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Chemistry

Chemical thermodynamics & chemical properties

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Displaying 226 - 250 of 284

Optimization Calculations for a 30 HZ, 4 K Regenerator with Helium-3 Working Fluid

June 28, 2009
Author(s)
Ray Radebaugh, Yonghua Huang, Agnes A. O'Gallagher, John M. Gary
The NIST numerical software, REGEN3.3, which incorporates both He-4 and He-3 properties, was used to calculate the losses and second law efficiencies of 4 K regenerators operating at 30 Hz. Operating parameters, such as average pressure, pressure ratio

Uncertainties in Scaling Factors for ab Initio Vibrational Zero-Point Energies

March 21, 2009
Author(s)
Karl K. Irikura, Russell D. Johnson III, Raghu N. Kacker, Ruediger Kessel
Vibrational zero-point energies (ZPEs) determined from ab initio calculations are often scaled by empirical factors. An empirical scaling factor partially compensates for the effects arising from vibrational anharmonicity and incomplete treatment of

Multichannel Decomposition and Isomerization of Octyl Radicals

October 9, 2008
Author(s)
Wing Tsang, William S. McGivern, Jeffrey A. Manion
The thermal cracking patterns from the decomposition and isomerization of octyl-1 radicals have been determined from the pyrolysis of n-octyl iodide in single pulse shock tube experiments at temperatures in the 850-1000 K range and pressures near 2 bar

Thermal Decomposition Kinetics of the Aviation Turbine Fuel Jet-A

July 2, 2008
Author(s)
Jason A. Widegren, Thomas J. Bruno
As part of a larger-scale thermophysical and transport property measurement project, the global decomposition kinetics of the aviation turbine fuel Jet-A was investigated. Decomposition reactions were performed at 375, 400, 425, and 450 °C in stainless

Calculated Performance of Low-Porosity Regenerators at 4 K with He-4 and He-3

June 9, 2008
Author(s)
Ray Radebaugh, Yonghua Huang, Agnes A. O'Gallagher, John M. Gary
Previously we have shown that the lower volumetric heat capacity and more ideal behavior of helium-3 compared with helium-4 at 4 K results in an improved performance for packed sphere regenerators operating with helium-3 between 4 K and about 20 K. In this

EQUATION OF STATE AND THERMOPHYSICAL PROPERTIES OF HELIUM-3

April 3, 2007
Author(s)
Yonghua Huang, G.B. Chen, V. Arp, Ray Radebaugh
Experimental data of the thermophysical properties of 3He were mined into a searchable database. Equilibrium equations along the vapor-liquid and liquid-solid lines were proposed. A general equation of state for normal fluid 3He based on the Debye specific

Development of an Experimental Database and Kinetic Models for Surrogate Jet Fuels

March 1, 2007
Author(s)
M Colket, T Edwards, S Williams, N Cernansky, D L. Miller, Fokion N. Egolfopoulos, P Linstedt, Ram Seshadri, F L. Dryer, C K. Law, Daniel G. Friend, David Lenhert, Heinz Pitsch, A Sarofim, M Smooke, Wing Tsang
The engineering and scientific community ha been searching for the identification of surrogate fuels that can reasonably represent the performance and emissions behavior of jet fuels (e.g. Jet A and JP-8) in engines. Many proposals exist in the literature

Ionic Liquids Database (ILThermo)

July 23, 2006
Author(s)
Qian Dong, Andrei F. Kazakov, Chris D. Muzny, Robert D. Chirico, Jason A. Widegren, Vladimir Diky, Joe W. Magee, Kenneth N. Marsh, Michael D. Frenkel
Ionic Liquids Database (ILThermo)is a free web research tool that allow users worldwide to access an up-to-data data collection from the publications on experimental studies of thermodynamic and transport properties of ionic liquids, as well as binary and

Proposed Rapid Cooldown Technique for Pulse Tube Cryocoolers

June 14, 2006
Author(s)
Ray Radebaugh, Agnes O?Gallagher, Michael A. Lewis, Peter E. Bradley
Some cryocooler applications, such as those for military operations dealing with high temperature superconducting (HTS) magnets, motors, or generators, require faster cooldown times than what can normally be provided with a cryocooler designed to

Inertance Tube Optimization for Pulse Tube Refrigerators

April 27, 2006
Author(s)
Ray Radebaugh, Michael A. Lewis, Ercang Lou, John M. Pfotenhauer, G. F. Nellis, L. F. Schunk
The efficiency of regenerative refrigerators is generally maximized when the pressure and flow are in phase near the midpoint of the regenerator. Such a phase relationship minimizes the amplitude of the mass flow for a given acoustic power flow through the

Regenerator Operation at Very High Frequencies for Microcryocoolers

April 27, 2006
Author(s)
Ray Radebaugh, Agnes A. O'Gallagher
The size of Stirling and Stirling-type pulse tube cryocoolers is dominated by the size of the pressure oscillator. Such cryocoolers typically operate at frequencies up to about 60 Hz for cold-end temperatures above about 60 K. Higher operating frequencies

Microscale Heat Transfer at Low Temperatures

September 26, 2005
Author(s)
Ray Radebaugh
This paper discusses the fundamentals and applications of heat transfer in small space and time domains at low temperatures. The modern trend toward miniaturization of devices requires a better understanding of heat transfer phenomena in small dimensions

Thermal decomposition kinetics of RP-1 rocket propellant

March 16, 2005
Author(s)
Peter C. Andersen, Thomas J. Bruno
As part of a thermophysical and transport property measurement project, the global decomposition kinetics of the kerosene based rocket propellant, RP-1, was investigated. We measured the decomposition of RP-1 at elevated temperatures (that is, under

Refrigeration for Superconductors

September 20, 2004
Author(s)
Ray Radebaugh
Temperatures in the range of 0.05 to 80 K are required for most applications of superconductors. Refrigeration powers range from fractions of a watt for many electronic applications to kilowatts for some large magnet and power applications. This paper

Structure and Reaction in the Active Site of Mammalian Adenylyl Cyclase

April 8, 2004
Author(s)
Y. S. Lee, Morris Krauss
The reaction path for the catalytic conversion of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP) by the enzyme mammalian adenylyl cyclase has been calculated theoretically using the Hartree-Fock method. The crystal structure of a

Progress in the Development of Combustion Databases for Liquid Fuels

January 21, 2004
Author(s)
Wing Tsang
This paper describes the present situation regarding chemical kinetic databases for the simulation of the combustion of liquid fuels. Past work in the area is summarized. Much is known about the, reactions of the smaller fragments from combustion process

Progress in the Development of a Kinetic Database for Heptane Combustion

March 1, 2003
Author(s)
Wing Tsang
This paper deals with the development of a chemical kinetic database for use in the simulation of heptane combustion. The database consists of the thermodynamic properties of all reactants, intermediates and products and the consequences, in terms of rate

Refrigeration Methods for Superconductors

December 1, 2002
Author(s)
Ray Radebaugh
This chapter reviews various methods commonly used for achieving the cryogenic temperatures required of superconducting materials. The problems associated with cryogenic refrigerators (cryocoolers), such as poor reliability, low efficiency, electromagnetic

Structural Basis of Thermostability: Analysis of Stabilizing Mutations in Subtilisin BPN

July 26, 2002
Author(s)
O Almog, David Travis Gallagher, Jane E. Ladner, S Strausberg, Patrick Alexander, Phillip Bryan, G L. Gilliland
The crystal structures of two thermally stabilized subtilisin BPN' variants, S63 and S88, are reported here at 1.8 and 1.9 resolution, respectively. The micromolar affinity calcium-binding site (site A) has been deleted (δ 75-83) in these variants

The IUPAC Chemical Identifier

July 1, 2002
Author(s)
Stephen E. Stein, Stephen R. Heller, Dmitrii V. Tchekhovskoi
The author presented two talks at the IUPAC/CAS conference of Chemical identifiers and XML in Chemistry, on July 1, 2002 in Columbus Ohio. He will be sending powerpoint presentations of these talks, both concerning on-going projects at NIST, to IUPAC for
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