CRYOGENIC ENGINEERING

INTERNATIONAL CRYOGENICS MONOGRAPH SERIES

General Editors: K.D. Timmerhaus, Chemical and Biological Engineering Department,

University of Colorado, Boulder, Colorado

Carlo Rizzuto, Department of Physics

University of Genoa, Genoa, Italy

Founding Editor: K. Mendelssohn, F.R.S. (deceased)

Current Volumes in this Series:

APPLIED SUPERCONDUCTIVITY,

METALLURGY, AND PHYSICS OF

TITANIUM ALLOYS • Collings, E.WVolume 1: Fundamentals

Volume 2: Applications

CRYOGENIC ENGINEERING: FIFTY YEARS

OF PROGRESS

• Timmerhaus, Klaus D.; and Reed, Richard P. (Eds.)

CRYOGENIC REGENERATIVE HEAT

EXCHANGERS • Ackermann, Robert A

HEAT CAPACITY AND THERMAL

EXPANSION AT LOW TEMPERATURES.

• Barron, T.H.K. and White, G.K

HELIUM CRYOGENICS • Van Sciver, and Steven W

MODERN GAS-BASED TEMPERATURE AND

PRESSURE MEASUREMENTS

• Pavese, Franco, and Molinar, Gianfranco

POLYMER PROPERTIES AT ROOM AND

CRYOGENIC TEMPERATURES • Hartwig, Gunther

SAFETY IN THE HANDLING OF CRYOGENIC

FLUIDS • Edeskuty, Frederick J., and Stewart, Walter F

THERMODYNAMIC PROPERTIES OF CRYOGENIC

FLUIDS • Jacobsen, Richard T., Penoncello, Steven G.,and Lemmon, Eric W

Klaus D. Timmerhaus and Richard P. Reed (Eds.)

CRYOGENIC ENGINEERING

Fifty Years of Progress

Klaus D. Timmerhaus Richard P. ReedDepartment of Chemical and Cryogenic Materials, Inc.

Biological Engineering 2625 IliffUniversity of Colorado Boulder, CO 80305Boulder, CO 80309 USAUSA rpreed@comcast.netKlaus.timmerhaus@colorado. edu

Library of Congress Control Number: 2006923488

ISBN-10: 0-387-33324-X e-ISBN-10: 0-387-46896-XISBN-13: 978-0-387-33324-3 e-ISBN-13: 978-0-387-46896-9

Printed on acid-free paper.

© 2007 Springer Science+Business Media, LLCAll rights reserved. This work may not be translated or copied in whole or in part without the writtenpermission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY 10013,USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with anyform of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilarmethodology now known or hereafter developed is forbidden.The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are notidentified as such, is not to be taken as an expression of opinion as to whether or not they are subject toproprietary rights.

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Preface

The Cryogenic Engineering Conference (CEC) marked its 50th anniversary thispast year. To highlight the occasion the CEC Board, in conjunction with the Inter-national Cryogenic Materials Conference (ICMC) Board, proposed that a special1-day anniversary program be scheduled prior to the CEC–ICMC joint meetingin Keystone, Colorado, that would review the advances in cryogenic engineeringwhich had occurred in this distinct but relatively invisible field of engineeringduring the past 50 years. Accordingly, a program of 14 papers, covering both theinterest of CEC attendees and ICMC attendees, was envisioned to cover the variousaspects of cryogenic engineering. Authors were invited to prepare these review pa-pers, but because of time restrictions the technical program was limited and not allpapers were presented orally. As a result, the CEC and ICMC boards recommendedthat a separate monograph, in addition to the regularly published two volumes ofAdvances in Cryogenic Engineering, be prepared which would include all of theinvited papers. This monograph is the result of that recommendation.

To provide an assessment of the status of cryogenic engineering 50 years ago,a historical summary of cryogenic activity is presented in the first chapter. Thepurpose is to review the events occurring during the 100-year period prior to 1950as well as to provide a better understanding of the events that took place after1950. With that historical background, the advances in establishing databases forcryogenic fluids and properties of materials, both metallic and nonmetallic, are dis-cussed and their present status evaluated. The advances in cryogenic fundamentalsare then covered, with reviews of cryogenic principles, progress in cryogenic insu-lation, development of low-loss storage systems for cryogenic fluids, establishmentof modern liquefaction processes, modifications occurring in helium cryogenics,and improvements achieved in cryogenic thermometry.

The monograph then reviews several well-established applications resultingfrom the cryogenic advances noted above. The cryocoolers developed for aerospacemissions are many in number and show a steady progress to achieve long-life cool-ers and cryostats. The actual application of superconductivity is noted in two chap-ters, one considering low-temperature superconductivity activities and the otherconsidering high-temperature superconductivity activities. Both are contributingto modern concepts of power transmission and storage, high-power magnets, and

v

vi Preface

sophisticated medical equipment. Cryopreservation of tissues and organs is under-going considerable change with a better understanding of the effects of cryopro-tectants. Obviously, there are other applications that could have been included, butthe value of the monograph would have been lost.

The preparation of even a monograph requires the assistance of many individu-als. The editors thank the authors for their interest and time required to prepare areview, a process that normally necessitates considerable effort in literature reviewand evaluation. We also want to thank the many reviewers of the chapters andthe constructive comments that were provided. Finally, we want to recognize themany contributions made by Cynthia Ocken, from the University of Colorado andassistant to one of the editors. Her daily updating of changes made in the chaptersover many months and the overall control of the publication process are greatlyappreciated and admired.

KLAUS D. TIMMERHAUS

RICHARD P. REED

Contents

About the Authors ix

Part 1. Background Information

1. Historical Summary of Cryogenic Activity Prior to 1950 ............. 3R. Radebaugh

Part 2. Advances in Cryogenic Data Development over thePast 50 Years

2. Sources of Cryogenic Data and Information.............................. 31R.A. Mohling, W.L. Hufferd, and E.D. Marquardt

3. Trends and Advances in Cryogenic Materials............................ 52R.P. Reed

4. History and Applications of Nonmetallic Materials .................... 84G. Hartwig

Part 3. Improvement in Cryogenic Fundamentals over thePast 50 Years

5. Advances in Cryogenic Principles ........................................... 105R.F. Barron

6. Insulation Progress since the Mid-1950s................................... 120K.D. Timmerhaus

vii

viii Contents

7. Development of Low-Loss Storage of Cryogenic Liquidsover the Past 50 Years .......................................................... 134R.G. Scurlock

8. Fifty-Years’ Development of Cryogenic Liquefaction Processes..... 146W.F. Castle

9. Advances in Helium Cryogenics ............................................. 161S.W. Van Sciver

10. Lessons Learned in 50 Years of Cryogenic Thermometry ............ 179F. Pavese

Part 4. Cryogenic Applications Development Over the Past 50 Years

11. Aerospace Coolers: A 50-Year Quest for Long-LifeCryogenic Cooling in Space ................................................... 225R.G. Ross, Jr.

12. Understanding Properties and Fabrication Processesof Superconducting Nb3Sn Wires............................................ 285M. Suenaga

13. High-Temperature Superconductors: A Reviewof YBa2Cu3O6+x and (Bi,Pb)2Sr2Ca2Cu3O10 ............................. 309H.C. Freyhardt and E.E. Hellstrom

14. A Paradigm Shift in Cryopreservation: Molecular-BasedAdvances to Improve Outcome............................................... 340J.M. Baust and J.G. Baust

Index 367

About the Authors

R.F. Barron is Professor Emeritus of Mechanical Engineering at the LouisianaTech University. He is the author of Cryogenic Systems (1st ed., 1965; 2nd ed.,1985; Russian translation, 1989) and Cryogenic Heat Transfer (1999). He is a pastmember of the Cryogenic Engineering Conference Board and a member of theCryogenic Society of America, where he serves on the Editorial Board of ColdFacts. He is a fellow of ASME.

J.G. Baust is Lead Professor in the Biological Sciences and Bioengineering De-partment and Director of the Institute of Biomedical Technology at the State Uni-versity of New York at Binghamton, New York. He has authored or coauthoredhundreds of papers, reviews, and patents in cell-tissue cryopreservation, hypother-mic organ preservation, tissue engineering, and cancer therapy. He has been heavilyinvolved in numerous cryobiology companies and presently serves as Presidentand CEO of BioLife Solutions, Inc.

J.M. Baust serves as President and CEO of Cell Preservation, Inc. and Professorin the Bioengineering and Biology Department at the State University of NewYork at Binghamton, New York. He has authored or coauthored many papers,reviews, and patents in the area of low-temperature biology and has been a leaderin advancing this field into the molecular biological arena, focusing on the areasof transduction and apoptosis. He serves on several advisory and editorial boardsof several biotech corporations and journals, respectively.

W.F. Castle is retired after working for BOC in the UK for 48 years, where he wasProject and Technical Director as well as International Sales Project Director. Heis the immediate Past President of Commission A2 of the International Institute ofRefrigeration and has presented many papers at international meetings coveringtopics on cryogenic process design, selection of air separation plants for specificproduct demands, and review of advances in cryogenic technology.

H.C. Freyhardt is Director of the Zentrum fur Funktionswerkstoffe in Goettingen,Germany, and a member of the University of Goettingen’s Institute fur Material-physik. Most of his extensive publications relate to his studies on superconductorsand semiconductors, including alloys, composites, thin film oxides, and thin film

ix

x About the Authors

high transition temperature alloys. He has been active in the International Cryo-genic Materials Conference.

G. Hartwig is retired from the Forschungszentrum Karlsruhe, where he developeda strong program investigating the low-temperature behavior of both polymersand composites. In this area he has published extensively and directed numerousinternational conferences.

E.E. Hellstrom has devoted nearly 20 years to the study of high-temperaturesuperconductors at the University of Wisconsin in Madison. His research interestsinvolve the study of the underlying materials science applicable to the developmentof wire conductors for high-current and high-field use, focusing on the Bi-basedhigh-temperature superconducting materials and recently on MgB2.

W.L. Hufferd has 40 years of experience in structural design and analysis of solid-fuel rocket engines. He is the author of many technical reports in this area, withstudies on stress and fracture analysis and materials aging and associated servicelife. He served as Director of the CPIA over the last 10 years on an extensiveliterature retrieval system while cooperatively reconstructing the former NationalBureau of Standards (NBS) cryogenic database.

E.D. Marquardt has more than 17 years of cryogenic experience at the National In-stitute of Standards and Technology (NIST) and Ball Aerospace and Technologies,with major emphasis on pulse-tube, Stirling, and Joule–Thomson cryocoolers. Heis actively involved in material properties and with development of cryogenic liter-ature databases. Presently, he serves on the boards of the International CryocoolerConference and the Cryogenic Engineering Conference.

R.A. Mohling has over 30 years of experience in cryogenic systems developmentwhile employed with AFRPL, Beech Aircraft/Cryogenic Division, Ball Aerospace,and Technology Applications, Inc. (TAI). He is currently President of TAI, a smallbusiness company specializing in technology development and fabricating proto-types of cryogenic and thermal management systems. He led a collaborative effortfor NASA—Marshall Space Flight Center with the CPIA and NIST to reconstructthe former NBS cryogenic database.

F. Pavese is Principal Scientist at the National Institute for Research in Metrology,formerly the Istituto di Metrologia (“G. Collonetti”) in Turin, Italy. He has over a40 year record in cryogenic thermometry, resulting in many publications, includingthe text Modern Gas-Based Temperature and Pressure Measurements. He also is arecognized authority in the establishment of recent international low-temperaturescales.

R. Radebaugh is Group Leader of the Cryogenic Technologies Center at theNIST in Boulder, Colorado. He has been a leader in cryocooler research and inthe development of models for cryogenic properties and processes at temperaturesranging from 10 mK to room temperature. He has authored or coauthored over 120

About the Authors xi

papers and has received a number of awards, including the DOC Gold and SilverMedal, the R&D 100 Award, and the J&E Hall Gold Medal.

R.F. Ross, Jr. is Supervisor of Cryogenics and Advanced Thermal Technologiesat NASA’s Jet Propulsion Laboratory, having been with the latter since 1968. Inhis work on many space-science and space-cryogenics missions, he has publishedmore than 160 papers, over 50 of which are in the field of cryocoolers and cryogenicinstruments. He is a past chair of the International Cryocooler Conference and hasbeen its Proceedings Editor for the past 12 years.

R.P. Reed has been heavily involved over the past 40 years in the study of low-temperature properties of materials, with an extensive publication record. He ini-tially was with the NIST in Boulder, Colorado, and now serves as President ofCryogenic Materials, Inc., consulting in the fields of cryogenic materials, special-izing in structural alloys and composites for superconducting applications.

R.G. Scurlock is Emeritus BOC Professor of Cryogenic Engineering andformer Director of the Institute of Cryogenic and Engineering at the Universityof Southhampton in the UK. With over 40 years of experience in cryogenicfluid mechanism and heat transfer, he now consults with Kryos Technology.Results of his work are now standard worldwide in low-loss storage con-tainers and are published in a text of that same title. He was awarded the CECS.C. Collins award and is the first individual outside of the US to receive this honor.

M. Suenaga currently directs the Metallurgy and Materials Science Division atBrookhaven National Laboratories and serves as Adjunct Professor of MaterialsScience at the State University of New York at Stony Brook. He has continuouslycontributed over the past 30 years to the understanding of type A15 and cupratesuperconductors and their use in many applications.

K.D. Timmerhaus is a President’s Teaching Scholar at the University of Coloradoin Boulder, Colorado, after 47 years of teaching, research, and administration at theinstitution. His 50-year association with the Cryogenic Engineering Conferencehas involved many offices, including editor of the Advances in Cryogenic Engi-neering for 25 years. He is the recipient of awards from the CEC, CSA, AIChE,ASEE, SAE, IIR, and NSF. He is Past President of the IIR, AIChE, Sigma Xi, anda member of the NAE.

S.W. Van Sciver is a Distinguished Research Professor in the Mechanical Engi-neering Department and Program Director with the National High Magnetic FieldLaboratory (NHMFL) at Florida State University. He is the author of over 150publications in low-temperature physics, liquid helium technology, cryogenic en-gineering, and magnet technology and is author of the textbook Helium Cryogenics(1986). He is a Fellow of ASME and American Editor for Cryogenics.

Part 1Background Information

1Historical Summary of CryogenicActivity Prior to 19501

R. RADEBAUGH

National Institute of Standards and Technology, Boulder, Colorado, 80305 USA

Abstract

Cryogenics is the science and technology dealing with temperatures less than about120 K, although this historical summary does not adhere to a strict 120 K definition.The techniques used to produce cryogenic temperatures differ in several ways fromthose dealing with conventional refrigeration. In practice, these two areas oftenoverlap and the boundary between conventional and cryogenic refrigeration isoften indistinct. Significant reductions in temperature often have very pronouncedeffects on the properties of materials and the behavior of systems.

Many cryogenic applications have developed as the refrigeration techniquesprior to 1950 have improved, although many applications still face stiff competi-tion from ambient temperature phenomena because of the associated refrigerationproblems. This review shows how the development of new applications over thepast 50 years is closely tied to the advances in cryogenic refrigeration prior to1950.

1.1 Introduction

Temperature affects processes and material properties more than any other variable,such as pressure, magnetic field, electric field, etc. The ability to harness and applythese temperature effects is a unique feature of mankind, and it has contributedto great advances in our civilization. Mankind has discovered abundant uses forhigh temperatures, beginning in prehistoric times with the use of fire for warmth,light, and cooking. Later, but still more than 20 centuries ago, mankind learned toforge tools and make crude pottery using heat from fires. As civilization advancedand higher temperatures could be achieved, stronger metals, such as iron, could beforged into tools, and much stronger pottery and china could be produced by thehigher temperature firing (sintering) of clay. The industrial revolution ushered in

1 Contribution of the National Institute of Standards and Technology, not subject tocopyright.

3

4 R. Radebaugh

the steam engine and the ability to generate tremendous power for efficient man-ufacturing and transportation. The enhancement of chemical reactions at highertemperatures has been exploited for the production of vast amounts of new andimproved materials in the last century or so.

High-temperature applications began rather early in the history of civilizationowing to the ease of producing increasingly hotter fires. In contrast, mankind’s useof low temperatures has greatly lagged that of high temperatures because of thegreater difficulty in producing low temperatures. Low-temperature applicationswere limited for many centuries to the use of naturally occurring ice. The practiceof using natural ice to treat injuries and inflammation was carried out by Egyptiansas early as 2500 BC [1], and the Chinese began to use crushed ice in food around2000 BC. Although ice was first created artificially in the laboratory in 1755,it was not until near the mid 1800s with the development of the steam engineand practical compressors in the industrial revolution that artificial ice could beproduced in sufficient quantities to replace natural ice cut from lakes. Until thenthe sole use of low temperatures was with natural ice for food preservation and afew medical procedures.

The science of thermodynamics was just beginning to develop around 1850,which related heat, work, and temperature. Though the concept of absolute zeroat –273 ◦C was put forward in the mid 1700s, the means of reaching temperaturesmuch below 0 ◦C were not known or possible until the development of thermo-dynamics and high-pressure reciprocating compressors around 1850. Thus, nearlyall understanding and uses of low temperatures have occurred in the last 150 years.Prior to that time, laboratory techniques for reducing temperatures relied on theliquefaction of a small quantity of gas at high pressure in a thick-walled glasstube surrounded by ice, followed by a rapid expansion of the vapor phase toatmospheric pressure through a valve. The temperature of the remaining liquidphase then dropped to its normal boiling point. Faraday used this one-shot pro-cess on several gases, beginning in 1823 with chlorine (normal boiling point of239 K) [2]. Over the next several decades nearly all of the gases were liquefiedat the ice point under sufficient pressure. Ethylene, with a critical temperatureof 282 K and a normal boiling point temperature of 169 K, yielded the lowestachievable temperature with this technique. Those known gases such as methane,carbon monoxide, oxygen, nitrogen, and hydrogen that could not be liquefiedby this technique, even with pressures up to 40 MPa, were called “permanent”gases.

In an 1834 British patent, Perkins, an American who had moved to England,showed how to carry out the Faraday process of liquefaction and expansion con-tinuously [3]. That was the beginning of today’s vapor-compression refrigerators,shown schematically in Figure 1.1. The Perkins refrigerator was designed for usewith ethyl ether, although the actual refrigerator built by John Hague and shownin Figure 1.2 used caoutchoucine, a distillate of India rubber readily available atthat time, to produce small quantities of ice soon after 1834.

New applications of cryogenics are made possible whenever some lower tem-perature is achieved. The difficulties and problems associated with achieving a

1. Historical Summary of Cryogenic Activity Prior to 1950 5

VAPOR-COMPRESSION CYCLE(Steady Flow)

FIGURE 1.1. Vapor compression cycle devel-

oped by Perkins [3].

particular temperature greatly influence the development of applications of thesetemperatures. As a result, this review examines the development of refrigera-tion techniques and cryocoolers to show how cryogenic applications are stronglydependent on improvements in refrigeration techniques.

FIGURE 1.2. Perkin ice machine built by Hague.

6 R. Radebaugh

FIGURE 1.3. Cryogenic developments from 1850 to 1950.

1.2 The Beginning of Cryogenics

In examining low-temperature developments over the past 150 years, we note thatthere is a convenient and interesting division into three 50-year time segments,where the developments in each time segment have their unique characteristics.Figure 1.3 summarizes the important developments in each time segment. Thoughthe papers in this monograph focus mostly on the last 50 years, it is instructive toexamine briefly the developments in refrigeration and cryogenics that occurred inthe two previous 50-year segments to understand how they contributed to the statusof cryogenics at the time of the first Cryogenic Engineering Conference (CEC) in1954. Also, by comparing developments in each 50-year segment, we may have abetter idea how quickly future developments might progress in the first half of the21st century.

Figure 1.3 shows that the development of thermodynamic fundamentals wasthe primary contributor to advances in cryogenics between about 1850 and 1900.The advances in that half century were primarily of interest only to scientists, andthere were almost no applications for temperatures below the ice point. At thebeginning of that time period the first and second laws of thermodynamics werejust being proposed. As part of those developments the thermodynamic cyclesrequired to liquefy the “permanent” gases like oxygen, nitrogen, hydrogen, andhelium were being invented. The critical temperatures of these “permanent” gasesare far below the ice point, and their very low normal boiling temperatures are now

1. Historical Summary of Cryogenic Activity Prior to 1950 7

referred to as cryogenic temperatures. Cryogenics is usually defined as the scienceand technology dealing with temperatures less than about 120 K [4,5], althoughthis review does not adhere to a strict 120 K definition. Onnes first coined theadjective “cryogenic” in 1894 by using it in a paper entitled, “On the cryogeniclaboratory at Leiden and on the production of very low temperatures” [6]. Thetechniques used to produce cryogenic temperatures differ significantly from thosedealing with conventional refrigeration. One of the most important differences isthe need to precool the compressed gas before it is expanded in order to reachcryogenic temperatures when starting from 0 ◦C or higher. Precooling can beaccomplished with a cascade of refrigerant baths or with a heat exchanger. Theconcept for a recuperative counterflow heat exchanger was developed by Gorrie [7]in 1851 and refined by Siemens [8] in 1857. The Joule–Thomson (JT) effectdiscovered in 1852 [9] was not sufficiently large to produce cryogenic temperatureswhen starting from the ice point without the precooling afforded by such a heatexchanger.

Oxygen was first liquefied (in the form of a mist) in 1877 by using the oldertechniques of Faraday and Perkins, but with a cascade of precooling baths. Cailletetin Paris used a hand-operated screw jack with mercury to pressurize oxygen hy-draulically (155 K critical temperature Tcr) to 20 MPa in a thick-walled glass tubecooled to 169 K by a surrounding bath of liquid ethylene. The liquid ethylene (Tcr =282 K) had been produced earlier using the Faraday technique with an ice bathfor precooling. When the pressure on the oxygen was released via the screw jackhandwheel, a fog appeared in the glass tube, but it quickly disappeared becauseof the heat input from the glass tube [9,10]. On the same day, Pictet in Genevaproduced a continuous mist of liquid oxygen from a JT valve by using a cascade ofvapor-compression systems for precooling the oxygen. The cascade of precoolingbaths was operated continuously using piston compressors. The cascade consistedof sulfur dioxide (Tcr = 431 K, TNBP = 263 K) and solid carbon dioxide (Tcr =304 K, Ts = 195 K). The flowing high-pressure oxygen was cooled successivelyby the two baths before expanding through the JT valve to the atmosphere. A jetof liquid oxygen mist at 90 K sprayed out from the JT valve [9,10]. The first toproduce enough liquid oxygen and liquid nitrogen to study their properties wereWroblewski and Olszewski of Poland in 1883. They used the same cascade methodas Cailletet, but the final stage was a pumped liquid ethylene bath at a temperatureof 137 K [11]. Because the temperature of that bath was less than the 155 K crit-ical temperature of oxygen, liquid formed inside the glass tube under a pressureof about 2.5 MPa. Upon reducing the pressure to 1 atm, a small quantity of liquidboiling at 90 K remained in the tube for a short period of time. Figure 1.4 showsthe path in a temperature entropy (T –S) diagram followed by the various methodsfor liquefying oxygen.

Though the recuperative heat exchanger had been invented in 1857 by Siemens,little use was made of it until 1895 when Hampson replaced the cascade bathsused previously for precooling oxygen with the recuperative heat exchanger. A JTvalve at the cold end of the heat exchanger provided the cooling during expansion.Figure 1.5 is a schematic of the cycle used by Hampson to liquefy air [12], which

8 R. Radebaugh

200

Vapor

100

100

150

200

250

300 Oxygen

263 K

195 K

155 K

137 K

169 K Ethylene

SO2

CO2

Pumped ethylene

Liquid

h = const.

40 M

Pa

20

5

4 2

0.5

P =

0.1

MP

a

150

Entropy (J/Mol-K)Cailletet (1877)Pictet (1877)Wroblewski and Olszewski (1883)Hampson (1895)Linde, simple cycle, (1895)Linde, dual pressure, (1895)

Tem

pera

ture

(K

)

FIGURE 1.4. Cryogenic approaches taken to liquefy oxygen and shown on a T –S diagram.

JOULE-THOMSON CYCLE(Linde-Hampson Cycle)

(Steady Flow)

FIGURE 1.5. Schematic of the JT cycle used by Hampson to liquefy air.

1. Historical Summary of Cryogenic Activity Prior to 1950 9

FIGURE 1.6. Drawing of Hampson’s air liquefier.

is usually referred to today as simply the JT cycle. Figure 1.6 is a drawing ofHampson’s air liquefier showing the closely packed copper tubing heat exchangerin the annular space between tubes D and F . The JT valve C is controlled bythe handle E . Glass wool surrounds the evaporator G and the heat exchanger.The liquefaction rate was 1 L/h [13]. A very effective heat exchanger is necessaryto reach cryogenic temperatures with the warm end at 300 K. The requirementfor such a heat exchanger is one feature that distinguishes cryogenic refrigerationfrom normal refrigeration. At the same time as Hampson’s work, Linde in Germanyalso used the combination of a JT valve and a recuperative heat exchanger for thecontinuous liquefaction of air in 1895 [14]. The simple cycle first used by Lindeis the same cycle Hampson used as depicted in Figure 1.5. Linde also developeda dual-pressure cycle, as sketched in Figure 1.7, which was more efficient thanthe simple cycle. About 80% of the gas was expanded from 20 MPa to 4 MPaand returned to the second-stage compressor. The remaining 20% (mostly liquid)was expanded from 4 MPa to 0.1 MPa, with the gas fraction being returned tothe first-stage compressor [15]. Figure 1.4 shows the path of this cycle on a T –Sdiagram. With this cycle Linde was able to produce about 10 L/h of liquid air.Linde quickly went on to commercialize the process and developed the techniqueof distilling liquid air into oxygen and nitrogen. By 1899 Linde was producing

10 R. Radebaugh

FIGURE 1.7. Drawing of Linde’s dual-pressure JT air liquefier.

liquid air at the rate of 50 L/h [13]. The early liquefiers of Hampson and Lindeused glass wool for insulation, even though Dewar had invented the use of vacuumfor thermal insulation in 1873 and the silvered glass vacuum container in 1892 [9].

The regenerative heat exchanger (regenerator) was invented by Stirling in 1816for use in an engine with oscillating flow. He called the device an economizer, inwhich heat is stored for a half cycle in the heat capacity of the regenerator matrix.The Stirling engine, as patented by Robert Stirling in 1817 [16], was first used topump water from a quarry and had the advantage of being much safer than thesteam engines of that time. The operating frequency was probably a few hertz.Stirling’s patent drawing, given in Figure 1.8, shows the use of a displacer (#9 inthe figure) to move the working gas between the hot and ambient temperatureregions. However, the drawing does not show an ambient temperature heat sinkor the specific regenerator arrangement. In 1834, Herschel proposed to reversethe cycle and use it as a refrigerator for producing ice [17]. However, it was notuntil about 1861 that Kirk [18] reduced the concept to practice. Figure 1.9 showsa drawing of the Kirk ice machine. The displacer filled with wire gauze O for the

1. Historical Summary of Cryogenic Activity Prior to 1950 11

FIGURE 1.8. Stirling engine patented by Stirling.

FIGURE 1.9. Kirk ice machine.

12 R. Radebaugh

FIGURE 1.10. Two versions of the Stirling refrigerator.

regenerator has conical end pieces connected to it with insulation between them.Fresh water entering at C removes the heat of compression. Air was the workingfluid in this early regenerative cooler. In spite of the high efficiency of the Stirlingcooler, Kirk never made any attempt to reach temperatures below about −40 ◦C.[19]. Schematics of two versions of the Stirling cooler are given in Figure 1.10.Kirk used the version with the internal regenerator. No further work was carriedout on the Stirling cooler for about the next 80 years.

An air-expansion engine for steady flow, similar to steam engines of that period,was first used by Gorrie in 1851 for an ice-making machine [7,19]. Several otherair expansion engines for use in producing ice were developed in the latter half of1800 [19]. In 1896, Onnes discussed in detail his concept to liquefy hydrogen withthe aid of an expansion engine, but the technical difficulties forced him to abandonthe idea [20]. The first successful use of an expansion engine to produce cryogenictemperatures was by Claude. He liquefied air in 1902 by allowing a portion of thehigh-pressure air in a JT cycle to expand and cool in a reciprocating engine beforereturning it to the low-pressure side of the heat exchanger [19,21]. This combinedcycle, now called the Claude cycle and shown in Figure 1.11, increased the effi-ciency of the liquefaction process and permitted the use of lower pressures. Thearrangement used by Claude in 1902 did not have the third heat exchanger (HX3)shown in Figure 1.11. The path on a T –S diagram is shown in Figure 1.4. Claudeinitially used a high pressure of 2.5 MPa (increased to 4 MPa by 1906), comparedwith the 20 MPa used by Hampson and Linde for a JT expansion [13]. Figure 1.12 isa photograph of the original expansion engine used by Claude. Its construction wasvery similar to the steam engines and compressors of that period. Claude foundthat a leather cup worked satisfactorily as a flexible and dry sealing mechanism

1. Historical Summary of Cryogenic Activity Prior to 1950 13

FIGURE 1.11. Schematic of the Claude air

liquefier.

for the piston at low temperatures [19]. Within a few weeks of liquefying air,Claude formed the company L’Air Liquide to commercialize the production ofoxygen using his air liquefaction technique and air separation through distillation.Oxygen could be produced by air separation much more cheaply than by chemicalmeans. Both Claude and Linde were marketing the oxygen to the rapidly growingdemands of the welding industry for use in oxyacetylene torches perfected by

FIGURE 1.12. Expansion engine used in

Claude liquefier.

14 R. Radebaugh

Picard in 1900 [13]. Steel welding and cutting then became the first significantapplication of cryogenics, and continues on to the present day.

Hydrogen was first liquefied at a temperature of 20 K in 1898 by Dewar usingthe JT techniques of Linde and Hampson, but with a precooling bath of liquid air[22]. The liquefaction rate was about 0.25 L/h. Dewar made use of the silvered,vacuum-insulated glass dewars he had invented earlier to hold the liquid air andliquid hydrogen with low boiloff rates after successfully liquefying hydrogen.

Helium was first discovered in the sun in 1868 and then found on Earth inthe mineral cleveite in 1895. After hydrogen was liquefied in 1898, the attentionof the cryogenic scientific community then turned to helium because it was theonly remaining “permanent” gas that had not been liquefied. Around 1900, bothDewar of the Royal Institution in England and Onnes of the University of Leidenin the Netherlands sought to obtain sufficient quantities of helium to liquefy it.Contrary to common belief, their competition to be the first to liquefy heliumremained rather cordial and each provided the other helpful suggestions [23]. Inorder to liquefy helium with the JT cycle, Onnes needed a sufficient quantity ofliquid hydrogen for precooling the helium. Previously, in 1894, Onnes had set upa cascade air liquefier using the vapor-compression cycle in four separate stagesof methyl chloride (249 K), ethylene (169 K), oxygen (90 K), and air (82 K) [6].No recuperative heat exchangers are required in this cycle. This liquefier produced14 L/h of liquid air. To liquefy hydrogen, Onnes would first liquefy a sufficientlylarge quantity of air (about 75 L) in the cascade liquefier. This liquid air wasthen siphoned into the hydrogen liquefier through an expansion valve, where theliquid air at subatmospheric pressure would precool the high-pressure hydrogen.The hydrogen was pressurized up to 20 MPa by a compressor that utilized acolumn of mercury to eliminate leakage of hydrogen by the piston. This typeof compressor was invented by Cailletet for his use in liquefying oxygen andnitrogen. Counterflow heat exchangers between the high-pressure hydrogen and thereturning low-pressure air and hydrogen were also incorporated into the apparatusto reduce the boiloff rate of the liquid air. After being cooled to 64 K, the high-pressure hydrogen passed into the recuperative heat exchanger and then expandedthrough the JT valve to form liquid hydrogen. Onnes completed this liquefierin 1906, which produced 4 L/h of liquid hydrogen, much more than the 1 L/hhydrogen liquefier of Dewar [24].

Onnes then built a similar liquefier for helium, but with the liquid air beingreplaced by liquid hydrogen, which precooled the high-pressure helium to 15 Kbefore entering the recuperative heat exchanger and expanding it in the JT valve tocool to the liquefaction point. The helium gas was pressurized to as high as 10 MPaby the same mercury-sealed compressor that had been used for the hydrogenliquefier. The unsilvered glass dewar for the liquid helium was surrounded by aliquid hydrogen bath and a liquid air bath, both of which were in silvered glassdewars with a slit in the silver to observe the liquid helium. Onnes succeeded inproducing about 100 mL of liquid helium at a temperature of 4.2 K on July 10,1908 [25], for which he received the Nobel Prize in 1913. With the capability toreach temperatures of 2 K, Onnes then discovered superconductivity in high-purity

1. Historical Summary of Cryogenic Activity Prior to 1950 15

mercury in 1911 at a temperature of 4.2 K [26]. No other laboratory was able toproduce liquid helium until 1923, when McLennan at the University of Torontobuilt a helium liquefier similar to that of Onnes. [27]. The first helium liquefier inthe US was constructed by Brickwedde at the US National Bureau of Standards(NBS) in 1931. It also used liquid air and liquid hydrogen baths for precooling aJT stage and produced 0.15 L/h of liquid helium [28].

As summarized in Figure 1.3, the years between 1900 and about 1950 sawsignificant improvements in liquefaction technology, in which efficiency and reli-ability were greatly improved and liquefaction rates were increased by orders ofmagnitude. In the case of liquid oxygen, the liquefaction rate for a typical plantwas increased from about 3 L/h in 1895 to 2 t/day in 1910 and to 100 t/day in1954 (1 t = 1000 kg). The fast growth in oxygen liquefaction capacity was drivenby the first commercial application of cryogenics, which was the use of oxygenfor oxygen–acetylene welding. Soon after Dewar liquefied hydrogen in 1898, heproposed an exhibit on liquid hydrogen for the British Pavilion at the 1904 St LouisWorld’s Fair. The hydrogen liquefier built for the fair had a two-stage reciprocatinghydrogen compressor capable of producing 20 MPa at the output with 0.6 MPa atthe intermediate stage [29]. The flow rate was about 14 N m3/h. The high-pressurehydrogen was precooled first to 203 K with liquid CO2, then to 83 K with liquidair at atmospheric pressure, and then to 68 K with a pumped liquid air bath beforeexpanding through a JT valve to form liquid at 20 K. The liquefaction rate was notgiven; but, if we assume a liquid yield of 7% (85% heat exchanger effectiveness),then about 1 L/h would have been produced. It performed well, but the leatherpiston rings had to be replaced during the night after each day’s run. Thus, itsmean time to failure was probably not much more than 1 day.

At the close of the 1904 World’s Fair, the NBS, formed in 1901 (called the Na-tional Institute of Standards and Technology after 1988), purchased the hydrogenliquefier for research at low temperatures. It was not used for several years becauseof the daily maintenance required; but, in the early 1920s it was overhauled by theBritish Oxygen Company, with the compressor being replaced by one using steelpiston rings. The overhauled liquefier produced 2 L/h of normal liquid hydrogen,which boiled rapidly because of the heat of conversion to parahydrogen [29]. Then,in 1950, the US Atomic Energy Commission funded the NBS to design and con-struct a much larger hydrogen liquefier for the development of the hydrogen bomb.In 1952, the equipment fabricated in Washington was shipped to the new NBS fa-cility in Boulder [30]. The plant first liquefied hydrogen on March 23, 1952, anda short time later was able to produce 320 L/h of normal liquid hydrogen [4,31].After installing an ortho–para converter in the liquefier in 1953, the plant couldproduce 240 L/h of liquid parahydrogen. The NBS liquefier used JT expansion ofhydrogen compressed to 12 MPa and precooled with baths of liquid nitrogen at77 K and 65 K. The liquid yield was 24.5%, compared with a theoretical value of26.1% [4], which indicates a heat exchanger effectiveness of 98.4%.

In 1934, Kapitza, working at the Royal Society Mond Laboratory of Cambridge,described a helium liquefier based on the Claude cycle [32]. The reciprocatingexpansion engine replaced the liquid hydrogen precooling bath of Onnes’s JT

16 R. Radebaugh

process. A liquid nitrogen bath was still used. The lower operating pressure of1.7 MPa also relaxed the requirements on the compressor. Kapitza developed anonlubricated expansion engine using a clearance seal with labyrinth grooves onthe piston. The expansion work was dissipated at room temperature in a hydraulicmechanism. The connecting rod, in the form of a thin-walled tube, had a room-temperature gland to prevent the leakage of helium. The liquefier produced about1.7 L/h of liquid helium [33].

Kapitza visited Moscow on vacation in 1934 and was detained there by govern-ment authorities until his death in 1984. He eventually became the director of theInstitute for Physical Sciences of the Academy of Sciences in Moscow. He builtanother helium liquefier in Moscow to study the properties of helium. In 1937,Kapitza [34] and Allen et al. [35] independently discovered superfluidity in liquidhelium below 2.17 K. Kapitza received the Nobel Prize in 1978 for this work andfor his work with helium liquefaction techniques.

The use of expansion turbines for gas liquefaction appears to have been firstcarried out in 1934 at the Linde facilities in Germany [19,36]. In 1939, Kapitzadescribed the design and construction of an air liquefier with an 80 mm diameterexpansion turbine supported by ball bearings at room temperature and rotating ata speed of 40,000 rpm [19,37]. The inlet pressure was 0.56 MPa, and the poweroutput of the turbine was 4 kW. The turbine handled about 570 kg/h of air andachieved an isentropic efficiency of 79%.

In 1935, Collins also began work on a helium liquefier using the Claude cycleand reciprocating expansion engines. The work was interrupted by World WarII, but the liquefier was completed in 1946 [38]. Collins used two reciprocatingexpansion engines to eliminate the need for both liquid nitrogen and liquid hy-drogen precooling. He also used a clearance seal on the piston, as did Kapitza,but the expansion space was on top of the piston, so the connecting rod was al-ways in tension. Thus, the connecting rod could be made with a thin flexible rodto minimize heat leaks. The liquefaction rate with no liquid nitrogen precoolingwas about 1 L/h using a commercial compressor providing a pressure of 1.5 MPaand driven with a 7.5 hp (about 10 kW) motor. This efficient helium liquefierhas become known as the Collins helium cryostat or liquefier [19]. This liquefierwas then commercialized and allowed laboratories all over the world to produceliquid helium for low-temperature research. The first commercial helium liquefierof about 1950, shown in Figure 1.13, produced about 4 L/h with liquid nitrogenprecooling. Between 1947 and 1970, 365 units were marketed [39].

After the liquefaction of 4He at 4.2 K by Onnes there was no other gas witha lower boiling point, except for the rare isotope 3He with a boiling point of3.2 K. Temperatures of about 0.7 K could be achieved by pumping on liquid 4He.An entirely new refrigeration method using adiabatic demagnetization of electronparamagnetic salts was proposed independently by Debye [40] and by Giauque [41]in 1926 to reach temperatures much lower than 1 K. For this technique the salt ismagnetized at a higher temperature around 1 K to align the magnetic spins withthe field and reduce the entropy. The heat of magnetization is transferred to thesurrounding bath. The salt is then thermally isolated from the bath and, as the

1. Historical Summary of Cryogenic Activity Prior to 1950 17

FIGURE 1.13. Collins helium

liquefier.

magnetic field is removed, the salt cools to some lower temperature. This is aone-shot process, and the salt warms up as it absorbs heat. The first successfulexperiment was carried out in Berkeley in 1933 by Giauque and MacDougall, inwhich a magnetic field of 0.8 T was applied to the Gd2(SO4)3·8H2O paramagneticsalt at 1.29 K and then demagnetized to a final temperature of 0.242 K [42]. Giauquereceived the Nobel Prize in 1949 for his work with adiabatic demagnetization andthe third law of thermodynamics. Many researchers enter this field of adiabaticdemagnetization of paramagnetic salts using higher magnetic fields and better saltsto achieve lower temperatures. In 1950, de Klerk et al. [43] at Leiden reached a lowtemperature of 1.4 mK using a mixed salt of chromium alum and aluminum alum.

In 1938, the Philips Research Laboratories in the Netherlands began research onthe Stirling engine to develop electric generators which were later used to powerradios in remote areas during World War II [44]. The effort was carried out duringthe war and led to a rather efficient engine. When it was driven in reverse withan electric motor it acted as an effective refrigerator, like the machine developedby Kirk in 1862 for production of ice. In 1946, the temperature of liquid air wasachieved when low-pressure hydrogen was used as the working fluid and loosecotton wool was used as the regenerator [45]. The refrigeration capacity was low,but the results were encouraging enough that a small group was set up at thePhilips Laboratories and headed by Kohler to study the Stirling cycle for use in

18 R. Radebaugh

FIGURE 1.14. Cross-sectional drawing of the Philips air liquefier.

liquefying air. After increasing the pressure of the hydrogen and using a densemetal screen, liquid air condensed on the outside of the cylinder at a rapid rate.An engineering model was demonstrated for the first time in 1953 at Grenoble forthe International Institute of Refrigeration [46] and the first commercial machine(called the A-machine) was on the market in 1955 [45]. The operating principlesand construction details were given by Kohler and Jonkers [47]. A cross-sectionaldrawing of the machine is shown in Figure 1.14. It is an integral machine with thepiston and displacer in the same cylinder. The regenerator of fine metal screen isin the annular space outside the displacer. The helium or hydrogen working fluidwas at an average pressure between 1.6 and 3.5 MPa with an operating frequencyof about 24 Hz. The high speed and the high pressure resulted in a small machinewith high refrigeration capacity. It could produce 6.6 L/h of liquid air with a yieldof 1.14 L/kWh. A photograph of the first commercial machine (A-machine) isshown in Figure 1.15.

1.3 Cryogenic Applications Around 1950

Around 1950 the only significant applications of cryogenics involved the use ofcryogenic liquids. The liquefaction technology for these cryogens was developedprimarily in the years between 1850 and 1900, and the transfer of the liquefaction

1. Historical Summary of Cryogenic Activity Prior to 1950 19

FIGURE 1.15. Photograph of

the Philips A-machine

liquefier.

technology to industry and the rapid scale up of liquefaction rates occurred primar-ily in the years from 1900 to 1950. As mentioned previously, the first applicationof cryogenics was for the production of oxygen to meet the needs of the weldingindustry. That application continues through to today. The size of a typical oxy-gen production plant grew from about 2 t/day in 1910 to 35 t/day in 1925 to about100 t/day in 1950. Figure 1.16 compares a 2 t/day plant from 1910 with a 100 t/dayplant of the early 1950s. The largest plants in 1950 produced about 200 t/day ofoxygen. In 1947, the US production for oxygen was 0.541 × 106 t (407 × 106 m3

of gas). By 1954 the production had increased to 0.830 × 106 t. The nitrogen pro-duction in 1947 was 0.0167 × 106 t, which increased to 0.534 × 106 t in 1960 [48].The delivery of oxygen or nitrogen from these plants to end users required the useof vacuum-insulated tank trucks and rail cars, a relatively large industry in itself atthis time. Some of the nitrogen from these air separation plants was used for inertatmospheres in the steel and aluminum industries and was beginning to be usedfor the production of some chemicals, such as ammonia. Development of the basicoxygen furnace for the production of steel was initiated in Switzerland by Durrerin the late 1940s. The use of pure oxygen in these furnaces oxidizes impuritiesmore efficiently, increases production rates and reduces the nitrogen content of thesteel compared with the use of air. The first commercial 35-ton converter was setup in Austria in 1952. Similar furnaces were soon being used in the US to meet therapidly growing steel demands of the automotive industry. This new applicationfor oxygen was poised in the early 1950s to bring about a very rapid increase inthe demand for oxygen. Other uses of oxygen in the 1950s were for medical andmilitary breathing supplies.

The first use of liquid oxygen for rocket propulsion began with experimentsby Goddard. On March 16, 1926, he achieved the first successful flight with a

20 R. Radebaugh

(a)

(b)

FIGURE 1.16. (a) 2 ton/day oxygen plant available around 1910. (b) 100 ton/day oxygen

plant available in the early 1950s.