OPTIMIZATION AND IMPLEMENTATION OF A THERMOACOUSTIC FLASHOVER DETECTOR
Hamburger, Kenneth A
Sunderland, Peter B
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The thermoacoustic flashover detector is to be a helmet-mounted device that responds to deteriorating conditions in a compartment fire and produces an audible alarm to alert emergency personnel in time for an escape or change in tactics. An operational prototype device was designed at University of Maryland in 2011, and featured an aluminum, copper, and MACOR tube 178 mm long and 25.4 mm in diameter. The prototype was powered by an external heat band, which provided 44 watts of power at 308 deg C. Optimization of the prototype is conducted across several parameters including power consumption and temperature gradient. To that end, two scaled-down models of diameters 22 mm and 17 mm are constructed, both of which fail to produce sustained sound. Adding water to the device reduces the onset power consumption to 22 watts and the maximum temperature to 285 deg C, which represents the most efficient prototype of the device. A system of radiant heat collector panels and copper-water heat pipes is designed to replace the external heat band as a power source. A heat transfer analysis is conducted to determine the necessary size of the collector panels for proper activation, as well as the response time of the system. Total required surface area will depend on future design parameters, but reasonable estimates suggest that it will be between 0.02-0.03 sq meters. An acoustic analysis of the optimized device is conducted, revealing a fundamental frequency of 500Hz at 101 dB.