was sponsored by the Danish company EnerDry ApS and Mars GmbH from Germany.

An overview of the conference proceedings is available for download.

odilioThis blog entry was written by Professor Odilio Alves-Filho at NTNU – the Department of Energy and Process Engineering.

The main photo of this blog entry is taken for NTNU by photographer Geir Mogen

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