Building, testing and modelling of a pulse tube cryogenic cooler

Smith, Gerrit Rohlandt (2006-12)

Thesis (MScIng) -- University of Stellenbosch, 2006.

Thesis

ENGLISH ABSTRACT: Pulse tube cryogenic coolers (cryocoolers) are among the latest innovations of cryogenic coolers. They fall in the same category as the reversed Stirling cycle cryocoolers that have been used for decades to cool infrared detectors in military and space applications. Pulse tube cryocoolers will replace most of the Stirling cryocoolers in future applications, because they have no moving parts at its cold point and therefore are subject to less vibrations, and hence has a longer service life. Pulse tube coolers, like domestic refrigerators, are also driven by a compressor. The type of compressor used in this project is of the reciprocating type which is driven by a linear, resonant motor which is similar to a loudspeaker mechanism. This project is about the building, testing and mathematical modelling of a pulse tube cryogenic cooler. The pulse tube cryocooler and its reciprocator (reciprocating compressor) was designed and manufactured. Numerous tests were conducted to evaluate the reciprocator. A complete mathematical model is presented for the reciprocator which was compared with the data obtained from the tests. The pulse tube cryocooler was modelled with a one-dimensional, time dependant CFO (computational fluid dynamics) model by solving the discretized conservation equations which were derived in this project from first principles. The discussions and conclusions regarding these results are presented, together with recommendations for future work.

AFRIKAANSE OPSOMMING: Pulsbuis kreogeniese koelers (kreokoelers) is een van die nuutste innovasies van kreogeniese koelers. Hui val in dieselfde kategorie as die verkeerdom Stirling siklus kreogeniese koelers wat al vir dekades in gebruik is vir die verkoeling van infrarooi detektors in militere en buiteruim toepassings. Pulsbuis kreogeniese koelers sal Stirling koelers in die toekoms vervang omdat hul geen bewegende dele in hul koue punt het nie. Gevolglik het hul 'n langer werkings lewe en veroorsaak hulle baie minder vibrasies. Net soos huishoudelike koelers het pulsbuis koelers ook 'n kompressor. Die tipe kompressor wat gebruik is in hierdie projek is van die resiprokeerende soort wat gedryf word deur 'n lineere, resonante motor soortgelyk aan 'n luidspreker meganisme. Hierdie projek handel oor die bou· toets en wiskundige modelering van 'n pulsebuis kreogeniese koeler asook sy resiprokeerende kompressor (resiprokeerder). Die pulsbuis kreokoeler en sy resiprokeeder was ontwerp en vervaardig en verskeie toetse was daarop uitgevoer. 'n Volledige wiskundige model is ontwikkel vir die resiprokeerder wat vergelyk was met die toets resultate. Die pulsbuis kreokoeler was gemodeleer met 'n een dimensionele, tyd afhanklike, NV (numeriese vloeimeganika) program. In hierdie program word die behoudsvergelykings opgelos wat van eerste beginsels afgelei is. Besprekings en gevolgtrekkings word gemaak na gelang van die resultate en waarnemings asook toekomstige voostellings vir verdere navorsings werk.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/50584
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