The work describes the heat transfer during free convection in inclined insulating gas layers and during forced convection in thin heat transfer layers, which occur in a new type of solar thermal all-glass collector developed at Nordhausen University of Applied Sciences.

Pascal Leibbrandt is not only a long-standing research assistant at Nordhausen University of Applied Sciences, but also a graduate. He studied Regenerative Energy Technology here from 2005 to 2009 and subsequently completed a Master's degree in Systems Engineering. He has been researching and teaching in the Department of Engineering since 2009.

Despite a full-time job, family and building a house, Pascal Leibbrandt never lost sight of his goal - and so he worked continuously on his doctoral thesis from 2014 to 2021 alongside all the other big and small tasks. In early autumn 2022, the time had come - the successful defence at the University of Kassel, which supervised the cooperative doctorate.

The thesis was graded Magna cum Laude, i.e. an A. The reviewers were Apl. Prof. Dr Ulrike Jordan (University of Kassel), Prof. Dr Thomas Schabbach (Nordhausen University of Applied Sciences), Univ.-Prof. Dr Wolfgang Streicher (University of Innsbruck), Prof. Dr Klaus Vajen (University of Kassel).

When asked how he managed the balancing act between his doctorate, job and family, Leibbrandt says: "I don't know myself."

"It took me seven years. The University of Kassel is very realistic. Doctoral students are told that you should allow around five years for a doctorate and an extra two years for each child. So in the end I was pretty quick," jokes Leibbrandt.

Without the support of the in.RET team and his family, who have always had his back, the promotion would not have been possible, emphasises Leibbrandt.

Of course, a doctor also needs a doctor's hat. The in.RET has a nice tradition for this. The doctoral hat for the current doctoral student is always made jointly by those who want to do their doctorate next. It is important that the design of the hat recognises the personality of the wearer as well as the respective research topic.

Pascal Leibbrandt's hat consists of an all-glass solar collector and a running shoe, as the passionate runner set up the university running group years ago.

Captions:

1. the "freshly baked" doctor Pascal Leibbrandt with the Dean of the Faculty of Engineering and reviewer of the dissertation, Prof Dr Thomas Schabbach

2 Dr Pascal Leibbrandt with his doctoral thesis

3. a different kind of doctoral hat - built by colleagues from the Institute for Regenerative Energy Technology (in.RET)

(Photos: Tina Bergknapp)