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JSteam Toolbox Engineering Units

The toolbox comes with flexibility to support multiple unit sets to suit the user. Examples below cover their use, based on Examples/JSteam_Units.m.

Viewing All Units​

To view all unit sets, and the available units, use the following function:

>> JSteamMEX('PrintUnits')

            Pressure Units: bar, barg, psi, psig, kPa, MPa, atm  [Set via JSteamMEX('SetUnit','Pressure',unit)]
         Temperature Units: C, F, K, R  [Set via JSteamMEX('SetUnit','Temperature',unit)]
           Mass Flow Units: tonne/hr, kg/hr, kg/s, lbm/hr, lbm/s, ton(UK)/hr, ton(US)/hr  [Set via JSteamMEX('SetUnit','MassFlow',unit)]
           Mole Flow Units: kmol/hr, kmol/s, mol/hr, mol/s  [Set via JSteamMEX('SetUnit','MoleFlow',unit)]
               Power Units: kW, MW, W, Btu/hr, MMBtu/hr, kcal/hr, kcal/s, ft.lbf/hr, ft.lbf/s, hp(Mech), hp(Metric), hp(Elec), hp(Blr)  [Set via JSteamMEX('SetUnit','Power',unit)]
              Energy Units: kJ, J, cal, kcal, cal(th), kcal(th), Btu, MMBtu  [Set via JSteamMEX('SetUnit','Energy',unit)]
              Volume Units: m3, cm3, in3, ft3, gal(UK), gal(US)  [Set via JSteamMEX('SetUnit','Volume',unit)]
                Mass Units: kg, g, lbm  [Set via JSteamMEX('SetUnit','Mass',unit)]
                Mole Units: kmol, mol, lbmol  [Set via JSteamMEX('SetUnit','Mole',unit)]
           Viscosity Units: uPa.s, mPa.s, Pa.s, uP, mP, cP, P, lb/(ft.hr), lb/(ft.s), lbf.s/ft2, lbf.s/in2  [Set via JSteamMEX('SetUnit','Viscosity',unit)]
Thermal Conductivity Units: mW/(m.K), W/(m.K), W/(cm.K), cal/(s.cm.K), kcal/(hr.m.K), Btu.in/(hr.ft2.F), Btu.in/(s.ft2.F), Btu.ft/(hr.ft2.F)  [Set via JSteamMEX('SetUnit','ThermalConductivity',unit)]
               Basis Units: mass, mole  [Set via JSteamMEX('SetUnit','Basis',unit)]

As viewable above, every engineering unit within JSteam is customizable to a wide range of metric and imperial options. At any point you can check the current unit set via:

>> JSteamMEX('GetCurrentUnits')

ans =

  12×1 cell array

    {'bar'     }
    {'C'       }
    {'tonne/hr'}
    {'kmol/hr' }
    {'kW'      }
    {'kJ'      }
    {'kg'      }
    {'kmol'    }
    {'m3'      }
    {'uPa.s'   }
    {'mW/(m.K)'}
    {'mass'    }

Or check a specific unit:

JSteamMEX('GetUnit','Pressure')

ans =

    'bar'

Changing Units​

To change units, simply use the SetUnit functionality:

JSteamMEX('SetUnit','Pressure','MPa')
JSteamMEX('SetUnit','Temperature','K')

%Get Current Units [to check]
>> JSteamMEX('GetCurrentUnits')

ans =

  12×1 cell array

    {'MPa'     }
    {'K'       }
    {'tonne/hr'}
    {'kmol/hr' }
    {'kW'      }
    {'kJ'      }
    {'kg'      }
    {'kmol'    }
    {'m3'      }
    {'uPa.s'   }
    {'mW/(m.K)'}
    {'mass'    }

Computations done with the new unit set will expect inputs in MPa and K, as below:

%Example thermo call
H = JSteamMEX('HPT',0.1,373.15)

H =

          2675.76736720583

At any point you can revert to the default unit set:

%Revert to default
JSteamMEX('SetDefaultUnits')

%Example thermo call
H = JSteamMEX('HPT',1,100)

H =

          2675.76736720583

You may also save the current unit set and return to it later, as below:

myUnits = JSteamMEX('GetCurrentUnits');

% Example computation in different units
JSteamMEX('SetUnit','Pressure','MPa');
H = JSteamMEX('HPT',0.1,100)

% Return to original unit set
JSteamMEX('SetCurrentUnits',myUnits);

Unit Conversion​

The toolbox also provides Unit Conversion functionality between any of the available units:

% Same Basis
JSteamMEX('ConvUnit',10,'kg/s','kg/hr')

% New Basis requires Molecular Weight
JSteamMEX('ConvUnit',350,'kJ/kg','cal(th)/lbmol',18)

Note if converting between mass vs mole you will need the molecular weight of the fluid/mixture.