Page 255 - ISES SWC50

Klaus Vajen
Country: Germany
Year Started Research: 1991
Title of Research: Direct Coupling of PV system with a pump connected
to uncovered collector field for heating a swimming pool.
University: University of Marburg (DE)
Still Active in Research: Yes

In July 1991 Prof. Ackermann, originally working on “traditional” solid state physics at the University of Marburg
(DE), was awarded with his first grant for a research project in solar energy. He asked Klaus Vajen to be one of the
two first PhD-students in the newly founded “Solar Energy Research Group” at the department of physics. The
project dealt with the direct coupling of a 3 kWp PV-system with the pump for a 700 m² uncovered collector field
for heating of a public swimming pool. The direct coupling didn’t deliver very promising results at the end, however
both, the PV and the solar heating system were very large for the time being and they delivered a lot of interesting
experimental and theoretical results. So, this project was the start of a fast-growing research group on solar energy
at the University of Marburg and from 2001, continued at the University of Kassel (both in DE). By now, eight of
the graduates became professors at different universities. The research in the “pioneer phase” included also the
development of high-performance solar cookers. The oven reached more than 300°C with heat pipe vacuum tube
collectors, the condenser was fixed in a boiling plate. But at that time the funding schemes in Germany were not as
developed as today, so most of the projects were individual, we could seldom continue the research with a follow up
project. Nevertheless, during that time solar researchers in Germany collected manifold experience in quite different
fields like construction of components (collector, storage, …) as well as monitoring, simulation and experimental
investigations of complex heat supply systems which turned out to be very helpful later on.

Ruzhu Wang
Country: China
Year Started Research: 1993
Title of Research: Solar cooling with solar thermal and solar PV
University: Shanghai Jiao Tong University
Still Active in Research: Yes

Ruzhu WANG got his PhD in 1990 from Shanghai Jiao Tong University (SJTU), he became the director of the
Institute of Refrigeration and Cryogenics of SJTU in 1993, and he was promoted to full professor in 1994. In 1993 he
started to select solar cooling as his main research area, the first research project was solar adsorption refrigeration
in which activated carbon-methanol was used as the working pair. As he was involved in solar thermal, thus he
had a lot of collaborations with Chinese solar thermal industries like Himin, Lino, Sunrain and etc.. His research was
developed with the growing market of Chinese solar water heaters and also solar heating/cooling and even solar
medium temperature boilers for industry applications. He started solar PV powered cooling in 2006, and now he
is also pioneered in solar PV driven air conditioning. Prof. Wang has published 4 books related to solar heating
and cooling, such as Advances in Solar Heating and Cooling., Elsevier-Woodhead Publishing publications, 2016,
ISBN: 978-0-08-100301-5; Handbook of Energy Systems in Green Building, Springer,2018, ISBN:978-3-662-
49088-4; Adsorption Refrigeration Technology: Theory and application, John Wiely & Sons Singapore Pte. Ltd.
2014, ISBN:978-1-118-19743-1; Solar Refrigeration, Chemical Industry Press (China), 2007,ISBN7-5025-9317-
9. He has published a lot of research papers of solar cooling and presented a lot of keynote lectures in international
conferences. Prof. Wang has published more than 500 SCI indexed papers with h index 69, and citations more than
17000 times. He was selected as Clarivate highly cited researcher in 2017 & 2018. He has won Chinese National
Research Awards in 2010 and 2014 respectively. Prof. Wang received the J & E Hall International Gold Medal from
the Institute of Refrigeration (UK) in 2013, Asia Refrigeration Academic Award in 2017, the Nukiyama Memorial
Award from the Japanese Society of Heat Transfer in 2018, the IIR-Gustav Lorentzen Medal from the International
Institute of Refrigeration in 2019.

ISES SWC50 - The Century of Solar-Stories and Visions | 237