Project Title:

Micromachined Evaporator for Wicked AMTEC Cells

92-1-10.03-3800                                                    NAS07-1216
Micromachined Evaporator for Wicked AMTEC Cells
Creare, Inc.
P.O. Box 71
Hanover, NH  03755
Christopher J. Crowley                               (603-643-3800)

Abstract:

     An evaporator component that completely eliminates the need
for electro-magnetic (EM) pumps in the alkali-metal, thermal-to-
electric conversion (AMTEC) cells being developed by NASA Jet
Propulsion Laboratory will be investigated. AMTEC power conversion
is attractive with radioisotope power sources at 1100 K because of
its high conversion efficiency, low mass, modularity, and
redundancy. AMTEC and a general purpose heat source will operate
at conversion efficiencies greater than 20 percent, thereby
increasing specific power by a factor of three compared with
present thermoelectric converter designs. Currently, the EM pump
component presents potential problems for cell reliability because
of freezing and thawing, physical blockage by contamination, or
vapor lock. This project will research a stable, mechanical,
micromachined evaporator which should experience a long life
unlike porous sintered wicks. The micromachined structure has
small capillary size (4 æm radius) so it can achieve the operating
pressures for high temperatures (  1100 K) that result in high
AMTEC conversion efficiencies and eliminate the need for an EM
pump. Porous sintered wicks, however, are limited to lower
pressures and temperatures. Phase I will experimentally
demonstrate the feasibility of using sodium to make a high-head
capillary evaporator. Phase II will complete the development by
building a working AMTEC cell and demonstrating its operation.

Potential Commercial Application:

Potential Commercial Applications:  Compatibility of AMTEC power
conversion with a wide variety of heat sources makes AMTEC
attractive for NASA, DOE, Air Force, and SDIO space missions or
for terrestrial applications with combustion systems, vehicle
propulsion, or silent power conversion for submarines.

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