Heat Transfer Engineering, 36:429–431, 2015
C Taylor and Francis Group, LLC
Copyright ISSN: 0145-7632 print / 1521-0537 online
DOI: 10.1080/01457632.2015.960304

in memoriam

Dr. Detlev Gustav Kröger, 1939–2014

Dr. Detlev Kröger, professor in the Department of Mechanical and Mechatronic Engineering at Stellenbosch University,
passed away on 16 March 2014. He died at the age of 74 after along illness, with his wife, Regine, the well-known painter, at hisside. We had been expecting it for a long time, since Detlev wasvery weak. He is survived by his wife and three children, Anja,Alfred and Gregor, as well as five grandchildren. A memorialservice was held for him in the German Lutheran Church in
Stellenbosch on 25 March 2014.
In his long career as professor at Stellenbosch University,
he established himself as a pioneer in heat transfer and specifically in the field of air-cooled heat exchangers and cooling
towers. Many people say he was probably better known outside
Stellenbosch than in Stellenbosch.
Detlev was born on 31 July 1939 in Cape Town, SouthAfrica as the eldest of three children. He first attended the German School in Cape Town, but later grew up in Hermanus.
He studied mechanical engineering at Stellenbosch University and was supposed to start working at the South African
Iron and Steel Corporation (Iscor) on completion of his undergraduate degree, BSc BEng (Mechanical Engineering), in1962.
He was, however, encouraged by a professor to further hisstudies. As he did not have the finances, he sold ice cream toraise money, and without sufficient funding for his tuition fees,
he flew to the US without the support and knowledge of Iscor.
He rented a very small storeroom in the attic of a house withpigeons keeping him company and enrolled at MIT for postgraduate studies. It took a while before some of the professors
at MIT discovered he had been attending class without being a
registered paying student. However, by that time they had also
noticed his good progress and assisted him in getting a scholarship, after which he received the Gerard Swope Fellowship fromMIT in 1965 and 1966, for “Students of exceptional ability andpromise, as a mark of highest distinction”. At MIT, he completed the following degrees in mechanical engineering: SM in
1965 and ScD in 1967. His supervisor at MIT was Prof. WarrenRohsenow.
After the completion of his studies at MIT, he returned toSouth Africa where he was appointed as a research engineer atIscor in 1967. In 1968, he was appointed as a senior lecturer
in the Department of Mechanical Engineering at Stellenbosch
University and in 1971, he was promoted to the position of professor. He was also the Chairman of the Department in 1974 and1983. He was a visiting professor at Lehigh University Bethlehem in 1978, as well as at three universities in Germany in1984. From 1979 to 1992, he was a director of BMI at Stellenbosch University and from 1992 to 1999, he was Director ofthe Institute for Thermodynamics and Mechanics (ITM). From
2003, he was also an extraordinary professor at the Universityof Pretoria.
In terms of professional societies and committees, Detlev wasvery active and only a short summary is given. He was a fellowof ASME, a member of the South African Academy of Arts andScience, South African representative of the International Institute of Refrigeration on commission B2 and a member of the IIR
working party “Saving of Energy in Refrigeration” from 1978to 1986. He was a member of the Editorial Board of the International Journal of Multiphase Flow (1971), a member of the CSIR
Working Group on Heat Mechanics (1982–1986), adviser to theChemical Engineering Group at the CSIR (1978–1981), memberof the Research Awards Committee of the CSIR (1978–1981),
member of university committees including Research,429

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IN MEMORIAM

Bursaries and Stipendia, member of the Scientific Committeeof the International Association for Hydraulics Research, member of the CSIR, FRD Committee (1987–1990), member ofthe FRD Collegium (1988–1990), officer and general memberof the Assembly of World Conference on Experimental HeatTransfer, Fluid Mechanics and Thermodynamics (1993–2001),
member of the ASME Power Division Heat Exchanger Committee and associate editor of Heat Transfer Engineering(1997–2000).
He received a long and impressive list of awards and honours: the Thomas Price Award in 1970 and 1975 from the South
African Institute of Mechanical Engineers, the South African
Chemical Processing Award in 1971 from the South African
Institute of Chemical Engineers, the Ernest Oppenheimer Fellowship in 1978 and 1984, the Dreosti Prize in 1981 from theSouth African Institute of Refrigeration and Air Conditioning,the Havenga Prize in 1986 from the South African Academyof Arts and Science, the Researcher of the Year award in 1987
and again in 1998 from the Faculty of Engineering, Stellenbosch University, the Campbell-Pitt award in 1990 and 2000
from the South African Institute of Mechanical Engineers, theSilver Medal award in 1994 from the South African Instituteof Mechanical Engineers, the Faculty of Engineering Dean’sAward for Lecturer of the Year in 1996. He became an A-rated
researcher in 1997 based on the National Research Foundation(NRF) peer evaluation system. The A-category researchers aredefined as researchers who without doubt are accepted by theirinternational peers as being world leaders for the high qualityof their recent research outputs. He also received the Rector’sAward from Stellenbosch University for outstanding researchin 1999. The 12th International Association of Hydraulics Research Symposium on Cooling Towers and Heat Exchangers inSydney in 2001 was in honour of Prof. D. G. Kröger, “whohas played a long and distinguished role, with substantial andsignificant contributions to the art and science of cooling towers
and heat exchangers”. He received the Bill Venter/Altron Literary Award for his book entitled “Air-cooled Heat Exchangers
and Cooling Towers” in 2003. He received two honorary doctorates; one from the University of Johannesburg in 2002 andthe other from Stellenbosch University in 2011. In China, he
was honoured as “a friend of China for 10,000 years”.
Under his leadership as a supervisor, more than 75 master’sand doctoral students graduated at Stellenbosch University, andfrom his pen, more than 200 scientific publications appeared.
The aim of his research was to investigate the fundamentals
of many of the still not adequately understood phenomena that
determine the performance of wet-, dry- and hybrid coolingsystems. These systems find application in the power, petrochemical, process, refrigeration, air-conditioning, automotive
and many other industries. He also worked on the refinementsor changes to improve the performance of such systems undervarious operating conditions. He used fundamental theoreticaland numerical analysis, laboratory experimentation and fullscale performance tests. Much of his work was summarised andcoherently put together in his book that was published in 2004
heat transfer engineeringwith the title “Air-cooled Heat Exchangers and Cooling Towers”(2 volumes). This book is the most detailed and comprehensive
scholarly book presenting modern practice and theory relevantto the thermal-flow design, evaluation, performance and optimisation of air-cooled heat exchangers and cooling towers.
His research finds application, among others, in mine coolingplants, thermal processes in the process and steel industries,
solar energy and dry-cooling power plants. In the latter field,
he was responsible for the design of the power station at drycooling plants at the Matimba and Kendal power plants, andmost recently at Medupi and Kusile, as well as power plants in
the USA, Europe, Russia, Australia, India, the Middle East andChina.
With reference to the authors below: I (J.P. Meyer) was inspired by Detlev’s work ethic, thoroughness and his absolute
passion for his work. He was focused and happy in his work andit gave him much satisfaction and happiness. As we have a lackof academic mentors in South Africa, he became my informal
academic mentor and we had long discussions on my researchand heat transfer research in general. His contributions to myresearch were always constructive and encouraging of nature.
We made one or two attempts to conduct research together but
it was not successful, as although both our research foci wereon heat transfer, we concentrated on different aspects of heattransfer. One of my best memories with Detlev was when Prof.
Art Bergles and his wife, Penny, visited me and we were invited for dinner by Detlev at his house in Stellenbosch. The
combination of the hospitality of Detlev and Regine, the good
food and wine and the conversations we had over dinner was
so extraordinary. What is unusual is that both my dear friends
Detlev and Art passed away within a few days of each other.
To me, two of the biggest trees in the international heat transfer community have fallen. Detlev, I will always remember you
as I will continuously be exposed to your presence with yourbook on my bookcase, all your articles that are so visible interms of impact and the good postgraduate students you havedelivered.
My (B. Skews) main contact with Detlev was when I wasin charge of research at Eskom, the South African Electricity
Supply Commission, at the time it was seriously looking at dry
cooling for its power stations. Detlev contributed his considerable scientific understanding, as well as his personal integrityand approach to the final decisions and implementation to thebuilding of some of the largest dry-cooled power stations in theworld. My association with him in our subsequent contact asacademics, although in somewhat different fields, was always
stimulating and enriching. I was honoured to be invited by him
to attend the Bill Venter/Altron Literary Award function for his
outstanding book, recognising the major contributions to thefield that it represented.
I (S. Saha) remember Prof. Kröger as the research adviser ofDr. J. P. du Plessis. The PhD thesis of Dr du Plessis came to myown PhD thesis adviser, Prof. A. W. Date, for adjudication and I
had the privilege of going through the thesis since I also worked
on twisted tapes for my PhD thesis. The thesis work of Dr. duvol. 36 no. 4 2015

IN MEMORIAM

Plessis advised by Dr. Kröger was an original contribution. I
will always remember Dr. Kröger for his work.
I (P. Stehlik) was very sorry to hear about Detlev’s passing
away this year. We were very good friends, and many years
ago when I was a relatively young guy, I appreciated so muchthat Detlev noticed me and made contact with me. I fully agreewith what was written above by Josua – he was an excellent
researcher and an even better human.
Detlev Kröger was a towering figure as a university professor.
He spoke openly about the importance of freedom. He wasfiercely proud of his American education, MIT, professors andideas. I (A. Bejan) first met him in 1986, and his example has
stayed with me.
My (von Backström) best career move was to do my PhD
under Detlev’s supervision in the nineteen seventies. Later, I
was privileged to be his colleague for 30 years up to his death,and I have never stopped learning from him.
Detlev Kröger was a remarkably focused and interesting person to meet and to have as a colleague for almost 20 years. He
was a deep thinker with an instinct for asking the right questions.
When applying for a lectureship in our now Mechanical andMechatronic Engineering Department, he roped me (T. Harms)
into his thermodynamics division, of which I became the head
upon his retirement. His engineering thoroughness, disciplineand capacity for work will continue to inspire all those whowere enriched by working with him.
I (H. Reuter) had the privilege of working closely with Detlev
Kröger, an undisputed leader is his field. I will always cherish hispatience and wisdom and everything he taught me over the years.

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He introduced me to many interesting people worldwide, manyof whom have become friends. We organised the 14th IAHR
Cooling Tower and Air-cooled Heat Exchanger Conference in
Stellenbosch and published various research papers together.
We collaborated on a number of consulting projects for thetop companies in the world and ultimately were partners indeveloping and patenting new cooling tower and heat exchanger
products. He has left us with a treasure of knowledge and novel
ideas, which I will help to develop and try to implement in theyears to come. The legacy of his quality teaching and excellent
research is immense and will live on at Stellenbosch University
and in the larger air-cooled heat exchanger and cooling tower
community. As written by Josua above, a truly big tree hasfallen.
Contributed by:
Josua P. Meyer, University of Pretoria, South Africa; BericSkews, University of the Witwatersrand, South Africa; Sujoy
Kumar Saha, Indian Institute of Engineering Science and Technology, India; Franz Winter, Vienna University of Technology,Austria; Jat du Toit, North-West University, South Africa; PetrStehlik, Brno University of Technology, Czech Republic; Holger Martin, Karlsruhe Institute of Technology, Germany; John
H Lienhard V, MIT, USA; Adrian Bejan, Duke University,USA; Peter Vadasz, Northern Arizona University, USA; Theovon Backström, Stellenbosch University, South Africa; ThomasHarms, Stellenbosch University, South Africa; Hanno Reuter,Stellenbosch University, South Africa.

vol. 36 no. 4 2015