NASA SBIR 2006 Solicitation


SUBTOPIC TITLE:Energy Conversion and Power Electronics for Deep Space Missions
PROPOSAL TITLE:Variable Conductance Heat Pipes for Radioisotope Stirling Systems

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
Advanced Cooling Technologies, Inc.
1046 New Holland Avenue
Lancaster, PA 17601-5688
(717) 295-6061

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
William G Anderson
1046 New Holland Avenue
Lancaster, PA  17601-5688
(717) 295-6104

TECHNICAL ABSTRACT ( Limit 2000 characters, approximately 200 words)
The overall program objective is to develop a high temperature variable conductance heat pipe (VCHP) backup radiator, and integrate it into a Stirling radioisotope power system. A VCHP is similar to a heat pipe, but has a reservoir and a controlled amount of non-condensable gas (NCG) inside the reservoir. At low power, most of the condenser is blocked by the NCG. As the power increases, more and more of the condenser becomes active. This allows a VCHP to passively control the temperature while the power varies. Aluminum/ammonia VCHPs are commonly used in spacecraft thermal control. The proposed program will extend this concept to the alkali metal heat pipes that will be required for a Stirling system. During normal operation, the VCHP will be inactive. If the Stirling engine stops working for any reason, the VCHP will passively remove the heat from the General Purpose Heat Source (GPHS) preventing the GPHS from overheating. The benefits of the VCHP radiator include increased safety and reliability, and the ability to design an optimum Stirling engine.

POTENTIAL NASA COMMERCIAL APPLICATIONS ( Limit 1500 characters, approximately 150 words)
The immediate NASA application is to provide backup cooling for a radioisotope Stirling system. This design has three benefits, the first two related to safety, and the last to performance. First, if the Stirling engine stops operating during ground testing, the VCHP radiator will prevent overtemperature of the MLI insulation. Second, the VCHP radiator will prevent overtemperature of the GPHS modules when in near earth orbit, preventing excessive grain growth from harming the integrity of the iridium shell on the GPHS module. Finally, the VCHP can be used to remove the excess heat at the beginning of the mission, allowing an optimum engine design.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS ( Limit 1500 characters, approximately 150 words)
Commercially, ACT believes that there is a commercial application for alkali metal VCHPs in fuel cell reformers. In a fuel cell reformer, diesel fuel and air pass through a series of high temperature reactors to generate hydrogen. The operating temperature of the reactors must be closely controlled to maintain their chemical equilibrium. A typical system must maintain inlet and outlet temperatures within 30oC despite a turndown ratio of 5:1 in reactant flow rate. The current scheme uses a bypass valve, which has several drawbacks: it requires active control, requires power, and has a large pressure drop. ACT believes that alkali metal VCHP heat exchangers can replace the current heat exchanger and control system with a passive system that automatically maintains the output stream from the heat exchanger at a constant temperature.

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.

Nuclear Conversion

Form Printed on 09-08-06 18:19