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Stephanie L. Outcalt


Ms. Outcalt received her bachelor's degree in Chemical Engineering from the University of Colorado in 1987 and has been employed at NIST since graduation.  She began her work at NIST measuring the fugacity of hydrogen in mixtures of importance to the fuel gas industry.  This work figured in the development of equations of state for natural gas and liquefied petroleum gas.  As part of this work, she was also involved with the development of analytical methods and devices for fuel gas, and was part of the development of analytical sampling and detection devices.  More recently, she has advanced measurements in a number of thermophysical properties, among them solubility, vapor pressure, density and bubble point. 

Ms. Outcalt also worked on correlations of equations of state for some of the early alternative refrigerants.  Her current areas of focus include the measurement of compressed-liquid densities of fuels and their constituents and measuring bubble points of binary mixtures as potential new refrigerants.  When not working, Ms. Outcalt is an avid swimmer and cyclist.

Google Scholar Citation Page   

Research Interests:  

Thermophysical Properties of Fuels

A critical aspect of efficient and clean fuel utilization is the design of modern liquid and gaseous fuels.  This also encompasses the optimization of the engines that use these fuels.  Both of these aspects depend on a thermophysical property infrastructure, and one of the most fundamental properties that is required is the density.  The density provides the pressure-volume-temperature (PVT) surface of a fluid, which is an indispensable part of equation of state development.  Ms. Outcalt and her colleagues have developed an automated instrument to measure the compressed liquid viscosity of fluids, thus providing access to the critical PVT surface.  This is an especially robust instrument that is suitable for real fuels and industrial fluids.  The measurements made by Ms. Outcalt on rocket fuels, aviation fuels and biofuels have been instrumental in the development of thermophysical property models for these fluids.   

Phase Equilibrium of Fluids:

In order to model industrial processes, some knowledge of the phase equilibrium of the major process constituents is commonly necessary.  This is because fluids usually undergo phase changes during a process regardless of whether it is a manufacturing process, a cleaning process, or a closed process such as heating or refrigeration systems.  Ms. Outcalt has developed an instrument to measure the bubble point of mixtures.  The instrument has also been used to measure the solubility of carbon dioxide, propane, propene, butane, and 1-butene in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]).

Recent Representative Publications

Outcalt, S. L.; Lemmon, E. W. Bubble-Point Measurements of Eight Binary Mixtures for Organic Rankine Cycle Applications. J. Chem. Eng. Data 2013, 58, 1853-1860.

Outcalt, S.L
. and Laesecke, A., Compressed-liquid densities of two highly polar + non-polar binary systems.  Journal of Molecular Liquids, 173 (September), 91-102, 2012

Outcalt, S. L.; Laesecke, A.; Fortin, T. J., Density and Speed of Sound Measurements of 1- and 2-Butanol. Journal of Molecular Liquids 2010, 151, 50-59.

Outcalt, S. L.; Laesecke, A.; Brumback, K. J., Thermophysical Properties Measurements of Rocket Propellants RP-1 and RP-2. Journal of Propulsion and Power 2009, 25, (5), 1032-1040.

Outcalt, S.L.; Laesecke, A.; Freund, M. B., Density and Speed of Sound Measurements of Jet A and S-8 Aviation Turbine Fuels. Energy and Fuels 2009, 23, 1626-1633.

Laesecke, A.; Outcalt, S. L.; Brumback, K. J., Density and Speed of Sound Measurements of Methyl- and Propylcyclohexane. Energy & Fuels 2008, 22, 2629-2636.

Outcalt, S. L.; McLinden, M. O., Automated Densimeter for the Rapid Characterization of Industrial Fluids. Ind. Eng. Chem. Res. 2007, 46, 8264-8269

Lee, B. C.; Outcalt, S. L., Solubilities of Gases in the Ionic Liquid 1-n-Butyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide. J. Chem. Eng. Data 2006, 51, 892-897.

Outcalt, S. L.; Lee, B. C., A Small-Volume Apparatus for the Measurement of Phase Equilibria. J. Res. Natl. Inst. Stand. Technol. 2004, 109, 525-531.

Stephanie Outcalt

Awards and Honors:

NIST Certificate of Appreciation, for "Outstanding Contributions to the Standard Reference Data Program in the area of high-accuracy refrigerant properties." 1994

Building Tomorrows' Workplace Award for "significant contributions in creating an inclusive workforce and working toward achieving affirmative employment and diversity goals."  2007


Chemical Engineer, NIST, 1987-present


B.S. Chemical Engineering, University of Colorado, 1987

Completion of LabView Advanced Application Development training program

Professional Service: 

Member, ASTM Committee DO2 on Petroleum Products and Lubricants.


Thermophysical Properties Division
Boulder, CO 80303-3337

phone: 303-497-5786
fax: 303-497-5044