Cooling Systems for Refuge Alternatives in Hot Mine Conditions

The accumulated heat and humidity inside occupied refuge alternatives (RAs) can impose risk of heat stress to the occupants. The accumulated heat could be from the metabolic and environmental sources. For hot mines, the high ambient temperature makes it more difficult to dissipate heat accumulated inside the RA. A cooling system is then needed to reduce the interior heat and humidity. Two types of cooling systems were tested out for their cooling capacity. One cooling system is a portable, battery-powered, air conditioning system and the other is a portable cryogenic air supply. During the testing, the mine air temperature surrounding the RA was elevated to and maintained at 85°F to simulate hot mine environment. The tests demonstrated that both cooling systems were able to control the air temperature inside the RA even though they did not last the entire duration of a 96-hour test. This paper provides an overview of the test methodology and findings as well as guidance on improving the performance of both cooling systems, including: optimizing the cooling cycle for the battery-powered AC system and increasing the flow rate and tank storage capacity for the cryogenic system. The information in this publication is useful for RA manufacturers and mines to develop the cooling systems that will enable providing the life sustaining environment in mines with elevated temperatures.