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Phd defense by Maral Rahimi

Phd defense by Maral Rahimi

Title: Control and prevention of ice formation on the surface of an aluminum alloy


20.02.2017 kl. 13.00 - 17.00


English summary

In cold climates, mechanical ventilation systems with heat recovery, e.g. air-to-air exchangers, are often used to reduce energy demand for heating. This, however, creates a risk of ice accretion on the fins of the heat exchanger as warm and humid exhausted air cools down which may lead to the deterioration of equipment performance.There are two approaches to controlling ice formation on heat exchangers: active and passive methods. The passive methods, which are related to the surface characteristics of the heat exchanger fins and their effect on the initial phases of ice formation, are the main focus of this PhD study. Since aluminum alloys are commonly used to build air-to-air heat exchangers, their surface characteristics play a crucial role in ice nucleation, formation and accretion. This study is specifically focused on aluminum alloy 8011.

In this PhD study, several types of surface modifications of aluminum alloy were developed that allowed us to obtain stable hydrophilic and hydrophobic surfaces. The effects of these modifications on surface morphology and wettability—the main parameters determining ice nucleation, formation, accretion and freezing delay—were studied comprehensively.

On the basis of the findings and observations of this study, it is found out  that tailoring the surface characteristics through the application of different chemical or mechanical methods is an effective method for changing the icing properties of a surface. Future studies might focus on studying the effect of different surface coatings with ion concentration on ice formation kinetics.

About Maral

Maral Rahimi holds a master in Mechanical Engineering from Linköping University, Sweden, 2010 and Bachelor of Material Engineering from Iran University of Science and Technology, 2007.

She has experimental and practical experiences in different laboratories with focus on new product development by research on different surface modification techniques, coating techniques, surface chemistry, material characteristics, modifications, testing techniques, standards and their appropriate implementation. During her PhD she worked in different labs and clean rooms (in Department of Physics and Nanotechnology Aalborg University, in the labs of Faculty of Engineering and Science, Danish Building Research Institute, Aalborg University, and in Chemistry Department of  Denmark technical University (DTU Kemi).

Maral now works as a Test Specialist in Strategic Protective R&D department of Hempel A/S.

Attend the PhD defence

Maral Rahimi defends her PhD 20 February 2017 at Aalborg University Copenhagen, Gæstekantinen.

All interested are invited to attend the PhD defence. After wards, SBi will host the reception.


Statens Byggeforskningsinsitut (SBi)


Gæstekantinen, A.C. Meyers Vænge 15, 2450 København SV

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