Meet the Fellow: Dr Marilize Everts

Pool boiling characteristics to investigate single-phase flow through tubes with a constant surface temperature

Interdisciplinary at its best – our Junior Fellow Dr. Marilize Everts from the University of Pretoria acted as a catalyst to initiate collaboration of two independent groups at the Engineering Thermodynamics and Transport Processes Department by Professor Brüggemann. 

Dr Marilize Everts

What are the foci of your joint research funded by the Grant?

Marilize Everts: The main focus of this research was to experimentally investigate the bubble dynamics of single bubbles in nucleate pool boiling. By combining my heat transfer and experimental methods expertise with the boiling heat transfer and optical methods expertise at the University of Bayreuth, we were able to follow a systematic approach to investigate single bubble dynamics using focused shadowgraphy.  This method can now be used to expand the research to include the effects of different cavities, surfaces and heat transfer fluids.  Two abstracts for conferences have already been submitted and I am currently busy with the data analysis and preparation of two journal papers.  This research will be applicable to the heat transfer community in general (experimental methods and fundamental understanding), but also to heat exchangers operating with multi-phase flow.

In what way is your work interdisciplinary, and what does interdisciplinarity mean to you inacademic work and life?

ME:This project once again highlighted to me the value of interdisciplinary research.  Through conducting interdisciplinary research, knowledge is not only transferred amongst the researchers, but more important, improved methods/findings based on the expertise of researchers from different backgrounds are developed. Being a heat transfer specialist, I was able to plan the research and experiments. However, I realised that I require knowledge on optical methods which I did not have.  The LTTT group in which the research was conducted fortunately consisted of both heat transfer and optical subgroups, however, they functioned completely independently.

After exploiting our heat transfer knowledge, I realised that collaboration with the optics group is critical in order to make the research happen.  The initial collaboration was to an extent slow and frustrating as we had to invest time and patience to get 'on the same page'. But shortly after we understood each other's needs and strengths, significant progress and breakthrough were made.  This also encouraged the two groups to start collaborating and I was told that I acted as an 'catalyst' to initiate collaboration.

What is in your opinion the future of your field? In what way can research in your fieldcontribute to meeting the urgent challenges of our time?

ME:The initial aim was to incorporate this research in my single-phase research in order to improve our fundamental understanding of heat exchangers to ultimately be in a position to design more efficient heat exchangers for renewable energy applications. More efficient heat exchangers operating with multi-phase flow can contribute to the seventh Sustainable Development Goal of ensuring access to affordable, reliable, sustainable and modern energy for all.

However, the method developed to use focused shadowgraphy for single bubble nucleate boiling can also be used to investigate heat transfer enhancement techniques such as surface modifications and coating in nucleate pool boiling.  This is especially applicable to the battery thermal management of electric vehicles, which is critical for the overall performance of electric vehicles. Being able to optimise the efficiency of electric vehicles can significantly.

What does international research mobility in today's world mean to you?

ME: International mobility is critical to ensure knowledge transfer which is not only required to conduct research, but also to develop researchers. This is something I did not appreciate enough until the global Covid lockdowns in 2020. Unfortunately something must first be taken away before you realise the full worth of it. Since then, I fully appreciate and enhance exchange opportunities for myself, my researchers and students.

Being involved in a EU project which also included many UK collaborators, Brexit created a lot of uncertainty which negatively impacted the planning of research exchanges, as well as 'quick' visits beween EU countries and the UK.  I pleased to read a while ago that the UK will still be considered as part of the EU research funding system.  Nowadays, a lot of attention is focused on collaboration with developing countries, especially in Africa. However, it is important to also ensure collaboration between developed countries as that will make those institutions even stronger and more capable to contribute to institutions in developing countries.

How did the current challenges influence your cooperation?

ME: Covid caused severe delays in my research last year, as the workshop was understaffed (due to illness) and there were delays in the delivery of material.  At that time I could not continue with the experimental research at all. However, I spent the time on my literature survey and the introductory sections of the papers, which saved time this year as I only had to focus on my work in the lab.  

So overall, there were some obstacles, but it was possible to work around them and still finish everything in time.  Over the years I have learned to deal with challenges and if one route seems to blocked, to follow another one.  I am thankful though that for neither of my visits there were any travel restrictions between South Africa and Germany, because that would have caused major delays.

The Fellow

Dr. Marilize Everts obtained her PhD from the University of Pretoria and is currently a Senior Lecturer in the department of Mechanical Engineering.  Her fundamentally focused research thus far led to new insights, perspectives and an improved fundamental understanding of mixed convective and developing single-phase flow, as well as the bubble dynamics of single bubbles in nucleate pool boiling. She has an H-index of 13 and published 16 journal articles, two book chapters and 37 conference papers (including 11 international keynotes). Her performance and contribution to science have been recognised by 30 awards and she has been acknowledged as an outstanding researcher nationally (Department of Science and Technology) and internationally (L’Oréal-UNESCO For Women in Science Foundation).