International Steam Tables - IAPWS-IF97
By Hans-Joachim Kretzschmar
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The "International Steam Tables - IAPWS-IF97" app has been developed by active members of the International Association for the Properties of Water and Steam (IAPWS) at the Zittau/Goerlitz University of Applied Sciences. The research group at the Department of Technical Thermodynamics in Zittau participated in the development of the "Industrial Formulation IAPWS-IF97 for the Properties of Water and Steam" and developed four supplementary standards for backward equations.
This universal app can be used on iPhone, iPad, and iPod touch, and is designed for comfortable use. The calculations of the thermodynamic properties are based on the Industrial Formulation IAPWS-IF97 and cover its full range of validity. In addition, transport properties, thermodynamic derivatives, and backward functions can be calculated.
This app is intended to be used by students and engineers in their daily work.
To learn more about the "International Steam Tables - IAPWS-IF97" app visit our website www.thermodynamics-zittau.de for a detailed User's Guide.
Features of the "International Steam Tables - IAPWS-IF97" app:
The following combinations of input variables can be chosen:
Pressure p and temperature t
Pressure p and vapor fraction x in wet steam region
Temperature t and vapor fraction x in wet steam region
Pressure p and specific enthalpy h
Pressure p and specific entropy s
Specific enthalpy h and specific entropy s
Specific internal energy u and specific volume v
Specific enthalpy h and specific volume v
The user just edits the values of the input variables and all results are calculated automatically. See the screenshots below this text for details.
Depending on the given pair of input variables the following properties will be calculated:
Pressure p or saturation pressure ps
Temperature t or saturation temperature ts
Vapor fraction x
Specific volume v
Specific internal energy u
Specific enthalpy h
Specific entropy s
Specific isobaric heat capacity cp
Specific isochoric heat capacity cv
Isentropic exponent kappa
Speed of sound w
Isobaric cubic expansion coefficient alpha_v
Isothermal compressibility kappa_t
Thermal conductivity lambda
Dynamic viscosity eta
Kinematic viscosity ny
Prandtl number Pr
Thermal diffusivity a
The calculated properties are displayed in a scrollable view. The user just needs to scroll down to see all the results. See the screenshots below for details.
If the user switches from one input variable combination to another the previously given or calculated values will be assigned to the new input values and the output is being calculated automatically. For example, if the user calculates a certain state point from pressure p and temperature t and switches to a calculation from pressure p and specific entropy s afterwards, the previously calculated value for s (from p and t) will be assigned as input value for s. This eases the calculation of thermodynamic processes in which one property is kept constant, e. g. of an isentropic expansion.
The user can choose SI or I-P unit systems. In addition a variety of other units are available,
K, °C, °F, °R for Temperature,
MPa, bar, psi, atm for pressure,
kg, lb for mass,
kJ, Btu, ft lbf, kcal for energy.
All units can be selected independently but the user might also switch between SI and IP unit system for all properties with just one tap. See the screenshots below this text for details.
Unit conversions will be effective immediately.
A detailed User's Guide explains the features and capabilities of this App. View the User's guide online on www.thermodynamics-zittau.de.
Nice for the practicing engineer!
Spot-checked against a copy of Keenan & Keyes (1969) with good agreement. I understand that the IAPWS-IF97 formulation gives slightly different results than the classic tables ... As the joke goes, if you're worried about the fourth significant digit, you're already in trouble! Nice and useable, fast results, and handy to have instead of a book taking up space.
Possible suggestions for future versions:
* please clarify I-P units (specify psia, for instance, instead of psi)
* it was not immediately obvious how to get to saturation properties (use the p,x or t,x tabs and set quality to 1 for vapor and 0 for liquid), maybe if there was a quick toggle option that would help
* take better advantage of the real estate on the iPad -- less scrolling or f, fg, and g saturation properties in a three-column table
* provide a way to mix units -- e.g., enter units in I-P and get SI results without having to toggle the entry units as well, but this may add needless complexity
* instead of verbose property descriptions consider the use of standard nomenclature (h instead of enthalpy, s instead of entropy, cp instead of isobaric heat capacity) with a touch to bring up verbose description or an option to switch between the two.
works great, solid app
this app is one of my most valuable tools. perfect for steam plant work and power systems analysis. quick, easy to use, and beats the HELL out of doing table lookups with interpolations all day.
one suggestion for improvement would be to include "thermodynamics" in the keywords list for AppStore searching. I almost didnt find this app? good thing I stumbled upon it.
USE THIS ONE!
If you're an engineering student, this is the steam app you want. It includes compressed water properties too, which the other apps don't have. Almost all units available including mixing an matching of English and Standard units. Great app, I wish I had this when I took Thermo.