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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Molecules in Cool Stars: The A 2 Π − X 2 Σ + and the B 2 Σ + − X 2 Σ + Band Systems of CaCl

Cool red giant stars exhibit absorption bands of calcium monochloride (CaCl) in the optical region. In this work, the bands of CaCl corresponding to the A 2 Π − X 2 Σ + transition with v' ≤ 4 and v'' ≤ 4, and B 2 Σ + − X 2 Σ + transition with v' ≤ 2 and v'' ≤ 2 are rotationally analyzed with PGOPHER, a multipurpose program for simulating and fitting molecular spectra. All bands were analyzed using high-resolution absorption spectra collected at the National Solar Observatory in 1985, calibrated with atomic lines from a high-resolution emission spectrum obtained in a separate hollow cathode experiment. The results are compared with previous laser-induced fluorescence measurements. Overall, the accuracy of spectroscopic constants for the A2Π and B2Σ+ states is improved. Scaled transition dipole moment calculations were used to obtain line strengths. Line lists are provided with Einstein A coefficients and oscillator strengths, which can be used to determine CaCl stellar abundances. Additionally, isotope splittings allowed us to estimate band origins for the 40 Ca 37 Cl isotopologue based on band-head positions.

Léo Lavy↗
NASA NTRS1981

Chromospheres and coronae in binary systems

Recent observations and spectral analysis of chromospheres and coronae are discussed for various types of binary systems containing cool stars. These include the W UMa-type systems, the RS CVn variables, and selected widely separated binary systems such as VV Cephei and the giant stars in the Hyades cluster. In many cases evidence for extreme examples of solar activity are found. Radiative losses in ultraviolet resonance lines can be at least one or two orders of magnitude larger than those found in the quiet sun. In lambda And, a RS CVn type system, there is evidence for inhomogeneous structure in the chromosphere and transition region. Rotation appears to be a determinant in the energy losses of these atmospheres although not the only one.

Dupree, A. K.↗
NASA NTRS2000

A Continuous Adiabatic Demagnetization Refrigerator for Use with Mechanical Coolers

We have begun developing an adiabatic demagnetization refrigerator (ADR) which can produce continuous cooling at temperatures of 50 mK or lower, with high cooling power (goal of 10 PW). The design uses multiple stages to cascade heat from a continuously-cooled stage up to a heat sink. The serial arrangement makes it possible to add stages to extend the operating range to lower temperature, or to raise the heat rejection temperature. Compared to conventional single-shot ADRS, this system achieves higher cooling power per unit mass and is able to reject its heat at a more uniform rate. For operation with a mechanical cryocooler, this latter feature stabilizes the heat sink temperature and allows both the ADR and cryocooler to operate more efficiently. The ADR is being designed to operate with a heat sink as warm as 10-12 K to make it compatible with a wide variety of mechanical coolers as part of a versatile, cryogen-free low temperature cooling system. A two-stage system has been constructed and a proof-of-principle demonstration was conducted at 100 mK. Details of the design and test results, as well as the direction of future work, are discussed.

Shirron, P.↗
NASA NTRS1992

640 x 480 MWIR and LWIR camera system developments

The performance of a 640 x 480 PtSi, 3,5 microns (MWIR), Stirling cooled camera system with a minimum resolvable temperature of 0.03 is considered. A preliminary specification of a full-TV resolution PtSi radiometer was developed using the measured performance characteristics of the Stirling cooled camera. The radiometer is capable of imaging rapid thermal transients from 25 to 250 C with better than 1 percent temperature resolution. This performance is achieved using the electronic exposure control capability of the MOS focal plane array (FPA). A liquid nitrogen cooled camera with an eight-position filter wheel has been developed using the 640 x 480 PtSi FPA. Low thermal mass packaging for the FPA was developed for Joule-Thomson applications.

Tower, J. R.↗
NASA NTRS1986

Space Infrared Telescope Facility (SIRTF) observatory design

The NASA Space IR Telescope Facility (SIRTF) is a 1-m aperture, cryogenically cooled IR observatory scheduled for launch into orbit in the mid-1990s. SIRTF will operate in the 2-700 micron range and yield a 1000-fold increase in sensitivity over NASA's IRAS observatory. A low inclination orbit compatible with Space Shuttle operations will be used. Results from comparisons of a system error budget allocation for the f/24 optical configuration with recent test data indicate that a figured fused silica mirror and a blade flexure mounting system can be cooled to cryogenic temperature while meeting required wavefront tolerances for substrate deformation. An all-He cooling system will be used in the low inclination orbit.

Brooks, W. F.↗
NASA NTRS2004

Waste-Heat-Driven Cooling Using Complex Compound Sorbents

Improved complex-compound sorption pumps are undergoing development for use as prime movers in heat-pump systems for cooling and dehumidification of habitats for humans on the Moon and for residential and commercial cooling on Earth. Among the advantages of sorption heat-pump systems are that they contain no moving parts except for check valves and they can be driven by heat from diverse sources: examples include waste heat from generation of electric power, solar heat, or heat from combustion of natural gas. The use of complex compound sorbents in cooling cycles is not new in itself: Marketing of residential refrigerators using SrCl2 was attempted in the 1920s and 30s and was abandoned because heat- and mass-transfer rates of the sorbents were too low. Addressing the issue that gave rise to the prior abandonment of complex compound sorption heat pumps, the primary accomplishment of the present development program thus far has been the characterization of many candidate sorption media, leading to large increases in achievable heat- and mass-transfer rates. In particular, two complex compounds (called "CC260-1260" and "CC260-2000") were found to be capable of functioning over the temperature range of interest for the lunar-habitat application and to offer heat- and mass-transfer rates and a temperature-lift capability adequate for that application. Regarding the temperature range: A heat pump based on either of these compounds is capable of providing a 95-K lift from a habitable temperature to a heat-rejection (radiator) temperature when driven by waste heat at an input temperature .500 K. Regarding the heat- and mass-transfer rates or, more precisely, the power densities made possible by these rates: Power densities observed in tests were 0.3 kilowatt of cooling per kilogram of sorbent and 2 kilowatts of heating per kilogram of sorbent. A prototype 1-kilowatt heat pump based on CC260-2000 has been built and demonstrated to function successfully.

Rocketfeller, Uwe↗
NASA NTRS1976

Microfog lubrication for aircraft engine bearings

An analysis and system study was performed to provide design information regarding lubricant and coolant flow rates and flow paths for effective utilization of the lubricant and coolant in a once through bearing oil mist (microfog) and coolant air system. Both static and dynamic tests were performed. Static tests were executed to evaluate and calibrate the mist supply system. A total of thirteen dynamic step speed bearing tests were performed using four different lubricants and several different mist and air supply configurations. The most effective configuration consisted of supplying the mist and the major portion of the cooling air axially through the bearing. The results of these tests have shown the feasibility of using a once through oil mist and cooling air system to lubricate and cool a high speed, high temperature aircraft engine mainshaft bearing.

Rosenlieb, J. W.↗
NASA NTRS2015

Cyrogenic Life Support Technology Development Project

KSC has used cryogenic life support (liquid air based) technology successfully for many years to support spaceflight operations. This technology has many benefits unique to cryogenics when compared to traditional compressed gas systems: passive cooling, lighter, longer duration, and lower operating pressure. However, there are also several limiting factors that have prevented the technology from being commercialized. The National Institute of Occupational Safety and Health, Office of Mine Safety and Health Research (NIOSH-OMSHR) has partnered with NASA to develop a complete liquid air based life support solution for emergency mine escape and rescue. The project will develop and demonstrate various prototype devices and incorporate new technological innovations that have to date prevented commercialization.

compressed gas systems: passive cooling↗
NASA NTRS1999

Vibration-Induced Droplet Atomization

Thermal management is critical to a number of technologies used in a microgravity environment and in Earth-based systems. Examples include electronic cooling, power generation systems, metal forming and extrusion, and HVAC (heating, venting, and air conditioning) systems. One technique that can deliver the large heat fluxes required for many of these technologies is two-phase heat transfer. This type of heat transfer is seen in the boiling or evaporation of a liquid and in the condensation of a vapor. Such processes provide very large heat fluxes with small temperature differences. Our research program is directed toward the development of a new, two-phase heat transfer cell for use in a microgravity environment. In this paper, we consider the main technology used in this cell, a novel technique for the atomization of a liquid called vibration-induced droplet atomization. In this process, a small liquid droplet is placed on a thin metal diaphragm that is made to vibrate by an attached piezoelectric transducer. The vibration induces capillary waves on the free surface of the droplet that grow in amplitude and then begin to eject small secondary droplets from the wave crests. In some situations, this ejection process develops so rapidly that the entire droplet seems to burst into a small cloud of atomized droplets that move away from the diaphragm at speeds of up to 50 cm/s. By incorporating this process into a heat transfer cell, the active atomization and transport of the small liquid droplets could provide a large heat flux capability for the device. Experimental results are presented that document the behavior of the diaphragm and the droplet during the course of a typical bursting event. In addition, a simple mathematical model is presented that qualitatively reproduces all of the essential features we have seen in a burst event. From these two investigations, we have shown that delayed droplet bursting results when the system passes through a resonance condition. This occurs when the initial acceleration of the diaphragm is higher than the critical acceleration and the driving frequency is larger than the initial resonance frequency of the diaphragm-droplet system. We have incorporated this droplet atomization device into a design for a new heat transfer cell for use in a microgravity environment. The cell is essentially a cylindrical container with a hot surface on one end and a cold surface on the other. The vibrating diaphragm is mounted in the center of the cold surface. Heat transfer occurs through droplet evaporation and condensation on the hot and cold ends of the cell. A prototype of this heat transfer cell has been built and tested. It can operate continuously and provides a modest level of heat transfer, about 20 W/sq cm. Our work during the next few years will be to optimize the design of this cell to see if we can produce a device that has significantly better performance than conventional heat exchangers and heat pipes.

Smith, M. K.↗
NASA NTRS1980

Solar heating, cooling, and domestic hot water system installed at Kaw Valley State Bank and Trust Company, Topeka, Kansas

The building has approximately 5600 square feet of conditioned space. Solar energy was used for space heating, space cooling, and preheating domestic hot water (DHW). The solar energy system had an array of evacuated tube-type collectors with an area of 1068 square feet. A 50/50 solution of ethylene glycol and water was the transfer medium that delivered solar energy to a tube-in-shell heat exchanger that in turn delivered solar heated water to a 1100 gallon pressurized hot water storage tank. When solar energy was insufficient to satisfy the space heating and/or cooling demand, a natural gas-fired boiler provided auxiliary energy to the fan coil loops and/or the absorption chillers. Extracts from the site files, specification references, drawings, and installation, operation and maintenance instructions are presented.

Source record↗
NASA NTRS1978

F-15/nonaxisymmetric nozzle system integration study support program

Nozzle and cooling methods were defined and analyzed to provide a viable system for demonstration 2-D nozzle technology on the F-15 aircraft. Two candidate cooling systems applied to each nozzle were evaluated. The F-100 engine mount and case modifications requirements were analyzed and the actuation and control system requirements for two dimensional nozzles were defined. Nozzle performance changes relative to the axisymmetric baseline nozzle were evaluated and performance and weight characteristics for axisymmetric reference configurations were estimated. The infrared radiation characteristics of these nozzles installed on the F-100 engine were predicted. A full scale development plan with associated costs to carry the F100 engine/two-dimensional (2-D) nozzle through flight tests was defined.

Stevens, H. L.↗
NASA NTRS1977

Advanced high pressure engine study for mixed-mode vehicle applications

High pressure liquid rocket engine design, performance, weight, envelope, and operational characteristics were evaluated for a variety of candidate engines for use in mixed-mode, single-stage-to-orbit applications. Propellant property and performance data were obtained for candidate Mode 1 fuels which included: RP-1, RJ-5, hydrazine, monomethyl-hydrazine, and methane. The common oxidizer was liquid oxygen. Oxygen, the candidate Mode 1 fuels, and hydrogen were evaluated as thrust chamber coolants. Oxygen, methane, and hydrogen were found to be the most viable cooling candidates. Water, lithium, and sodium-potassium were also evaluated as auxiliary coolant systems. Water proved to be the best of these, but the system was heavier than those systems which cooled with the engine propellants. Engine weight and envelope parametric data were established for candidate Mode 1, Mode 2, and dual-fuel engines. Delivered engine performance data were also calculated for all candidate Mode 1 and dual-fuel engines.

Luscher, W. P.↗
NASA NTRS2005

Cooled Ceramic Matrix Composite Propulsion Structures Demonstrated

NASA's Next Generation Launch Technology (NGLT) Program has successfully demonstrated cooled ceramic matrix composite (CMC) technology in a scramjet engine test. This demonstration represented the world s largest cooled nonmetallic matrix composite panel fabricated for a scramjet engine and the first cooled nonmetallic composite to be tested in a scramjet facility. Lightweight, high-temperature, actively cooled structures have been identified as a key technology for enabling reliable and low-cost space access. Tradeoff studies have shown this to be the case for a variety of launch platforms, including rockets and hypersonic cruise vehicles. Actively cooled carbon and CMC structures may meet high-performance goals at significantly lower weight, while improving safety by operating with a higher margin between the design temperature and material upper-use temperature. Studies have shown that using actively cooled CMCs can reduce the weight of the cooled flow-path component from 4.5 to 1.6 lb/sq ft and the weight of the propulsion system s cooled surface area by more than 50 percent. This weight savings enables advanced concepts, increased payload, and increased range. The ability of the cooled CMC flow-path components to operate over 1000 F hotter than the state-of-the-art metallic concept adds system design flexibility to space-access vehicle concepts. Other potential system-level benefits include smaller fuel pumps, lower part count, lower cost, and increased operating margin.

Jaskowiak, Martha H.↗