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Results for “Temperature control”

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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Programmable temperature control system for biological materials

A system was constructed which allows programmable temperature-time control for a 5 cu cm sample volume of arbitrary biological material. The system also measures the parameters necessary for the determination of the sample volume specific heat and thermal conductivity as a function of temperature, and provides a detailed measurement of the temperature during phase change and a means of calculating the heat of the phase change. Steady-state and dynamic temperature control is obtained by supplying heat to the sample volume through resistive elements constructed as an integral part of the sample container. For cooling purposes, this container is totally immersed into a cold heat sink. Using a mixture of dry ice and alcohol at 79 C, the sample volume can be controlled from +40 to -60 C at rates from steady state to + or - 65 C/min. Steady-state temperature precision is better than 0.2 C, while the dynamic capability depends on the temperature rate of change as well as the mass of both the sample and the container.

Anselmo, V. J.↗
NASA NTRS1972

Heat pipes for spacecraft temperature control: Their usefulness and limitations

Heat pipes are used in spacecraft to equalize the temperature of structures and maintain temperature control of electronic components. Information is provided for a designer on: (1) a typical mounting technique, (2) choices available in wick geometries and fluids, (3) tests involved in flight-qualifying the design, and (4) heat pipe limitations. An evaluation of several heat pipe designs showed that the behavior of heat pipes at room temperature does not necessarily correlate with the classic equations used to predict their performance. They are sensitive to such parameters as temperature, fluid inventory, orientation, and noncondensable gases.

Ollendorf, S.↗
NASA NTRS1990

Definition study for temperature control in advanced protein crystal growth

Some of the technical requirements for an expedient application of temperature control to advanced protein crystal growth activities are defined. Lysozome was used to study the effects of temperature ramping and temperature gradients for nucleation/dissolution and consecutive growth of sizable crystals and, to determine a prototype temperature program. The solubility study was conducted using equine serum albumin (ESA) which is an extremely stable, clinically important protein due to its capability to bind and transport many different small ions and molecules.

Nyce, Thomas A.↗
NASA NTRS1986

Controlled-Temperature Hot-Air Gun

Materials that find applications in wind tunnels first tested in laboratory. Hot-Air Gun differs from commercial units in that flow rate and temperature monitored and controlled. With typical compressed-airsupply pressure of 25 to 38 psi (170 to 260 kPa), flow rate and maximum temperature are 34 stdft3/min (0.96 stdm3/min) and 1,090 degrees F (590 degrees C), respectively. Resembling elaborate but carefully regulated hot-air gun, setup used to apply blasts of air temperatures above 1,500 degrees F (815 degrees C) to test specimens.

Munoz, M. C.↗
NASA NTRS1973

Effects of backlash and dead band on temperature control of the primary loop of a conceptual nuclear Brayton space powerplant

An analytical study was made of the stability of a closed-loop liquid-lithium temperature control of the primary loop of a conceptual nuclear Brayton space powerplant. The operating point was varied from 20 to 120 percent of design. A describing-function technique was used to evaluate the effects of temperature dead band and control coupling backlash. From the system investigation, it was predicted that a limit cycle will not exist with a temperature dead band, but a limit cycle will not exist when backlash is present. The results compare favorably with a digital computer simulation.

Petrick, E. J.↗
NASA NTRS1989

Variable conductance heat pipe technology for precise temperature control of the NASA/DDLT transmitter

The application of variable conductance heat pipe technology for achieving precise temperature control to + or - 0.1 C for a space-based laser diode transmitter is described. Heat pipe theory of operation and test data are presented along with a discussion of its applicability for NASA's Direct Detection Laser Transceiver (DDLT) program. This design for the DDLT transmitter features a reduction in space radiator size and up to 42 percent reduction in prime power requirements.

Vanevenhoven, D. E.↗
NASA NTRS1972

Water/glycol temperature control circuit failed in the automatic mode: Apollo 16

An anomaly report concerning failure of the water/glycol temperature control circuit during the Apollo 16 flight is presented. The anomaly is described and diagrams of the system are presented. The malfunction was caused by cracked semiconductor chips in the output silicon-controlled rectifier. Surface contamination in the crack allowed the device to self-gate on and remain on, resulting in a secondary failure of the feedback capacitor.

Source record↗
NASA NTRS1966

Auxiliary coil controls temperature of RF induction heater

Auxiliary coil controls the temperature of an RF induction furnace that is powered by a relatively unstable RF generator. Manual or servoed adjustments of the relative position of the auxiliary coil, which is placed in close proximity to the RF coil, changes the looseness of the RF coil and hence the corresponding heating effect of its RF field.

Source record↗
NASA NTRS1979

Transparent electrically conducting thin films for spacecraft temperature control applications

Thin transparent films of In2O3 or In2O3 + SnO2 prepared by evaporation or sputtering have been tested for use as surface layers for spacecraft temperature control coatings. The films are intended to prevent nonuniform electric charge buildup on the spacecraft exterior. Film thicknesses of 300 to 500 A were found to be optimal in terms of durability and minimum impact on the solar absorptance and the thermal emissivity of the underlayers. As a verification of their suitability for long-duration space missions, the films were subjected to simulated solar UV plus proton irradiation in a vacuum.

Hass, G.↗
NASA NTRS1988

A facility for precise temperature control applications in microgravity

The general design, main components, and operation of the isothermal dendritic growth apparatus (IDGA) designed for microgravity experimentation are described. The four major subsystems of the IDGA are a temperature controlled thermostatic bath capable of milli-kelvin stability, a photographic data collection system, a crystal growth chamber, and a growth detection system to initiate data collection. Some of the specific experiments that could utilize the capabilities of the IDGA are dendritic growth in alloys, monotectic systems, life science experiments, and technological applications.

Glicksman, M. E.↗
NASA NTRS1981

Holes help control temperature

Study of passive thermal control for the Solar Terrestrial Subsatellite (STSS) has found that array of "see through" holes substantially improves performance of system. Holes in payload mounting plates allow line of sight radiative heat transfer between hot and cold ends of spacecraft and between mounting plates and ends. Temperature gradients between plates are thereby reduced, as is temperature of each plate. Holes and selected exterior paints and finishes keep payload cool for all orientations and operating modes of STSS.

Chhatpar, C. K.↗
NASA NTRS1994

Using a temperature-controlled quartz crystal microbalance in a space equipment cleanroom to monitor molecular contamination

There is a need for continuous monitoring for molecular contamination in clean rooms where spaceflight equipment is assembled, integrated, and tested to insure that contamination budgets are met. The TQCM (temperature-controlled quartz crystal microbalance) can be used to provide both a real time warning and a cumulative measurement of molecular contamination. It has advantages over the other measurement methods such as witness mirrors, NVR (non-volatile residue) plates, and gas analyzers. A comparison of the TQCM sensitivity and ease of operations is made with the other methods. The surface acoustic wave microbalance (SAW), a newly developed instrument similar to TQCM, is considered in the comparison. An example is provided of TQCM use at Goddard Space Flight Center when the Wide Field Planetary Camera 2(WFPC-2) and the Corrective Optics Space Telescope Axial Replacement (COSTAR) were undergoing integrated testing prior to their installation in the Hubble Space Telescope on its first servicing mission. Areas for further investigation are presented.

Mitchell, William J.↗
NASA NTRS1948

Pressure-Sensitive System for Gas-Temperature Control

A thermodynamic relation is derived and simplified for use as a temperature-limiting control equation involving measurement of gas temperature before combustion and gas pressures before and after combustion. For critical flow in the turbine nozzles of gas-turbine engines, the control equation is further simplified to require only measurements upstream of the burner. Hypothetical control systems are discussed to illustrate application of the control equations.

Cesaro, Richard S↗