Advanced search Help
Searching for terms: EXACT: "Waits, C. Mike" in: author
Clear all search criteria
Only 2/3! You are seeing results from the Public Collection, not the complete Full Collection. Sign in to search everything (see eligibility).
-
Stress and Displacement Analysis of Microreactors During Thermal and Vacuum Loading
"Compact power sources with high energy and power densities are critical for many military applications. These applications span from personal or squad-level power sources for long-duration missions without resupply to unmanned air vehicles requiring only a few hours of running time. In the 10-100 W+ power range, battery technology is the best solution currently available, but higher-energy dense technologies are needed to augment batteries and extend the available energy density well beyond state-of-the-art battery technology. One way to approach this is to take advantage of the large energy content of hydrocarbons. Conversion efficiencies of only a few percent can provide comparable energy density to battery technology. One technology being pursued by the US Army Research Laboratory is combustion-based thermophotovoltaic power sources. Combustion can be used to convert fuel to heat a surface to temperatures above 500 °C. An emitter could be vacuum brazed to the heated surface. This assembly method creates stresses due to difference in the coefficient of thermal expansion of the materials. Additional stresses are introduced, since the exterior of the assembly operates at vacuum while the interior is at ambient pressure. This report provides an analysis of 2 approaches to manage the stresses in the assembly."
U.S. Army Research Laboratory
Allmon, William; Waits, C. Mike
2017-09
-
Thermal Fluid Analysis of the Heat Sink and Chip Carrier Assembly for a US Army Research Laboratory Liquid-Fueled Thermophotovoltaic Power Source Demonstrator
"Compact power sources with high energy and power densities are critical for many military applications. These applications span from personal or squad-level power sources for long-duration missions without resupply to unmanned air vehicles requiring only a few hours of running time. In the 10-100 W+ power range, battery technology is the best solution currently available, but higher-energy dense technologies are needed to augment batteries and extend the available energy density well beyond state-of-the-art battery technology. One way to approach this is to take advantage of the large energy content of hydrocarbons or alcohols. Conversion efficiencies of only a few percent can provide comparable energy density to battery technology with the added advantage of instant recharge. One technology being pursued by the US Army Research Laboratory is combustion-based thermophotovoltaic power sources. Combustion can be used to convert fuel to heat a surface to temperatures above 500 deg C. To support this work, this report details the analysis of the chip carrier and water-cooled heat sink to control the temperature of the photovoltaic cell while exposed to radiation from the emitter."
U.S. Army Research Laboratory
Allmon, William R.; Waits, C. Mike
2016-09
-
Fabrication and Testing of Tapered Electro-Spray Nozzles
"The U.S. Army is interested in compact fuel-to-electric power systems to provide portable power sources for Soldiers and unmanned aerial vehicles (UAVs). This work describes multiple methods aimed at creating microfabricated, tapered-tip, electro-spray (E-spray) nozzles for efficient fuel injection. It has been shown that E-spray scaling depends on a number of factors, including nozzle/emitter geometry. Use of the new tapered nozzle tip diameters of 18 μm compared to a previous minimum of 30 μm allowed for E-spray operation below 0.01 ml/h at 70 °C fuel pre-heat, which is a 25-fold decrease over the minimum of 0.25 ml/h possible with 90-μm-diameter, flat topped nozzles at 56 °C. A dense array of tapered nozzles could meet a minimum power requirement, while using very low flow rates per nozzle to obtain small combustor geometries."
United States. Army Research Laboratory. Sensors and Electron Device
Hanrahan, Brendan M.; Waits, C. Mike
2012-09
1
