Storage Time and Venting Characteristics for Cryogenic Air Supplies on Cryocooler Shutdown

Details

• Personal Author:
  Carr, Jacob L. ; DeGennaro CR ; Fernando RD ; Reyes MA ; Srednicki JR ; Yan L ; Yantek, David S. ; Yonkey JA
• Description:
  Cryogenic air supplies are a developing technology that may be able to serve as both a breathable air source and a heat mitigation strategy for refuge alternatives (RA) used in underground mines. Before cryogenic air is supplied to an occupied RA, the temperature of the cryogenic air is kept at -195 degrees C (-318 degrees F) inside a large dewar using a cryocooler, or cryo-refrigerator, which uses electrical power. In some cases, the cryocooler might lose power due to a planned or unplanned power outage that may occur when relocating the cryogenic air supply or during a mine emergency. Without cooling provided by the cryocooler, the temperature of the liquid air will rise and the pressure within the cryogenic air supply's dewar will increase due to the buildup of vapor pressure. To ensure safety, once the pressure in the dewar is high enough, the cryogenic air vents through a relief valve. Before deploying a cryogenic air supply in an underground mine, the maximum storage time and venting characteristics of the air supply when cooling is interrupted must be determined In this paper, researchers at the National Institute for Occupational Safety and Health (NIOSH) investigated the maximum storage time and venting pattern for two different cryogenic systems when their cryocoolers were turned off: a 425-liter vertical dewar system and a 2,000-liter horizontal dewar system. The testing showed that about 11 liters of cryogenic air was lost per day by the 425-liter vertical dewar system. For the 2,000-liter horizontal dewar system, the cryogenic air vented about every 2 hours, and about 28 liters of cryogenic air was lost per day. The information in this paper could be useful for manufacturers and mines considering the use of a cryogenic air supply as a source of breathable air and/or heat mitigation for refuge alternatives. [Description provided by NIOSH]
• Subjects:
  Emergencies Mining Occupational Health Safety
• Keywords:
  Cooling Systems Cryogenics Emergency Equipment Emerging Technology Liquefied Gases Mine Disasters Mining Industry Underground Mining
• Series:
  Mining Publications
• ISBN:
  9781934021071
• ISSN:
  1549-1757
• Publisher:
  ICC Press
• Document Type:
  Text
• Genre:
  Proceedings
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PMRD - Pittsburgh Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  85-95
• NIOSHTIC Number:
  nn:20062714
• Citation:
  Cryocoolers 21: Proceedings of the 21st International Cryocooler Conference, December 7-10, 2020, virtual event. Ross RG Jr., Raab JR, Miller SD eds. Boulder, CO: ICC Press, 2021 Mar; :85-95
• Editor(s):
  Ross RG Jr.; Raab JR; Miller SD
• Federal Fiscal Year:
  2021
• NORA Priority Area:
  Mining
• Peer Reviewed:
  False
• Source Full Name:
  Cryocoolers 21: Proceedings of the 21st International Cryocooler Conference, December 7-10, 2020, virtual event
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:93fc6274892c4471ed3b870488b501c9a87f027b89a10b5d0d0ec5d5107d26eb20017acd4f8b57e5bda233dba676c691b7197dd328023ec1264c713053776be7
• Download URL:
  https://stacks.cdc.gov/view/cdc/215416/cdc_215416_DS1.pdf
• File Type:
  [PDF - 1.77 MB ]