Steam Dump Tube Calculation Example in VBA
The picture below shows steam dump tube calculation example using the nozzle functions of ES_StableIF97_AddIn Demo software in VBA(Visual Basic Application), in which Design and Off-design calculations are possible.
In Design calculation, dump tube hole area is calculated, while in Off-design calculation the flow rate through dump tube is calculated based on the hole area fixed in Design calculation.
In the right hand part of the picture below, a command button "Calculate" and a combo box are located, and in the combo box User can select either one of "Design(Area Calc)" or "Off-design(Flow Calc)".
In the picture below, the dump tube hole area is "0.07285 m2" and the inlet steam pressure and temperature of dump tube are "3 bara" and "200 oC" respectively. And the steam flow rate through the dump tube is calculated as "31.5547 kg/s" by Off-design(Flow Calc).
Please note that design inlet steam pressure and temperature of the dump tube were "5 bara" and "250 oC" respectively and the dump tube hole area was calculated as "0.07285 m2" by Design(Area Calc).
The VBA codes of the example above are as shown in the picture below.
In the VBA codes "cmbOption" is the name of the combo box and "cmdCalculate" is the name of the command button of the picture above.
For VBA coding please refer to relevant text book and for how to use ES_StableIF97_AddIn software in VBA please refer to Use in MS Office VBA and Visual Basic.
In the codes below, it is seen in the event of "Private Sub cmdCalculate_Click()" that the unit numbers inclusive PressUnitNo refer to the cells of "Sheet3", which has the sheet name of "Nzl Unit" and includes the Unit Legend. Therefore, by change of the unit numbers of the Unit Legend in the "Nzl Unit" sheets, the units of this Excel VBA program can be changed.
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