NASA SBIR 2005 Solicitation


SUBTOPIC TITLE:Power Generation & Transmission
PROPOSAL TITLE:High Specific Power Multiple-Cylinder Free-Piston Alpha Stirling

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
Sunpower, Inc.
182 Mill Street
Athens ,OH 45701 - 2627
(740) 594 - 2221

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Seon Yong Kim
Sunpower, Inc. 182 Mill Street
Athens, OH  45701 -2627
(740) 594 - 2221

NASA seeks highly efficient, long life solar dynamic power conversion systems. The requirements for these missions emphasize low mass and high conversion efficiencies. A reliable and highly efficient Stirling convertor would provide mission planners with less costly spacecraft power options than currently exist. Current Stirling technologies have demonstrated a beginning of life specific power level of 4.2 W/kg, and a useful life greater than 10 years. The proposed effort will result in the preliminary design for an innovative multiple-cylinder alpha free-piston Stirling engine (AFPSE) for high power applications. The program approach minimizes development risk by combining proven technologies, experiences and innovative concepts of Sunpower Inc. and Global Cooling BV (GCBV) with AFPSE. The proposed system is a compact, highly efficient, long life, low mass Stirling machine for a high power conversion system. This configuration having multi-pistons in separate cylinders connected by rejector and acceptor is not only very simple due to one moving part in one cylinder with no displacer, but also highly adaptable due to its versatile shape. This machine is very innovative because it is anticipated to achieve a specific power greater than 100W/kg as well as a heat input to electrical output conversion efficiency greater than 30%.

The resulting convertor will give spacecraft designers the option of utilizing a 1.) compact, low mass, and highly efficient power supply, 2.) a power supply module that can be clustered together to provide higher power levels, 3.) a power supply which can be adapted to both space and planetary atmospheres via simple changes to the gas management system with no impact on the operation of the critical dynamic components inside the convertor, and 4.) a controller design philosophy that allows the system to be easily adapted to varying mission requirements. Such a system is extensible to several areas of NASA's power generation needs including electric propulsion, robotic rovers, and backup power supplies for human surface expeditions.

In addition to the space applications which this proposal directly addresses, there is a significant potential market for commercial small-scale power generation, particularly in light of increasing attention to the environmental cost of fuel consumption and the new stringency of fuel emissions regulations in some areas of the world. Sunpower licensee MicroGen, for example, has determined a substantial European and worldwide market for household cogeneration devices. Additionally there are numerous opportunities for remote and mobile power generation applications, including the marine market, auxiliary power markets, remote power generation, standby emergency power generation, peaking generation, truck-mounted power, power for oil and gas fields and other exploratory and off-grid sites.

NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.

Thermodynamic Conversion

Form Printed on 09-19-05 13:12