% Verbal description for system CarnotCycle (CarnotCycle_desc.tex)
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   The acausal bond graph of system \textbf{CarnotCycle} is
   displayed in Figure \Ref{CarnotCycle_abg} and its label
   file is listed in Section \Ref{sec:CarnotCycle_lbl}.
   The subsystems are listed in Section \Ref{sec:CarnotCycle_sub}.

The Carnot cycle is a simple closed thermodynamic cycle with four parts:
\begin{enumerate}
\item Isentropic compression
\item Heat injection at constant temperature
\item Isentropic expansion
\item Heat extraction at constant temperature
\end{enumerate}

The subsystem \textbf{Cycle} (Section \Ref{sec:Cycle}) is a two-port
component describing an ideal gas. It has two energy ports which, with
integral causality correspond to
\begin{enumerate}
\item Entropy flow in; temperature out
\item Volume rate of change in; pressure out
\end{enumerate}

In contast to the Otto cycle (see Table
\Ref{tab:cycles} where each table entry gives the causality on the
heat and work ports respectively). The ideal Carnot cycle has
derivative causality on the {\bf [Heat]} port for two parts of the
cycle.

To avoid this causlity change, the Carnot cycle is approximated by
applying the heat from a temperature source via a thermal resistance
{\bf RT} component. During the {\em heat injection\/} and {\em heat
extraction\/} parts of the cycle, the resistance parameter $r\approx
0$, but during the {\em isentropic compression\/} and {\em isentropic
expansion\/} parts of the cycle, the resistance parameter $r\approx
\inf$.

The simulation parameters appear in Section
\Ref{sec:CarnotCycle_numpar.txt}. The results are plotted against time
as follows:
\begin{itemize}
\item Volume (Figure \Ref{fig:CarnotCycle_odeso.ps-CarnotCycle-cycle-V})
\item Pressure (Figure
\Ref{fig:CarnotCycle_odeso.ps-CarnotCycle-cycle-P})
\item Entropy (Figure \Ref{fig:CarnotCycle_odeso.ps-CarnotCycle-cycle-S})
\item Temperature (Figure
\Ref{fig:CarnotCycle_odeso.ps-CarnotCycle-cycle-T})
\end{itemize}

These values are replotted as the standard PV and TS diagrams in
Figures
\Ref{fig:CarnotCycle_odeso.ps-CarnotCycle-cycle-V:CarnotCycle-cycle-P}
and
\Ref{fig:CarnotCycle_odeso.ps-CarnotCycle-cycle-S:CarnotCycle-cycle-T}
respectively.

The PV diagram shows the long and thin form typical of the Carnot
cycle -- this implies a poor work ratio. The TS diagram is not
informative; it is not the expected rectangle because both T and S
change in a stepwise manner.

% Verbal description for system OttoCycle (OttoCycle_desc.tex)
% Generated by MTT on Thu Dec 4 15:59:55 GMT 1997.

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% Revision 1.1  1997/12/08  09:37:04  peterg
% Initial revision
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   The acausal bond graph of system \textbf{OttoCycle} is
   displayed in Figure \Ref{OttoCycle_abg} and its label
   file is listed in Section \Ref{sec:OttoCycle_lbl}.
   The subsystems are listed in Section \Ref{sec:OttoCycle_sub}.


The Otto cycle is a simple closed thermodynamic cycle with four parts:
\begin{enumerate}
\item Isentropic compression
\item Heating at constant volume
\item Isentropic expansion
\item Cooling at constant volume
\end{enumerate}

The subsystem \textbf{Cycle} (Section \Ref{sec:Cycle}) is a two-port
component describing an ideal gas. It has two energy ports which, with
integral causality correspond to
\begin{enumerate}
\item Entropy flow in; temperature out
\item Volume rate of change in; pressure out
\end{enumerate}

In Bond Graph terms, each of the four parts of the Otto cycle
correspond to integral causality as in each case a \emph{flow} is
constrained. This is in contrast to other cycles listed in Table
\Ref{tab:cycles} where each table entry gives the causality on the
heat and work ports respectively. This is possibly why the Otto cycle
is conceptually and practically simple.

The simulation parameters appear in Section
\Ref{sec:OttoCycle_numpar.txt}. The results are plotted against time
as follows:
\begin{itemize}
\item Volume (Figure \Ref{fig:OttoCycle_odeso.ps-OttoCycle-cycle-V})
\item Pressure (Figure
\Ref{fig:OttoCycle_odeso.ps-OttoCycle-cycle-P})
\item Entropy (Figure \Ref{fig:OttoCycle_odeso.ps-OttoCycle-cycle-S})
\item Temperature (Figure
\Ref{fig:OttoCycle_odeso.ps-OttoCycle-cycle-T})
\end{itemize}

These values are replotted as the standard PV and TS diagrams in
Figures
\Ref{fig:OttoCycle_odeso.ps-OttoCycle-cycle-V:OttoCycle-cycle-P}
and
\Ref{fig:OttoCycle_odeso.ps-OttoCycle-cycle-S:OttoCycle-cycle-T}
respectively.