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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Requirements and test results for the qualification of thermal control coatings

Paint type coatings are often used as engineering materials in critical satellite temperature control applications. The functional features of coatings used for temperature control purposes must remain stable throughout the satellite manufacturing process and the satellite mission. The selection of a particular coating depends on matching coating characteristics to mission requirements. The use of paint coatings on satellites, although having an extensive history, requires that the paint be qualified to each application on an individual basis. Thus, the qualification process through testing serves to ensure that paint coatings as engineering materials will fulfill design requirements.

Brzuskiewicz, J. E.↗
DOE OSTI2014

Low-temperature Bessel beam trap for single submicrometer aerosol particle studies

We report on a new instrument for single aerosol particle studies at low temperatures that combines an optical trap consisting of two counter-propagating Bessel beams (CPBBs) and temperature control down to 223 K (−50 °C). The apparatus is capable of capturing and stably trapping individual submicrometer- to micrometer-sized aerosol particles for up to several hours. First results from studies of hexadecane, dodecane, and water aerosols reveal that we can trap and freeze supercooled droplets ranging in size from ∼450 nm to 5500 nm (radius). We have conducted homogeneous and heterogeneous freezing experiments, freezing-melting cycles, and evaporation studies. To our knowledge, this is the first reported observation of the freezing process for levitated single submicrometer-sized droplets in air using optical trapping techniques. These results show that a temperature-controlled CPBB trap is an attractive new method for studying phase transitions of individual submicrometer aerosol particles.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1980

Controller and temperature monitor for solar heating

Report describes development and certification of 77-171 differential thermostat for controlling solar-heating and cooling systems and 77-180 temperature monitor of indoor, outdoor, and storage temperatures. Units are commercially available.

Hankins, J. D.↗
DOE OSTI2015

Controlling the Temperature and Speed of the Phase Transition of VO 2 Microcrystals

Here, we investigated the control of two important parameters of vanadium dioxide (VO 2 ) microcrystals, the phase transition temperature and speed, by varying microcrystal width. By using the reflectivity change between insulating and metallic phases, phase transition temperature is measured by optical microscopy. As the width of square cylinder-shaped microcrystals decreases from ~70 to ~1 μm, the phase transition temperature (67 °C for bulk) varied as much as 26.1 °C (19.7 °C) during heating (cooling). In addition, the propagation speed of phase boundary in the microcrystal, i.e., phase transition speed, is monitored at the onset of phase transition by using the high-speed resistance measurement. The phase transition speed increases from 4.6 × 10 2 to 1.7 × 10 4 μm/s as the width decreases from ~50 to ~2 μm. While the statistical description for a heterogeneous nucleation process explains the size dependence on phase transition temperature of VO 2 , the increase of effective thermal exchange process is responsible for the enhancement of phase transition speed of small VO 2 microcrystals. These findings not only enhance the understanding of VO 2 intrinsic properties but also contribute to the development of innovative electronic devices.

36 MATERIALS SCIENCE↗
NASA NTRS1989

Thermal design of the Wide Field/Planetary Camera

The Wide Field/Planetary Camera is an imaging system developed by the Jet Propulsion Laboratory for the NASA Hubble Space Telescope currently scheduled to be launched in December 1989 aboard the space shuttle. The temperature control design of the instrument utilizes multilayered insulation, electric resistance heaters, aluminum/ammonia heat pipes, thermoelectric coolers, temperature control coatings, and space radiators. A feedback control system maintains stable sensor temperatures. Thermal capacitance maintains stable optics and electronics temperatures during transient conditions. Schedule slips and launch delays have allowed extensive thermal testing of the instrument. Six instrument thermal vacuum tests and a spacecraft thermal vacuum test were performed. Several modifications have been made to the instrument to correct icing and contamination problems that have been discovered during thermal vacuum testing. This paper describes the thermal design, last instrument thermal vacuum test, results, and thermal model correlation.

Garcia, R. D.↗
NASA NTRS1990

Low-temperature thermal control for a lunar base

The generic problem of rejecting low- to moderate-temperature heat from space facilities located in a hot thermal sink environment is studied, and the example of a lunar base located near the equator is described. The effective thermal sink temperature is often above or near nominal room temperature. A three heat pump assisted thermal bus concept appears to be the most viable as they are the least sensitive to environmental conditions. Weight estimates are also developed for each of the five thermal control concepts studied: (1) 149kg/kW for a central thermal loop with unitary heat pumps; (2) 133 kg/kW for a conventional bus connected to large, central heat pumps at the radiator; (3) 134 kg/kW for a central, dual loop heat pump concept; (4) 95 kg/kW for the selective field-of-view radiator; and (5) 126 kg/kW for the regolith concept.

Swanson, Theodore D.↗
DOE OSTI2016

Control Strategies to Reduce the Energy Consumption of Central Domestic Hot Water Systems

Domestic hot water (DHW) is the second-largest energy end use in U.S. buildings; it is exceeded only by space conditioning. In this study, the U.S. Department of Energy's Building America research team Advanced Research Integrated Energy Solutions installed and tested two types of recirculation controls in a pair of buildings to evaluate their energy savings potential. Demand control, temperature modulation (TM) controls, and their simultaneous operation were compared to the baseline case of constant recirculation.

Array↗
NASA NTRS1980

Solid state crystal physics at very low temperatures

The mechanical dissipation (Q) and resonant frequency of a 15 kg silicon crystal were measured at cryogenic temperatures. In the experiment described, temperature control was incorporated to reduce the time derivative of the temperature. The results of the Q measurements with and without this temperature control are quite different. Measurements of the resonant frequency of the fundamental longitudinal mode of the silicon crystal from 6 to 300 Kelvin are presented and discussed with respect to temperature, df/dT. It is observed that frequency increases as temperature decreases down to about 16 Kelvin, i.e. dt/dT is negative. However, below this temperature the frequency decreases as temperature decreases, i.e. dt/dT is positive. It is suggested that this behavior is related to the coefficient of thermal contraction of silicon, which changes sign at 18 Kelvin. Continuation of these experiments to 20 mK is discussed.

Davis, W.↗
NASA NTRS1970

Multi-chamber controllable heat pipe

A temperature controllable heat pipe switching device is reported. It includes separate evaporating and condensing chambers interconnected by separate vapor flow and liquid return conduits. The vapor flow conduit can be opened or closed to the flow of vapor, whereas the liquid return conduit blocks vapor flow at all times. When the vapor flow path is open, the device has high thermal conductivity, and when the vapor flow path is blocked the device has low thermal conductivity.

Shlosinger, A. P.↗
DOE OSTI2013

Absolute cavity pyrgeometer

Implementations of the present disclosure involve an apparatus and method to measure the long-wave irradiance of the atmosphere or long-wave source. The apparatus may involve a thermopile, a concentrator and temperature controller. The incoming long-wave irradiance may be reflected from the concentrator to a thermopile receiver located at the bottom of the concentrator to receive the reflected long-wave irradiance. In addition, the thermopile may be thermally connected to a temperature controller to control the device temperature. Through use of the apparatus, the long-wave irradiance of the atmosphere may be calculated from several measurements provided by the apparatus. In addition, the apparatus may provide an international standard of pyrgeometers' calibration that is traceable back to the International System of Units (SI) rather than to a blackbody atmospheric simulator.

47 OTHER INSTRUMENTATION↗
NASA NTRS1997

High sensitivity real-time NVR monitor

A real time non-volatile residue (NVR) monitor, which utilizes surface acoustic wave (SAW) resonators to detect molecular contamination in a given environment. The SAW resonators operate at a resonant frequency of approximately 200 MHz-2,000 MHz which enables the NVR monitor to detect molecular contamination on the order of 10.sup.-11 g-cm.sup.-2 to 10.sup.-13 g-cm.sup.2. The NVR monitor utilizes active temperature control of (SAW) resonators to achieve a stable resonant frequency. The temperature control system of the NVR monitor is able to directly heat and cool the SAW resonators utilizing a thermoelectric element to maintain the resonators at a present temperature independent of the environmental conditions. In order to enable the direct heating and cooling of the SAW resonators, the SAW resonators are operatively mounted to a heat sink. In one embodiment, the heat sink is located in between the SAW resonators and an electronic circuit board which contains at least a portion of the SAW control electronics. The electrical leads of the SAW resonators are connected through the heat sink to the circuit board via an electronic path which prevents inaccurate frequency measurement.

Bowers, William D.↗
NASA NTRS1973

Aerodynamic thermal simulation system. Part 1: Radiant array (instruction manual)

An aerodynamic thermal simulation system (ATSS) is presented. The construction of the system, the maintenance, set up, and operations are reported. System description of the radiant array is given along with the array subsystems modular heating unit, adjustable stanchion frame, cooling water system, and the gaseous nitrogen cooling system. The array configuration procedure outlines the set up and the start up. Maintenance procedures involve both lamp maintenance and reflector maintenance along with weather protection. Drawing codes are included. Descriptions of the 36 zone ATSS controls are also given. Each zone is an independent closed loop temperature control circuit. Procedures are presented for starting and stopping the system. The DATA-TRAK programmer and its operation, instruction manuals for the temperature controller and the power regulator and discriptions of peripheral equipment are discussed.

Kitchar, A. F.↗
NASA NTRS2004

Thermal performance of a multi-evaporator loop heat pipe with thermal masses and thermal electrical coolers

This paper describes thermal performance of a loop heat pipe (LHP) with two evaporators and two condensers in ambient testing. Each evaporator has an outer diameter of 15mm and a length of 76mm, and has an integral compensation chamber (CC). An aluminum mass of 500 grams is attached to each evaporator to simulate the instrument mass. A thermal electric cooler (TEC) is installed on each CC to provide heating as well as cooling for CC temperature control. A flow regulator is installed in the condenser section to prevent vapor from going back to the evaporators in the event that one of condenser is fully utilized. Ammonia was used ad the working fluid. Tests conducted included start-up, power cycle, heat load sharing, sink temperature cycle, operating temperature control with TECs, and capillary limit tests. Experimental data showed that the loop could start with a heat load of less than 1OW even with added thermal masses. The loop operated stably with even and uneven evaporator heat loads, and even and uneven condenser sink temperatures. The operating temperature could be controlled within +/-0.5K of the set point temperature using either or both TECs, and the required TEC control heater power was less than 2W under most test conditions. Heat load sharing between the two evaporators was also successfully demonstrated. The loop had a heat transport capability of 120W to 140W, and could recover from a dry-out when the heat load was reduced. The 500-gram aluminum mass on each evaporator had a negligible effect on the loop operation. Existing LHPs servicing the orbiting spacecraft have a single evaporator with an outer diameter of about 25mm. Important performance characteristics demonstrated by this LHP included: 1) Operation of an LHP with 15mm diameter evaporators; 2) Robustness and reliability of an LHP with multiple evaporators and multiple condensers under various test conditions; 3) Heat load sharing among LHP evaporators; 4) Effectiveness of TECs in controlling the LHP operating temperature; and 5) Effectiveness of the flow regulator in preventing vapor from going back the evaporators.

loop heat pipes↗
NASA NTRS2004

Thermal Performance of a Multi-Evaporator Loop Heat Pipe with Thermal Masses and Thermoelectric Coolers

This paper describes thermal performance of a loop heat pipe (LHP) with two evaporators and two condensers in ambient testing. Each evaporator has an outer diameter of 15mm and a length of 76mm, and has an integral compensation chamber (CC). An aluminum mass of 500 grams is attached to each evaporator to simulate the instrument mass. A thermoelectric cooler (TEC) is installed on each CC to provide heating as well as cooling for CC temperature control. A flow regulator is installed in the condenser section to prevent vapor from going back to the evaporators in the event that one of the condensers is fully utilized. Ammonia was used as the working fluid. Tests conducted included start-up, power cycle, heat load sharing, sink temperature cycle, operating temperature control with TECs, and capillary limit tests. Experimental data showed that the loop could start with a heat load of less than 10W even with added thermal masses. The loop operated stably with even and uneven evaporator heat loads, and even and uneven condenser sink temperatures. The operating temperature could be controlled within +/- 0.5K of the set point temperature using either or both TECs, and the required TEC control heater power was less than 2W under most test conditions. Heat load sharing between the two evaporators was also successfully demonstrated. The loop had a heat transport capability of 120W to 140W, and could recover from a dry-out when the heat load was reduced. The 500-gram aluminum mass on each evaporator had a negligible effect on the loop operation. Existing LHPs servicing orbiting spacecraft have a single evaporator with an outer diameter of about 25mm. Important performance characteristics demonstrated by this LHP included: 1) Operation of an LHP with 15mm diameter evaporators; 2) Robustness and reliability of an LHP with multiple evaporators and multiple condensers under various test conditions; 3) Heat load sharing among LHP evaporators; 4) Effectiveness of TECs in controlling the LHP operating temperature; and 5 ) Effectiveness of the flow regulator in preventing vapor from going back the evaporators.

Ku, Jen-Tung↗
NASA NTRS1994

Process modelling for materials preparation experiments

The main goals of the research under this grant consist of the development of mathematical tools and measurement techniques for transport properties necessary for high fidelity modelling of crystal growth from the melt and solution. Of the tasks described in detail in the original proposal, two remain to be worked on: development of a spectral code for moving boundary problems, and development of an expedient diffusivity measurement technique for concentrated and supersaturated solutions. We have focused on developing a code to solve for interface shape, heat and species transport during directional solidification. The work involved the computation of heat, mass and momentum transfer during Bridgman-Stockbarger solidification of compound semiconductors. Domain decomposition techniques and preconditioning methods were used in conjunction with Chebyshev spectral methods to accelerate convergence while retaining the high-order spectral accuracy. During the report period we have further improved our experimental setup. These improvements include: temperature control of the measurement cell to 0.1 C between 10 and 60 C; enclosure of the optical measurement path outside the ZYGO interferometer in a metal housing that is temperature controlled to the same temperature setting as the measurement cell; simultaneous dispensing and partial removal of the lower concentration (lighter) solution above the higher concentration (heavier) solution through independently motor-driven syringes; three-fold increase in data resolution by orientation of the interferometer with respect to diffusion direction; and increase of the optical path length in the solution cell to 12 mm.

Rosenberger, Franz↗
NASA NTRS1984

Better Thermal Insulation in Solar-Array Laminators

Glass marbles improve temperature control. Modified vacuum laminator for photovoltaic solar arrays includes thermal insulation made of conventional glass marbles. Marbles serve as insulation for temperature control of lamination process at cure temperatures as high as 350 degrees F. Used to replace original insulation made of asbestos cement.

Burger, D. R.↗