Heat Mass Transfer (2009) 45:829–830
DOI 10.1007/s00231-007-0327-7

LAUDATIO

Professor Dr.-Ing. Dieter Gorenflo, in celebrationof his 70th birthday
David Kenning

Published online: 18 August 2007
Ó Springer-Verlag 2007

This selection of papers from the 6th International Conference on Boiling Heat Transfer is dedicated to ProfessorDr.-Ing. Dieter Gorenflo, in celebration of his 70th birthday
on 2 February 2007 and in recognition of his outstanding
contributions to the science of boiling heat transfer and its
application to refrigeration. These contributions throughout
a long career have been marked previously by awards fromthe DKV (German Association of Refrigeration and AirConditioning) in 1976 and from the International Instituteof Refrigeration in 1991.
Dieter Gorenflo was born and educated in Karlsruhe. He
obtained the degree of Diplomingenieur from Karlsruhe
University in 1962 and the degree of Dr.-Ing. in 1996 forresearch on boiling heat transfer in the Institute of Thermodynamics and Refrigeration, which was founded byProf. Rudolf Plank, one of the leaders in the developmentof refrigeration. In 1971, he was appointed as the Head ofthe Refrigeration Department in the Institute. He waselected as a member of the International Institute ofRefrigeration in 1975. In 1979, he left Karlsruhe to take up
the position of Professor in charge of Thermodynamics,
Heat Transfer and Refrigeration at the University-GHPaderborn, where he later served as the Dean of the Facultyof Mechanical and Chemical Engineering. Under hisleadership, the Institute Wärme-und Kältetechnik developed its reputation as a centre of excellence in boilingresearch and launched the careers of many talented graduate students. The Institute hosted two very successful
Eurotherm Seminars on Pool Boiling in 1989 and1996 andan IIR Conference on Thermophysical Properties andD. Kenning (&)
School of Engineering and Design, Brunel University,Uxbridge, Middlesex UB8 3PH, UKe-mail: david.kenning@brunel.ac.uk

Transfer Processes in 2001. Professor Gorenflo was theSecretary of the Eurotherm Committee 1993–1997. He has
been prominent in promoting the professional applicationof research in heat transfer and refrigeration at a nationallevel, in DKV and VDI/GVC (German Association of
Mechanical and Chemical Engineers), and internationally
first as a Vice-President and since 1999 as President ofCommission B1 of the International Institute of Refrigeration, over a period when refrigeration has figured
prominently in international deliberations on environmental impact and energy efficiency. Commission B1 is
responsible for a remarkably wide range of activities,
including thermophysical properties of refrigerants andmixtures, heat and mass transfer and two-phase flow,
lubricants and insulants and cycle performance. Official
retirement in 2002 and transfer to an Emeritus Professorship at Paderborn appeared to have little effect on his levelof activity.
Dieter Gorenflo’s research has had a breadth to matchthat of Commission B1, including challenging problems
such boiling of partially-immiscible mixtures and highly
viscous liquids and boiling on enhanced surfaces, but thecore activity has been the fundamental study of poolboiling on horizontal cylinders, with rigorous attention toexperimental accuracy and reproducibility. The ‘‘standard
pool boiling apparatus’’, which provided stable conditions
around and within the boiling vessel should be studied by
all graduate students as an object lesson in the high standard of engineering that can be achieved in experimentalequipment. The same standard was applied to the construction of the test sections and the placing of sensors.
Consequently, highly accurate and reproducible boilingdata were obtained for a wide range of fluids and conditions, even at the very low wall superheats characteristic ofnear-critical pressures. This information was developed

123

830

into a widely-used correlation based on corresponding
states that recognised the important influence of reducedpressure. Dieter Gorenflo argued that the apparently
anomalous behaviour of water as a boiling fluid was primarily due to its employment at lower reduced pressuresthan other fluids. The correlation was incorporated in theVDI-Wärmeatlas and has been continuously improved. The
accurate measurement of small azimuthal variations in wall
temperature, combined with the analysis of high-speed
video recordings, led to important deductions concerning
the contribution of coalescing and sliding bubbles to heattransfer in nucleate boiling and their complex dependence
on reduced pressure, heat flux and the availability ofnucleation sites. These were incorporated in a semi-analytical model that extended earlier interpretations of boilingcurves as size distributions of active site density. Dieter
Gorenflo campaigned for all the data relevant to boilingperformance to be measured in every experiment, surface
condition and microgeometry being particularly challenging. In a fruitful collaboration with Dr. Andrea Luke (nowProfessor of Fluids and Thermodynamics, University ofHannover), he developed two contrasting methods of preparing surfaces reproducibly: sandblasting giving a random
texture and grinding with emery paper to give anisotropicfeatures. The texture was measured by scanning on a
micron length scale and interpreted by more sophisticatedparameters than conventional rms roughness. Variations insurface characteristics between different macroscopic features of enhanced boiling surfaces provided further insights
into boiling mechanisms. Examples of continuing developments in these lines of research are given in the papers inthis volume.
So far, this note has been about the career of Professor
Gorenflo. I would like to end with some brief remarks to fillout the picture of my friend Dieter. It is one of the great
pleasures of the international nature of research that professional respect can develop into life-long friendship,
despite irregular opportunities to meet. The meetings havealways been stimulating and often strenuous. A working
day at Paderborn started early, was punctuated by a brief
but inviolable period of rest in the middle of the day, might123

Heat Mass Transfer (2009) 45:829–830

later include an indulgence in Dieter’s enthusiasm forphysical exercise and ended much later with a ‘‘sleepingbeer’’. I knew that Dieter’s graduate students were expected to develop their practical skills on the ski slopes of
Davos but my own experience of following Dieter down asteep hill was confined to a descent of the near-vertical cliff
below the castle at Lake Bled in total darkness after aparticularly good conference dinner. I had complete confidence in his leadership, perhaps because the darkness hid
the yawning void below us. Dieter developed an enthusiasm for the English language by listening to the radio as hedrove to work early in his time at Paderborn. I think its
irregularities appealed to his instinct to develop rules forany complex situation. I was sometimes hard-pressed toprovide a rule to justify what I instinctively knew to be acorrect usage that conflicted with more logical German
grammar, so visits to Paderborn or e-mail consultations
about the wording of a paper sometimes led to quick
consultations of the Oxford English Dictionary. Dieter’s
love of a logical approach extends to other aspects of life. I
was a passenger in his car on a long drive through a seriesof mountain tunnels at a time when concerns about fire had
led to the batch processing of traffic. Three lanes of traffic
followed a stop-go cycle, reducing Dieter’s normal speedby an order of magnitude and having the opposite effect on
the gap between his car and the vehicle in front. After
50 km, he decided that it was illogical to respond to every
cycle and he remained stationary, while the traffic in ourlane vanished round a bend. The other lanes appeared tomake progress past us and eventually this became
unbearable for the driver of the car behind us and she got
out to interrogate Dieter. To my amazement, she seemed toaccept his explanation and returned, looking slightly
bemused, to her car.
Dieter says that he will really retire this time and spend
his time renovating the house that he had built with his own
hands many years ago in Karlsruhe. I wonder if he will
indeed resist the lure of bubbles? Whatever he does next, I
am delighted to have this opportunity to congratulate him
on his career so far and I am sure I shall be joined by his
many friends and colleagues.