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Indian Institute of Science

1. Kumar, Kranthi J R A. Studies on Single and Two Stage Stirling Type Pulse Tube Coolers of Low and Medium Capacities including Performance Enhancement of Pressure Wave GeneratoI and a Novel Helium Recondensation System.

Degree: PhD, Engineering, 2019, Indian Institute of Science

Cryocoolers are mechanical devices that produce cold at temperatures below -150 °C. Work required to produce the cold is supplied by a Pressure Wave Generator (PWG). This thesis is concerned with the development and analysis of Stirling type pulse tube cooler (PTC) systems of low and medium capacities along with performance improvement of PWG and design of a novel oil free and low maintenance helium recondensation system based on Stirling type pulse tube coolers and Joule-Thomson expansion. Pressure Wave Generator is a crucial part of pulse tube cooler system. Performance of PWG depends on many parameters like the seal gap, piston diameter etc. E ects of these parameters have been studied in detail. Analysis was done to arrive at optimal values and a methodology is suggested to improve performance. The analysis was applied extensively to indigenously developed Pressure Wave Generator (PWG-1). A signi cant improvement, reduced mechanical losses and lowered input electric current, has been found by application of the suggested methodology. The development of pulse tube coolers of low and medium capacities was studied. In low capacity coolers, the available PV power is low; thus, requiring an ultra e cient design. In medium capacity coolers, the available PV power can pose problems like acoustic matching, streaming etc. A low capacity pulse tube cryocooler capable of 0.5 W at 80 K and acoustically matched to indigenous Pressure Wave Generator PWG-1 was designed, fabricated and tested. Inertance tube con guration which plays signi cant role in low input power coolers has been analyzed. A no load temperature of 74 K was achieved with input power of 59 W; corresponding to a cooling power of 0.22 W at 80 K. The amplitude of mass ow passing into the pulse tube cooler has been measured by using a hot wire anemometer calibrated in oscillatory ow condition. A medium capacity pulse tube cryocooler capable of 10 W at 80 K was designed and developed. It requires an estimated input PV power of 375 W. On the other hand, the only available large PWG for this work, PWG-2, has a rated PV power output of 900 W at the rated piston stroke, thus posing the problem of acoustic matching. Improvement of acoustic matching between the PTC and PWG was studied by varying lling pressure, inertance tube con guration, and by using a long transfer line. A no load temperature of 72 K corresponding to 1 W at 80 K was achieved. It is concluded that steps to improve acoustic matching are useful only to a limited extent and acoustic matching has to be ensured at the design stage itself. A medium capacity two stage pulse tube cooler capable of reaching 25 K is described. Analytical proof has been given to shown that a two stage pulse tube cooler is thermo-dynamically less e cient than a single stage pulse tube cooler. But a two stage PTC is required to reduce regenerator losses. A no load temperature of 40.4 K was achieved at 24.1 bar lling pressure with an input power of 750 W. The e ects of pulse tube volume and regenerator con… Advisors/Committee Members: Jacob, Subhash (advisor).

Subjects/Keywords: Pulse Tube Cooler; Hybrid Cryocoolers; Pressure Wave Generator (PWG); PTC; Helium Recondensation System; Pulse Tube Cryocooler; Pulse Tube Refrigerator; PWG-1; Instrumentation and Applied Physics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Kumar, K. J. R. A. (2019). Studies on Single and Two Stage Stirling Type Pulse Tube Coolers of Low and Medium Capacities including Performance Enhancement of Pressure Wave GeneratoI and a Novel Helium Recondensation System. (Doctoral Dissertation). Indian Institute of Science. Retrieved from http://etd.iisc.ac.in/handle/2005/4224

Chicago Manual of Style (16th Edition):

Kumar, Kranthi J R A. “Studies on Single and Two Stage Stirling Type Pulse Tube Coolers of Low and Medium Capacities including Performance Enhancement of Pressure Wave GeneratoI and a Novel Helium Recondensation System.” 2019. Doctoral Dissertation, Indian Institute of Science. Accessed October 20, 2020. http://etd.iisc.ac.in/handle/2005/4224.

MLA Handbook (7th Edition):

Kumar, Kranthi J R A. “Studies on Single and Two Stage Stirling Type Pulse Tube Coolers of Low and Medium Capacities including Performance Enhancement of Pressure Wave GeneratoI and a Novel Helium Recondensation System.” 2019. Web. 20 Oct 2020.

Vancouver:

Kumar KJRA. Studies on Single and Two Stage Stirling Type Pulse Tube Coolers of Low and Medium Capacities including Performance Enhancement of Pressure Wave GeneratoI and a Novel Helium Recondensation System. [Internet] [Doctoral dissertation]. Indian Institute of Science; 2019. [cited 2020 Oct 20]. Available from: http://etd.iisc.ac.in/handle/2005/4224.

Council of Science Editors:

Kumar KJRA. Studies on Single and Two Stage Stirling Type Pulse Tube Coolers of Low and Medium Capacities including Performance Enhancement of Pressure Wave GeneratoI and a Novel Helium Recondensation System. [Doctoral Dissertation]. Indian Institute of Science; 2019. Available from: http://etd.iisc.ac.in/handle/2005/4224

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