Cryogenic Refuge Alternative Supply System (Cryorass) Tested in a Built-In-Place RA

"BACKGROUND The design, development, fabrication, and test of a cryogenic supply for a refuge alternative is part of a larger effort funded by the National Institute for Occupational Safety and Health and managed through a Space Act Agreement with the National Aeronautics and Space Administration at the Kennedy Space Center, FL to create cryogenically based life support equipment responsive to the needs of miners as required by the Miner Act of 2008. This work is done by a joint contractor/NASA team. In particular, the Cryogenic Refuge Alternative Supply System (CryoRASS) serves to provide a respirable air source to miners confined for 96 hours in a mine refuge alternative. This system stores liquid air in a zero-loss cryogenic reservoir (Dewar) until an emergency requires use. The system does not require electric power when in use by miners. Because of the very cold nature of the liquid air, considerable heat stress relief and reduction of humidity is provided in addition to the required replenishment of oxygen. Moderate dilution of CO2 also occurs.INTRODUCTION The design of this new cryogenic refuge alternative supply system (CryoRASS) uses NASA/Kennedy Space Center technology as a development baseline. The design stores cryogenic (liquid) air that is warmed in an air handler box and the resulting gaseous air is introduced to the chamber that not only causes air circulation, but relies upon environmental and human heat to expand the liquid air to a gaseous state. Therefore, the primary benefits of the liquid air source, besides atmosphere maintenance (oxygen), is refuge cooling and dehumidification. This results in reduction of human heat stress and this occurs without the need for electrical power in the refuge chamber. This reduction is a major factor in ""apparent heat"" and the human perception of comfort. Another benefit with introduction of ""air"" vs only ""oxygen"" is the dilution of carbon dioxide. The volume of new air will displace existing refuge air and this air laden with humidity/CO2/low O2 passes out of the refuge relief valves. These RVs should be strategically placed to vent stagnant air preferentially. An initial system test was conducted in our Florida facility in a production 10-person hard chamber for 96 hours. Last year (2014) the system was tested with a 23 person inflatable refuge alternative in Bruceton. For this test, the CryoRASS air handler was redesigned to offer superior characteristics when installed in a Built-in-Place refuge alternative. This report describes the results of the modified system being tested in the Pittsburgh Experimental Mine while attached to a 30 person refuge for 96 (+/-) hours."