Engineering Papers⌕ Search

SEARCH · Engineering Papers

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Temperature control to reduce capacity mismatch in parallel-connected lithium ion cells

The temperature and capacity of individual cells affect the current distribution in a battery pack. Non uniform current distribution among parallel-connected cells can lead to capacity imbalance and premature aging. This paper develops models that calculate the current in parallel-connected cells and predict their capacity fade. The model is validated experimentally for a nonuniform battery pack at different temperatures. The paper also proposes and validates the hypothesis that temperature control can reduce capacity mismatch in parallel-connected cells. Three Lithium Iron Phosphate cells, two cells at higher initial capacity than the third cell, are connected in parallel. The pack is cycled for 1500 Hybrid Electric Vehicles cycles with the higher capacity cells regulated at 40 C and the lower capacity cell at 20 C. As predicted by the model, the higher capacity and temperature cells age faster, reducing the capacity mismatch by 48% over the 1500 cycles. A case study shows that cooling of low capacity cells can reduce capacity mismatch and extend pack life.

25 ENERGY STORAGE↗
NASA NTRS1980

Temperature control simulation for a microwave transmitter cooling system

The thermal performance of a temperature control system for the antenna microwave transmitter (klystron tube) of the Deep Space Network antenna tracking system is discussed. In particular the mathematical model is presented along with the details of a computer program which is written for the system simulation and the performance parameterization. Analytical expressions are presented.

Yung, C. S.↗
NASA NTRS1996

Some Sources of Contaminants in the Shuttle Bay Measured with Temperature-Controlled Quartz Crystal Microbalances (TQCM)

The sources of molecular deposits on a Temperature-Controlled Quartz Crystal Microbalance (TQCM) attached to the shuttle bay wall at some distance from the payload and pointing out of the bay have been investigated. Explored as possible sources are: (1) the outgassing of the shuttle tiles treated with the water proofing di-methyl-ethoxy-silane (DMES) compound, scattered back by the ambient molecules into the bay; (2) The ambient scattered return flux of the outgassing, from the RTV 560 silicone which is used as the adhesive for the tiles; (3) the ambient scattered return flux of the payload outgassing; (4) the return C, flux from outgassing source originating near, below, or adjacent to the package containing the TQCM; and (5) the self-scattering of venting plumes and outgassing above the monitor package depositing on the TQCM. In all of these sources, the magnitudes of the outgassing, of the leakage rates, and venting had to be estimated in the absence of data. The resulting analyses which can be useful for similar investigations, indicates that the outgassin- from the tiles, the RTV, the payloads, or the shuttle may not have been the sources of the deposit (about 1 micro g/cm(sup 2) during a the period from bay door opening and payload release from the bay). It appears more probable that the origin is the self- and/or ambient-scattered return fluxes originating near, below, or internal to the monitor package.

Scialdone, John J.↗
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.↗
DOE OSTI2016

System and method for air temperature control in an oxygen transport membrane based reactor

A system and method for air temperature control in an oxygen transport membrane based reactor is provided. The system and method involves introducing a specific quantity of cooling air or trim air in between stages in a multistage oxygen transport membrane based reactor or furnace to maintain generally consistent surface temperatures of the oxygen transport membrane elements and associated reactors. The associated reactors may include reforming reactors, boilers or process gas heaters.

03 NATURAL GAS↗
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.↗
DOE OSTI2017

Lead(II) coordination polymers based on rigid-flexible 3,5-bis-oxyacetate-benzoic acid: Structural transition driven by temperature control

Three Pb(II) complexes ([Pb{sub 3}(BOABA){sub 2}(H{sub 2}O)]·H{sub 2}O){sub n} (1), ([Pb{sub 4}(BOABA){sub 2}(µ{sub 4}-O)(H{sub 2}O){sub 2}]·H{sub 2}O){sub n} (2), and [Pb{sub 3}(BOABA){sub 2}(H{sub 2}O)]{sub n} (3) (H{sub 3}BOABA=3,5-bis-oxyacetate-benzoic acid) were obtained under the same reaction systems with different temperatures. Complexes 1 and 2 are two dimensional (2D) networks based on Pb-BOABA chains and Pb{sub 4}(µ{sub 4}-O)(COO){sub 6} SBUs, respectively. Complex 3 presents an interesting three dimensional (3D) framework, was obtained by increasing the reaction temperature. Structural transition of the crystallization products is largely dependent on the reaction temperature. Moreover, the fluorescence properties of complexes 1–3 have been investigated. - Graphical abstract: Three Pb(II) coordination polymers were obtained under the same reaction systems with different temperatures. Both of complexes 1 and 2 are 2D network. 3 presents a 3D framework based on Pb–O–C rods SBUs. The 2D to 3D structures transition between three complexes was achieved successfully by temperature control. - Highlights: • Three Pb(II) complexes were obtained under the same reaction systems with different temperatures. • Structural transition of the crystallization products is largely dependent on the reaction temperature. • The luminescence properties studies reveal that three complexes exhibit yellow fluorescence emission behavior, which might be good candidates for obtaining photoluminescent materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
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↗