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Title	Diesel Burner Development for 500-Watt Portable Thermophotovoltaic Generator
Creator	Scotto, Mark V.
Publisher	Digitized by J. Willard Marriott Library, University of Utah
Date	1999
Spatial Coverage	presented at San Francisco, California
Abstract	McDermott Technology, Inc. (MTI) and JX Crystals (JXC) are developing a portable thermophotovoltaic (TPV) electric generator under a Defense Advanced Research Projects Agency (DARPA) contract. The contract is managed by the U.S. Army's Communication and Electronic Command (CECOM) due to its interest in the device for field applications. The generator is designed to burn diesel fuel (DF-2) at an overall efficiency of 8% -10% and net output of 500 watts DC power. MTI is developing the burner/emitter/recuperator (BER), which converts chemical energy in the fuel to a uniform radiant heat flux directed toward the photovoltaic cells. A thermally integrated, high-temperature recuperator was used to increase fuel efficiency by preheating the combustion air. The power converter assembly (PCA) developed by JXC converts the radiant flux that emanates from the emitter to electrical power using an array of photovoltaic cells. This paper describes the burner development work at MTI. A burner system was designed and fabricated to efficiently elevate the emitter to a uniform temperature exceeding 2400°F, the required temperature to efficiently convert the radiant flux to electricity. The burner system generated a stable feed of vaporized fuel using a flow orifice. A short compact flame was produced with rapid heat release near the burner to achieve high energy efficiency and low emission of CO and soo'. Emitter temperature data for integrated systems under different operational conditions are presented.
Type	Text
Format	application/pdf
Language	eng
Rights	This material may be protected by copyright. Permission required for use in any form. For further information please contact the American Flame Research Committee.
Conversion Specifications	Original scanned with Canon EOS-1Ds Mark II, 16.7 megapixel digital camera and saved as 400 ppi uncompressed TIFF, 16 bit depth.
Scanning Technician	Cliodhna Davis
ARK	ark:/87278/s6862k19
Setname	uu_afrc
ID	11714
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6862k19

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Title	Page 9
Format	application/pdf
OCR Text	Show • Thinly Insulated Emitter (Ideal PCA) • Water-Cooled PCA • Air-Cooled PCA 15000 20000 25000 Power Input (Btu/hr) 30000 Figure 9: Average emitter temperature for the BER integrated with an ideal PCA and two experimental PCAs Metallic components showed some signs of oxidation over short-term use at the highest operating temperatures. Some metal was observed to flake away off the surface. A ceramic burner cap was used to shield the other burner parts from the highest flame temperatures. The burner cap can be seen extending into the combustion volume through the burner sleeve in Figure 6; the left photo shows a metallic cap, and the right shows a ceramic cap. The ceramic cap was machined from an alumina refractory and held to the metallic burner with a metallic pin and ceramic epoxy. The underlying metal surfaces were observed to improve with the ceramic cap after testing at similar conditions. However, it is still likely that long-term use in systems that require high emitter temperatures (>2400°F) will necessitate ceramic components. Silicon carbide is a good candidate, since its operating temperature can be as high as 3000°F and commercial vendors can machine swirl vanes from this material. Carbon deposits were observed at the flow orifice at the exit to the fuel vaporization. The deposits at the orifice are sporadic and frequently lead to the type of pressure rise shown in Figure 10. A needle was attached to the end of the electrical heating element within the vaporization tube. The heater is inserted through a packing joint that enables it to move along the tube's axis so that the needle could be passed through the orifice to keep an open flow passage. The needle was not used during operation but only at start-up, since the device was to be designed for unattended operation. Therefore, the pressure rise should be insignificant over the time required to burn a tank of fuel. Design modifications to the orifice may also reduce the pressure rise by minimizing deposits near the orifice. Figure 10 shows the mere presence of the needle near the orifice appeared to diminish the pressure rise. Deposits at the orifice are not perceived to be a significant operational problem.Carbon deposits were also occasionally observed at the fuel vapor injection point into the combustion air stream under certain conditions. This was confirmed by observations after testing at this location. Another indication
Setname	uu_afrc
ID	11711
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6862k19/11711