Spectral control development for thermophotovoltaics
Gallium Antimonide (GaSb) infrared photovoltaic cells are light weight whereas batteries are heavy. The specific energy in a hydrocarbon fuel is high at 12,900 W-hr per kg but a lithium ion rechargeable battery has a specific energy of only 145 W-hr per kg. A 10% efficient portable lightweight thermophotovoltaic (TPV) cylindrical generator when compared with a battery can have 6.5 times higher specific energy, operates 7 times longer, and be quickly refueled. The key is the 10% efficiency goal. This efficiency goal depends on matching the spectrum from a combustion heated ceramic IR emitter to the response band of the IR PV cell. Herein, spectral measurements are presented for a propane burner and ceramic IR emitter assembly surrounded by a fused silica glass envelope. The cylindrical IR ceramic emitter consists of an array of NiO doped MgO rods or slats. The Ni ion emission line is centered at 1.6 microns and it matches the GaSb IR response band extending out to 1.8 microns. The ceramic IR emitter is combustion heated to approximately 1200 C. The fuel and air combustion efficiency and hot gas coupling efficiency to the IR emitter are also important parameters.
Scale Up Designs for Hand-Held Light-Weight TPV DC Power Supply
Both solar cells and batteries generate quiet DC electric power. Infrared (IR) sensitive GaSb photovoltaic cells can convert energy from a combustion heated glowing ceramic IR emitter into electricity. The result is a lightweight thermophotovoltaic (TPV) battery replacement that operates day and night. We present here the design and operation of a first stand alone TPV generator. Test results on this unit have allowed us to design a scale-up hand-held 10% efficient 50 W TPV generator weighing 1.5 kg. The 50 W scale-up TPV power supply along with 1.5 kg of fuel has a projected weight specific energy density of 645 Wh/kg. This is 4 times larger than for a Li ion battery.
Representation of systems disturbed by wide band noise
In this paper, a method of handling and working with wide band noise is developed. We represent wide band noise as a distributed delay of white noise and use it to reduce a nonlinear system disturbed by wide band noise to a nonlinear system disturbed by white noise. An application of this reduction to a nonlinear filtering problem under a wide band noise disturbance is discussed.