TEMPERATURE CONTROL OF CRYSTAL OPTICS FOR ULTRAHIGH-RESOLUTION APPLICATIONS
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36 MATERIALS SCIENCE↗
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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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Molten-salt Research Temperature-controlled Irradiation (MRTI) Conceptual Design Review
This document contains the results of conceptual design efforts on an experiment vehicle capable of testing molten fissile-bearing salts in the Neutron Radiography Reactor (NRAD).
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Controlling Transistor Temperature During Burn-In
Boiling refrigerant provides simple temperature control for newly manufactured power transistors. Heat-transfer liquid is Fluorinert FC-77 (or equivalent). Liquid boils at 100 degrees C, which is specified temperature at which transistor cases should be maintained during burn-in with this technique.
Scott, B. C.↗
Development of UItra-Low Temperature Motor Controllers: Ultra Low Temperatures Evaluation and Characterization of Semiconductor Technologies For The Next Generation Space Telescope
Electronics designed for low temperature operation will result in more efficient systems than room temperature. This improvement is a result of better electronic, electrical, and thermal properties of materials at low temperatures. In particular, the performance of certain semiconductor devices improves with decreasing temperature down to ultra-low temperature (-273 'C). The Low Temperature Electronics Program at the NASA Glenn Research Center focuses on research and development of electrical components and systems suitable for applications in deep space missions. Research is being conducted on devices and systems for use down to liquid helium temperatures (-273 'C). Some of the components that are being characterized include semiconductor switching devices, resistors, magnetics, and capacitors. The work performed this summer has focused on the evaluation of silicon-, silicon-germanium- and gallium-Arsenide-based (GaAs) bipolar, MOS and CMOS discrete components and integrated circuits (ICs), from room temperature (23 'C) down to ultra low temperatures (-263 'C).
Elbuluk, Malik E.↗
Development of an Outdoor Temperature-Based Control Algorithm for Residential Mechanical Ventilation Control
Smart ventilation systems use controls to ventilate more during those periods that provide either an energy or IAQ advantage (or both) and less during periods that provide a dis advantage. Using detailed building simulations, this study addresses one of the simplest and lowest cost types of smart controllers —outdoor temperature- based control. If the outdoor temperature falls below a certain cut- off, the fan is simply turned off. T he main principle of smart ventilation used in this study is to shift ventilation from time periods with large indoor -outdoor temperature differences, to periods where these differences are smaller, and their energy impacts are expected to be less. Energy and IAQ performance are assessed relative to a base case of a continuously operated ventilation fan sized to comply with ASHRAE 62.2-2013 whole house ventilation requirements. In order to satisfy 62.2-2013, annual pollutant exposure must be equivalent between the temperature controlled and continuous fan cases. This requires ventilation to be greater than 62.2 requirements when the ventilation system operates. This is achieved by increasing the mechanical ventilation system air flow rates.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Fuzzy Logic Controller for Low Temperature Application
The most common temperature controller used in low temperature experiments is the proportional-integral-derivative (PID) controller due to its simplicity and robustness. However, the performance of temperature regulation using the PID controller depends on initial parameter setup, which often requires operator's expert knowledge on the system. In this paper, we present a computer-assisted temperature controller based on the well known.
proportional-integral-derivative controller PID fu↗
Using Dynamic Simulation to Evaluate Attemperator Operation in a Natural Gas Combined Cycle With Duct Burners in the Heat Recovery Steam Generator
A generic training simulator of a natural gas combined cycle was modified to match operations at a real plant. The objective was to use the simulator to analyze cycling operations of the plant. Initial operation of the simulator revealed the potential for saturation conditions in the final high pressure superheater as the attemperator tried to control temperature at the superheater outlet during gas turbine loading and unloading. Subsequent plant operational data confirmed simulation results. Multiple simulations were performed during loading and unloading of the gas turbine to determine operational strategies that prevented saturation and increased the approach to saturation temperature. The solutions included changes to the attemperator temperature control setpoints and strategic control of the steam turbine inlet pressure control valve.
20 FOSSIL-FUELED POWER PLANTS↗
High Fidelity Dynamic Simulation of Cycling in a Natural Gas Combined Cycle Power Plant
The CRADA objective is to use a high-fidelity natural gas combined cycle (NGCC) dynamic simulator deployed at the National Energy Technology Laboratory (NETL) to produce practical engineering ideas that would either reduce the impact on equipment resulting from cycling, or improve certain plant operational modes. The goal is to demonstrate to National Rural Electric Cooperative Association (NRECA) that a high-fidelity dynamic simulator offers a relatively low-cost option for investigation and testing without direct plant experimentation. Initial operation of the simulator revealed the potential for saturation conditions in the final high pressure superheater as the attemperator tried to control temperature at the superheater outlet during gas turbine loading and unloading. Subsequent plant operational data confirmed simulation results. Thus, this particular area was chosen for further investigation. Multiple simulations were performed during loading and unloading of the gas turbine in order to determine operational strategies that prevented saturation and increased the approach to saturation temperature. The results of these simulations are presented in this report. The summary at the end of this report suggests trials that could be performed at the plant to confirm the benefits seen by simulator investigations, such as changes to the attemperator temperature control setpoints and strategic control of the steam turbine inlet pressure control valve.
03 NATURAL GAS↗
Development of experimental systems for material sciences under microgravity
As part of the Space Experiment Program of the Society of Japanese Aerospace Companies, three experimental systems (G452, G453, G454) have been developed for materials science studies under microgravity by the NEC Corporation. These systems are to be flown as Get Away Special payloads for studying the feasibility of producing new materials. Together with the experimental modules carrying the hardware specific to the experiment, the three systems all comprise standard subsystems consisting of a power supply, sequence controller, temperature controller, data recorder, and video recorder.
Tanii, Jun↗
Improved Readout Scheme for SQUID-Based Thermometry
An improved readout scheme has been proposed for high-resolution thermometers, (HRTs) based on the use of superconducting quantum interference devices (SQUIDs) to measure temperature- dependent magnetic susceptibilities. The proposed scheme would eliminate counting ambiguities that arise in the conventional scheme, while maintaining the superior magnetic-flux sensitivity of the conventional scheme. The proposed scheme is expected to be especially beneficial for HRT-based temperature control of multiplexed SQUIDbased bolometer sensor arrays. SQUID-based HRTs have become standard for measuring and controlling temperatures in the sub-nano-Kelvin temperature range in a broad range of low-temperature scientific and engineering applications. A typical SQUIDbased HRT that utilizes the conventional scheme includes a coil wound on a core made of a material that has temperature- dependent magnetic susceptibility in the temperature range of interest. The core and the coil are placed in a DC magnetic field provided either by a permanent magnet or as magnetic flux inside a superconducting outer wall. The aforementioned coil is connected to an input coil of a SQUID. Changes in temperature lead to changes in the susceptibility of the core and to changes in the magnetic flux detected by the SQUID. The SQUID readout instrumentation is capable of measuring magnetic-flux changes that correspond to temperature changes down to a noise limit .0.1 nK/Hz1/2. When the flux exceeds a few fundamental flux units, which typically corresponds to a temperature of .100 nK, the SQUID is reset. The temperature range can be greatly expanded if the reset events are carefully tracked and counted, either by a computer running appropriate software or by a dedicated piece of hardware.
Penanen, Konstantin↗
Statistical Analysis in Support of Control Fuel Temperature for the Advanced Gas Reactor Experiments
There are four completed tests among a series of Advanced Gas Reactor (AGR) irradiation experiments that are being conducted within the Advanced Reactor Technologies (ART) Fuel Development and Qualification Program. The main objectives of the fuel experimental campaigns are to provide the necessary data on fuel performance to support fuel process development, qualify a fuel design and fabrication process for normal operation and hypothetical accident conditions, and support development and validation of fuel performance and fission product transport models and codes.1 Since this tristructural isotropic fuel is qualified to be used in high temperature gas-cooled reactors (HTGRs), it is essential that the testing conditions of fuel irradiations are designed to mimic those in the conceptual gas reactors. As a result, temperatures of the AGR test fuel have to be maintained within a specified range that is typical of the HTGRs. In each AGR capsule, the test fuel temperature is controlled independently using a variable fraction neon and helium gas mixture that fills the gap volume for each capsule. The temperature as measured by a thermocouple (TC) terminated in the graphite holder (which houses fuel compacts) is used as a feedback for the gas flow controllers. Direct temperature measurement for fuel compacts is not possible because contact between a TC head and fuel particle could lead to undesirable failures. Therefore, an ABAQUS based finite element thermal model was created to predict the daily average fuel temperatures during the entire irradiation period.2,3 It is well-known that extended exposure to neutron irradiation and high temperatures leads to changes in geometries of fuel compacts and graphite holder, which result in changes of the gas gap leading to a change in the relationship between TC and fuel temperatures. In addition, TCs are also expected to drift and sometimes fail under irradiation conditions. These facts make maintaining test fuel temperature within a specified range challenging. This paper describes how the regression analysis methods are used in conjunction of calculated fuel temperatures from early irradiation periods (when irradiation effect is relatively small) to effectively control fuel temperature for the remaining irradiation, when irradiation effect became profound. This is particularly important in the event of all TCs in a capsule fail.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Active Control of the Operating Temperature in a Loop Heat Pipe with Two Evaporators and Two Condensers
The operating temperature of a loop heat pipe (LHP) with multiple evaporators is a function of the total heat load, heat load distribution among evaporators, condenser temperature and ambient temperature. Because of the many variables involved, the operating temperature also showed more hystereses than an LHP with a single evaporator. Tight temperature control can be achieved by controlling its compensation chamber (CC) temperatures at the desired set point. This paper describes a test program on active control of the operating temperature in an LHP with two evaporators and two condensers. Temperature control was achieved by heating one or both CC's. Tests performed included start-up, power cycle, sink temperature cycle, CC temperature cycle, and capillary limit. Test results show that, regardless one or two CC's were heated to the set point temperature, one of CC's was always flooded with liquid. The loop could operate successfully at the desired set point temperature under most conditions, including some fast transients. At low heat loads, however, the CC temperature could suddenly increase above the set point temperature, possibly due to a sudden change of the vapor content inside the evaporator core.
Ku, Jentung↗
Temperature or pressure controller
Silicon chip thermal sensor coupled into a solid state power source controls temperature or pressure in combustion research. The silicon chip sensing element is embedded in a ceramic support for insulation, and connected to a high resistance bridge which operates the solid state power amplifiers.
Gillett, J. D.↗
Implementation of a self-controlling heater
Temperature control of radiation sensors, targets, and other critical components is a common requirement in modern scientific instruments. Conventional control systems use a heater and a temperature sensor mounted on the body to be controlled. For proportional control, the sensor provides feedback to circuitry which drives the heater with an amount of power proportional to the temperature error. It is impractical or undesirable to mount both a heater and a sensor on certain components such as ultra-small parts or thin filaments. In principle, a variable current through the element is used for heating, and the change in voltage drop due to the element's temperature coefficient is separated and used to monitor or control its own temperature. Since there are no thermal propagation delays between heater and sensor, such control systems are exceptionally stable.
Strange, M. G.↗
Flexible sample environment for high resolution neutron imaging at high temperatures in controlled atmosphere
In high material penetration by neutrons allows for experiments using sophisticated sample environments providing complex conditions. Thus, neutron imaging holds potential for performing in situ nondestructive measurements on large samples or even full technological systems, which are not possible with any other technique. Our paper presents a new sample environment for in situ high resolution neutron imaging experiments at temperatures from room temperature up to 1100 degrees C and/or using controllable flow of reactive atmospheres. The design also offers the possibility to directly combine imaging with diffraction measurements. Design, special features, and specification of the furnace are described. In addition, examples of experiments successfully performed at various neutron facilities with the furnace, as well as examples of possible applications are presented. Our work covers a broad field of research from fundamental to technological investigations of various types of materials and components.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Light-Controlled Room Temperature Ferromagnetism in Vanadium-Doped Tungsten Disulfide Semiconducting Monolayers
Not provided.
Materials Science↗
Thermoelectric Control Of Temperatures Of Pressure Sensors
Prototype controlled-temperature enclosure containing thermoelectric devices developed to house electronically scanned array of pressure sensors. Enclosure needed because (1) temperatures of transducers in sensors must be maintained at specified set point to ensure proper operation and calibration and (2) sensors sometimes used to measure pressure in hostile environments (wind tunnels in original application) that are hotter or colder than set point. Thus, depending on temperature of pressure-measurement environment, thermoelectric devices in enclosure used to heat or cool transducers to keep them at set point.
Burkett, Cecil G., Jr.↗