ASHRAE Journal - June 2022 - 64

REFRIGERATION APPLICATIONS
COLUMN
Andy Pearson
Rudolph Who?
BY ANDY PEARSON, PH.D., C.ENG., FELLOW ASHRAE
If I asked you to name ten famous Rudolphs I suspect that number one would be the
fictional reindeer with the very shiny nose and others might include Valentino (the
actor), Nureyev (the ballet dancer) and Diesel (the engineer). You might also think of
those who shorten their name to Rudi (or Rudy): Dassler (German sneakers manufacturer),
Voller (German soccer player), Lewis (lead singer of the Drifters) or Giuliani
(enough said). Would there be room in your top ten for Rudolph Clausius?
Clausius has arguably had more impact on your life
and career than all the other Rudis put together. He was
born 200 years ago in the Prussian city of Köslin, a small
port on the Baltic coast which is now named Koszalin
and lies halfway between the Polish ports of Szczecin
and Gdansk. His father was a school teacher and Pastor
and young Rudi was taught by him until
he went to high school in Szczecin at the
age of 16. This began a thirty year drift in
a south-westerly direction across central
Europe; firstly to the University of Berlin
to study math and physics, then to Halle
for his doctorate in atmospheric optics
and then, after a brief spell back in Berlin
as professor of physics, to the newly
founded Federal Institute of Technology
(ETH) in Zurich.
" we ought not to suffer ourselves to be daunted by these
difficulties; but that, on the contrary, we must look
steadfastly into this theory that calls heat a motion as in
this way alone can we arrive at the means of establishing
it or refuting it. " He went on to write, " Besides this, I do
not imagine that the difficulties are so great as Thomson
considers them to be; for although a certain
alteration in our way of regarding the subject
is necessary, still I find that this is in no case
contradicted by proved facts. "
Cheer up, Rudi. It's your birthday!
While completing his doctoral thesis in
Halle he became interested in the work of Carnot and
Clapeyron and noted similar interest in England and
Scotland, particularly in the work of James Joule and
William Rankine. Neither Joule nor Rankine held an
academic post at the time and they were conducting
their research as hobbies, albeit with an intense passion,
alongside their day jobs. Clausius also noted that
William Thomson-later known as Lord Kelvin-who was
two years his junior, had started to apply more scientific
rigor to Joule's work, but was having doubts about
" innumerable other difficulties " which he described
as " altogether insurmountable. " In his first major work
on heat and power, published in Germany in 1850 and
quickly translated into English to be laid alongside
Thomson and Rankine's publications, Clausius wrote
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J U N E 2022
This was the first of nine memoirs published
by Clausius over the next fifteen years
which led ultimately to his description and
naming of a previously unnoticed property
of state, entropy, in 1865. Along the way there
were some feisty exchanges with Thomson
and his followers. There is no doubt,
although they were all floating around in the
same pool, that Clausius produced a completely fresh
concept with entropy (which means " in transformation " )
and unlocked the puzzle that was holding all the
proto-thermodynamicists back. However, it is less clear
whether he fully understood what he had in his hands.
It needed the next generation of thinkers, including
Josiah Gibbs, Ludwig Boltzmann and James Clerk
Maxwell, to take entropy and run with it in the process
moving it from the world of physics to chemistry. Gibbs
wrote an obituary of Clausius in 1889, concluding that
" his true monument lies not on the shelves of libraries,
but in the thoughts of men, and in the history of more
than one science. "
Andy Pearson, Ph.D., C.Eng., is group managing director at Star Refrigeration in
Glasgow, UK.
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ASHRAE Journal - June 2022

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