Joseph F. Ivanenok

Modeling of Remote Condensing AMTEC Cells

The Alkali Metal Thermal to Electric Converter (AMTEC) is a thermally regenerated sodium concentration cell that converts heat directly into electricity without moving parts. The high efficiency of AMTEC cells is useful for power generation in space and terrestrial applications (Ivanenok et al. 1993a, 1993b). One of the advanced features proposed in current high efficiency AMTEC cell designs is remote condensing. Remote condensing occurs when the condensing surface of the cell is thermally isolated from the high temperature β“ ‐alumina solid electrolyte (BASE) tube. The parasitic heat losses are significantly reduced, thereby improving the cell efficiency. However, this configuration also increases the local Na vapor pressure (sodium concentration) on the cathode side of the BASE tube, and thus lowers the BASE tubes power output. The balance of these opposing effects is very important in optimizing system designs. This paper derives the equations necessary to calculate the vapor flow pressure drop, and c...

Design and Testing of AMTEC Mini‐Cells

The Alkali Metal Thermal to Electric Converter (AMTEC) technology is under development for both terrestrial and space power applications. System designs for these applications are compact and provide power at efficiencies between 20 and 35 %. Converter systems for space power applications have been designed that incorporate simple, compact AMTEC cells. A series of these cells, leading from the February 1993 state of the art to a flight qualified engineering prototype, are being designed and tested. Mechanical and thermal performance tests have been performed on the first four cells of this series. Testing is planned for another 12 cells. Mechanical testing demonstrated that the cell design is capable of worst case random vibration and shock loads of the launch environment. Measured cell efficiency is currently 10% at 923 K, and the cell mass is 110 g. Only a premature failure of a pressure boundary component prevented measured efficiencies from exceeding 14% in the fourth cell. The target cell efficiency ...

Small capillary pumped AMTEC systems

Alkali Metal Thermoelectric Converter (AMTEC) systems offer significant potential advantages for space power. Recent experiments have shown that electromagnetic pumps can operate with a negative priming head and so may be suitable for space applications in microgravity (Hunt et al. 1992). Capillary pumped cells offer an alternative approach to microgravity compatibility. We have designed, built, and operated capillary pumped AMTEC cells in various orientations with respect to gravity in order to provide a presumptive demonstration of zero‐G capability (Sievers et al. 1992). We report lifetime and performance data for these capillary pumped AMTEC cells. Progress on other issues relating to space flight testing of AMTEC systems is also discussed.

Modular radioisotope AMTEC power system

The Alakli Metal Thermal to Electric Converter (AMTEC) technology is extremely amenable to a modular configuration. Several modular designs have been proposed for coupling to the radioisotope general purpose heat source (GPHS). Current AMTEC cell designs, producing approximately 5 W at over 20% efficiency, can be integrated into a radioisotope heated module that provides 10–28 per 250 Wth GPHS. The mass of these modules is approximately 4 kg. The cell design used in this concept is under development. The first generation model has already been operated for one year. Smaller, higher efficiency cells are now being fabricated.

AMTEC Module Test Program

The Alkali Metal Thermal to Electric Converter (AMTEC) is a thermally regenerated sodium concentration cell that statically converts heat directly into electricity. The high efficiency of AMTEC will be useful for power generation in space and terrestrial applications. A series of 6 geometrically similar cells with identical wick structures has been fabricated by Advanced Modular Power Systems (AMPS). Three electrode/current collector designs have been included in the testing matrix. Two cells of each design were built. One cell in each set had a thermocouple installed at the electrode/current collector interface to measure the temperature of the beta‐alumina solid electrolyte (BASE) tube. This thermocouple can also be used to measure the voltage at the cathode since its sheath is electrically isolated from ground. The BASE tubes used to build the cells were all from the same production lot. This testing program represents a unique opportunity to comparatively evaluate the performance of geometrically iden...

AMTEC power systems for remote site applications Conference on alternative powere from space; Conference

The Department of Defense, US Forest Service and the University of Alaska operate more than 200 remote sites in the Arctic. Most of these sites are now operated on fuel‐burning thermoelectric converters with an efficiency of less than 4%. The cost of supplying even moderate electric power requirements to remote environmental, treaty monitoring and communication sites is strongly dependent on the fuel delivery requirements. In the Arctic where solar input is frequently unreliable, the problem is particularly severe. On average, these sites need only about 60 watts of electrical power but will burn over 2,200 kg of propane per year for continuous operation. At these power levels, Alkali Metal Thermal to Electric Converter (AMTEC) systems with their projected 20% to 25% thermal to electric conversion efficiency can provide power for these remote sites with potential annual logistics cost savings (primarily in reduced fuel supply costs) reaching tens of millions of dollars.