Pulse Tube Modeling as a Means of Teaching the Design of Cryogenic Refrigerators

Abstract

A design manual titled “Low Temperature Pulse Tube Coolers”” has been developed for use in a university course on the design of cryogenic machines. It allows students to be involved in the entire design process by using simple mathematical solutions of the rather difficult physical processes that exist in cryogenic gas machines with pulse tubes. Using the manual, students fulfill a real design of a pulse tube cooler.

The manual consists of two parts. The first part treats a variety of topics including: 1) details of the thermal-physical processes involved and their mathematical modeling, 2) the “method of characteristics” for solution of the equations of gas dynamics, and 3) the definition and discussion of the principal items of cooler losses. For performing calculations, the students use object oriented programming, since examining pulse tube modifications parametrically has group properties. The construction of a model for optimization permits the students to find the optimum solution among all device modifications. The check of a chosen optimum device with appropriate parameters can be conducted with a more complex mathematical model, which is presently under development.

Skill at reviewing and understanding the technical literature and, in particular, the patent literature has a large significance in designing. In the second part of the design manual one can find a literal description of the existing patents and tasks for the development of skills for the analysis of such materials.

The design process for a given technology can last several semesters and includes elements of scientific research work. To reduce the designing course length, “design teams” can be formed; here a group of students with various participating roles fulfill the work. The group can consist of the students of 3rd-5th years of learning.