22.1.2020

Koja continues to take part in world class research

Koja's PhD Student Turo Välikangas has finished a collaboration article with Aalto University, Aalborg University and Tampere University. The article is published in the International Journal of Heat & Mass Transfer in the beginning of 2020.

In the article Turo Välikangas and co. have developed a method to numerically study the fouling propensity of enhanced fin types in fin-and-tube heat exchangers. Before this study, certain fin design have been avoided in hazardous air conditioning environments due to pre-existing knowledge about their more rapid fouling characteristics. This way, the enhanced fin shapes with higher thermal-hydraulic efficiency have been consciously avoided in applications where cleaning of the heat transfer surfaces is impossible. Still, there has been no kvantitative data about the fouling rate of different fin shapes and therefore comparisons are very difficult to be made. In this study, the material properties for the fouling particles are defined based on the experimental results of the critical velocity of high-adhesive and low-adhesive real world aerosols. The critical velocity in this context is the velocity of which the particle sticks to the surface that it impacts with. If the incident velocity is higher than the critical velocity, the particle will bounce and re-entrain to the flow.

Välikangas started working as a Senior Research Scientist at Koja Oy in the beginning of January 2020. The results from the studies will be published during this year. Turo is studying at the Doctoral school of industrial innovation at the Tampere University under the supervision of Miikka Dal Maso. During the spring 2017 Turo visited Aalborg University where his colleague Jakob Hærvig was just finishing his PhD thesis. Now Jakob is an Assistant Professor of Thermal Energy and Process Engineering at Aalborg University and has made a huge contribution in the design and scientific support for the article. Aalto University’s Professor Ville Vuorinen and his PhD student Petteri Peltonen have played a major role in the writing of the article and support in the CFD related topics. The method for defining the material properties for the fouling particles is based on the measurements by Heino Kuuluvainen from Tampere University.

This is the third published publication which will be included in Turo’s dissertation “Fin-and-tube heat exchanger development with numerical means”. The results from this thesis project will be utilised in Koja’s future product development. New innovations can be measured and tested in Koja’s own R&D Center to develope better performing heat exchangers for the customers.

The article is now available online and free for the next 50 days in the Elsevier ScienceDirect publication platform.

The International Journal of Heat & Mass Transfer has an impact factor of IF=4.346 and it has been rapidly increasing during the last few years.