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Development of a cold stage for a 80 K vibration-free cooler
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Nowadays, many satellites are observing the earth for many purposes (climatology,
agriculture, defence and security, etc.) using infrared sensors. One of the key element of these sensors is their high resolution obtained due to their quite low operating temperature provided by mechanical cryocoolers.
However, the introduction of vibrations by the most of the cryocoolers is a recurring
problem for space applications, and because of that the development of a system
that eliminates these vibrations is very important. So, in the framework of a European
Space agency project, a 40-80 K vibration-free cooler is being developed that combines two cryocoolers (one that uses Nitrogen that precool another cryocooler that uses Neon), functioning without introducing vibrations in the system.
This thesis is focused on the nitrogen cryocooler more specifically on the dimensioning
and development of its cold part’s components as the Joule-Thomson valve, the
counterflow heat exchanger, and its test systems.
The majority of the work on this thesis was focused on the design of the Joule-Thomson (JT) valve. Since Its dimensions and properties are empirically obtained, an extended experimental study of the performance of two different JT valves under several temperatures, pressures and mass flow conditions was made. The data obtained allowed us to dimension a JT valve for the required conditions and also confirm the operating principles of the cryocooler cold part.
The counterflow heat exchanger was dimensioned, built and integrated in a Gifford-
Mac Mahon cryocooler and is ready to be tested as soon as the Joule Thomson valve is determined.
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Cryogenics Vibration-free cooler Joule-Thomson Counter-flow heat exchanger