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Mark O. McLinden

Dr. McLinden received his BS degree from the University of Missouri-Columbia and MS and PhD degrees from the University of Wisconsin-Madison, all in chemical engineering. He joined what was then the National Bureau of Standards in 1984 and worked in the Thermal Machinery Group of NBS–Gaithersburg, where he developed an nist-equation of state for refrigerant mixtures, carried out analytical studies on the optimum thermodynamic characteristics of refrigerants, and constructed an experimental apparatus to measure evaporative heat transfer coefficients. He joined the Thermophysical Properties Division of NIST in Boulder in 1988 where his research through the 1990s focused on the properties of alternatives to the ozone-depleting CFC and HCFC refrigerants. His current focus is on highly accurate measurements of fluid properties over wide ranges of temperature and pressure and the design and fabrication of instruments for such measurements. The current interest in low-GWP alternatives to the HFC refrigerants has reignited his research in the refrigerants area. He is the author or coauthor of more than 60 peer-reviewed publications and has received several awards related to his refrigerants research. When not in the lab, Dr. McLinden enjoys hiking the mountains of Colorado, often carrying 10 kg of large-format (i.e. film-based, old-school) camera gear; he maintains that film is not dead yet and has the landscape photos to prove it.

Google Scholar Citation Page(link is external)

Research Areas

Instrument Development:

State-of-the art property measurements have been the hallmark of the Fluid Properties Group for more than four decades. Many of these measurements have been carried out on one-of-a-kind instruments developed at NIST, and Dr. McLinden continues this tradition. He developed, in collaboration with Rubotherm GmbH of Bocum, Germany ( is external)) a two-sinker magnetic suspension densimeter for the measurement of fluid p-r-T (pressure-density-temperature) properties. This instrument applies the Archimedes (bouyancy) principle together with a magnetic suspension coupling to separate the sinkers (sensing elements) from the balance that weighs them to allow measurements over very wide ranges of temperature and pressure (220 K to 505 K, with pressures to 40 MPa). This instrument is one of only a handful of its kind worldwide and is the world's most accurate instrument for wide-ranging density measurements. In addition to developing the densimeter (which was largely fabricated in the NIST Instrument Shops), Dr. McLinden has advanced this general type of instrument by analyzing the effects of the so-called "force transmision error." He has developed a single-sinker hydrostatic-balance densimeter operating at temperatures up to 500 ˚C and pressures to 50 MPa (also in collaboration with Rubotherm). He is currently collaborating with Dr. Richard Perkins to put into operation a spherical resonator for the measurement of vapor-phase speed of sound data.

McLinden, M. O. and Lösch-Will, C. (2007). Apparatus for wide-ranging, high-accuracy fluid (p-ρ-T) measurements based on a compact two-sinker densimeter. J. Chem. Thermodynamics 39: 507-530.

McLinden, M. O., Kleinrahm, R., and Wagner, W. (2007). Force transmission errors in magnetic suspension densimeters. Int. J. Thermophysics 28: 429-448.

Piston Gauge  _ densimeter


Standard Reference Fluid p-ρ-T Data:

Dr. McLinden's measurements, and in particular those made with the two-sinker densimeter, feed into standards and improved fluid models and theory. His extensive measurements on propane were key data in developing a new nist-equation of state that is among the most accurate for any fluid; propane is an important reference fluid for applications including natural gas and liquid fuels. In a collaboration with Dr. Michael Moldover, his measurements on helium were combined with theory to yield the most accurate virial coefficients available for this gas; these will be used in the development of a new primary pressure standard based on fundamental physical properties of helium.

He demonstrated that high-accuracy density measurements on gases could determine thermodynamic temperatures and thus be the basis for a new type of gas thermometer. The densimeter was used to extend the range of the Standard Reference Material® for liquid density based on toluene from the near-ambient conditions of the previous SRM to –50 ˚C to 150 ˚C, with pressures to 30 MPa; this is the widest range of temperature and pressure for a density standard from any National Metrology Institute.
A similar project to extend the range of the iso-octane standard is in progress.

McLinden, M. O. (2009). Thermodynamic properties of propane. I. p-r-Tbehavior from 265 K to 500 K with pressures to 36 MPa. J. Chem. Engr. Data 54: 3181-3191.

Moldover, M. R.; McLinden, M. O. (2010) Using Ab Initio "Data" to Accurately Determine the Fourth Density Virial Coefficient of Helium. J. Chem. Thermo. 42: 1193-1203.

McLinden, M.O. (2006) Densimetry for primary temperature metrology and a method for the in-situ determination of densimeter sinker volumes. Measurement Science and Technology 17: 2597-2612.

McLinden, M. O. and Splett, J.D. (2008). A liquid density standard over wide ranges of temperature and pressure based on toluene. Journal of Research of the National Institute of Standards and Technology 113: 29-67.

Refrigerant Properties:

Dr. McLinden has been actively engaged in researching "new" refrigerants for virtually his entire career. This work has included the development of nist-equations of state and other property models and the development of the REFPROP database. He studied the optimum thermodynamic characteristics of refrigerantsin relation to the phase-out of the ozone-depleting CFC and HCFC refrigerants in the 1990s and is currently Principal Investigator for a major new DOE-funded project to search for and evaluate the thermodynamic potential of low-GWP alternatives to the HFC refrigerants. He chaired an International Energy Agency working group, known as Annex 18—Thermophysical Properties of the Environmentally Acceptable Refrigerants from 1990 to 1999 and served on an ISO Working Group which developed an international standard for refrigerant properties. He serves on several ASHRAE committees concerned with refrigerants. His interests in refrigerants and laboratory work recently intersected with measurements on two new fluorinated-propene refrigerants, R1234yf and R1234ze(E).

Younglove, B.A. and McLinden, M.O. (1994). An international standard nist-equation-of-state formulation of the thermodynamic properties of refrigerant 123 (2,2-dichloro-1,1,1-trifluoroethane). J. Phys. Chem. Ref. Data 23: 731-779.

McLinden, M.O., Klein, S.A. and Perkins, R.A. (2000). An extended corresponding states model for the thermal conductivity of refrigerants and refrigerant mixtures. Int. J. Refrigeration 23: 43-63.

McLinden, M.O. (1990). Optimum refrigerants for non-ideal cycles: An analysis employing corresponding states. USNC/IIR–Purdue Refrigeration Conference and ASHRAE-Purdue CFC Conference, W. Lafayette, IN, July 17-20, 69-79.

McLinden, M.O. and Watanabe, K. (1999). International collaboration on the thermophysical properties of alternative refrigerants: Results of IEA Annex 18. 20th International Congress of Refrigeration, Sydney, Australia, September 19-24, International Institute of Refrigeration, 678-687.

McLinden, M. O.; Thol, M.; Lemmon, E. W. Thermodynamic properties of trans-1,3,3,3-tetrafluoropropene [R1234ze(E)]: Measurements of density and vapor pressure and a comprehensive nist-equation of state. International Refrigeration and Air Conditioning Conference at Purdue, W. Lafayette, IN, July 12-15, 2010; paper 2189.


The NIST REFPROP Standard Reference Database ( provides properties for a wide variety of industrially important fluids. It is the de facto industry standard for the properties of refrigerants and is increasingly used in the natural gas and chemical process industries. It is one of the main tech transfer mechanisms for the outputs of the Thermophysical Properties Division. The various versions of REFPROP are the work of eight co-authors and numerous other contributors, and Dr. McLinden has been a co-author of every release of the NIST REFPROP database from version 1 in December 1989 to the current version 9, released in November 2010. REFPROP has its roots in an early, simple nist-equation of state for refrigerant mixtures developed by Dr. Graham Morrison and coded by McLinden and informally distributed on magnetic tape. "REFPROP" originally stood for "REFrigerant PROPerties" and version 1 included just 15 pure refrigerants and their binary mixtures. Version 6 (1998) introduced a modern graphical user interface (coded largely by Prof. S.A. Klein of the University of Wisconsin) and a complete restructuring of the core property code. With version 7 the meaning of the name was changed to "REference Fluid PROPerties" to reflect the greater scope of the database. The current version includes 105 pure fluids and mixtures with up to 20 components; natural gas constituents, other hydrocarbons up to dodecane (C12H26), water/steam, cryogenic fluids, and other simple inorganic fluids are included in addition to refrigerants. Primary responsibility for REFPROP passed to Dr. Eric Lemmon (of the Theory of Fluids Group) in 2002 with version 7, but Dr. McLinden remains involved in its development and support.

Morrison, G. and McLinden, M.O. (1986). Application of the Carnahan-Starling-DeSantis nist-equation of state to mixtures of refrigerants. ASME Winter Annual Meeting, paper 86-WA/HT-59.

McLinden, M.O., Lemmon, E.W. and Huber, M.L. (2003). The REFPROP database for the thermophysical properties of refrigerants. 21st International Congress of Refrigeration, Washington, DC, International Institute of Refrigeration, paper ICR0443.

Lemmon, E.W., Huber, M.L., and McLinden, M.O. (2010) NIST Standard Reference Database 23, NIST Reference Fluid Thermodynamic and Transport Properties—REFPROP, version 9.0. Standard Reference Data Program, National Institute of Standards and Technology.


Department of Commerce Silver Medal (1988), jointly with Graham Morrison, “For significant contributions to the U.S. refrigeration industry in the characterization and search for ozone-safe refrigerants.”

ASHRAE Journal Paper Award and the NIST Edward Uhler Condon Award (1988), jointly with David Didion, for authoring “CFCs—Quest for Alternatives.” The Condon award cited the paper as “a landmark contribution to the field of … refrigerants.” 
[McLinden, M.O. and Didion, D.A. (1987). CFCs:  Quest for Alternatives. ASHRAE J.  29(12): 32-42]

NIST Applied Research Award (1992), jointly with Graham Morrison, “For developing practical models for predicting the thermodynamic properties of refrigerants.”

NIST William P. Schlicter Award (1999), “For working closely with the air-conditioning/refrigeration industries to replace ozone-depleting chlorofluorocarbons with environmentally acceptable alternatives.”

Department of Commerce/NIST Federal Engineer of the Year (1995).

NIST Judson C. French Award (2001), jointly with Eric Lemmon and Daniel Friend, “For the development of the NIST Pure Fluids Standard Reference Database that dramatically upgrades a key part of the nation’s metrology infrastructure.”

American Society of Heating Refrigerating and Air Conditioning Engineers (ASHRAE), Distinguished Service Award (2005) in recognition of those “giving freely of their time and talent to the Society.”

Best paper award 2013-2014, International Journal of Refrigeration, for the paper:
McLinden, M. O.; Kazakov, A. F.; Brown, J. S.; Domanski, P. A., A thermodynamic analysis of refrigerants: Possibilities and tradeoffs for Low-GWP refrigerants. Int. J. Refrigeration 2014, 38, 80-92.



The (R)Evolution of Refrigerants

Mark O. McLinden, Marcia L. Huber
As we enter the “fourth generation” of refrigerants, we consider the evolution of refrigerant molecules, the ever-changing constraints and regulations that have

Options for Low-GWP Refrigerants

Mark O. McLinden, Andrei F. Kazakov, J S. Brown, Riccardo Brignoli, Ian H. Bell, Piotr A. Domanski
We summarize a systematic examination of possible low-GWP (global warming potential) replacements for the HFC (hydrofluorocarbon) refrigerants currently used in
Created August 15, 2019, Updated December 13, 2019