# IAPWS-IF97 Equations for Regions 1, 2, 3 and 5 Compute thermodynamic and transport properties of water and steam using the IAPWS industrial formulation 1997. ```r if97(what, p, t, h, state = NULL) ``` ## Arguments - `what`: a character vector listing the output properties. See Details for available properties. - `p`: a numeric vector giving the pressure values in MPa. - `t`: a numeric vector giving the temperature values in K. - `h`: a numeric vector giving the specific enthalpy values in kJ/kg. - `state`: `NULL` or a character vector giving the physical state. One of `"liquid"`, `"gas"` or `"supercritical"`. In case of `NULL`, the state is determined by the function `if97_state()`. ## Details The available properties for `what` are: * `"f"`: the specific free energy in kJ/kg. * `"g"`: the specific Gibbs enthalpy in kJ/kg. * `"u"`: the specific internal energy in kJ/kg. * `"h"`: the specific enthalpy in kJ/kg. * `"s"`: the specific entropy in kJ/K/kg. * `"t"`: the temperature in K. * `"p"`: the pressure in MPa. * `"v"`: the specific volume in m$^3$/kg. * `"rho"`: the mass density in kg/m$^3$. * `"cv"`: the specific isochoric heat capacity in kJ/K/kg. * `"cp"`: the specific isobaric heat capacity in kJ/K/kg. * `"alpha"`: the expansion coefficient in 1/K * `"beta"`: the pressure coefficient in MPa/K. * `"kappat"`: the isothermal compressibility in 1/MPa. * `"w"`: the speed of sound in m/s. * `"eta"`: the dynamic viscosity in $\mu$Pa.s. * `"lambda"`: the thermal conductivity in mW/K/m. A valid pair of `p`, `t` and `h` is needed: either `(p, t)` or `(p, h)`. ## Returns A numeric matrix of dimension `c(n, length(what))` with `n` the maximum length of either `p`, `t`, `h` or `state`. ## References International Association for the Properties of Water and Steam, IAPWS R7-97(2012), **Revised Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam.** International Association for the Properties of Water and Steam, IAPWS R12-08(2008), **Release on the IAPWS Formulation 2008 for the Viscosity of Ordinary Water Substance.** International Association for the Properties of Water and Steam, IAPWS R15-11(2011), **Release on the IAPWS Formulation 2011 for the Thermal Conductivity of Ordinary Water Substance.** ## Author(s) Jonathan Debove ## Note Computing several properties in a single call may be more efficient than separately because most of the computation time is shared. ## Examples ```r what <- c("v", "h", "u", "s", "cp", "w") # Region 1 Tab. 5 tab5 <- if97(what, t = c(300, 300, 500), p = c(3, 80, 3)) format(tab5, scientific = TRUE, digits = 9) # Region 2 Tab. 15 tab15 <- if97(what, t = c(300, 700, 700), p = c(3.5e-3, 3.5e-3, 30)) format(tab15, scientific = TRUE, digits = 9) # Region 2 metastable Tab. 18 tab18 <- if97(what, t = c(450, 440, 450), p = c(1, 1, 1.5), state = "gas") format(tab18, scientific = TRUE, digits = 9) # Region 3 Tab. 33 tab33 <- if97(what, t = c(650, 650, 750), p = c(0.255837018e2, 0.222930643e2, 0.783095639e2)) format(tab33, scientific = TRUE, digits = 9) # Region 5 Tab. 42 tab42 <- if97(what, t = c(1500, 1500, 2000), p = c(0.5, 30, 30)) format(tab42, scientific = TRUE, digits = 9) # Viscosity and thermal conductivity what <- c("lambda", "eta") # Region 1 Tab. 7 tab7 <- if97(what, p = c(20, 50), t = c(620, 620)) format(tab7, scientific = TRUE, digits = 9) # Region 2 Tab. 8 tab8 <- if97(what, p = c(0.3, 50), t = c(650, 800)) format(tab8, scientific = TRUE, digits = 9) ## Region 3 Tab. 9 #tab9 <- if97_rhot(c("lambda", "rho", "cp", "cv", "eta"), # rho = c(0.3, 50), t = c(222, 322)), #format(tab9, scientific = TRUE, digits = 9) ```

if97 function