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Alireza Azarbadegan
Dr William Suen
Evaluation of Joule-Thomson coefficient in
micro-diffuser/nozzle elements
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What is a cryocooler?
Benefits and problems
Joule Thomson coolers
What is our contribution?
Overview
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Infrared sensors for surveillance and atmospheric
studies
Superconducting electronics, magnets, and power
systems
Create clean vacuums in semiconductor
fabrication processes
Liquefaction of industrial gas
Cryogenic temperatures (below 150 C, 238 F
or 123 K) are required for many technology
areas:
What is a cryocooler?
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Reliability
Efficiency
Size and weight
Cooldown time
Vibration
Electromagnetic interference (EMI)
Heat rejection
Cost
Preservation of biological material and food
Densification (liquefaction and separation)
Quantum effects (superfluidity and superconductivity)
Low thermal noise
Low vapor pressure (cryopumping)
Property changes (temporary and permanent)
Tissue ablation (cryosurgery)
Benefits of cryogenic temperatures
Potential problems with cryocoolers
Benefits and Problems
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Common types of cryocoolers
Schematics of five common types of cryocoolers
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Joule-Thomson coolers
The temperature behaviour of a fluid during a throttling (h
constant) process is described by the Joule-Thomson
coefficient, defined as
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Joule-Thomson coolers
Linde-Hampson cycle
JT valve
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Joule-Thomson coolers
Microfabrication
Lerou P et al 2006 Fabrication of a micro cryogenic cold stage
using MEMS-technology J. Micromech. Microeng.
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What is our contribution?
Optimization DOE (Design of Experiment) and MOGA
(Multi-Objective Genetic
Algorithm)
d
W2
W1
L
Maximize
Maximize Efficiency
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What is our contribution?
Micropumps and Micro-compressor
Working principle of valveless micropumps
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What is our contribution?
Fabrication and Experiment
Micro milling
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http://www.cstl.nist.gov
Little W A 1984 Rev. Sci. Instrum. 55 661
Lerou P P P M, Venhorst G C F, Bereads C F, Veenstra T T, Blom
M, Burger J F, ter Brake H J M
and Rogalla H 2006 J. Micromech. Microeng
Radebaugh R, Zimmerman J, Smith D R and Louie B 1986 Adv. Cryog.
Eng. 31 779
Cengel 2006, Thermodynamics - An Engineering Approach, 5th
Edition, McGraw-Hill
http://lt.tnw.utwente.nl/research/cooling/Technology/linde_hampson.doc/
http://www.mmr.com/mmr_overview.html
References
