1.2 Software

Engineering Equation Solver (EES)™

Engineering Equation Solver (EES) is a stand-alone software package. It can be purchase from F-Chart software. Many academic institutions and industrial companies have site licenses for EES.

In EES, system equations are entered in free format. Properties are accessed by calling various property routines. For example, to compute the density of water at 20°C and 101.325 kPa, the following EES statement is entered into the equation window,

rho = DENSITY(water, T=20, P=101.325)

The resulting density is calculated an displayed in the solutions window. When using property calls, the units for the various independent property inputs must be consist with the unit settings in EES.

REFPROP

REFPROP is a thermophysical property calculation package developed by the National Institute of Standards and Technology (NIST). The REFPROP DLL can be accessed as a MS Excel add-in allowing properties to be calculated within spreadsheet cells.

Once the REFPROP addin is enabled in a spreadsheet, The call within a spreadsheet cell takes on the following form:

= REFPROP(code, fluid, input code, units, property 1, property 2)

code indicates which property is being calculated. There are many properties available in REFPROP. The common thermodynamic and transport property codes are,

    • T = temperature
    • P = pressure
    • Qmass = quality (mass basis)
    • D = density
    • E = internal energy
    • H = enthalpy
    • S = entropy
    • CV = isochoric heat capacity
    • CP = isobaric heat capacity
    • VIS = dynamic viscosity
    • KV = kinematic viscosity
    • TCX = thermal conductivity
    • PRANDTL = Prandtl number

The property code must be contained within double quotes, or referenced to a spreadsheet cell.

fluid is the REFPROP fluid name. REFPROP has an extensive pure fluid, pseudo-pure fluid, and mixture database. The tables in Appendix B were generated using REFPROP. The fluid names shown in the various property tables can be used for the fluid variable in the function call. The fluid name must be contained within double quotes, or referenced to a spreadsheet cell.

input code indicates the known independent property pair being used to find the property identified by code. There are many input codes allowed in REFPROP. The common input pairs are,

    • TP = temperature and pressure
    • TD = temperature and density
    • TS = temperature and entropy
    • TQ = temperature and quality
    • PD = pressure and density
    • PE = pressure and internal energy
    • PH = pressure and enthalpy
    • PS = pressure and entropy
    • PQ = pressure and quality
    • DE = density and internal energy
    • DH = density and enthalpy
    • DS = density and entropy
    • DQ = density and quality
    • ES = internal energy and entropy
    • EQ = internal energy and quality
    • HS = enthalpy and entropy
    • HQ = enthalpy and quality
    • SQ = entropy and quality

The input property code must be contained within double quotes, or referenced to a spreadsheet cell.

units signifies the unit system being used. There are several unit sets available. The most common, along with the actual units used within the unit syste are,

    • SI = SI system (K, MPa, kg/m^3, kJ/kg, kJ/kg-K, uPa-s, cm^2/s, mW/m-K)
    • C = SI system with temperatures in °C (°C, MPa, kg/m^3, kJ/kg, kJ/kg-K, uPa-s, cm^2/s, mW/m-K)
    • E = IP system (°F, psia, lbm/ft^3, Btu/lbm, Btu/lbm-°R, lbm/ft-s, ft^2/s, Btu/hr-ft-°R)

The units code must be contained within double quotes, or referenced to a spreadsheet cell.

property1 and property2 are the numerical values of the properties consistent with the input code. The numerical values of the properties must be consistent with the unit system defined by units.

When REFPROP is installed on a computer, the file REFPROP.XLS is created in the "Program Files/REFPROP" or "Program Files (x86)/REFPROP" folder. This spreadsheet file contains the details all of the MS Excel features that are available.

CoolProp

CoolProp is an open-source thermophysical property calculation package. When installed, a CoolProp add-in becomes available for MS Excel allowing properties to be calculated within spreadsheet cells. The CoolProp windows installer automatically installs the coolprop.xlam file in the users addin folder and automatically activates the Excel addin. This can become problematic in a course setting when Excel files are shared among different computers since there are different usernames for different computers (C:\Users\). A workaround for this is to have all users in the course create a common folder (e.g., C:\xla), relocate the coolprop.xlam file to that folder, and update the CoolProp add-in source in MS Excel.

Properties are calculated with spreadsheet cells using the following function,

=PropsSI(code, input code 1, property1, input code 2, property2, fluid)

Notice that there is no input for the unit system. This is because CoolProp works exclusively in the SI unit system. The units associated with each property are indicated in the code explanation below.

code indicates which property is being calculated. There are many properties available in CoolProp. The common thermodynamic and transport property codes, along with their associated SI units are,

    • T = temperature (K)
    • P = pressure (Pa)
    • Q = quality (mass basis)
    • D = density (kg/m^3)
    • U = internal energy (J/kg)
    • H = enthalpy (J/kg)
    • S = entropy (J/kg-K)
    • O = isochoric heat capacity (J/kg-K)
    • C = isobaric heat capacity (J/kg-K)
    • V = dynamic viscosity (Pa-s)
    • L = thermal conductivity (W/m-K)
    • PRANDTL = Prandtl number

This is an abbreviated list. The full list of CoolProp property codes can be found here.

input code 1 and input code 2 represent the known independent property pair being used to find the property identified by code. The allowed inputs are: P, T, D, U, H, S, and Q. The input codes must be contained within double quotes, or referenced to a spreadsheet cell.

property1 and property2 are the numerical values of the properties referred to by input code 1 and input code 2. The values must be consistent with the SI unit set defined by the code value.

fluid is the fluid name code. The fluid name code is similar to the fluid names in Appendix B, with the exception of the normal hydrocarbons. For the normal hydrocarbons, the fluid name is preceeded with "n-". For example, the hexane fluid code is n-Hexane. A complete list of fluids in the CoolProp data base can be found here.

CoolProp has the advantage of being free since it is open source. However, it also has an advantage over REFPROP in that it can compute incompressible fluid properties for many substances and mixtures, including brines (Appendix B.4). There are a wide variety of incompressible fluids available in CoolProp. For the brines, the general form of the fluid code

INCOMP::fluid[xxx]

The fluid codes for the brines listed in Appendix B.4 are,

  • MEG = ethylene glycol-water solutions
  • MPG = propylene glycol-water solutions
  • VMA = methanol-water solutions
  • MEA = ethanol-water solutions
  • MCA = calcium chloride-water solutions
  • MMG = magnesium chloride-water solutions
  • MNA = sodium chloride-water solutions

xxx represents the mass percent of the water additive. This can be expressed as a decimal value between 0 and 1, or as a percent. For example, to compute the density of a 15% calcium chloride solution at 270 K, the CoolProp function call is,

=PropsSI("D", "T", 270, "Q", 0, "INCOMP::MCA[0.15]") or =PropsSI("D", "T", 270, "Q", 0, "INCOMP::MCA[15%]")

A complete list of incompressible substances available in CoolProp can be found here.