Cryogenics
Code
10530
Academic unit
Faculdade de Ciências e Tecnologia
Department
Departamento de Física
Credits
3.0
Teacher in charge
Gregoire Marie Jean Bonfait
Weekly hours
2
Total hours
28
Teaching language
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) Teaching to make a "superficial" analysis of a "simple" problem of cryogenics (Sr Engineer, wanted to cool 1 kg of copper at 80 K, as it does?), And determine the main difficulties.
4) To learn to sketch a simple cryostat and a system of basic characterization (limit temperature, cooling power at various temperatures, ...) and system test.
5) To know how to do some simple calculations that permit or issue a diagnosis or provide orders of magnitude involved in designing a cryostat.
Prerequisites
Completed 1st cycle of a Course in Physics, Physics engineering, Mechanics ou similar.
Elementary thermodynamics will be necessary: Internal energy, Enthalpy, Specific heat, Thermal conductivity)
Subject matter
I-Introduction
I-1 Cryogenics: why and when?
I-2 The main issues of Cryogenics
II-Cryogenic Liquids:
II-1 My first cryostat
II-2 Cryogenic liquids
II-The case of 4He and 3He
II-4 Main Features of cryogenic liquids
III Heat transfer by radiation
III-1 The Stefan Boltzmann law
III-2 Thermal shields at constant temperature
III-3 Multilayer insulation-MLI
IV-Thermal Conduction
IV-1 Importance of thermal conduction
IV-2 Mechanism of thermal conduction
IV-3 Heat transfer by conduction
IV-4 Conduction in gases
V-Thermal machines
V-1 Introduction
V-2 Liquefiers
V-3 Cryocoolers
Laboratory component:
Determination of the modes of heat transfer between a solid surface and the liquid nitrogen. Leidenfrost effect.
Utilization of worksheet and web pages for resolution of issues frequently occurring in cryogenics (Diagrams of pure substance, Thermal time constant, thermal conductivity integrals)
Bibliography
The Art of Cryogenics; Low-Temperature Experimental Techniques
http://fulviofrisone.com/attachments/article/403/the%20art%20of%20cryogenics.pdf
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%)