by Guy Gistau Baguer, guy.gistau@orange.fr

Meet the Author, Guy Gistau Baguer
I have spent most of my working time dealing with helium refrigeration and liquefaction. I was hired by Air Liquide in 1965 for my first job in the “Centre d’Etudes Cryogéniques” in Sassenage, France, where I was in charge of building seven L/h helium liquefiers. Then, I helped operate an air separation plant and its distribution system, sold specialty gases, coordinated the activities of electronic gases and liquid helium among subsidiaries and, finally, in 1975, I came back to the Sassenage site where I dedicated myself again to helium refrigeration.

As the team was very small, I had the opportunity (or, more exactly, the requirement!) to deal with all steps of a project: sales, design, construction, erection, tests, after sales, troubleshooting and, simultaneously, development. That was an incredibly efficient way to become familiar, or even intimate, with all aspects of helium refrigeration, since at the time there was no possibility to get such information from literature.

Of my various projects, a few stand out. In the beginning of the ‘80s, our team gave birth to the first fully automatic liquefier/refrigerator: HELIAL. The expertise that was acquired at this occasion, especially in automation of the process, later allowed us to deal with much more complicated systems. A few years later, the controlled thermonuclear fusion project Tore Supra needed 300 W at 1.8 K, a size of plant that had already been built, incorporating a lot of room temperature Roots machines. With the hope that fusion would progress, it was decided to develop centrifugal cryogenic compressors that were integrated into the refrigerator, making it the first one operating on such technology: the way to the modern large systems operating at temperatures lower than 4.5 K. Finally, when CERN required refrigerators for large power at
1.8 K, I was able to integrate my knowledge in helium refrigeration into the design.

During this period, I had the opportunity to write around 50 publications, mainly about the machines that were built, but also on topics dealing with helium refrigeration. A few patents on helium refrigeration were filed over the years, too. In 2011, the largest helium liquefier being built by my younger colleagues delivered 7000 L/h! Therefore, in my life, I had the opportunity to see the helium liquefier size increasing by three orders of magnitude.

Attending the usual cryogenic conferences led me to be a member of the International Cryogenic Engineering Committee for 16 years and finally to be the Chairman of the Committee for another 12 years.

When it came time to retire in 2000, I felt guilty to let such an amount of self-gained experience (mistakes, thinking, trying again, success sometimes…) to be lost. Therefore, I decided I would try to transfer this knowledge to other people who would need it, especially young ones. Up to now, I have held more than 60 sessions of education in cryogenics.

In 2012, I wrote a text for the French Techniques de l’ingénieur about helium refrigeration. All the material was to stay within 16 pages: what a challenge to stuff the subject into a rather compact digest! This exercise gave me the idea to write down the talks I give at each school. This is the idea that gave birth to the present book.

In 2020, I was awarded the Mendelssohn Award that should have been presented to me at the International Cryogenic Engineering Conference that was to be held in Hangzhou, China, in August 2020, but that has been shifted to 2022 due to the COVID-19 pandemic.

By the way, this book is kind of my “cryogenic testament”!

About the Work
A book on helium refrigeration has recently been released: “Cryogenic Helium Refrigeration for Middle and Large Powers,” written by me, Guy Gistau Baguer. In this book I have tried to concentrate on almost everything one needs to deal with helium refrigeration. I wanted this book to be a very pragmatic tool.

I split the work into various chapters, the first one dealing with theory of cycles. Prior to getting into the topic, short refreshers about cryogenics and heat exchangers are given. These basic cycles are considered: Joule Thomson, Brayton and Claude. They are calculated and discussed using the REFPROP software by NIST in conjunction with Excel®. They are followed by special cycles for high powers or colder temperatures. Some examples of possible connections between cold box and cryostat are introduced.

The technology chapter takes care of compression with oil lubricated screw compressors and the necessary oil management system, heat exchange, cryogenic expansion and cryogenic compression. Examples of typical refrigeration systems are discussed.

Prior to dealing with system control, I provide a glance at the behavior of a refrigerator in off-design operation. Helium purification, both by adsorption and cryo-freezing, is discussed, followed by basic helium analysis.

In the everyday life of the plant, an operator has to deal with the important issues included in operation and maintenance. Some advice is given about points that must not be forgotten in writing a request for quotation and how to perform accurate commissioning tests.

The Cryo Tool Box explains how to perform a set of typical thermodynamic calculations with REFPROP and Excel, like heat exchangers or expansion turbines that are very useful in an operator’s daily life. Finally, a quick trip through the “saga” of refrigeration is performed.

Thanks to Springer, the book is color-printed, which makes it rather attractive as well. I hope this book will be useful for the worldwide cryogenic community.

Cryogenic Helium Refrigeration for Middle and Large Powers is available at Springer Nature at: http://www.springer.com/gp/book/9783030516765 ■