Jpye at 07:03, 19 May 2011

2011-05-19T07:03:58Z

← Older revision		Revision as of 07:03, 19 May 2011
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	The current {{src\|models/thermodynamics.a4l}} library in ASCEND does not allow for compressibility of liquids and is therefore too simplistic for use at the elevated pressures seen in large-scale power systems.		The current {{src\|models/thermodynamics.a4l}} library in ASCEND does not allow for compressibility of liquids and is therefore too simplistic for use at the elevated pressures seen in large-scale power systems.


	== Connection to freesteam ==		== Connection to freesteam ==

	[http://freesteam.sourceforge.net Freesteam] provides a free open-source implementation of the standard IAPWS IF-97 steam properties correlations for use with ASCEND via the [[external relation]] mechanism. Example models using these property correlations include those in {{src\|models/johnpye/rankine.a4c}}, which demonstrate a range of steam power cycle calculations.		[http://freesteam.sourceforge.net Freesteam] provides a free open-source implementation of the standard IAPWS IF-97 steam properties correlations for use with ASCEND via the [[external relation]] mechanism. Example models using these property correlations include those in {{src\|models/johnpye/rankine.a4c}}, which demonstrate a range of steam power cycle calculations.


	== IAPWS-95 Implementation ==		== IAPWS-95 Implementation ==
	~~<div class="notice metadata" id="~~outdated~~" style="border:solid 2pt #FDB; width:70ex; background~~-~~color:#FFF8F4;padding:4px;margin-bottom:6px">''This~~ section ~~is '''outdated'''. You can help out by <span class="plainlinks">[http://ascendwiki.cheme.cmu.edu/index.php?title=Steam_properties&action=edit updating it]</span>. ''</div>~~		{{outdated-section}}

	The [http://www.iapws.org/relguide/IAPWS95.pdf IAPWS-95 (pdf)] steam properties correlations have been implemented and can currently be used to obtain properties of single-phase steam. We are working on getting a stable two-phase model that is able to correctly accomodate the saturated region using a separate IAPWS correlation for the [http://www.iapws.org/relguide/supsat.pdf saturation curves (pdf)].		The [http://www.iapws.org/relguide/IAPWS95.pdf IAPWS-95 (pdf)] steam properties correlations have been implemented and can currently be used to obtain properties of single-phase steam. We are working on getting a stable two-phase model that is able to correctly accomodate the saturated region using a separate IAPWS correlation for the [http://www.iapws.org/relguide/supsat.pdf saturation curves (pdf)].
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	To see the current state of the steam tables work, go over to John Pye's ASCEND models at {{srcdir\|models/johnpye}}.		To see the current state of the steam tables work, go over to John Pye's ASCEND models at {{srcdir\|models/johnpye}}.


	== Other implementations ==		== Other implementations ==

	There is some interesting information to be gleaned from the Modelica ThermoFluid library, [http://sourceforge.net/projects/thermofluid]. This set of Modelica/Dymola models includes IAPWS-IF97 as well as some interesting although very complex approaches to the problems of modelling thermodynamic processes involving water and steam.		There is some interesting information to be gleaned from the Modelica ThermoFluid library, [http://sourceforge.net/projects/thermofluid]. This set of Modelica/Dymola models includes IAPWS-IF97 as well as some interesting although very complex approaches to the problems of modelling thermodynamic processes involving water and steam.


	== See also ==		== See also ==
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	* [http://cantera.sourceforge.net/documentation.html Cantera] (a C++/Python chemical reactions toolkit)		* [http://cantera.sourceforge.net/documentation.html Cantera] (a C++/Python chemical reactions toolkit)
	* Sublimation curve from IAPWS: {{src\|models/johnpye/sublimation.a4c}}		* Sublimation curve from IAPWS: {{src\|models/johnpye/sublimation.a4c}}



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== Background ==

In order to accurately model large-scale power systems such as boilers and steam turbines, accurate correlations for steam properties are required. The [http://www.iapws.org International Association for the Properties of Water and Steam] has industry-standard correlations for water and steam properties at pressures up to 10MPa and temperatures up to 1073 K. Higher temperatures are possible too, but not at the full range of pressures. These correlations are in many cases stipulated requirements when consulting engineers are contracted to perform analysis - in order that competing proposals are competing on a fair basis. In large-scale design, even quite small variations in steam properties can result in large differences in overall cost estimates.

The current {{src|models/thermodynamics.a4l}} library in ASCEND does not allow for compressibility of liquids and is therefore too simplistic for use at the elevated pressures seen in large-scale power systems.

== Connection to freesteam ==

[http://freesteam.sourceforge.net Freesteam] provides a free open-source implementation of the standard IAPWS IF-97 steam properties correlations for use with ASCEND via the [[external relation]] mechanism. Example models using these property correlations include those in {{src|models/johnpye/rankine.a4c}}, which demonstrate a range of steam power cycle calculations.

== IAPWS-95 Implementation ==
<div class="notice metadata" id="outdated" style="border:solid 2pt #FDB; width:70ex; background-color:#FFF8F4;padding:4px;margin-bottom:6px">''This section is '''outdated'''. You can help out by <span class="plainlinks">[http://ascendwiki.cheme.cmu.edu/index.php?title=Steam_properties&action=edit updating it]</span>. ''</div>

The [http://www.iapws.org/relguide/IAPWS95.pdf IAPWS-95 (pdf)] steam properties correlations have been implemented and can currently be used to obtain properties of single-phase steam. We are working on getting a stable two-phase model that is able to correctly accomodate the saturated region using a separate IAPWS correlation for the [http://www.iapws.org/relguide/supsat.pdf saturation curves (pdf)].

This work in ASCEND is to facilitate modelling of solar thermal and conventional power station systems.

For further information about IAPWS correlations and a list of some other IAPWS-savvy software, see [http://freesteam.sourceforge.net Freesteam].

To see the current state of the steam tables work, go over to John Pye's ASCEND models at {{srcdir|models/johnpye}}.

== Other implementations ==

There is some interesting information to be gleaned from the Modelica ThermoFluid library, [http://sourceforge.net/projects/thermofluid]. This set of Modelica/Dymola models includes IAPWS-IF97 as well as some interesting although very complex approaches to the problems of modelling thermodynamic processes involving water and steam.

== See also ==

* [[Thermodynamics with ASCEND]]
* [http://freesteam.sourceforge.net freesteam]
* [http://cantera.sourceforge.net/documentation.html Cantera] (a C++/Python chemical reactions toolkit)
* Sublimation curve from IAPWS: {{src|models/johnpye/sublimation.a4c}}

[[Category:Outdated]]

Steam properties - Revision history

Jpye at 07:03, 19 May 2011

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