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Merge pull request #1457 from open-ideas/issue1381_EmbeddedPipe
Issue1381 embedded pipe
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‎IDEAS/Fluid/HeatExchangers/RadiantSlab/BaseClasses/RadiantSlabChar.mo‎

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within IDEAS.Fluid.HeatExchangers.RadiantSlab.BaseClasses;
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record RadiantSlabChar
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"Record containing all parameters for a given a floor heating of concrete core activation"
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// The terminology from prEN 15377 is followed, even if I find the development of the theory
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// by Koschenz and Lehmann better (see Thermoaktive Bauteilsysteme tabs, from Empa)
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// First Version 20110622
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// Changed 20110629:
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// Important: this record ALSO contains the parameters that are specific to the building.
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"Record containing all parameters for a given thermally activated building system (TABS) or a floor heating system."
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extends Modelica.Icons.Record;
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parameter Boolean tabs = true
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"true if the model is used for tabs, false if the model is used for floor heating. This is used for the correction factor of the thermal resistances in EmbeddedPipe";
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"= true, if the model is used for TABS (assuming no insulation layer below the slab).";
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parameter Modelica.Units.SI.Length T(
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min=0.15,
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max=0.3) = 0.2 "Pipe spacing, limits imposed by prEN 15377-3 p22";
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max=0.3) = 0.2 "Pipe spacing, limits imposed by EN 15377-3 p22";
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parameter Modelica.Units.SI.Length d_a=0.02 "External diameter of the pipe";
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parameter Modelica.Units.SI.Length s_r=0.0025 "Thickness of the pipe wall";
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parameter Modelica.Units.SI.ThermalConductivity lambda_r=0.35
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// Extra parameters for floor heating
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parameter Modelica.Units.SI.ThermalConductivity lambda_i=0.036
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"heat conductivity of the isolation";
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parameter Modelica.Units.SI.Length d_i=0.05 "Thickness of the insulation";
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final parameter Real alp2 = lambda_i / d_i
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"help variable for resistance calculation";
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"Heat conductivity of the insulation" annotation(Dialog(enable=not tabs));
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parameter Modelica.Units.SI.Length d_i=0.05
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"Thickness of the insulation" annotation(Dialog(enable=not tabs));
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parameter Modelica.Units.SI.CoefficientOfHeatTransfer alp1 = 3
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"Convective heat transfer coefficient between the floor layer and the room above" annotation(Dialog(enable=S_1<=0.3*T and S_2<=0.3*T));
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parameter Modelica.Units.SI.CoefficientOfHeatTransfer alp2 = if tabs then 0.3 else lambda_i / d_i
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"Convective heat transfer coefficient between the floor layer and the room below.
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In case of a floor heating system, this variable is set equal to the ratio of the heat conductivity and thickness of the insulation" annotation(Dialog(enable=S_1<=0.3*T and S_2<=0.3*T));
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annotation (Documentation(info="<html>
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<p><b>Description</b> </p>
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<p>Record containing the properties of a floor heating or TABS. The&nbsp;terminology&nbsp;from&nbsp;prEN&nbsp;15377&nbsp;is&nbsp;followed,&nbsp;even&nbsp;if&nbsp;I&nbsp;find&nbsp;the&nbsp;development&nbsp;of&nbsp;the&nbsp;theory by&nbsp;Koschenz&nbsp;and&nbsp;Lehmann&nbsp;better&nbsp;(see&nbsp;Thermoaktive&nbsp;Bauteilsysteme&nbsp;tabs,&nbsp;from&nbsp;Empa)</p>
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<h4>Model use</h4>
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<ol>
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<li>It&apos;s important to set at least the floor surface to something different from 1</li>
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<li>The embeddedPipe model has a few assertions to check the validity of some parameters and their combinations.</li>
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</ol>
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<p>
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Record containing the properties of a thermally activated building system (TABS) or floor heating system.
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The terminology from EN 15377 is followed, while the
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<a href=modelica://IDEAS.Fluid.HeatExchangers.RadiantSlab.EmbeddedPipe>EmbeddedPipe</a> model
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itself is based on the model of Koschenz and Lehmann.
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</p>
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<p>
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Note that this record contains parameters that are related to the building envelope, i.e. construction layer thicknesses and material properties.
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The user is responsible to use consistent parameters for the building envelope components and the embedded pipe model.
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When filling in the parameters, take into account that:
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<ul>
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<li>
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the insulation parameters (<code>lambda_i</code>, <code>d_i</code>) only need to be provided if
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you model a floor heating system (if <code>tabs=false</code>)
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</li>
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<li>
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the convective heat transfer coefficients (<code>alp1</code> and <code>alp2</code>) only need to be provided if
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<code>S_1</code> and/or <code>S_2</code> are smaller or equal to 0.3 times the pipe spacing (<code>T</code>).
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</li>
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<li>
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the floor layer thicknesses (<code>S_1</code>, <code>S_2</code>) and pipe diameter (<code>d_a</code>) are subject to some constraints,
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which are checked in the <a href=modelica://IDEAS.Fluid.HeatExchangers.RadiantSlab.EmbeddedPipe>EmbeddedPipe</a> model, i.e.:
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<ul>
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<li>
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<code>d_a &geq; S_1+S_2</code>
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</li>
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<li>
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if <code>tabs=false</code>, then <code>alp2 &geq; 1.212</code>
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</li>
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<li>
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if <code>tabs=false</code>, then <code>d_a/2 &geq; S_2</code>
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</li>
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</ul>
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</li>
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</ul>
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</p>
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<p>
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The default values of convective heat transfer coefficients <code>alp1</code> and <code>alp2</code> (in case of <code>tabs=true</code>)
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are determined using the interior convection correlations as provided in the documentation of
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<a href=modelica://IDEAS.Buildings.Components.BaseClasses.ConvectiveHeatTransfer.InteriorConvection>
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IDEAS.Buildings.Components.BaseClasses.ConvectiveHeatTransfer.InteriorConvection</a>,
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for a room of <i>25 m<sup>2</sup></i> and a temperature difference between the slab and the room of <i>5°C</i>.
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If <code>tabs=false</code>, <code>alp2</code> is set equal to <i>&lambda;<sub>i</sub> / d<sub>i</sub></i>,
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which is a valid assumption since the conductive thermal resistance of the floor heating's insulation is
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significantly higher than the convective thermal resistance between the slab's surface and the room.
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</p>
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<h4>References</h4>
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<p>
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EN 15377, <i>Heating systems in buildings – Design of embedded water-based surface heating and cooling systems</i>, 2008.
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</p>
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<p>
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M. Koschenz and B. Lehmann, <i>Thermoaktive Bauteilsysteme tabs.</i>
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D&uuml;bendorf, Switzerland: EMPA Energyiesysteme/Haustechnik, 2000, ISBN: 9783905594195.
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</p>
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</html>", revisions="<html>
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<ul>
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<li>2013 May, Roel De Coninck, documentation</li>
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<li>2011 June, Roel De Coninck, first version</li>
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<li>
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August 12, 2025, by Jelger Jansen:<br/>
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Add convective heat transfer coefficient <code>alp1</code>, update default value of <code>alp2</code>, and update documentation.<br/>
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See <a href=https://github.com/open-ideas/IDEAS/issues/1381>#1381</a>.
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</li>
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<li>
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May, 2013, by Roel De Coninck:<br/>
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Add documentation.
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</li>
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<li>
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June, 2011, by Roel De Coninck:<br/>
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First implementation.
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</li>
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</ul>
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</html>"));
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end RadiantSlabChar;

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