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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Optimize out-of-core thermionic energy conversion for nuclear electric propulsion

Current designs for out of core thermionic energy conversion (TEC) to power nuclear electric propulsion (NEP) were evaluated. Approaches to improve out of core TEC are emphasized and probabilities for success are indicated. TEC gains are available with higher emitter temperatures and greater power densities. Good potentialities for accommodating external high temperature, high power density TEC with heat pipe cooled reactors exist.

Morris, J. F.↗
NASA NTRS1981

Development of a high-temperature durable catalyst for use in catalytic combustors for advanced automotive gas turbine engines

Durable catalytic reactors for advanced gas turbine engines were developed. Objectives were: to evaluate furnace aging as a cost effective catalytic reactor screening test, measure reactor degradation as a function of furnace aging, demonstrate 1,000 hours of combustion durability, and define a catalytic reactor system with a high probability of successful integration into an automotive gas turbine engine. Fourteen different catalytic reactor concepts were evaluated, leading to the selection of one for a durability combustion test with diesel fuel for combustion conditions. Eight additional catalytic reactors were evaluated and one of these was successfully combustion tested on propane fuel. This durability reactor used graded cell honeycombs and a combination of noble metal and metal oxide catalysts. The reactor was catalytically active and structurally sound at the end of the durability test.

Tong, H.↗
NASA NTRS2011

Software Architecture to Support the Evolution of the ISRU RESOLVE Engineering Breadboard Unit 2 (EBU2)

The In-Situ Resource Utilization (ISRU) Regolith & Environmental Science and Oxygen & Lunar Volatiles Extraction (RESOLVE) software provides operation of the physical plant from a remote location with a high-level interface that can access and control the data from external software applications of other subsystems. This software allows autonomous control over the entire system with manual computer control of individual system/process components. It gives non-programmer operators the capability to easily modify the high-level autonomous sequencing while the software is in operation, as well as the ability to modify the low-level, file-based sequences prior to the system operation. Local automated control in a distributed system is also enabled where component control is maintained during the loss of network connectivity with the remote workstation. This innovation also minimizes network traffic. The software architecture commands and controls the latest generation of RESOLVE processes used to obtain, process, and quantify lunar regolith. The system is grouped into six sub-processes: Drill, Crush, Reactor, Lunar Water Resource Demonstration (LWRD), Regolith Volatiles Characterization (RVC) (see example), and Regolith Oxygen Extraction (ROE). Some processes are independent, some are dependent on other processes, and some are independent but run concurrently with other processes. The first goal is to analyze the volatiles emanating from lunar regolith, such as water, carbon monoxide, carbon dioxide, ammonia, hydrogen, and others. This is done by heating the soil and analyzing and capturing the volatilized product. The second goal is to produce water by reducing the soil at high temperatures with hydrogen. This is done by raising the reactor temperature in the range of 800 to 900 C, causing the reaction to progress by adding hydrogen, and then capturing the water product in a desiccant bed. The software needs to run the entire unit and all sub-processes; however, throughout testing, many variables and parameters need to be changed as more is learned about the system operation. The Master Events Controller (MEC) is run on a standard laptop PC using Windows XP. This PC runs in parallel to another laptop that monitors the GC, and a third PC that monitors the drilling/ crushing operation. These three PCs interface to the process through a CompactRIO, OPC Servers, and modems.

Moss, Thomas↗
NASA NTRSDate not supplied

An Overview of Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Capabilities, Upgrades, and Overlaps in Advanced Material Testing Areas

The Nuclear Thermal Rocket Element Environmental Simulator (NTREES) was designed to perform non-nuclear testing of nuclear thermal rocket (NTR) fuel elements and materials. NTREES can simulate the thermal hydraulic environment within the reactor of an NTR and has been leveraged to provide data on the thermochemical, thermomechanical and thermohydraulic performance of components and materials. Active upgrades to the NTREES facility include installing a DC power supply for DC powered joule heating, a supply gas chiller for a cryogenically cool gas supply, gas pre-heaters with sample holders for testing samples too small to be inductively heated by bathing them in hot gas, and a high temperature digital image correlation (DIC) capability for measuring high temperature strains real time. In addition to NTR testing, given the commonality of high enthalpy flow environments between the reactor of an NTP engine and the aerothermal heating of high-speed flight, the unique capabilities of NTREES to provide high temperature gas flows at high pressure without combustion or electrode spallation byproducts may lend itself to additional usage of the facility beyond the original intent.

Michael P Schoenfeld↗
NASA NTRS1981

High temperature durable catalyst development

A program has been carried out to develop a catalytic reactor capable of operation in environments representative of those anticipated for advanced automotive gas turbine engines. A reactor consisting of a graded cell honeycomb support with a combination of noble metal and metal oxide catalyst coatings was built and successfully operated for 1000 hr. At an air preheat temperature of 740 K and a propane/air ratio of 0.028 by mass, the adiabatic flame temperature was held at about 1700 K. The graded cell monolithic reaction measured 5 cm in diameter by 10.2 cm in length and was operated at a reference velocity of 14.0 m/s at 1 atm. Measured NOx levels remained below 5 ppm, while unburned hydrocarbon concentrations registered near zero and carbon monoxide levels were nominally below 20 ppm.

Snow, G. C.↗
NASA NTRS2010

Microwave Plasma Hydrogen Recovery System

A microwave plasma reactor was developed for the recovery of hydrogen contained within waste methane produced by Carbon Dioxide Reduction Assembly (CRA), which reclaims oxygen from CO2. Since half of the H2 reductant used by the CRA is lost as CH4, the ability to reclaim this valuable resource will simplify supply logistics for longterm manned missions. Microwave plasmas provide an extreme thermal environment within a very small and precisely controlled region of space, resulting in very high energy densities at low overall power, and thus can drive high-temperature reactions using equipment that is smaller, lighter, and less power-consuming than traditional fixed-bed and fluidized-bed catalytic reactors. The high energy density provides an economical means to conduct endothermic reactions that become thermodynamically favorable only at very high temperatures. Microwave plasma methods were developed for the effective recovery of H2 using two primary reaction schemes: (1) methane pyrolysis to H2 and solid-phase carbon, and (2) methane oligomerization to H2 and acetylene. While the carbon problem is substantially reduced using plasma methods, it is not completely eliminated. For this reason, advanced methods were developed to promote CH4 oligomerization, which recovers a maximum of 75 percent of the H2 content of methane in a single reactor pass, and virtually eliminates the carbon problem. These methods were embodied in a prototype H2 recovery system capable of sustained high-efficiency operation. NASA can incorporate the innovation into flight hardware systems for deployment in support of future long-duration exploration objectives such as a Space Station retrofit, Lunar outpost, Mars transit, or Mars base. The primary application will be for the recovery of hydrogen lost in the Sabatier process for CO2 reduction to produce water in Exploration Life Support systems. Secondarily, this process may also be used in conjunction with a Sabatier reactor employed to stockpile life-support oxygen as well as propellant and fuel production from Martian atmospheric CO2

Atwater, James↗
NASA NTRS1986

The high-temperature oxidation of aromatic hydrocarbons

Chemical mechanisms of the atmospheric pressure, high-temperature (875-1500 K) gas-phase oxidation of benzene, toluene, ethylbenzene, and propylbenzene are described and discussed. Oxidation trends evident from turbulent flow reactor experiments serve as the basis for the mechanisms of the oxidation of benzene and alkylated aromatics. The potential effects of very high temperatures and pressures on the chemistry of oxidation of aromatics are described. The oxidation of benzene and phenyl radical has been found to proceed in a stepwise C6-C5-C4 sequence. Species profiles obtained from flow-reactor experiments suggest that the oxidation of benzene and phenyl radical follows the generalized route via phenoxy, cyclopentadienyl and butadienyl radical. The oxidation of the C4 species branches into multiple pathways that yield copious amounts of ethylene and acetylene. Certain major trends are evident: the alkylated aromatics on initial attack either form styrene, benzyl radical or benzene. The styrene reacts further to produce a benzyl radical or benzene. The oxidation of an alkylated aromatic hydrocarbon appears eventually to reduce to the oxidation of either phenyl radical or benzene.

Brezinsky, K.↗
NASA NTRS1978

Control system studies for thermionic reactors

In core thermionic reactor concepts are of interest for space missions that require electrical power in the range of a few tens of kilowatts up to several megawatts. The physical principle involved--thermionic direct conversion of heat to electricity at net efficiencies up to 15 percent--offers potential advantages when compared to other nuclear powerplant concepts. However, the integration of the thermionic diode electrode structure with high-temperature nuclear fuel materials presents new design problems and new reactor physical constraints. Among the topics that must be investigated are those associated with the control system. The results of analytical and simulation studies of thermionic reactor control performed at the Jet Propulsion Laboratory are discussed.

Hermsen, R. J.↗
NASA NTRSDate not supplied

Heat Pipe Development For Space Fission Demonstration Missions

NASA is currently formulating a flight mission that will demonstrate a 10 kWe nuclear electric fission power system for use on the lunar surface. While preliminary mission concepts leverage the successful Kilopower Reactor Using Stirling Technology ground prototype demonstration of a 1 kWe reactor, there are significant engineering challenges associated with adapting that prototype reactor for flight. One of these challenges is to modify the high temperature sodium heat pipes for use in space operation. Ongoing technical work at the NASA Glenn Research Center seeks to address several key areas of heat pipe development, focusing on fluid return under reduced or microgravity conditions and improved interfaces for both the reactor and the power conversion ends of the heat pipe.

Fission↗
NASA NTRS1991

Silicon carbide, an emerging high temperature semiconductor

In recent years, the aerospace propulsion and space power communities have expressed a growing need for electronic devices that are capable of sustained high temperature operation. Applications for high temperature electronic devices include development instrumentation within engines, engine control, and condition monitoring systems, and power conditioning and control systems for space platforms and satellites. Other earth-based applications include deep-well drilling instrumentation, nuclear reactor instrumentation and control, and automotive sensors. To meet the needs of these applications, the High Temperature Electronics Program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. Research is focussed on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of silicon carbide electronic devices and integrated sensors. The progress made in developing silicon carbide is presented, and the challenges that lie ahead are discussed.

Matus, Lawrence G.↗
NASA NTRS1979

High temperature UF6 and plasma research

Research currently under way on technology for uranium plasma core reactors is reviewed. A feeder system to provide a controlled and steady flow of UF6 at rates up to 5 g/sec and temperatures up to 500 K into rf plasma test chambers operating at pressures of up to 20 atm has been developed. Plasma emission and dye laser absorption measurements have been used to estimate the radial distribution of uranium atom number density within the plasma. X-ray absorption equipment and techniques have also been employed to measure the amount of uranium in the plasma, and dc plasma torch experiments have shown variations in plasma VUV emission with temperature. Analysis of residues deposited on various test-chamber components after plasma tests reveals traces of several uranium oxides, including UO2F2, and various exhaust duct configurations with flow augmentation are under investigation as means of preventing uranium deposition. Other areas of research include off- and on-line exhaust gas diagnostics, and a UF6/Ar injection, separation and recirculation system.

Roman, W. C.↗
NASA NTRS2011

Design of a Mechanical NaK Pump for Fission Space Power

Alkali liquid metal cooled fission reactor concepts are under development for spaceflight power requirements. One such concept utilizes a sodium-potassium eutectic (NaK) as the primary loop working fluid, which has specific pumping requirements. Traditionally, electromagnetic linear induction pumps have been used to provide the required flow and pressure head conditions for NaK systems but they can be limited in performance, efficiency, and number of available vendors. The objective of the project was to develop a mechanical NaK centrifugal pump that takes advantages of technology advances not available in previous liquid metal mechanical pump designs. This paper details the design, build, and performance test of a mechanical NaK pump developed at NASA Marshall Space Flight Center. The pump was designed to meet reactor cooling requirements using commercially available components modified for high temperature NaK service.

Mireles, Omar R.↗
NASA NTRS2010

Design of a Mechanical NaK Pump for Fission Space Power Systems

Alkali liquid metal cooled fission reactor concepts are under development for mid-range spaceflight power requirements. One such concept utilizes a sodium-potassium eutectic (NaK) as the primary loop working fluid. Traditionally, linear induction pumps have been used to provide the required flow and head conditions for liquid metal systems but can be limited in performance. This paper details the design, build, and check-out test of a mechanical NaK pump. The pump was designed to meet reactor cooling requirements using commercially available components modified for high temperature NaK service.

Mireles, Omar R.↗
NASA NTRS2019

The Kilopower Space Nuclear Fission Power Reactor

Nuclear fission power offers an attractive alternative to solar electric or radioisotope power systems for certain applications on the Moon, Mars, and deep space science missions. The advantages of independence from solar irradiance, high energy density, and abundance of fuel allow fission power systems to enable novel, high power mission architectures. While NASA has had numerous fission power programs throughout its history, few have gone far beyond the design phase. The recent test campaign called the Kilopower Reactor Using Stirling Technology project (KRUSTY) focused on a low power, kilowatt-scale design for simplicity and reduced cost, with the driving motivation to perform a full nuclear hardware prototype test. Following the successful completion of the KRUSTY nuclear hardware test in March of 2018, NASA has begun the formulation process for a Technology Demonstration Mission (TDM) using the Kilopower reactor technology. In support of NASA's lunar surface initiatives, the Kilopower TDM will target a 1-3 kW fission electric power system that can survive the lunar night and operate for one year. The system will be heavily influenced by the KRUSTY reactor design, using a solid Uranium metal core with high temperature heat pipes and Stirling engine power conversion. During this formulation phase, continued engineering efforts are ongoing to improve heat transfer efficiency in the system, examine fission radiation damage effects, and begin to address the thermal and structural requirements of a Kilopower flight system.

Chaiken, Max↗
NASA NTRS2016

Extraction and Capture of Water from Martian Regolith Experimental Proof-of-Concept

Mars Design Reference Architecture 5.0:Lists in-situ resource utilization (ISRU) as enabling for robust human Mars missionsLO2LCH4 ascent propulsion 25,000 kg oxygen from atmosphere for ascent and life support Atmospheric based ISRU processes less operationally complex than surface based limited concept evaluation to date and Mars surface water property and distribution uncertainty would not allow [Mars soil water processing] to be base lined at this time Limited Concept Evaluation to Date Lunar regolith O2 extraction processing experience Lunar regolith is fluidized and heated to high temperatures with H2 to produce H2O from iron-bearing minerals Mars similarity concept: Soil placed in fluidized bed reactor Heated to moderate temperatures Inert gas flow used to fluidize the bed and help with water desorption Challenges: High-temperature dusty seals Working gas requires downstream separation and recycling to reduce consumables loss Batch process heating thermally inefficient.

in situ resource utilization↗
NASA NTRS1991

Droplet Core Nuclear Rocket (DCNR)

The most basic design feature of the droplet core nuclear reactor is to spray liquid uranium into the core in the form of droplets on the order of five to ten microns in size, to bring the reactor to critical conditions. The liquid uranium fuel ejector is driven by hydrogen, and more hydrogen is injected from the side of the reactor to about one and a half meters from the top. High temperature hydrogen is expanded through a nozzle to produce thrust. The hydrogen pressure in the system can be somewhere between 50 and 500 atmospheres; the higher pressure is more desirable. In the lower core region, hydrogen is tangentially injected to serve two purposes: (1) to provide a swirling flow to protect the wall from impingement of hot uranium droplets: (2) to generate a vortex flow that can be used for fuel separation. The reactor is designed to maximize the energy generation in the upper region of the core. The system can result in and Isp of 2000 per second, and a thrust-to-weight ratio of 1.6 for the shielded reactor. The nuclear engine system can reduce the Mars mission duration to less than 200 days. It can reduce the hydrogen consumption by a factor of 2 to 3, which reduces the hydrogen load by about 130 to 150 metric tons.

Anghaie, Samim↗
NASA NTRS1989

Moon base reactor system

The objective of our reactor design is to supply a lunar-based research facility with 20 MW(e). The fundamental layout of this lunar-based system includes the reactor, power conversion devices, and a radiator. The additional aim of this reactor is a longevity of 12 to 15 years. The reactor is a liquid metal fast breeder that has a breeding ratio very close to 1.0. The geometry of the core is cylindrical. The metallic fuel rods are of beryllium oxide enriched with varying degrees of uranium, with a beryllium core reflector. The liquid metal coolant chosen was natural lithium. After the liquid metal coolant leaves the reactor, it goes directly into the power conversion devices. The power conversion devices are Stirling engines. The heated coolant acts as a hot reservoir to the device. It then enters the radiator to be cooled and reenters the Stirling engine acting as a cold reservoir. The engines' operating fluid is helium, a highly conductive gas. These Stirling engines are hermetically sealed. Although natural lithium produces a lower breeding ratio, it does have a larger temperature range than sodium. It is also corrosive to steel. This is why the container material must be carefully chosen. One option is to use an expensive alloy of cerbium and zirconium. The radiator must be made of a highly conductive material whose melting point temperature is not exceeded in the reactor and whose structural strength can withstand meteor showers.

Chavez, H.↗
NASA NTRS1999

Methane Pyrolysis and Disposing Off Resulting Carbon

Sabatier/Electrolysis (S/E) is a leading process for producing methane and oxygen for application to Mars ISPP. One significant problem with this process is that it produces an excess of methane for combustion with the amount of oxygen that is produced. Therefore, one must discard roughly half of the methane to obtain the proper stoichiometric methane/oxygen mixture for ascent from Mars. This is a waste of hydrogen, which must be brought from Earth and is difficult to transport to Mars and store on Mars. To reduce the problem of transporting hydrogen to Mars, the S/E process can be augmented by another process which reduces overall hydrogen requirement. Three conceptual approaches for doing this are (i) recover hydrogen from the excess methane produced by the S/E process, (ii) convert the methane to a higher hydrocarbon or other organic with a lower H/C ratio than methane, and (iii) use a separate process (such as zirconia or reverse water gas shift reaction) to produce additional oxygen, thus utilizing all the methane produced by the Sabatier process. We report our results here on recovering hydrogen from the excess methane using pyrolysis of methane. Pyrolysis has the advantage that it produces almost pure hydrogen, and any unreacted methane can pass through the S/E process reactor. It has the disadvantage that disposing of the carbon produced by pyrolysis presents difficulties. The goals of a research program on recovery of hydrogen from methane are (in descending priority order): 1) Study the kinetics of pyrolysis to arrive at a pyrolysis reactor design that produces high yields in a confined volume at the lowest possible operating temperature; 2) Study the kinetics of carbon burnoff to determine whether high yields can be obtained in a confined volume at acceptable operating temperatures; and 3) Investigate catalytic techniques for depositing carbon as a fine soot which can be physically separated from the reactor. In the JPL program, we have made significant measurements in regard to goal 1, cursory measurements in regard to goal 2, and would plan to pursue goal 3 if additional resources are secured.

Sharma, P. K.↗