NIST Offers Expanded Database on Properties of Alternative Refrigerants

A newly expanded database on the physical properties of alternative refrigerants will help U.S. industry convert from chemicals that are thought to harm the ozone layer to more environmentally acceptable refrigerants.

Chemists at the National Institute of Standards and Technology have added 12 new pure fluid refrigerants to REFPROP, a database widely used in industry for predicting efficiency and capacity of equipment that will use new refrigerants. Scientists included fluids of high interest to the refrigeration industry, such as R32 and R125, because highly accurate data are now available for these compounds. The expanded database now contains data on 38 pure refrigerants.

The new version, REFPROP 4.0, also contains 27 new refrigerant mixtures with data on their interaction parameters. Interaction parameters, based on measurements, are available for 65 binary mixture pairs. Interaction parameters for all other mixtures are estimated from a correlation.

In addition to expanding the number of pure fluids and mixtures in the database, NIST scientists have improved the quality and accuracy of the data for several of the compounds. Highly accurate, multiparameter equations of state are available for 12 of the pure fluids. REFPROP 4.0 represents a significant improvement in an industry tool for evaluating fluids for refrigeration and air conditioning.

The database is one of more than 30 available from the NIST Standard Reference Data Program which has been providing evaluated, high-quality data for a wide range of applications to industry, government and academic institutions for over 27 years.

NIST began providing industry with data on the thermophysical properties of refrigerants in the 1920s, when it was known as the National Bureau of Standards. Prior to the discovery that chlorofluorocarbons, or CFCs, made excellent refrigerants, the young refrigeration industry used ammonia and other fluids in its equipment. Engineers relied on the NBS data tables as they designed refrigeration systems.

CFCs were first commercialized in the 1930s, when they were widely adopted as refrigerants, blowing agents and cleaning compounds. NIST revived its measurements of refrigerant properties in response to concern that CFCs are destroying the Earth's protective ozone layer.

NIST first introduced REFPROP in 1989 to provide industry with the most accurate measurements of thermophysical and transport properties of promising alternative refrigerants. By an international agreement, known as the Montreal Protocol, many industrialized and developing nations have pledged to phase out CFC refrigerants by the year 2000. The U.S. target date for ceasing production of CFCs is Dec. 31, 1995.

Version 4.0 of REFPROP is available for $465. Owners of a previous version may upgrade for $100. The database requires MS-DOS, PC-DOS 2.0 or higher. A math co-processor is recommended, and a minimum memory of 512K is required.

To order REFPROP 4.0, NIST Standard Reference Database 23, contact the Standard Reference Data Program, A320 Physics Building, NIST, Gaithersburg, Md. 20899-0001, (301) 975-2208, fax: (301) 975-0416, e-mail: srdata [at] enh.nist.gov (srdata[at]enh[dot]nist[dot]gov) (via Internet).

As a non-regulatory agency of the Commerce Department's Technology Administration, NIST promotes U.S. economic growth by working with industry to develop and apply technology, measurements and standards.