recordBubbleDewStatePropertiesBaseDataDefinition
Extends from Modelica.Icons.Record (Icon for records).
Information
This record is a base data definition for fitting coefficients of the thermodynamic state properties at bubble and dew line. If these state properties are not expressed as fitted formula, the state properties at vapour-liquid equilibrium will be identified iteratively and, as a consequence, the computing time will rise (Thorade and Matthias, 2012). In order to reduce the computing time, the thermodynamic state properties are expressed as fitted formula based on the approach presented by Sangi et al. within their " Fast_Propane" model.
Sangi et al. used the following fitting approaches, which are
also implemented within
AixLib.Media.Refrigerants.Interfaces.TemplateHybridTwoPhaseMediumRecord:
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Saturation pressure |
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Saturation temperature |
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Bubble density |
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Dew density |
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Bubble Enthalpy |
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Dew Enthalpy |
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Bubble Entropy |
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Dew Entropy |
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As it can be seen, the fitted formulas consist basically of the coefficient ei as well as of the parameters Meani and Stdi. These coefficients are the fitting coefficients and must be obtained during a fitting procedure. While the fitting procedure, the formulas presented above are fitted to external data (e.g. obtained from measurements or external media libraries) and the fitting coefficients are determined.
Assumptions and limitations
The fitting procedure is performed for a predefined range of the external data that is given in terms of, for example, temperature and pressure. As a consequence, the fitting coefficients are also just valid within the predefined range of external data.
References
Thorade, Matthis; Saadat, Ali (2012): HelmholtzMedia - A fluid properties library. In: Proceedings of the 9th International Modelica Conference; September 3-5; 2012; Munich; Germany. Linköping University Electronic Press, S. 63–70.
Sangi, Roozbeh; Jahangiri, Pooyan; Klasing, Freerk; Streblow, Rita; Müller, Dirk (2014): A Medium Model for the Refrigerant Propane for Fast and Accurate Dynamic Simulations. In: The 10th International Modelica Conference. Lund, Sweden, March 10-12, 2014: Linköping University Electronic Press (Linköping Electronic Conference Proceedings), S. 1271–1275
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| General | |||
| String | name | Short description of the record | |
| Saturation pressure | |||
| Integer | psat_Nt | Number of terms for saturation pressure | |
| Real[:] | psat_N | First coefficient for saturation pressure | |
| Real[:] | psat_E | Second coefficient for saturation pressure | |
| Saturation temperature | |||
| Integer | Tsat_Nt | Number of terms for saturation temperature | |
| Real[:] | Tsat_N | Fitting coefficients for saturation temperature | |
| Real[:] | Tsat_IO | Mean input (p) | Std input (p) | Mean output (T) | Std output (T) | |
| Bubble density | |||
| Integer | dl_Nt | Number of terms for bubble density | |
| Real[:] | dl_N | Fitting coefficients for bubble density | |
| Real[:] | dl_IO | Mean input (T) | Std input (T) | Mean output (dl) | Std output (dl) | |
| Dew density | |||
| Integer | dv_Nt | Number of terms for dew density | |
| Real[:] | dv_N | Fitting coefficients for dew density | |
| Real[:] | dv_IO | Mean input (T) | Std input (T) | Mean output (dv) | Std output (dv) | |
| Bubble Enthalpy | |||
| Integer | hl_Nt | Number of terms for bubble enthalpy | |
| Real[:] | hl_N | Fitting coefficients for bubble enthalpy | |
| Real[:] | hl_IO | Mean input (p) | Std input (p) | Mean output (hl) | Std output (hl) | |
| Dew Enthalpy | |||
| Integer | hv_Nt | Number of terms for dew enthalpy | |
| Real[:] | hv_N | Fitting coefficients for dew enthalpy | |
| Real[:] | hv_IO | Mean input (p) | Std input (p) | Mean output (hv) | Std output (hv) | |
| Bubble Entropy | |||
| Integer | sl_Nt | Number of terms for bubble entropy | |
| Real[:] | sl_N | Fitting coefficients for bubble entropy | |
| Real[:] | sl_IO | Mean input (p) | Std input (p) | Mean output (sl) | Std output (sl) | |
| Dew Entropy | |||
| Integer | sv_Nt | Number of terms for dew entropy | |
| Real[:] | sv_N | Fitting coefficients for dew entropy | |
| Real[:] | sv_IO | Mean input (p) | Std input (p) | Mean output (sv) | Std output (sv) | |
Revisions
- June 9, 2017, by Mirko Engelpracht, Christian Vering:
First implementation (see issue 408).