Cryogenics And Refrigeration

Refrigeration plays a prominent role in our everyday lives, and cryogenics plays a major role in medical science, space technology and the cooling of low-temperature electronics. This volume contains chapters on basic refrigeration systems, non-compression refrigeration and cooling, and topics related to global environmental issues, alternative refrigerants, optimum refrigerant selection, cost-quality optimization of refrigerants, advanced thermodynamics of reverse-cycle machines, applications in medicine, cryogenics, heat pipes, gas-solid absorption refrigeration, multisalt resorption heat pumps, cryocoolers, thermoacoustic refrigeration, cryogenic heat transfer and enhancement and other topics covering theory, design, and applications, such as pulse tube refrigeration, which is the most efficient of all cryocoolers and can be used in space missions.

About 4839 references (v. 1, about 3000; v. 2, 1839), intended to trace development of production of low temperatures and to show its use in science and technology. v. 1 primarily covers period 1950-Dec., 1966 ; v. 2, 1966-1968. Classifiedarrangement. Each entry includes bibliographical citation, brief annotation, and usually a notation about the number of references cited and the time period covered by such references. Author, subject indexes.

Most conventional cryogenic refrigerators and liquefiers operate with pure fluids, the major exception being natural gas liquefiers that use mixed refrigerant processes. The fundamental aspects of mixed refrigerant processes, though very innovative, have not received the due attention in open literature in view of commercial interests. Hundreds of patents exist on different aspects of mixed refrigerant processes. However, it is difficult to piece together the existing information to choose an appropriate process and an optimum composition or a given application. The aim of the book is to teach (a.) the need for refrigerant mixtures, (b.) the type of mixtures that can be used for different refrigeration and liquefaction applications, (c.) the different processes that can be used and (d.) the methods to be adopted for choosing the components of a mixture and their concentration for different applications.

This book offers a practical introduction to helium refrigeration engineering, taking a logical and structured approach to the design, building, commissioning, operation and maintenance of refrigeration systems. It begins with a short refresher of cryogenic principles, and a review of the theory of heat exchangers, allowing the reader to understand the importance of the heat exchanger role in the various thermodynamic cycle structures. The cycles are considered from the simplest (Joule Thomson) to the most complicated ones for the very large refrigeration plants and, finally, those operating at temperatures lower than 4.5 K. The focus then turns to the operation, ability and limitations of the main components, including room temperature cycle screw compressors, heat exchangers, cryogenic expansion turbines, cryogenic centrifugal compressors and circulators. The book also describes the basic principles of process control and studies the operating situations of helium plants, with emphasis on high level efficiency. A major issue is helium purity, and the book explains why helium is polluted, how to purify it and then how to check its purity, to ensure that all components are filled with pure helium prior to starting. Although the intention of the book is not to design thermodynamic cycles, it is of interest to a designer or operator of a cryogenic system to perform some simplified calculations to get an idea of how components or systems are behaving. Throughout the book, such calculations are generally performed using Microsoft® Excel and the Gaspak® or Hepak® software.

In the early 1980s, Graham Walker wrote his classic two-volume monograph Cryocoolers. Records show that sections of this work have been referenced more often and by more authors than any other cryogenic paper published in the mid-1980s. Nevertheless, the significant time lapse in so dynamica field and Walker and Bingham's experience of teaching short courses has revealed the need for a more up-to-date book - one that is more compact, lower in cost, and embraces more topics. Low-capacity Cryogenic Refrigeration provides an elementary yet comprehensive introduction to the subject, with diverse applications in scientific, medical, educational, military, and civil systems. It is complementary to the earlier two-volume work, but covers a wider field and has a wealth ofinformation about the new developments in the last fifteen years. In addition to descriptions of all the principal methods to achieve low-capacity cryogenic refrigeration, this new volume contains a valuable guide to the literature sources and references more advanced works.

Cryogenics, a term commonly used to refer to very low temperatures, had its beginning in the latter half of the last century when man learned, for the first time, how to cool objects to a temperature lower than had ever existed na tu rally on the face of the earth. The air we breathe was first liquefied in 1883 by a Polish scientist named Olszewski. Ten years later he and a British scientist, Sir James Dewar, liquefied hydrogen. Helium, the last of the so-caBed permanent gases, was finally liquefied by the Dutch physicist Kamerlingh Onnes in 1908. Thus, by the beginning of the twentieth century the door had been opened to astrange new world of experimentation in which aB substances, except liquid helium, are solids and where the absolute temperature is only a few microdegrees away. However, the point on the temperature scale at which refrigeration in the ordinary sense of the term ends and cryogenics begins has ne ver been weB defined. Most workers in the field have chosen to restrict cryogenics to a tem perature range below -150°C (123 K). This is a reasonable dividing line since the normal boiling points of the more permanent gases, such as helium, hydrogen, neon, nitrogen, oxygen, and air, lie below this temperature, while the more common refrigerants have boiling points that are above this temperature. Cryogenic engineering is concerned with the design and development of low-temperature systems and components.