# Cryogenics

10530

### Department

Departamento de Física

3.0

### Teacher in charge

Gregoire Marie Jean Bonfait

2

28

Português

### Objectives

1) Provide general knowledge about what is cryogenics and its importance as a "technology frontier" among many sciences and engineering as thermodynamics, solid state physics, instrumentation, metrology, vacuum technology, the technologies related to space, medicine, etc .... examples of use of cryogenics will be the topics of exercises throughout the semester.

2) Provide the student the ability to, in front of a cryogenic system, quickly realize the basic principles of its operation. Facing a "simple" problem of cryogenics (Sr Engineer, I would like to cool 1 kg of copper at 80 K, what is the most economic way?), the student should know the specific requirements of the application (technical specifications), propose appropriate solutions, choose one and explain the reasons for this choice.

3) To know how to do some simple dimensioning calculations or address a diagnosis or provide orders of magnitude involved in designing a cryostat.

### Prerequisites

Elementary thermodynamics will be necessary: Internal energy, Enthalpy, Specific heat, Thermal conductivity)

### Subject matter

I- Introduction
I-1 Some example of application of Cryogenics
I-2 Main cryogenic issues

II- Cryogenic liquids
II-1 My first cryostat
II-2 Cryogenic liquids (TII-3 The case of liquids helium
II-4 Características importantes dos líquidos criogénicos

III-1 Stefan Boltzmann’s law
III-2 Thermal screen at constant temperature
III-3 Multiple thermal screen (Multilayer insulation -MLI)

IV- Heat transfer by thermal conduction
IV-1 Introduction
IV-2 Thermal conduction mechanism
IV-3 Heat transfer by thermal conduction
IV-4 Thermal conduction in gases

V- Thermal engines for cryogenics
V-1 Introduction
V-2 Liquefiers
V-3 Cryocoolers

Lab: Heat transfer coefficient between a solid wall and liquid nitrogen, Critical flux (Leidenfrost effect)

### Bibliography

The Art of Cryogenics, G. Ventura & L. Risegari, Elsevier 2010

Cryogenic Process Engineering, Klaus D. Timmerhaus, Thomas M. Flynn (auth.)

Internet

Notes of the teacher

### Teaching method

Lectures and problem-solving sessions.

At home: Presentation of cryogenics data in the plot form and solution by simple numerical calculation of small typical cryogenics problems using worksheet and web pages

### Evaluation method

2 tests (1 h) (50%)

Used of worksheet for presentation of  cryogenic data  (similar to those prposed during the semester) (25%)

One laboratory session (25%)