Measuring Thermal Conductivity of Powder Insulation at Cryogenic Temperatures
A device to measure bulk effective thermal conductivity of powder insulation at cryogenic temperatures has been designed and tested. The design consists of two concentric cylinders which are suspended inside of a cryostat. The insulation being tested is filled into the annular space between the cyli...
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ndltd-fsu.edu-oai-fsu.digital.flvc.org-fsu_1756782020-06-05T03:07:11Z Measuring Thermal Conductivity of Powder Insulation at Cryogenic Temperatures Barrios, Matthew (authoraut) Van Sciver, Steven (professor directing thesis) Luongo, Cesar (committee member) Schwartz, Justin (committee member) Department of Mechanical Engineering (degree granting department) Florida State University (degree granting institution) Text text Florida State University Florida State University English eng 1 online resource computer application/pdf A device to measure bulk effective thermal conductivity of powder insulation at cryogenic temperatures has been designed and tested. The design consists of two concentric cylinders which are suspended inside of a cryostat. The insulation being tested is filled into the annular space between the cylinders. In the first test method the insulation space is evacuated, and the cryostat is filled with LN2 until the outer cylinder is completely submerged. The ensuing temperature drop of the inner cylinder over time is recorded. The rate of temperature decrease is used to calculate the bulk effective thermal conductivity of the insulation. For the second test method, a Gifford-McMahon single stage cryocooler is used to cool the apparatus to a desired temperature range. The insulation is evacuated, and a heater mounted on the inside cylinder creates a temperature difference between the two cylinders. Fourier's law of heat conduction is used to relate that temperature difference to a bulk effective thermal conductivity of the powder insulation. The insulation specimen used for this experiment was aerogel bead insulation. The first test method covered an average temperature range of 85-130 Kelvin. The calculated bulk effective thermal conductivity from the first method for this range increases from 0.333 to 0.714 mW/m*K. Six data points have been produced by the second test method. The average temperature for the second method ranged from 30-80 Kelvin. Over this temperature range the thermal conductivity shows an increase from 0.142 to 0.377 mW/m*K. Feasibility of use of the concentric cylinder thermal conductivity measurement apparatus as a standard measurement technique is discussed. The implementation of a cryocooler gives the ability to reach lower temperature ranges and create smaller temperature differences than previous research has produced. However, a few difficulties such as electrical problems and an unexpected temperature gradient through the outer cylinder must be resolved prior to further implementation of the apparatus. Plans for further research and development of the apparatus are presented. A Thesis Submitted to the Department of Mechanical Engineering in Partial Fulfillment of the Requirements for the Degree of Master of Science. Fall Semester, 2006. August 9, 2006. Aerogel, Powder Insulation, Cryogenics, Thermal Conductivity Includes bibliographical references. Steven Van Sciver, Professor Directing Thesis; Cesar Luongo, Committee Member; Justin Schwartz, Committee Member. Mechanical engineering FSU_migr_etd-1112 http://purl.flvc.org/fsu/fd/FSU_migr_etd-1112 This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. http://diginole.lib.fsu.edu/islandora/object/fsu%3A175678/datastream/TN/view/Measuring%20Thermal%20Conductivity%20of%20Powder%20Insulation%20at%20Cryogenic%20Temperatures.jpg |
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Mechanical engineering Measuring Thermal Conductivity of Powder Insulation at Cryogenic Temperatures |
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A device to measure bulk effective thermal conductivity of powder insulation at cryogenic temperatures has been designed and tested. The design consists of two concentric cylinders which are suspended inside of a cryostat. The insulation being tested is filled into the annular space between the cylinders. In the first test method the insulation space is evacuated, and the cryostat is filled with LN2 until the outer cylinder is completely submerged. The ensuing temperature drop of the inner cylinder over time is recorded. The rate of temperature decrease is used to calculate the bulk effective thermal conductivity of the insulation. For the second test method, a Gifford-McMahon single stage cryocooler is used to cool the apparatus to a desired temperature range. The insulation is evacuated, and a heater mounted on the inside cylinder creates a temperature difference between the two cylinders. Fourier's law of heat conduction is used to relate that temperature difference to a bulk effective thermal conductivity of the powder insulation. The insulation specimen used for this experiment was aerogel bead insulation. The first test method covered an average temperature range of 85-130 Kelvin. The calculated bulk effective thermal conductivity from the first method for this range increases from 0.333 to 0.714 mW/m*K. Six data points have been produced by the second test method. The average temperature for the second method ranged from 30-80 Kelvin. Over this temperature range the thermal conductivity shows an increase from 0.142 to 0.377 mW/m*K. Feasibility of use of the concentric cylinder thermal conductivity measurement apparatus as a standard measurement technique is discussed. The implementation of a cryocooler gives the ability to reach lower temperature ranges and create smaller temperature differences than previous research has produced. However, a few difficulties such as electrical problems and an unexpected temperature gradient through the outer cylinder must be resolved prior to further implementation of the apparatus. Plans for further research and development of the apparatus are presented. === A Thesis Submitted to the Department of Mechanical Engineering in Partial
Fulfillment of the Requirements for the Degree of Master of Science. === Fall Semester, 2006. === August 9, 2006. === Aerogel, Powder Insulation, Cryogenics, Thermal Conductivity === Includes bibliographical references. === Steven Van Sciver, Professor Directing Thesis; Cesar Luongo, Committee Member; Justin Schwartz, Committee Member. |
author2 |
Barrios, Matthew (authoraut) |
author_facet |
Barrios, Matthew (authoraut) |
title |
Measuring Thermal Conductivity of Powder Insulation at Cryogenic Temperatures |
title_short |
Measuring Thermal Conductivity of Powder Insulation at Cryogenic Temperatures |
title_full |
Measuring Thermal Conductivity of Powder Insulation at Cryogenic Temperatures |
title_fullStr |
Measuring Thermal Conductivity of Powder Insulation at Cryogenic Temperatures |
title_full_unstemmed |
Measuring Thermal Conductivity of Powder Insulation at Cryogenic Temperatures |
title_sort |
measuring thermal conductivity of powder insulation at cryogenic temperatures |
publisher |
Florida State University |
url |
http://purl.flvc.org/fsu/fd/FSU_migr_etd-1112 |
_version_ |
1719317691438727168 |