The recovery of energy is interesting, both for the economy and the environment. Therefore, heat exchangers can be found in all parts of industry and in everyday life. However, the price of classical heat exchanger materials such as copper is increasing, which makes the investment in heat exchangers less interesting.

One solution is the transition to cheaper materials, but there are not many options. Heat exchangers are typically used in applications with high pressures and/or temperatures, whether or not in combination with corrosive fluids. Since metals are not all equally resistant to these corrosive conditions, the possible use of polymers was investigated. Indeed, plastics often possess good chemical resistance, but they exhibit low thermal conductivity.

"In my PhD, I investigated the potential of heat exchangers made from fiber-reinforced plastics," says Joanna.

"The goal was to find suitable material combinations, to modify the design of a classical heat exchanger to maximize the benefits of thermoplastics, and to determine the mechanical properties, specifically the stiffness and strength of these materials," Joanna continues.

"As part of my PhD, I investigated different test methods for both short- and long-term studies to evaluate the performance of heat exchangers made of fiber reinforced plastics," Joanna explains.

"I realized a setup to test a small prototype under realistic operating conditions where the deformation could be measured very accurately. Furthermore, an optimization of measurements in standardized tests was carried out in combination with a parameter study through Dynamic Mechanical Analysis, to allow short and long term studies for heat exchanger materials. Finally, the debonding of short fibers within a polymer matrix was also studied, in preparation for the numerical modeling of such behavior, necessary for an even better understanding of the mechanical behavior of this class of materials," Joanna concludes.

Read a more detailed summary or the entire PhD

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PhD Title: Experimental Characterisation of Short Fibre Reinforced Thermoplastic Materials for the Use in Heat Exchangers: Development of Test Setups and Methodology for Subcomponents, Coupons and Embedded Single Fibres

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Contact: Joanna Schalnat, Lode Daelemans, Wim Van Paepegem

Joanna Schalnat was born on September 13th, 1990 in Hannover, Germany. From there, she moved to Dresden, Germany to study process engineering with a focus on wood and fibre material technology at the technical university of Dresden. As a student job aside, she took the opportunity to work for several PhD students. Her main task was characterising strength and stiffness on wood and wooden composites, which motivated her to search for more opportunities for mechanical testing.

In internships at Danzer in Kesselsdorf, Germany and at SP in Borås, Sweden, she could extend her knowledge on the production and testing of laminates as well as composites and successfully achieved her engineering diploma in 2016.

Without ever having been to Belgium before, she decided enthusiastically to join the research group Mechanics of Materials and Structures at Ghent University. Funded by the Compohex project and the Relicario project, she has spent a great time in the mechanical lab to learn about testing, composites, test-setups and the importance of teamwork. The results are presented in this dissertation. During her studies, she contributed to scientific publications and participated in several international conferences.

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Editor: Jeroen Ongenae -  Illustrator: Roger Van Hecke