Cryogenics

Robert P. Jackson, P.E.

Course Outline

This six (6) hour course attempts to follow a logical progression, moving through the following primary “blocks” of information:

• INTRODUTION
• BENEFITS FROM THE USE OF CRYOGENIC PROCESSES
• COMMERCIAL AND MONETARY VALUE OF CRYOGENICS
• APPLICATION  AND  USES OF CRYOGENIC COOLING
• HISTORY OF CRYOGENICS
• DESCRIPTION OF TEMPERATURE SCALES
• SAFETY  HAZARDS AND PERSONAL PROTECTIVE EQUIPMENT REQUIRED FOR HANDLING CRYO-MATERIALS
• CRYOGENIC PROPERTIES OF VARIOUS GASES
• THERMODYNAMIC LAWS, EQUATIONS AND THEORY GOVERNING REFRIGERATION AND COOLING.
• CRYOGENIC CYCLES  INCLUDING LIQUIFICATION OF GASES
• MEASUREMENT DEVICES FOR MONITORING AND LOGGING CRYO-TEMPERATURES
• EQUIPMENT TO PRODUCE CRYOGENIC TEMPERATURES
• MATERIALS SUITABLE FOR TRANSFER AND STORAGE OF CRYOGENIC MATERIALS
• STORAGE OF SUB-ZERO LIQUIDS
• APPENDIX
  • GLOSSARY OF TERMS
  • USEFUL RELTAIONSHIPS FOR THERMODYNAMIC PROCESSES
    

This course includes a multiple choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

Upon completion of this course, the student will have an understanding and working knowledge of the following areas relating to the science of Cryogenics:

• A complete glossary of terms used in cryogenic and refrigeration technology;
• A definition for the science of cryogenics;
• Benefits of cryogenic processes;
• History of cryogenics;
• Various commercial and scientific applications of cryogenic technology and methodology;
• Gases that can be processed to achieve cryogenic temperatures;
• Cryogenic properties and characteristics of certain common gases used as cryogenic fluids;
• Understanding  “cryo-pumping”  methodology;
• Thermodynamic laws governing obtainment of cryogenic temperatures;
• Equations that define the laws governing obtainment of cryogenic temperatures;
• Definition of temperature scales directly relating to refrigeration and cryo-temperatures;
• Equipment and devices used to measure cryogenic temperatures;
• Cryogenic cycles used in the liquefaction of gases; i.e. Claude Cycle, Linde Cycle, etc.;
• Effects of low temperatures on materials—specifically metals and cryogenic tempering;
• Metals  suitable for use in cryogenic processes;
• Equipment used within processes to provide cryogenic temperatures;
• Storage methods for gases at cryogenic temperatures;
• Detection of leaks in cryostats and transfer piping;
• Temperature measuring devices used in cryogenic processes;
• Cost effectiveness of cryogenic metal tempering and stress relieving;
• Tool failure due to absence of cryogenic tempering;
• Best practices when using cryogenic processes;
• Hazards associated with cryogenic  technology; and
• Personal protective equipment (PPE) required when working around cryogenic processes.

Intended Audience

This course is intended for those individuals interested in discovering the complexities of cryogenics and   cryogenic processes. Our intention is to deliver information that exceeds the basics so an individual can continue independent study.  It is also intended to be a refresher course for those with some experience distant or otherwise in the field but having the need to “brush-up”.   The following professions would definitely benefit if participating in areas of design, manufacturing, maintenance, instrumentation and management:

• Engineering Managers involved with refrigeration and cooling processes
• Laboratory technicians dealing with low temperature processes
• Mechanical Engineers given the task of designing or maintaining cryogenic systems
• Design Engineers within  the field of refrigeration and low-temperature cooling
• Quality Control Inspectors
• Fabrication and assembly  specialists within the refrigeration industry
• Individuals in the frozen food industry
• Manufacturing engineers dealing with refrigeration technologies
• Environmental Engineers (“Green engineering” is becoming a very viable technology and understanding cryo-processes are very important.)
• Test Technicians Involved with oversight of cryogenic technology and operation
• Metallurgists
• Material Specialists
• Medical practitioners using low temperature and cryogenic devices
• Chemists
• Individuals “new” to refrigeration and cryo-technology
  

Benefit to Attendees

This six (6) hour course is designed to give an engineer, manager or technician more than the basics of cryogenics technology and will allow necessary information to make possible greater knowledge through independent study.   The uses of cryogenic technology grow on an annual basis and now represent a multi-billion dollar commercial industry.   Unrelated fields such as medicine, treatment of metals, the frozen food industry,  superconductivity of current-carrying metals, and super-cooling of mechanical devices such as the Hadron Collider at CERN take advantage of cryogenic methodology.  Billions of dollars each year are saved by virtue of cryogenic application.  The liquefaction of gasses and cryogenic processes used in the frozen food industry alone provide significant “value added” to the lives of millions.  Discovery of the Higgs Boson (“God particle”) would have been impossible without the cryo-cooling provided.  This course strives to explain the history and the processes used to bring about low temperatures required and used by all of these commercial processes.   The course also covers various safety issues in dealing with cryo-processes.  We have included a “best practices” section as a cursory checklist.  Also included are paragraphs dedicated to storage and transfer of cryogenic materials.

Course Introduction

Cryogenics is the science that addresses the production and effects of very low temperatures.  The word originates from the Greek words 'kryos' meaning "frost" and 'genic' meaning "to produce." Under such a definition it could be used to include all temperatures below the freezing point of water (0°C). However, Professor Kamerlingh Onnes of the University of Leiden in the Netherlands first used the word in 1894 to describe the art and science of producing temperatures much lower than common for that time. He used the word in reference to the liquefaction of permanent gases such as oxygen, nitrogen, hydrogen, and helium. Oxygen had been liquefied at -183° C a few years earlier (in 1887), and a race was in progress to liquefy the remaining permanent gases at even lower temperatures. The techniques employed in producing such low temperatures were quite different from those used somewhat earlier in the production of artificial ice. In particular, efficient heat exchangers are required to reach very low temperatures. Over the years the term cryogenics has generally been used to refer to temperatures below approximately -150 °C.
It is a very important technology in our daily lives even if we seldom know of its application.  We definitely use the application and benefits of this basic science in ways now seemingly commonplace.  Varying applications of cryogenic technology have provided significant benefits and made possible the following advances in technology:

• Super-cooling devices used for : 1.) The Large Hadron Collider at CERN, 2.) Ship propulsion motors, 3.) Experimental fusion reactors and 4.)  Whole-body MRI scans.
• Perhaps the most often used purpose for “super-cooling” is stress relief and treatment of steels.  The benefits of this technology may be seen as follows:
• Reduces abrasive and adhesive wear. Treated material typically yield two to three times the production of non-treated material
• Permanently changes the structure of the metal resulting in improved machining properties. Treated components may be ground after treatment and the benefits of treatment are retained. 
• Reduce the frequency and cost of tool remanufacture. Worn treated tools require less material removal to restore a uniform cutting edge. Furthermore, treated tools may be reground more times before falling below the minimum acceptable dimensions.
• Substantially reduce machine downtime caused by tool replacement. 
• Improved surface finishing on material being manufactured with treated tooling. Treated tooling stays sharper and in tolerance longer than untreated. 
• Reduces likelihood of catastrophic tool failures due to stress fracture.
• Stress relieves to reduce inherit/residual stress caused by manufacture.
• Increases the overall durability of the treated product.
• Fast freezing of foods
• Preservation of biological materials such as livestock semen as well as human blood, tissue, and embryos.
• The practice of freezing an entire human body after death in the hope of later restoring life is known as cryonics, but it is not an accepted scientific application of cryogenics.
• The freezing of portions of the body to destroy unwanted or malfunctioning tissue is known as cryosurgery. It is used to treat cancers and abnormalities of the skin, cervix, uterus, prostate gland, and liver.
• Stem cell research
• Superconductivity of metals
• Liquefaction of gasses
• Separation of various gaseous constituents of oxygen

It is a very important part of our daily lives, even if we seldom know of its application.

Course Content

The course content is in a PDF file:

Cryogenics

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Course Summary

The study of cryogenics and cryogenic processes is one of the most important  fields of study for an engineer or technician working within the refrigeration industry.  It has a fascinating history and truly represents a science that has evolved and matured over the centuries.  It actually is a fairly “old” science in the truest since of the word, although commercial applications today represent billions of dollars in value-added to everyday lives.  We benefit greatly from cryogenic applications and several very important research programs; i.e. stem cell, superconductivity, etc would not be possible without this science.   Cryogenic cooling has its roots in thermodynamics which this course will attempt to describe in some detail.   We will describe the various thermodynamic cycles AND the equipment used to bring about sub-cooling of gases, metals and assemblies.  One very important part of the course is how theory and thermodynamic laws governing cryogenics cycles are used to define the processes themselves.   We look at equipment in use today necessary for providing very low temperature. 

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

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DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.

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