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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

A programmable heater control circuit for spacecraft

Spacecraft thermal control is accomplished for many components through use of multilayer insulation systems, electrical heaters, and radiator systems. The heaters are commanded to maintain component temperatures within design specifications. The programmable heater control circuit (PHCC) was designed to obtain an effective and efficient means of spacecraft thermal control. The hybrid circuit provides use of control instrumentation as temperature data, available to the spacecraft central data system, reprogramming capability of the local microprocessor during the spacecraft's mission, and the elimination of significant spacecraft wiring. The hybrid integrated circuit has a temperature sensing and conditioning circuit, a microprocessor, and a heater power and control circuit. The device is miniature and housed in a volume which allows physical integration with the component to be controlled. Applications might include alternate battery-powered logic-circuit configurations. A prototype unit with appropriate physical and functional interfaces was procured for testing. The physical functionality and the feasibility of fabrication of the hybrid integrated circuit were successfully verified. The remaining work to develop a flight-qualified device includes fabrication and testing of a Mil-certified part. An option for completing the PHCC flight qualification testing is to enter into a joint venture with industry.

Nguyen, D. D.↗
NASA NTRS1994

Lunar base heat pump, phase 1

This report describes the Phase 1 process and analysis used to select a refrigerant and thermodynamic cycle as the basis of a vapor compression heat pump requiring a high temperature lift, then to perform a preliminary design to implement the selected concept, including major component selection. Use of a vapor compression heat pump versus other types was based on prior work performed for the Electric Power Research Institute. A high lift heat pump is needed to enable a thermal control system to remove heat down to 275 K from a habitable volume when the external thermal environment is severe. For example, a long-term lunar base habitat will reject heat from a space radiator to a 325 K environment. The first step in the selection process was to perform an optimization trade study, quantifying the effect of radiator operating temperature and heat pump efficiency on total system mass; then, select the radiator operating temperature corresponding to the lowest system mass. Total system mass included radiators, all heat pump components, and the power supply system. The study showed that lunar night operation, with no temperature lift, dictated the radiator size. To operate otherwise would require a high mass penalty to store power. With the defined radiation surface, and heat pump performances assumed to be from 40 percent to 60 percent of the Carnot ideal, the optimum heat rejection temperature ranged from 387 K to 377 K, as a function of heat pump performance. Refrigerant and thermodynamic cycles were then selected to best meet the previously determined design conditions. The system was then adapted as a ground-based prototype lifting temperature to 360 K (versus 385 K for flight unit) and using readily available commercial-grade components. Over 40 refrigerants, separated into wet and dry compression behavioral types, were considered in the selection process. Refrigerants were initially screened for acceptable critical temperature. The acceptable refrigerants were analyzed in ideal single and two-stage thermodynamic cycles. Top candidates were analyzed assuming realistic component limits and system pressure drops, and were evaluated for other considerations such as safety, environmental impact, and commercial availability. A maximum coefficient of performance (COP) of 56 percent of the Carnot ideal was achievable for a three-stage CFC-11 cycle operating under the flight conditions above. The program was completed by defining a control scheme and by researching and selecting the major components, compressor and heat exchangers, that could be used to implement the thermodynamic cycle selected. Special attention was paid to using similar technologies for the SIRF and flight heat pumps resulting in the commercially available equivalent of the flight unit. A package concept was generated for the components selected and mass and volume estimated.

Goldman, Jeffrey H.↗
NASA NTRS1992

Thermoregulatory responses of rhesus monkeys during spaceflight

This study examines the activity, axillary temperature (T(ax)), and ankle skin temperature (Tsk) of two male Rhesus monkeys exposed to microgravity in space. The animals were flown on a Soviet biosatellite mission (COSMOS 1514). Measurements on the flight animals, as well as synchronous flight controls, were performed in the Soviet Union. Additional control studies were performed in the United States to examine the possible role of metabolic heat production in the T(ax) response observed during the spaceflight. All monkeys were exposed to a 24-h light-dark cycle (LD 16:8) throughout these studies. During weightlessness, T(ax) in both flight animals was lower than on earth. The largest difference (0.75 degree C) occurred during the night. There was a reduction in mean heart rate and Tsk during flight. This suggests a reduction in both heat loss and metabolic rate during spaceflight. Although the circadian rhythms in all variables were present during flight, some differences were noted. For example, the amplitude of the rhythms in Tsk and activity were attenuated. Furthermore, the T(ax) and activity rhythms did not have precise 24.0 hour periods and may have been externally desynchronized from the 24-h LD cycle. These data suggest a weakening of the coupling between the internal circadian pacemaker and the external LD synchronizer.

Sulzman, F. M.↗
NASA NTRS1995

Arctic Ozone Depletion from UARS MLS Measurements

Microwave Limb Sounder (MLS) measurements of ozone during four Arctic winters are compared. The evolution of ozone in the lower stratosphere is related to temperature, chlorine monoxide (also measured by MLS), and the evolution of the polar vortex. Lagrangian transport calculations using winds from the United Kingdom Meteorological Office's Stratosphere-Troposphere Data Assimilation system are used to estimate to what extent the evolution of lower stratospheric ozone is controlled by dynamics. Observations, along with calculations of the expected dynamical behavior, show evidence for chemical ozone depletion throughout most of the Arctic lower stratospheric vortex during the 1992-93 middle and late winter, and during all of the 1994-95 winter that was observed by MLS. Both of these winters were unusually cold and had unusually cold and had unusually strong Arctic polar vortices compared to meteorological data over the past 17 years.

UARS MLS↗
NASA NTRS2015

The NASA MSFC Electrostatic Levitation (ESL) Laboratory: Summary of Capabilities, Recent Upgrades, and Future Work

The NASA Marshall Space Flight Center (MSFC) electrostatic levitation (ESL) laboratory has a long history of providing materials research and thermophysical property data. A summary of the labs capabilities, recent upgrades, and ongoing and future work will be provided. The laboratory has recently added two new capabilities to its main levitation chamber: a rapid quench system and an oxygen control system. The rapid quench system allows samples to be dropped into a quench vessel that can be filled with a low melting point material, such as a gallium or indium alloy. Thereby allowing rapid quenching of undercooled liquid metals. The oxygen control system consists of an oxygen sensor, oxygen pump, and a control unit. The sensor is a potentiometric device that determines the difference in oxygen activity between two gas compartments separated by an electrolyte, which is yttria-stabilized zirconia. The pump utilizes coulometric titration to either add or remove oxygen. The system is controlled by a desktop control unit, which can also be accessed via a computer. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled, theoretically in the range from 10-36 to 100 bar. The ESL laboratory also has an emissometer, called the High-Temperature Emissivity Measurement System (HiTEMS). This system measures the spectral emissivity of materials from 600degC to 3,000degC. The system consists of a vacuum chamber, a black body source, and a Fourier Transform Infrared Spectrometer (FTIR). The system utilizes optics to swap the signal between the sample and the black body. The system was originally designed to measure the hemispherical spectral emissivity of levitated samples, which are typically 2.5mm spheres. Levitation allows emissivity measurements of molten samples, but more work is required to develop this capability. The system is currently setup measure the near-normal spectral emissivity of stationary samples, which has been used to take measurements of ablative materials, rocket nozzle coating materials, and materials for spacecraft instruments.

SanSoucie, Michael P.↗
NASA NTRS1982

Transit Thermal Control Design for Galileo Entry Probe for Planet Jupiter

A totally passive design was completed for the thermal control of the Galileo entry probe during its transit to the planet Jupiter. The design utilizes radio isotope heater units, multilayer insulation blankets and a thermal radiator in conjunction with a design conductance support structure to achieve both the required storage and critical initial planet atmosphere entry temperatures. The probe transit thermal design was completed and verified based on thermal vacuum testing of a prototype probe thermal test model.

Haverly, George C.↗
NASA NTRS1982

Development status of the small community solar power system

The development status and test results for the Small Community Solar Thermal Power Experiment are presented. Activities on the phase 2 power module development effort are presented with emphasis on the receiver, the plant control subsystem, and the energy transport subsystem. The components include a single prototype power module consisting of a parabolic dish concentrator, a power conversion assembly (PCA), and a multiple-module plant control subsystem. The PCA consists of a cavity receiver coupled to an organic Rankine cycle engine-alternator unit defined as the power conversion subsystem; the PCA is mounted at the focus of a parabolic dish concentrator. At a solar insolation of 100 W/sq m and ambient temperature of 28 C (82 F), the power module produces approximately 20 kW of 3-phase, 3 kHz ac power, depending on the concentrator employed. A ground-mounted rectifier to the central collection site where it is supplied directly to the common dc bus which collects the power from all modules in the plant.

Pons, R. L.↗
NASA NTRS1995

Low volume packaging for a microinstrumentation system

A folding, multi-platform assembly has been developed for the packaging of a multi-chip microinstrumentation system. The assembly includes three solid platforms connected by flexible micromachined ribbon cables and it can be populated by sensors and electronics from a variety of technologies including surface mount and integrated circuit (IC) processes. The entire structure is fabricated from a four-inch silicon wafer using a simple four mask process and a post-process EDP etch. The micromachined ribbon cables allow the platform assembly to be folded into a three level structure with control electronics on the bottom level, microsensors and interface electronics on the second level, and sensors that need environmental access on the top level. Using the silicon multi-platform assembly, a prototype microinstrumentation system has been developed that includes a microcontroller unit and sensors for measuring temperature, barometric pressure, humidity, altitude, and acceleration as well as a telemetry device for wireless communication. When folded in the three level structure, this microsystem occupies only 5 cc and can be placed in an outer case the size of a wristwatch.

Mason, A.↗
NASA NTRS2000

Size Exclusion Chromatography Studies of the Initial Self-Association Steps of Chicken Egg White Lysozyme Nucleation

Nucleation is one of the least understood aspects of crystallogenesis. In the case of macromolecule nucleation, this understanding is further hampered by uncertainty over what precisely is being discussed. We define the process of solute self-association (aggregation, oligomerization, interaction, clustering, etc.) whereby n-mers (n > or = 2) having a crystallographic or nascent crystallographic arrangement leading to the critical nucleus reversibly form in the solution, to be part of the nucleation process. This reversible self-association process is a fundamental part of the nucleation process, and occurs as a function of the solute concentration. In the case of chicken egg white lysozyme, a considerable body of experimental evidence leads us to the conclusion that it also forms the crystal growth units. Size exclusion chromatography is a simple and direct method for determining the equilibrium constants for the self-association process. A Pharmacia FPLC system was used to provide accurate solution flow rates. The column, injection valve, and sample loop were all mounted within a temperature-controlled chamber. Chromatographically re-purified lysozyme was first dialyzed against the column equilibration buffer, with injection onto the column after several hours pre-incubation at the running temperature. Preliminary experiments, were carried out using a Toyopearl HW-50F column (1 x 50cm), equilibrated with 0.1 M sodium acetate, 5% sodium chloride, pH 4.6, at 15C. Protein concentrations from 0.1 to 4 mg/ml were employed (C(sub sat) = 1.2 mg/ml). The data from several different protein preparations consistently shows a progressively decreasing elution volume with increasing protein concentration, indicating that reversible self-association is occurring. The dotted line indicates the monomeric lysozyme elution volume. However, lysozyme interacts with the column matrix in these experiments, which complicates data analysis.Accordingly, we are testing silica-based HPLC columns in an effort to eliminate this problem and substantially reduce the column volume and experimental run time. The results and data analysis from these and subsequent experiments will be presented.

Ewing, Felecia↗
NASA NTRS2000

Protein Crystal Growth Dynamics and Impurity Incorporation

The general concepts and theories of crystal growth are proven to work for biomolecular crystallization. This allowed us to extract basic parameters controlling growth kinetics - free surface energy, alpha, and kinetic coefficient, beta, for steps. Surface energy per molecular site in thermal units, alpha(omega)(sup 2/3)/kT approx. = 1, is close to the one for inorganic crystals in solution (omega is the specific molecular volume, T is the temperature). Entropic restrictions on incorporation of biomolecules into the lattice reduce the incorporation rate, beta, by a factor of 10(exp 2) - 10(exp 3) relative to inorganic crystals. A dehydration barrier of approx. 18kcal/mol may explain approx. 10(exp -6) times difference between frequencies of adding a molecule to the lattice and Brownian attempts to do so. The latter was obtained from AFM measurements of step and kink growth rates on orthorhombic lysozyme. Protein and many inorganic crystals typically do not belong to the Kossel type, thus requiring a theory to account for inequivalent molecular positions within its unit cell. Orthorhombic lysozyme will serve as an example of how to develop such a theory. Factors deteriorating crystal quality - stress and strain, mosaicity, molecular disorder - will be reviewed with emphasis on impurities. Dimers in ferritin and lysozyme and acetylated lysozyme, are microheterogeneous i.e. nearly isomorphic impurities that are shown to be preferentially trapped by tetragonal lysozyme and ferritin crystals, respectively. The distribution coefficient, K defined as a ratio of the (impurity/protein) ratios in crystal and in solution is a measure of trapping. For acetylated lysoyzme, K = 2.15 or, 3.42 for differently acetylated forms, is independent of both the impurity and the crystallizing protein concentration. The reason is that impurity flux to the surface is constant while the growth rate rises with supersaturation. About 3 times lower dimer concentration in space grown ferritin and lysozyme crystals might be examples explaining higher quality of the space grown protein crystal. Depletion of solution with respect to isomorphic impurities around a growing crystal may be K times deeper than with respect to the crystallizing protein.

Chernov, Alex A.↗
NASA NTRS1980

Advanced technology applications for second and third general coal gasification systems

The historical background of coal conversion is reviewed and the programmatic status (operational, construction, design, proposed) of coal gasification processes is tabulated for both commercial and demonstration projects as well as for large and small pilot plants. Both second and third generation processes typically operate at higher temperatures and pressures than first generation methods. Much of the equipment that has been tested has failed. The most difficult problems are in process control. The mechanics of three-phase flow are not fully understood. Companies participating in coal conversion projects are ordering duplicates of failure prone units. No real solutions to any of the significant problems in technology development have been developed in recent years.

Bradford, R.↗
NASA NTRS1985

Space shuttle main engine: Interactive design challenges

The operating requirements established by NASA for the SSME were considerably more demanding than those for earlier rocket engines used in the military launch vehicles or Apollo program. The SSME, in order to achieve the high performance, low weight, long life, reusable objectives, embodied technical demands far in excess of its predecessor rocket engines. The requirements dictated the use of high combustion pressure and the staged combustion cycle which maximizes performance through total use of all propellants in the main combustion process. This approach presented a myriad of technical challenges for maximization of performance within attainable state of the art capabilities for operating pressures, operating temperatures and rotating machinery efficiencies. Controlling uniformity of the high pressure turbomachinery turbine temperature environment was a key challenge for thrust level and life capability demanding innovative engineering. New approaches in the design of the components were necessary to accommodate the multiple use, minimum maintenance objectives. Included were the use of line replaceable units to facilitate field maintenance automatic checkout and internal inspection capabilities.

Mccarty, J. P.↗
NASA NTRS1993

The effect of SST and soil moisture anomalies on GLA model simulations of the 1988 U.S. summer drought

A series of simulations of the late spring and early summer of 1988 were conducted in order to study the relative importance of different boundary forcings to the Goddard Laboratory for Atmospheres (GLA) model's simulation of the heat wave and drought over the Great Plains of the United States during this time period. Separate 60-day simulations were generated from 10, 20, and 30 May 1988 with a variety of boundary condition datasets. For the control experiment, climatological boundary conditions were used. This was followed by experiments in which either the observed 1988 sea surface temperatures (SST) or derived 1988 soil moisture values, or both, were used in place of the climatological fields. Additional experiments were conducted in which only tropical or midlatitude SST anomalies were used. The impact of the different boundary forcings was evaluated relative to the control simulations of the precipitation and surface air temperature over the Great Plains. It was found that the tropical SST anomalies had a significant effect in reducing precipitation in this area, while the midlatitude anomalies did not. Due to the prescribed climatological soil moistures for the SST experiments, a significant increase in surface temperature did not occur in these simulations. In contrast, the simulations with the anomalous 1988 soil moistures produced both a larger reduction of precipitation and a significant increase in surface temperature over the Great Plains. The simulations with both anomalous SST and soil moisture showed only a slight augmentation of the heat wave and drought relative to the experiments with anomalous soil moisture alone.

Atlas, R.↗
NASA NTRS1997

Advanced Film Cooling Rig: Development and Test Results

The Advanced Film Cooling Rig (AFCR) test was a program to develop a thermal imaging camera system to measure the effectiveness of multihole film cooling. This system was used to evaluate low-thermal conductivity ceramic test panels incorporating a wide range of multihole cooling geometries. Tests were conducted with a mainstream flow of 600 F at Mach numbers of 0.37 and 1.57. Coolant flow was controlled to give a blowing parameter variation of up to 2.9. Data reduction techniques are given for camera calibration, rig temperature reflection correction, and deriving surface temperatures from video images. Results are presented in terms of overall and film cooling effectiveness distributions. A one-dimensional analysis of a unit film cooling hole was performed to generate film temperature.

Reilly, R. S.↗
NASA NTRS2005

Prototype development of a Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR)

Weather prediction and hurricane tracking would greatly benefit of a continuous imaging capability of a hemisphere at millimeter wave frequencies. We are developing a synthetic thinned aperture radiometer (STAR) prototype operating from 50 to 56 GHz as a ground-based testbed to demonstrate the technologies needed to do full earth disk atmospheric temperature soundings from Geostationary orbit with very high spatial resolution. The prototype consists of a Y-array of 24 MMIC receivers that are compact units implemented with low noise InP MMIC LNAs, second harmonic I-Q mixers, low power IF amplifiers and include internal digital bias control with serial line communication to enable low cost testing and system integration. Furthermore, this prototype STAR includes independent LO and noise calibration signal phase switching circuitry for each arm of the Y-array to verify the operation and calibration of the system.

Millimeter wave low noise amplifiers↗
NASA NTRS2010

Fabrication of Single, Vertically Aligned Carbon Nanotubes in 3D Nanoscale Architectures

Plasma-enhanced chemical vapor deposition (PECVD) and high-throughput manufacturing techniques for integrating single, aligned carbon nanotubes (CNTs) into novel 3D nanoscale architectures have been developed. First, the PECVD growth technique ensures excellent alignment of the tubes, since the tubes align in the direction of the electric field in the plasma as they are growing. Second, the tubes generated with this technique are all metallic, so their chirality is predetermined, which is important for electronic applications. Third, a wafer-scale manufacturing process was developed that is high-throughput and low-cost, and yet enables the integration of just single, aligned tubes with nanoscale 3D architectures with unprecedented placement accuracy and does not rely on e-beam lithography. Such techniques should lend themselves to the integration of PECVD grown tubes for applications ranging from interconnects, nanoelectromechanical systems (NEMS), sensors, bioprobes, or other 3D electronic devices. Chemically amplified polyhydroxystyrene-resin-based deep UV resists were used in conjunction with excimer laser-based (lambda = 248 nm) step-and-repeat lithography to form Ni catalyst dots = 300 nm in diameter that nucleated single, vertically aligned tubes with high yield using dc PECVD growth. This is the first time such chemically amplified resists have been used, resulting in the nucleation of single, vertically aligned tubes. In addition, novel 3D nanoscale architectures have been created using topdown techniques that integrate single, vertically aligned tubes. These were enabled by implementing techniques that use deep-UV chemically amplified resists for small-feature-size resolution; optical lithography units that allow unprecedented control over layer-to-layer registration; and ICP (inductively coupled plasma) etching techniques that result in near-vertical, high-aspect-ratio, 3D nanoscale architectures, in conjunction with the use of materials that are structurally and chemically compatible with the high-temperature synthesis of the PECVD-grown tubes. The techniques offer a wafer-scale process solution for integrating single PECVD-grown nanotubes into novel architectures that should accelerate their integration in 3D electronics in general. NASA can directly benefit from this technology for its extreme-environment planetary missions. Current Si transistors are inherently more susceptible to high radiation, and do not tolerate extremes in temperature. These novel 3D nanoscale architectures can form the basis for NEMS switches that are inherently less susceptible to radiation or to thermal extremes.

Kaul, Anupama B.↗
NASA NTRS1999

Flight Testing of a Cryogenic Capillary Pumped Loop

Future space-based cryogenic systems will require enhanced integration flexibility, lower weight reduced parasitic penalties, better vibration isolation, and a variety of other improvements to meet performance goals. Additionally, there is an increasing need to locate cooling sources remotely from cooled components. In the past flexible conductive links were used and worked well in most cases. However, as the transport lengths increase, conductive couplings become heavier and less effective, and must be replaced by higher performance systems. One available option, which can meet many of these future requirements, is the cryogenic capillary pumped loop (CCPL). The development of the CCPL technology started in 1992, following the success of the room temperature CPLS. The extrapolation of CCPL technology to cryogenic temperatures offers many performance benefits, which are not currently within the reach of traditional heat pipes or conductive links. Specific advantages of the CCPL technology pertaining to cryocooler integration include: (1) greater capillary pumping pressure for improved ground testability; (2) improved mechanical isolation; (3) faster diode shutdown and lower reverse heat leaks; (4) tighter control of detector temperature; (5) variable or fixed conductance operation; and (6) ease of integration due to their flexibility. The applications of CCPL technology are numerous. Military and commercial applications include surveillance satellites, earth observing satellites, deep space observation systems, medical devices, and many other cryogenic systems. Over the past few years, several breadboard and prototype CCPLs have been built and ground tested. A prototype CCPL has demonstrated successful operation between 80K and 110K with heat loads between O.5W and 12W using nitrogen as the working fluid, and 35K and 40K with head loads of 0.25W to 3.5W using neon. In order to verify CCPL performance in a microgravity environment, a flight unit, CCPL-5, was tested onboard the Space Shuttle STS-95 in October of 1998 as part of the CRYOTSU Flight Experiment. This flight was the first in-space demonstration of the CCPL. The CCPL-5 utilized nitrogen as the working fluid and operated between 75K and 110K. Flight results indicated excellent performance of the CCPL-5 under zero-G environment The CCPL could start from a supercritical condition in all tests, and the loop operating temperature could be tightly controlled regardless of changes in the heat load and/or the sink temperature. In addition, the loop demonstrated successful operation with a heat load of 0.5W as well as with parasitic heat loads alone. There were no noticeable differences between zero-G and one-G operation.

Ku, Jentung↗