Contents - Index

Fluid Property Information


EES provides built-in thermophysical property data for the fluids listed below. The fluids are grouped into Real Fluids, Ideal Gases,  Brines, Incompressible Substances, and Mixtures (modeled as pseudo-pure substances).   Property data for air-water mixtures (psychrometrics) are provided by fluid AirH2O.  Thermophysical property data for hundreds of materials are also available in the Incompressible Substances, TPSX and NASA libraries.




------------------- REAL FLUIDS --------------------          ---------MIXTURES ----------

Acetone m-Xylene R32 Air_ha  R500

Acetylene Methane R40 NH3H2O  R502

Ammonia Methanol R41 R404A R507A

Argon n-Butane R113 R407C R508B

Benzene n-Decane R114 R407H* R512A

Butene n-Dodecane R115 R410A R513A

Carbondioxide n-Heptane R116 R417A  R513B*

Carbonmonoxide n-Hexane R123 R422D* R514A

CarbonylSulfide n-Octane R124 R423A* R515A

Chlorine n-Nonane R125 R427A*  R515B*

Cis-2-Butene n-Pentane R134a R428A* R516A*

Cyclohexane n-Undecane R141b R438A*

Cyclopentane Neon R142b R448A

D4 Neopentane R143a R449A

D5  Nitrogen R143m R450A

Deuterium NitrousOxide R152a R452A

DeuteriumOxide Novec649 R161 R452B

DiethylEther o-Xylene R218 R453A*

DimethylCarbonate orthoHydrogen R227ea R454A

DimethylEther Oxygen R236ea R454B

Ethane o-Zylene R245fa R454C

Ethanol paraHydrogen R236fa  R455A*

Ethylbenzene Propane R290  R457A*

Ethylene p-Xylene R365mfc  R460A*

EthyleneOxide Propylene R600 R463A*

Fluorine Propyne R600a  R466A

Helium SES36 R717 R469A*

HFE7000 Steam R718 R470A*

HFE7100 Steam_IAPWS R744 R470B*

HFE7200 Steam_NBS RC318

HFE7500 SulfurDioxide R1216 

Hydrogen SulfurHexafluoride R1224yd(Z)

HydrogenChloride Toluene R1225ye(Z)  

HydrogenSulfide trans-2-butene R1233zd(E)            *Professional version only

Ice Water R1234yf

Isobutane Xenon R1234ze(E)

Isobutene R11 R1234ze(Z)

Isohexane R12 R1243zf

Isooctane R13 R1336mzz(Z)   

Isopentane R13I1 RE245cb2  

Krypton R14   RE245fa2  

MDM R22      

MD2M R23




FLD files*



----- IDEAL GASES -----            ------ BRINES ------                         ------ INCOMPRESSIBLE ------

Air CACL2   (Calcium Chloride-Water)               The Function Information dialog displays the 

AirH2O EA  (Ethylene Alcohol-Water)                       materials in the Incompressible Substances.

Ar EG  (Ethylene Glycol-Water)                        and the TPSX libraries.

CH3OH GLYC  (Glycerol-Water)                               

CH4 K2CO3  (Potassium Carbonate-Water)         Specific heat, enthalpy and entropy data are 

C2H2 KAC  (Potassium Acetate-Water)                 available for condensed substances in the 

C2H4 KFO  (Potassium Formate-Water)                NASA database.

C2H6 LICL  (Lithium Chloride-Water)

C2H5OH MA  (Methyl Alcohol-Water)                         NASA_EES procedure

C3H8 MGCL2  (Magnesium Chloride-Water)

C4H10 NACL  (Sodium Chloride-Water)

C5H12 NH3W  (Ammonia-Water)

C6H14 PG  (Propylene Glycol-Water)












NASA Gases



Liquid Metals library


The fluid properties are of three distinct types:  ideal gas, real fluid and brines/incompressible.  The enthalpy and internal energy of ideal gas substances are dependent only upon temperature.  EES will not accept pressure, along with temperature, as an independent property input in the Enthalpy and IntEnergy functions for ideal gas substances.  A general rule is that substances having a name that is a chemical formula, e.g.,  N2 or CO2, are implemented to be ideal gases whereas real fluids use spelled-out names, e.g., Nitrogen and CarbonDioxide.  Air and AirH2O (psychrometric relations) are exceptions to this rule in that both are based on ideal gas behavior.  Whenever a chemical symbol notation (e.g., Ar, N2, CO2, CH4 etc.) is used, the substance is modeled as an ideal gas and the enthalpy and entropy values are based on JANAF table references.  The JANAF table reference for enthalpy is based on the elements having an enthalpy value of 0 at 298K (537R).  The entropy of these substances is based on the Third Law of Thermodynamics. 


Whenever the substance name is spelled out (e.g., Argon, Steam (or Water or R718), Nitrogen, R12, CarbonDioxide, Methane, etc.) the substance is modeled as a real fluid with subcooled, saturated, and superheated phases.  Most of the real fluids in the table above employ a high accuracy equation of state that accurately provides property information at all conditions including the vicinity of the critical point and the subcooled region.  Specific references to the equation of state are provided for each fluid.  Otherwise, the fluid properties in the subcooled region are determined using the Martin-Hou equation of state (A.I.Ch.E. Journal, Vol. 1, No. 2, 1955, pp. 142-151) and by assuming the fluid is incompressible.  The Martin-Hou equation of state has a claimed accuracy of 1% in specific volume for conditions at which the density is less than 1.5 * Critical density.   Thermodynamic properties at densities greater than 1.5 * critical density or in the vicinity of the critical point may be inaccurate with the Martin-Hou equation of state.


Brine properties are provided given the temperature and mass concentration in %.  


NH3H2O (ammonia-water) is a mixture.  It requires 3 independent properties. The property designators are the same as for pure fluids with the following two differences.  X designates mass fraction.  Q designates quality.


Starting with version 10.364, the property keywords Water, Steam, R718 and Steam_IAPWS are treated identically.  All four keywords provided access to property correlations use the Steam_IAPWS property correlations, which provide the most accurate property data for water substance and it is the current international standard.  Steam_NBS and Ice use the property correlations published by Harr, Gallagher, and Kell (Hemisphere, 1984).These property correlations were the basis of the international standard for water before 1995.


Starting with version 10.627, EES can read .FDL files used with the NIST REFPROP program, which extends the number of pure fluids for which EES can provide property information.