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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Space Station solar water heater

The feasibility of directly converting solar energy for crew water heating on the Space Station Freedom (SSF) and other human-tended missions such as a geosynchronous space station, lunar base, or Mars spacecraft was investigated. Computer codes were developed to model the systems, and a proof-of-concept thermal vacuum test was conducted to evaluate system performance in an environment simulating the SSF. The results indicate that a solar water heater is feasible. It could provide up to 100 percent of the design heating load without a significant configuration change to the SSF or other missions. The solar heater system requires only 15 percent of the electricity that an all-electric system on the SSF would require. This allows a reduction in the solar array or a surplus of electricity for onboard experiments.

Horan, D. C.↗
NASA NTRS1992

Radiative transfer in the electrode region of an arc heater

Radiation from hot gases in the electrode region of an arc heater are discussed. Major original contributions are made: (1) an analytical expression for the radiative heat flux, for an axisymmetric geometry and a grey reflecting wall, is derived, (2) the expression is rendered analytically differentiable/integrable by using appropriate techniques to remove the singularities, and (3), finally a two band model is devised to compute the radiative heat load at the walls in NASA Ames' jet facility. The advantage of using these techniques is that the time taken for the numerical integration is considerably reduced and computation of a 39 x 39 axisymmetric geometry becomes manageable. Fluid equations, representative of a high current arc heater, are numerically solved for an axisymmetric geometry. The computed average heat load of 400 Watts/sq cm using the two band model agrees well with the experimental estimates made at NASA Ames' facility.

Durgapal, P.↗
NASA NTRS1993

"Starfish" Heater Head For Stirling Engine

Proposed "starfish" heater head for Stirling engine enables safe use of liquid sodium as heat-transfer fluid. Sodium makes direct contact with heater head but does not come in contact with any structural welds. Design concept minimizes number of, and simplifies nonstructural thermal welds and facilitates inspection of such welds.

Vitale, N.↗
NASA NTRS1993

Strongly coupled radiative transfer and Joule heating in the cathode of an arc heater

Radiation and Joule heating in the electrode region of an arc heater are discussed. Radiative transport equations for a true axisymmetric geometry are used. A subsonic code is developed to numerically solve the fluid equations with strongly coupled radiation and Joule heating representative of a high pressure and high current arc heater. Analytic expression for the divergence of radiative heat flux derived previously is used. Jacobians of the radiation term are derived. The Joule heating term is computed using a previously developed code. The equilibrium gas model consists of seven species. The fluxes are differenced using Van Leer flux splitting. Using this code, the effects of radiative cooling on the thermodynamic parameters of the arc core are discussed.

Durgapal, P.↗
NASA NTRS1995

Improved Controllers For Heaters In Toxic-Gas Combustors

Commercial electronic proportional controllers installed in place of mechanical power controllers for electric heaters in toxic-gas combustors at NASA's Jet Propulsion Laboratory. Designed to maintain temperature of heater at preset value by turning power fully on or fully off when temperature falls below or rises above that value, respectively. Solid-state power controllers overcome deficiencies of mechanical power controllers.

Wishard, James↗
NASA NTRS1999

Boiling Heat Transfer Measurements on Highly Conductive Surfaces Using Microscale Heater and Temperature Arrays

Two systems have been developed to study boiling heat transfer on the microscale. The first system utilizes a 32 x 32 array of diodes to measure the local temperature fluctuations during boiling on a silicon wafer heated from below. The second system utilizes an array of 96 microscale heaters each maintained at constant surface temperature using electronic feedback loops. The power required to keep each heater at constant temperature is measured, enabling the local heat transfer coefficient to be determined. Both of these systems as well as some preliminary results are discussed.

Kim, J.↗
NASA NTRS2004

Boiling Heat Transfer Mechanisms in Earth and Low Gravity: Boundary Condition and Heater Aspect Ratio Effects

Boiling is a complex phenomenon where hydrodynamics, heat transfer, mass transfer, and interfacial phenomena are tightly interwoven. An understanding of boiling and critical heat flux in microgravity environments is of importance to space based hardware and processes such as heat exchange, cryogenic fuel storage and transportation, electronic cooling, and material processing due to the large amounts of heat that can be removed with relatively little increase in temperature. Although research in this area has been performed in the past four decades, the mechanisms by which heat is removed from surfaces in microgravity are still unclear. Recently, time and space resolved heat transfer data were obtained in both earth and low gravity environments using an array of microheaters varying in size between 100 microns to 700 microns. These heaters were operated in both constant temperature as well as constant heat flux mode. Heat transfer under nucleating bubbles in earth gravity were directly measured using a microheater array with 100 m resolution operated in constant temperature mode with low and high subcooled bulk liquid along with images from below and from the side. The individual bubble departure diameter and energy transfer were larger with low subcooling but the departure frequency increased at high subcooling, resulting in higher overall heat transfer. The bubble growth for both subcoolings was primarily due to energy transfer from the superheated liquid layer relatively little was due to wall heat transfer during the bubble growth process. Oscillating bubbles and sliding bubbles were also observed in highly subcooled boiling. Transient conduction and/or microconvection was the dominant heat transfer mechanism in the above cases. A transient conduction model was developed and compared with the experimental data with good agreement. Data was also obtained with the heater array operated in a constant heat flux mode and measuring the temperature distribution across the array during boiling. The instantaneous heat transfer into the substrate was numerically determined and subtracted from the supplied heat to obtain the wall to liquid heat flux.

Kim, Jungho↗
NASA NTRS2005

Benchmark Calibration Tests Completed for Stirling Convertor Heater Head Life Assessment

A major phase of benchmark testing has been completed at the NASA Glenn Research Center (http://www.nasa.gov/glenn/), where a critical component of the Stirling Radioisotope Generator (SRG) is undergoing extensive experimentation to aid the development of an analytical life-prediction methodology. Two special-purpose test rigs subjected SRG heater-head pressure-vessel test articles to accelerated creep conditions, using the standard design temperatures to stay within the wall material s operating creep-response regime, but increasing wall stresses up to 7 times over the design point. This resulted in well-controlled "ballooning" of the heater-head hot end. The test plan was developed to provide critical input to analytical parameters in a reasonable period of time.

Krause, David L.↗
NASA NTRS1992

Edge-defined contact heater apparatus and method for floating zone crystal growth

An apparatus for growing a monocrystalline body (30) from a polycrystalline feed rod (22) includes a heater (20) that is positioned to heat a short section of the polycrystalline rod (22) to create a molten zone (34). The heater (20) is formed to include a shaper (40) that contacts the polycrystalline rod (22) in the molten zone (34) and has a hole (46) to allow flow in the molten zone (34) between the polycrystalline rod (22) side and the monocrystalline body (30) side of the shaper. The shaper (40) has an edge (42) that defines the boundary of the cross-section of the monocrystalline body (30) that is formed as the molten material solidifies.

Kou, Sindo↗
NASA NTRS1947

Simulated Altitude Investigation of Stewart-Warner Model 906-B Combustion Heater

An investigation has been conducted to determine thermal and pressure-drop performance and the operational characteristics of a Stewart-Warner model 906-B combustion heater. The performance tests covered a range of ventilating-air flows from 500 to 3185 pounds per hour, combustion-air pressure drops from 5 to 35 inches of water, and pressure altitudes from sea level to 41,000 feet. The operational characteristics investigated were the combustion-air flows for sustained combustion and for consistent ignition covering fuel-air ratios ranging from 0.033 to 0.10 and pressure altitudes from sea level to 45,000 feet. Rated heat output of 50,000 Btu per hour was obtained at pressure altitudes up to 27,000 feet for ventilating-air flows greater than 800 pounds per hour; rated output was not obtained at ventilating-air flow below 800 pounds per hour at any altitude. The maximum heater efficiency was found to be 60.7 percent at a fuel-air ratio of 0.050, a sea-level pressure altitude, a ventilating-air temperature of 0 F, combustion-air temperature of 14 F, a ventilating-air flow of 690 pounds per hour, and a combustion-air flow of 72.7 pounds per hour. The minimum combustion-air flow for sustained combustion at a pressure altitude of 25,000 feet was about 9 pounds per hour for fuel-air ratios between 0.037 and 0.099 and at a pressure altitude of 45,000 feet increased to 18 pounds per hour at a fuel-air ratio of 0.099 and 55 pounds per hour at a fuel-air ratio of 0.036. Combustion could be sustained at combustion-air flows above values of practical interest. The maximum flow was limited, however, by excessively high exhaust-gas temperature or high pressure drop. Both maximum and minimum combustion-air flows for consistent ignition decrease with increasing pressure altitude and the two curves intersect at a pressure altitude of approximately 25,000 feet and a combustion-air flow of approximately 28 pounds per hour.

Ebersbach, Frederick R.↗
NASA NTRS2015

Solar Probe Plus MAG Sensor Thermal Design for Low Heater Power and Extreme Thermal Environment

The heater power available for the Solar Probe Plus FIELDS MAG sensor is less than half of the heritage value for other missions. Nominally the MAG sensors are in the spacecraft's umbra. In the worst hot case, approximately 200 spacecraft communication downlinks, up to 10 hours each, are required at 0.7 AU. These downlinks require the spacecraft to slew 45 deg. about the Y-axis, exposing the MAG sensors and boom to sunlight. This paper presents the thermal design to meet the MAG sensor thermal requirements in the extreme thermal environment and with low heater power. A thermal balance test on the MAG sensor engineering model has verified the thermal design and correlated the thermal model for flight temperature predictions.

Thermal design↗