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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

An investigation of sulfate production in clouds using a flow-through chemical reactor model approach

A flow-through chemical reactor model is developed to describe the mass transfer and chemical processes that atmospheric gases undergo in clouds. The model includes the simultaneous absorption of SO2, NH3, O3, NO(x), HNO3, CO2 and H2O2, the accompanying dissociation and oxidation reactions in cloud water, considers electrical neutrality, and includes qualitative parameterization of cloud microphysics. The model is used to assess the importance of the oxidation reactions H2O2-S(IV), O3-S(IV), and S(IV)-Mn(2+) catalysis, and the effects of cloud parameters such as drop size, rain intensity, liquid water content, and updraft velocity. Both precipitating and nonprecipitating clouds are studied. Model results predict sulfate production rates varying from 3 percent/hr to 230 percent/hr. The actual rate is highly dependent on the chemical composition of the uptake air and the physical conditions of the cloud. Model results also show that both the H2O2 and the O3 oxidation reactions can be significant.

Hong, M. S.↗
NASA NTRS1999

Microchemical and Thermal Systems for In-Situ Resource Utilization

Process Intensification and Process Miniaturization can simultaneously be achieved through the application of microfabricated chemical process systems, based on the rapid heat and mass transport in engineered microchannels. Researchers at NASA's Johnson Space Center (JSC) and the Department of Energy's Pacific Northwest National Laboratory (PNNL) are collaboratively developing micro thermal and chemical systems for NASA's Mission to Mars program. Preliminary results show that many standard chemical process components (e.g., heat exchangers, chemical reactors and chemical separations units) can be reduced in hardware volume without a corresponding reduction in chemical production rates. Low pressure drops and improved thermal integration are also accomplished when appropriate scaling rules are applied and when individual microchemical components are packaged together into integral systems.

Wegeng, Robert S.↗
NASA NTRS1999

Microchemical and Thermal Systems for In-Situ Resource Utilization

Process Intensification and Process Miniaturization can simultaneously be achieved through the application of microfabricated chemical process systems, based on the rapid heat and mass transport in engineered microchannels. Researchers at NASA's Johnson Space Center (JSC) and the Department of Energy's Pacific Northwest National Laboratory (PNNL) are collaboratively developing micro thermal and chemical systems for NASA's Mission to Mars program. Preliminary results show that many standard chemical process components (e.g., heat exchangers, chemical reactors and chemical separations units) can be reduced in hardware volume without a corresponding reduction in chemical production rates. Low pressure drops and improved thermal integration are also accomplished when appropriate scaling rules are applied and when individual microchemical components are packaged together into integral systems.

Wegeng, Robert S.↗
NASA NTRS2000

Micro Thermal and Chemical Systems for In Situ Resource Utilization on Mars

Robotic sample return missions and postulated human missions to Mars can be greatly aided through the development and utilization of compact chemical processing systems that process atmospheric gases and other indigenous resources to produce hydrocarbon propellants/fuels, oxygen, and other needed chemicals. When used to reduce earth launch mass, substantial cost savings can result. Process Intensification and Process Miniaturization can simultaneously be achieved through the application of microfabricated chemical process systems, based on the rapid heat and mass transport in engineered microchannels. Researchers at NASA's Johnson Space Center (JSC) and the Department of Energy's Pacific Northwest National Laboratory (PNNL) are collaboratively developing micro thermal and chemical systems for NASA's Mission to Mars program. Preliminary results show that many standard chemical process components (e.g., heat exchangers, chemical reactors and chemical separations units) can be reduced in hardware volume without a corresponding reduction in chemical production rates. Low pressure drops are also achievable when appropriate scaling rules are applied. This paper will discuss current progress in the development of engineered microchemical systems for space and terrestrial applications, including fabrication methods, expected operating characteristics, and specific experimental results.

Wegeng, Robert S.↗
NASA NTRS2007

Development of a Reactor Model for Chemical Conversion of Lunar Regolith

Lunar regolith will be used for a variety of purposes such as oxygen and propellant production and manufacture of various materials. The design and development of chemical conversion reactors for processing lunar regolith will require an understanding of the coupling among the chemical, mass and energy transport processes occurring at the length and time scales of the overall reactor with those occurring at the corresponding scales of the regolith particles. To this end, a coupled transport model is developed using, as an example, the reduction of ilmenite-containing regolith by a continuous flow of hydrogen in a flow-through reactor. The ilmenite conversion occurs on the surface and within the regolith particles. As the ilmenite reduction proceeds, the hydrogen in the reactor is consumed, and this, in turn, affects the conversion rate of the ilmenite in the particles. Several important quantities are identified as a result of the analysis. Reactor scale parameters include the void fraction (i.e., the fraction of the reactor volume not occupied by the regolith particles) and the residence time of hydrogen in the reactor. Particle scale quantities include the time for hydrogen to diffuse into the pores of the regolith particles and the chemical reaction time. The paper investigates the relationships between these quantities and their impact on the regolith conversion. Application of the model to various chemical reactor types, such as fluidized-bed, packed-bed, and rotary-bed configurations, are discussed.

Hedge, uday↗
NASA NTRS2009

Development of a Reactor Model for Chemical Conversion of Lunar Regolith

Lunar regolith will be used for a variety of purposes such as oxygen and propellant production and manufacture of various materials. The design and development of chemical conversion reactors for processing lunar regolith will require an understanding of the coupling among the chemical, mass and energy transport processes occurring at the length and time scales of the overall reactor with those occurring at the corresponding scales of the regolith particles. To this end, a coupled transport model is developed using, as an example, the reduction of ilmenite-containing regolith by a continuous flow of hydrogen in a flow-through reactor. The ilmenite conversion occurs on the surface and within the regolith particles. As the ilmenite reduction proceeds, the hydrogen in the reactor is consumed, and this, in turn, affects the conversion rate of the ilmenite in the particles. Several important quantities are identified as a result of the analysis. Reactor scale parameters include the void fraction (i.e., the fraction of the reactor volume not occupied by the regolith particles) and the residence time of hydrogen in the reactor. Particle scale quantities include the time for hydrogen to diffuse into the pores of the regolith particles and the chemical reaction time. The paper investigates the relationships between these quantities and their impact on the regolith conversion. Application of the model to various chemical reactor types, such as fluidized-bed, packed-bed, and rotary-bed configurations, are discussed.

Hegde, U.↗
NASA NTRS1977

Chemical vapor deposition reactor

An improved chemical vapor deposition reactor is characterized by a vapor deposition chamber configured to substantially eliminate non-uniformities in films deposited on substrates by control of gas flow and removing gas phase reaction materials from the chamber. Uniformity in the thickness of films is produced by having reactive gases injected through multiple jets which are placed at uniformally distributed locations. Gas phase reaction materials are removed through an exhaust chimney which is positioned above the centrally located, heated pad or platform on which substrates are placed. A baffle is situated above the heated platform below the mouth of the chimney to prevent downdraft dispersion and scattering of gas phase reactant materials.

Chern, S. S.↗
NASA NTRS1985

Windowless High-Pressure Solar Reactor

Obscuration by reaction products eliminated. Chemical reactor heated by Sunlight employs rocket technology to maintain internal pressure. Instead of keeping chamber tightly closed, pressure maintained by momentum balance between incoming and outgoing materials. Windowless solar reactor admits concentrated Sunlight through exhaust aperture. Pressure in reactor maintained dynamically.

Ramohalli, K. N. R.↗
NASA NTRS1963

Space applications

Fuel cells as energy storage and chemical reactor during space flights

CHEMICAL REACTOR↗
NASA NTRS1985

Turbulent flow model for vapor collection efficiency of a high-purity silicon reactor

In this study a mathematical model and a computer code based on this model was developed to allow prediction of the product distribution in chemical reactors for converting gaseous silicon compounds to condensed-phase silicon. Specifically, the model formulated describes the silicon vapor separation/collection from the developing turbulent flow stream within reactors of the Westinghouse type. Migration of the silicon vapor to the reactor walls was described by the parametric solutions presented here, in order to reduce the experimentation necessary in the design of such reactors. Calculations relating to the collection efficiencies of such reactors are presented as a function of the reactor throughflow and distance along its length.

Srivastava, R.↗
NASA NTRS1983

Fluidized bed coal desulfurization

Laboratory scale experiments were conducted on two high volatile bituminous coals in a bench scale batch fluidized bed reactor. Chemical pretreatment and posttreatment of coals were tried as a means of enhancing desulfurization. Sequential chlorination and dechlorination cum hydrodesulfurization under modest conditions relative to the water slurry process were found to result in substantial sulfur reductions of about 80%. Sulfur forms as well as proximate and ultimate analyses of the processed coals are included. These studies indicate that a fluidized bed reactor process has considerable potential for being developed into a simple and economic process for coal desulfurization.

Ravindram, M.↗
NASA NTRS1979

Electroplated "cold patch" for critical parts

Cracks in metal parts are filled by electrodeposition in plating tank that conforms to part to be repaired. Principle is applicable to repair of cracks in components of chemical reactors and other critical structures.

Tripp, H. A.↗
NASA NTRS1979

Development of a model and computer code to describe solar grade silicon production processes

Mathematical models, and computer codes based on these models were developed which allow prediction of the product distribution in chemical reactors in which gaseous silicon compounds are converted to condensed phase silicon. The reactors to be modeled are flow reactors in which silane or one of the halogenated silanes is thermally decomposed or reacted with an alkali metal, H2 or H atoms. Because the product of interest is particulate silicon, processes which must be modeled, in addition to mixing and reaction of gas-phase reactants, include the nucleation and growth of condensed Si via coagulation, condensation, and heterogeneous reaction.

Srivastava, R.↗
NASA NTRS1979

Development of a Model and Computer Code to Describe Solar Grade Silicon Production Processes

Mathematical models and computer codes based on these models, which allow prediction of the product distribution in chemical reactors for converting gaseous silicon compounds to condensed-phase silicon were developed. The following tasks were accomplished: (1) formulation of a model for silicon vapor separation/collection from the developing turbulent flow stream within reactors of the Westinghouse (2) modification of an available general parabolic code to achieve solutions to the governing partial differential equations (boundary layer type) which describe migration of the vapor to the reactor walls, (3) a parametric study using the boundary layer code to optimize the performance characteristics of the Westinghouse reactor, (4) calculations relating to the collection efficiency of the new AeroChem reactor, and (5) final testing of the modified LAPP code for use as a method of predicting Si(1) droplet sizes in these reactors.

Srivastava, R.↗