Steam Pad app for iPhone and iPad

1. Introduction
Steam Pad calculates the thermodynamic and transport properties of water and steam, using the latest releases of IAPWS. It has some distinctive features, and is applicable for industrial, engineering, and teaching processes:
− Uses any selected 2 basic parameters to calculate others.
− Provides T-S, H-S, P-H, T-H charts, and locates results (point locations) on them.
− Computes additional thermodynamic and transport parameters.
− Allows saving the results, and supports restoring one of them.

2. Calculator
2.1 Inputs and outputs
By given any selected 2 parameters as the inputs from the Basics (Pressure, Temperature, Enthalpy, Entropy, Specific volume, Vapour Fraction), this App calculates other 4 parameters, and calculates some other thermodynamic and transport parameters. The inputs and outputs of the basics can alternate, which fulfills alterable calculating demands.
2.2 The range of validity
The range of validity defined by pressure and temperature for general properties is the same to the definition in the release of IAPWS IF97.
2.3 Single-Phase regions and Two-Phase region
The calculating demands are handled coordinately both for the Single-Phase regions and the Two-Phase region. The calculated properties and the corresponding region of the results can be distinguished from inputs automatically, and will be displayed in the outputs list box. For example, the saturation properties can be derived from the given P (less than 22.06395Mpa) and X (0.0-1.0).
2.4 Other properties
The optional parameters are calculated based on the releases of IAPWS, or on the physical models, which include:
− u: Specific internal energy
− Specific isobaric heat capacity
− Specific isochoric heat capacity
− Speed of sound
− Dynamic viscosity
− Kinematic viscosity
− Thermal conductivity
− Entropy index
− Static Dielectric Constant
− Prandtl number
2.5 Units
The parameters are shown in SI(metric) or in I-P(English) system of units, which can be reset in the Outputs Setting function of the app.

3. Charts
3.1 Chart types
Typical thermodynamic charts are embedded in this app, and displayed as vector-graphs. Only regions 1 to 4 are shown in the charts, and region 5 is ignored for the applicative concern. The gradual changes (the lines) of the other 4 parameters along with the X and Y ordinates, are shown in the charts.
There are 4 charts available:
− T-S Chart
− H-S Chart
− P-H Chart
− T-H Chart
3.2 Charts display
− The lines of other 4 parameters are displayed in different colors.
− Lines are displayed or hidden by checking the checkboxes.
− The charts can be moved, enlarged or contracted by dragging or pinching gestures of fingers.
− The corresponding values are attached along with the lines at certain intervals.
− The boundary of the saturation region, and the critical point, are especially identified.
3.3 Calculated results
The calculated results will be located in the charts as an identifying point (or points) with the corresponding ordinates.

4. Results
The calculated records, each of which contains 6 basic parameters, can be stored in a row in the list of the Results panel by clicking the Save button on the Calculator panel.
− The 2 inputs of one record are displayed in a distinctive color.
− The region of each result, as well as the possible arrangement number of multiple outputs, is shown on the top of the row.
− The records can be re-arranged and be deleted.
− The selected record can be restored both on the Calculator panel and on the Charts panel, by clicking the Restore button.