**ES_StableIF97 AddIn**

ES_StableIF97 AddIn provides steam table add-in functions for use in Microsoft(R)(hereinafter MS) Excel 2002(version 10.0) or later version. ES_StableIF97 AddIn uses the MS Office software technology of Automation Add-in and COM Add-in.

One of the reasons that engineers use Excel so frequently is its handy calculation functions including its built-ins such as SUM, IF, LOOKUP, etc. ES_StableIF97 AddIn adds steam table functions to the built-in Excel functions, and make you forget about steam table lookup in Excel operation.

The steam table functions of ES_StableIF97 AddIn provides property values based on IAPWS-IF97 equations. IAPWS-IF97 stands for "IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam" and IAPWS is an international non-profit association of national organization with the full name of "The International Association for the Properties of Water and Steam".

Salient features of ES_StableIF97 AddIn are as below :

**148
Numbers Steam Table Functions**

As an example, the ES_StableIF97 AddIn function "=ESStb_HbyPT(A1, A2, PUN, TUN, HUN)" performs lookup of enthalpy for a pressure value of cell A1 and a temperature value of cell A2, and then assigns the enthalpy value to the cell value that includes the function.

PUN, TUN, and HUN is specific unit numbers for pressure, temperature and enthalpy. ES_StableIF97 AddIn provides 148 numbers of steam table functions.

ES_StalbeIF97 steam table function covers the pressure and temperature range same with IAPWS-IF97. That is, 611.213 Pa <= Pressure <= 100 MPa for 273.15 K <= Temperature <= 1073.15 K, and 611.213 Pa <= Pressure <= 50 MPa for 1073.15 K < Temperature <= 2273.15 K.

Among the steam table functions, there are 7 metastable vapor functions for the range of "0.00611213 bar <= Pressure <= 100 bara" and "273.15 K <= Temperature <= 1073.15 K"

Nozzle functions are also provided. There are two kinds of nozzle functions. One is choking nozzle functions, and the other is sub-critical nozzle functions with nozzle outlet pressure given.

**9
Numbers Unit Conversion Functions and Unit String Functions**

The output value's units of steam table functions can be varied by changing the output unit number arguments of the functions. For example, by changing the HUN argument of "ESStb_HbyPT", the output enthalpy unit is changed.

However, the input property values, e.g., the pressure and temperature of the function "ESStb_HbyPT" can not be changed by changing the respective Unit Numbers, e.g. PUN and TUN arguments of the "ESStb_HbyPT" function. Such input property values respond to unit number changes when they are input by ES_StableIF97 Unit Conversion Functions.

As an example, the Pressure Unit Conversion Function of "ESStb_CvtP(30, 2, 0)" converts "30" "bar a" pressure into "kg/cm2 a" unit. In the function, "30" is source value and "2" is the unit number of the source value. Pressure Unit Number(PUN) "2" represents "bar a". The last argument "0" is the unit number of the output value. PUN "0" represents "kg/cm2 a". If in the function the output unit number changes another unit number, the unit of output value can be changed accordingly.

In the example above, the user may embed into the cell A1 a pressure unit conversion function as "= ESStb_CvtP(30, 2, N1)" and embed into the cell A3 the steam table function as "=ESStb_HbyPT(A1, A2, N1, TUN, HUN)". After that, if the user changes the pressure unit number of cell N1 to the number he wants, the pressure value in cell A1 changes automatically to the number he wants and the enthalpy value in cell A3 remains as it was. No enthalpy change in cell A3 is not wrong because the real pressure value in cell A1 is always 30 "bar a" in any cases.

Other ES_StableIF97 AddIn functions are the functions providing the user with unit description string for unit numbers. By unit numbers only, it is not easy for the user to recognize what they are. As an example, the pressure unit string function "ESStb_PUnitStr(0)" value is "kg/cm2 a", where "0" is pressure unit number. As another example, the user may input the pressure unit number in cell A1 and embed into cell A2 the pressure unit string function "= ESStb_PUnitStr(A1)". Then, if the user changes the unit number in cell A1, then cell A2 represents the pressure unit string the user changes.

**Function
Embedding by Form**

The steam table functions can be embedded into Excel by using a form, named "ES_StableIF97 AddIn Functions", that guides the user's function embedding. The user does not need to remember the syntax of ES_StableIF97 AddIn functions. The form can be invoked by ES_StableIF97 AddIn's own menu or toolbar that are automatically embedded in Excel menu bar and toolbar.

**Unit
Selection by Form**

The unit of each property can be set independently so that the user may set any combination of units as he want. But, a separate form, named "ES_StableIF97 AddIn Units", is provided to guide the user's unit selection. The form can be invoked by ES_StableIF97 AddIn's menu or toolbar, too. The user's selection of units can be saved as a default unit set that is invoked every time the user starts Excel.

**Unit
Legend**

The unit set of the user's selection in "ES_StableIF97 AddIn Units" form can be embedded into Excel, as an Unit Legend, by which the user can manipulate the units of all functions he has already embedded into an Excel workbook. In order to change the units of functions in an Excel workbook, the user does not need to change the unit integer numbers of every function he embedded. By changing unit integer numbers of the Unit Legend, the user can change the units of all functions in the Excel workbook, if the user embedded the functions with the cell addresses of the Unit Legend for unit number arguments. Once a Unit Legend is embedded or located before invoking "ES_StableIF97 AddIn Function" form, the cell addresses of the Unit Legend input into function equations can be automatically done in "ES_StableIF97 AddIn Function" form,

The Unit Legend is embedded into Excel by the form "ES_StableIF97 AddIn Units", where a checkbox named "Embed or Locate <ESStb> Unit Legend" is provided for the user's selection. By checking the checkbox, the Unit Legend is embedded into Excel or located existing Unit Legend. For the selection between embedding and location, two option buttons are provided inside of the form.

The function embedding form "ES_StableIF97 AddIn Functions" has a checkbox for toggling between unit numbers and cell addresses for unit number arguments input. The name of the checkbox is "Cell Address Input for Unit Number"

**Other
References and Examples :**

Numerical Consistency of ES_StableIF97 Steam Table Functions

Numerical Consistency of ES_StableIF97 Dynamic Viscosity Functions

Numerical Consistency of IAPWS-IF97 Backward Equations

Region 1 Pressure with Temperature and Enthalpy Given

Region 5 Steam Property Values

Jurisdiction of 1073.15 oK Temperature

Use in MS Office VBA and Visual Basic

Samples of Direct Function Input in MS Excel

Steam Turbine Calculation Example

Steam Dump Tube Calculation Example

Steam Dump Tube Calculation Example in VBA

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