NASA SBIR 2008 Solicitation


PROPOSAL NUMBER: 08-1 X3.03-9281
SUBTOPIC TITLE: Lunar ISRU Development and Precursor Activities
PROPOSAL TITLE: Solid-Solid Vacuum Regolith Heat-Exchanger for Oxygen Production

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
Grainflow Dynamics, Inc.
1141 Catalina Drive, PMB #270
Livermore, CA 94550 - 5928
(925) 447-4293

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Otis Walton
1141 Catalina Drive, PMB #270
Livermore, CA 94550 - 5928
(925) 447-4293

Expected Technology Readiness Level (TRL) upon completion of contract: 3

TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
This SBIR Phase-1 project will demonstrate the feasibility of using a novel coaxial counterflow solid-solid heat exchanger to recover heat energy from spent regolith at 1050oC to pre-heat inlet regolith to 750oC, either continuously, or in 20kg batches. In granular solids the area of contacts between 'touching' grains is quite small. Thus, solid-solid conduction often plays only a minor role in heat transfer through granular solids (i.e., 'effective' conduction), and when an interstitial gas is present, heat transfer occurs primarily via conduction through the gas. If the granular solid is also flowing, then solids convection becomes a significant factor in overall heat transfer and effective 'conduction'. Under vacuum conditions, and at temperatures above 700oC, radiation will dominate most heat transfer processes; however, solids convection can also play a very significant secondary role. Utilizing judicious placement of radiation baffles, and a novel counterflow configuration, the approach proposed in this SBIR can accomplish the desired heat transfer between spent and fresh regolith with only one moving mechanical part, by making effective use of both radiative heat transfer and solids convection. Discrete-element simulations of regolith flow will be utilized to refine the concept. Utilization of an existing ~1.4 cubic meter partial-vacuum facility at the University of Florida will facilitate construction of feasibility demonstration prototypes during Phase-1 and/or Phase-2. The Phase-1 project will demonstrate the effectiveness of combining solids convection with radiative heat transfer to rapidly transfer heat from 1050C spent material to heat fresh regolith to 750C under vacuum conditions.

POTENTIAL NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
As currently envisioned, the production of oxygen from lunar regolith requires heating the material to a temperature of 1050C. Since the minerals of interest for oxygen production are stable to temperatures of 750C, the regolith can be preheated to that temperature, before entering the actual reactor without loss of potential product. Utilization of the sensible heat of the spent regolith (exiting the reactor at 1050C) to preheat the fresh regolith to 750C, can provide significant energy savings, dramatically increasing the efficiency of the oxygen recovery process. Other lunar volatile recovery operations may, also, benefit from the efficiency of preheating fresh regolith in a vacuum using the sensible heat of the spent material exiting the process.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
Similar configurations may also be of use in terrestrial mineral recovery operations; however, the potential existence of an interstitial gas in most terrestrial environments dramatically changes the character of heat transfer in/to/from granular solids. Thus, terrestrial applications of the specific configurations designed for lunar conditions may be limited to situations where interstitial gases need to be excluded for some other chemical or operational reason.

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In-situ Resource Utilization

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