An Excel workbook with open-source user-defined Visual Basic functions in module 'FluidProps.bas' to calculate the following thermophysical properties, and is usesful for engineers, meteorologists and others:
- Psychrometrics of moist air
- Atmospheric properties: Wind, temperature and pressure as a function of altitude
- Gases: Dry air and ideal gases
- Water
- Antifreeze coolants
- Refrigerants
- Flow friction in pipes/ducts
Conventional fluid property software solve equation-of-state (EOS) equations for each constitulent molecule in the fluid mixture. This approach is very flexible, but has two drawbacks: (i) It is slow because some properties, e.g. enthalpy, are calculated by a combination of root-solving iteration and numerical integration, and (ii) The most popular forms (Cubic EOS) are known to deviate significantly from true measured thermophysical properties. FluidProps instead applies regressions that are significantly faster, and pretty accurate. For the refrigerants in particular, the propeties apply up to the critical-point with optimized rational functions of reduced temperature. In the code is documented the range of applicability, correlation coefficient (R²), and maximum deviation, for most of the correlations.
- Water_Dens(Tw_K)
[kg/m³] Density of liquid water at 101325 Pa - Water_Cp(Tw_K)
[J/(kg·K)] Heat capacity of liquid water at 101325 Pa - Water_Conduct(Tw_K)
[W/(m·K)] Thermal conductivity of liquid water and solid ice at 101325 Pa - Water_KineVisc(Tw_K)
[m²/s] Kinematic viscosity of liquid water at 101325 Pa - Water_DynaVisc(Tw_K)
[Pa·s] Dynamic viscosity of liquid water at 101325 Pa - Water_Pr(Tw_K)
[-] Prandtl number of liquid water at 101325 Pa - Water_Enth(Tw_K)
[J/kg] Specific enthalpy of liquid water at 101325 Pa - Water_thermDiff(Tw_K)
[m²/s] Thermal diffusivity of liquid water at standard pressure (101325 Pa) - Vapour_Pws(Tdry_K, Optional ice As Boolean = False)
[Pa] Saturation vapour pressure, i.e. the equilibrium water vapor pressure above a flat surface - Vapour_Cp(Tdry_K)
[J/(kg·K)] Heat capacity of water vapour, valid near 101325 Pa - Vapour_Dv(Tdry_K, Patm_Pa)
[m²/s] Vapour mass diffusivity of water vapour in air. A.k.a. diffustion coefficient. Used to calculate Schmidt number - EthyleneGlycol_VolFraction(Tfreeze_C)
[-] Minimum required volume fraction of Ethylene Glycol for freezing point Tfreeze_C, valid at 101325 Pa - EthyleneGlycol_Dens(T_C, VolFraction)
[kg/m³] Density of aqueous solution of ethylene glycol coolant/antifreeze - EthyleneGlycol_Cp(T_C, VolFraction)
[J/(kg·K)] Specific heat capacity of aqueous solution of ethylene glycol coolant/antifreeze - EthyleneGlycol_Conduct(T_C, VolFraction)
[W/(m·K)] Thermal conductivity of aqueous solution of ethylene glycol coolant/antifreeze - EthyleneGlycol_DynaVisc(T_C, VolFraction)
[Pa·s] Dynamic viscosity of aqueous solution of ethylene glycol coolant/antifreeze - PropyleneGlycol_VolFraction(Tfreeze_C)
[-] Minimum required volume fraction of Propylene Glycol for freezing point Tfreeze_C, valid at 101325 Pa - PropyleneGlycol_Dens(T_C, VolFraction)
[kg/m³] Density of aqueous solution of Propylene glycol coolant/antifreeze - PropyleneGlycol_Cp(T_C, VolFraction)
[J/(kg·K)] Specific heat capacity of aqueous solution of Propylene glycol coolant/antifreeze - PropyleneGlycol_Conduct(T_C, VolFraction)
[W/mK] Thermal conductivity of aqueous solution of Propylene glycol coolant/antifreeze - PropyleneGlycol_DynaVisc(T_C, VolFraction)
[Pa·s] Dynamic viscosity of aqueous solution of Propylene glycol coolant/antifreeze - Refrigerant_Sbubble(Refrigerant, TK)
[kJ/kg] Bubble-point entropy, i.e. left side of Ts-diagram - Refrigerant_Sdew(Refrigerant, TK)
[kJ/kg] Dew-point entropy, i.e. right side of Ts-diagram - Refrigerant_CpDew(Refrigerant, TK)
[kJ/(kg·K)] Refrigerant gas-phase specific heat capacity, at dew-point temperature and pressure - Refrigerant_Hbubble(Refrigerant, TK)
[kJ/kg] Bubble-point enthalpy, i.e. left side of Ph-diagram - Refrigerant_Hdew(Refrigerant, TK)
[kJ/kg] Dew-point enthalpy, i.e. right side of Ph-diagram - Refrigerant_Tdew(Refrigerant, Pa)
[K] Dew-point temperature at pressure Pa - Refrigerant_Pdew(Refrigerant, TK)
[Pa] Stauration pressure given dew-point temperature - DryAir_KineVisc(Tdry_K)
[m²/s] Kinematic viscosity of dry air, valid at 101325 Pa - DryAir_DynaVisc(Tdry_K)
[Pa·s] Dynamic viscosity of dry air, valid at 101325 Pa - DryAir_Cp(Tdry_K)
[J/(kg·K)] Specific heat capacity of dry air, valid at 101325 Pa - DryAir_Conduct(Tdry_K)
[W/mK] Specific heat capacity of dry air, valid at 101325 Pa - DryAir_Pr(Tdry_K)
[-] Prandtl number of dry air, valid at 101325 Pa - DryAir_thermDiff(Tdry_K)
[m²/s] Thermal diffusivity of dry air at standard atmospheric pressure (101325 Pa) - Air_Cp(Tdry_K, HumidRatio)
[J/(k·gK)] Specific heat capacity of moist air - Air_Enth(Tdry_K, HumidRatio)
[J/kg dry air] Air specific enthalpy per kg dry air - Air_DryBulb(Enthalpy_Jkg, HumidRatio)
[K] Dry-bulb air temperature - Air_DensR(Tdry_K, RH, Patm_Pa)
[kg/m³] Air density, given RH - Air_DensH(Tdry_K, HumidRatio, Patm_Pa)
[kg/m³] Air density, given humidity ratio - Air_TdewP(Tdry_K, Pv_Pa)
[K] Dew-point (or frost-point) temperature, given parial pressure of vapour - Air_TdewH(Tdry_K, HumidRatio, Patm_Pa)
[K] Dew-point (or frost-point) temperature, given humidity ratio - Air_TdewR(Tdry_K, RH)
[K] Dew-point (or frost-point) temperature, given RH - Air_TdewW(Tdry_K, Twet_K, Patm_Pa)
[K] Dew-point (or frost-point) temperature, given wet-bulb temperature - Air_HumidRatioR(Tdry_K, RH, Patm_Pa)
[kg water vapour / kg dry air] Humidity ratio of moist air, given RH - Air_HumidRatioD(Tdew_K, Patm_Pa)
[kg water vapour / kg dry air] Humidity ratio of moist air, given dew-point temperature - Air_HumidRatioW(Tdry_K, Twet_K, Patm_Pa)
[kg water vapour / kg dry air] Humidity ratio of moist air, given wet-bulb tempeature - Air_HumidRatioX(SpecificHumid)
[kg water vapour / kg dry air] Humidity ratio of moist air, given specific humidity - Air_RHd(Tdry_K, Tdew_K, Optional ice As Boolean = False)
[-] Relative humidity (over liquid water), given dew-point temperature - Air_RHh(Tdry_K, HumidRatio, Patm_Pa)
[-] Relative humidity (over liquid water), given humidity ratio - Air_RHw(Tdry_K, Twet_K, Patm_Pa)
[-] Relative humidity (over liquid water), given wet-bulb temperature - Air_TwetH(Tdry_K, HumidRatio, Patm_Pa)
[K] Wet-bulb temperature, given humidity ratio. Fast iterative reverse calculation by secant method - Air_TwetR(Tdry_K, RH, Patm_Pa)
[K] Wet-bulb temperature, given RH - Air_TwetD(Tdry_K, Tdew_K, Patm_Pa)
[K] Wet-bulb temperature, given dew-point temperature - Atmos_Pa(Height_over_sea_level_m)
[Pa] Estimate of standard-atmosphere barometric pressure as a function of height over sea level - Atmos_Pa2(Atmos_Pa1, Atmos_T1, Altitude1_m, Altitude2_m)
[Pa] Estimate of atmospheric pressure at altitude 1 (e.g. sea level, og building site) given pressure andtemperature at Altitude2 (e.g. station altitude) - Atmos_T(Height_over_sea_level_m)
[K] Estimate temperature as a function of height over sea level. Valid in troposphere (<11km) - Atmos_T2(Atmos_T1, Altitude1_m, Altitude2_m)
[K] Estimate of dry-bulb temperature at Altitude2_m given Tdry1_K at aAltitude1_m. Assumes Environmental Lapse Rate (ELR) - Wind_Loc2_ms(Wind_Loc1_ms, Alpha_Loc1, Alpha_Loc2, Height_Loc2_m)
[m/s] Wind speed at Location 2 given wind speed from 10 m high weather station at Location1. - OrificeMassFlow_m3s(Tappings_str, DuctDia_m, OrificeDia_m, Tdry_K, RH, Patm_Pa, dP_Pa)
[m³/s] Volumetric air flow rate measured by means of pressure drop over an ISO 5167-1 orifice plate - Air_DuctFriction(FlowRate_m3s, Diam_m, Roughness_m, Tdry_K, RH, Patm_Pa)
[Pa/m] Pressure drop per meter duct, for airflow in ducts - Water_PipeFriction(FlowRate_m3s, Diam_m, Roughness_m, T_K)
[Pa/m] Pressure drop per meter pipe, for water flow in pipes - FrictionFactor(Re, relRough)
[-] Darcy friction factor for laminar or turbulent flow calculated with the Colebrook-White equation.
References are given for each individual function. Sources include "ASHRAE Fundamentals" handbook, and NIST chem. database
Free share-alike license (CC BY-SA 4.0): https://creativecommons.org/licenses/by-sa/4.0/. Provided with no warranty of any kind.
Source code and workbook are copyright peter.schild@oslomet.no
@Misc{Schild20,
author = {Schild, Peter G.},
title = {{FluidProps}: Open-source code to calculate therrmophysical properties for engineering},
howpublished = {\url{https://github.com/SchildCode/FluidProps/}},
doi = {10.5281/zenodo.10370491},
url = {https://doi.org/10.5281/zenodo.10370491}
year = {2020}
}