Worked on making heat transfer formulations more consistent

This closes #150.

Author: mtiller

CHANGELOG.md

@@ -26,6 +26,9 @@ This file collects the significant changes to the book since its initial public
     various functions/operators (issue
     [#187](https://github.com/xogeny/ModelicaBook/pull/187)
 
+  * Used a consistent heat transfer formulation throughout the book (issue
+    [#150](https://github.com/xogeny/ModelicaBook/pull/150)
+
 ### Version 0.3.2
 
 #### Enhancements

ModelicaByExample/Components/BlockDiagrams/Examples/MultiDomainControl.mo

@@ -5,6 +5,7 @@ model MultiDomainControl
   import Modelica.SIunits.Conversions.from_degC;
 
   parameter Real h = 0.7 "Convection coefficient";
+  parameter Real A = 1.0 "Area";
   parameter Real m = 0.1 "Thermal maass";
   parameter Real c_p = 1.2 "Specific heat";
   parameter Real T_inf = from_degC(25) "Ambient temperature";
@@ -20,8 +21,7 @@ model MultiDomainControl
   HeatTransfer.ThermalCapacitance cap(C=m*c_p, T0 = from_degC(90))
     "Thermal capacitance component"
     annotation (Placement(transformation(extent={{-30,-30},{-10,-10}})));
-  HeatTransfer.Convection
-             convection2(h=h)
+  HeatTransfer.Convection convection2(h=h*A)
     annotation (Placement(transformation(extent={{10,-30},{30,-10}})));
   HeatTransfer.AmbientCondition
                    amb(T_amb(displayUnit="K") = T_inf)

ModelicaByExample/Components/BlockDiagrams/Examples/MultiDomainControl.svg

@@ -2,6 +2,7 @@ within ModelicaByExample.Components.BlockDiagrams.Examples;
 model NewtonCooling "Newton cooling system modeled with blocks"
   import Modelica.SIunits.Conversions.from_degC;
   parameter Real h = 0.7 "Convection coefficient";
+  parameter Real A = 1.0 "Area";
   parameter Real m = 0.1 "Thermal mass";
   parameter Real c_p = 1.2 "Specific heat";
   parameter Real T_inf = from_degC(25) "Ambient temperature";
@@ -13,7 +14,7 @@ model NewtonCooling "Newton cooling system modeled with blocks"
     annotation (Placement(transformation(extent={{10,-40},{30,-20}})));
   Components.Sum sum(nin=2)
     annotation (Placement(transformation(extent={{52,-20},{72,0}})));
-  Components.Gain gain1(k=h/(m*c_p))
+  Components.Gain gain1(k=h*A/(m*c_p))
     annotation (Placement(transformation(extent={{-70,-10},{-50,10}})));
 equation
   connect(T.y, gain.u) annotation (Line(

ModelicaByExample/Components/BlockDiagrams/Examples/NewtonCooling.mo

@@ -259,7 +259,7 @@ revisit the equation associated with this example:
 .. todo:: this and some following expressions involving T are not being rendered
           correctly using https://book-preview.herokuapp.com
 
-.. math:: m c_p \dot{T} = h (T_{\infty}-T)
+.. math:: m c_p \dot{T} = h A (T_{\infty}-T)
 
 The following block diagram will solve for the temperature profile,
 :math:`T`: