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\section*{Main equations}
Here an equation
    \begin{equation}\label{eq:heatflux}
        \dot{Q} = k \cdot A \cdot \Delta T
    \end{equation}%
    \nomenclature[aQ]{$\dot{Q}$}{heat flux}{W}{}%
    \nomenclature[ak]{$k$}{overall heat transfer
      coefficient}{\watt\per(\square\meter\kelvin)}{see
      eq.~(\ref{eq:ohtc})}%
    \nomenclature[aA]{$A$}{area}{\square\meter}{}%
    \nomenclature[aL]{$L$}{length}{\meter}{SI base quantity}%
    \nomenclature[aT]{$T$}{temperature}{\kelvin}{SI base quantity}%
    \nomenclature[aT]{$\Delta T$}{temperature difference}{\kelvin}{SI base quantity}%
or another one
    \begin{equation}\label{eq:ohtc}
        \frac{1}{k} = \left[\frac{1}{\alpha _{\mathrm{i}}\,r_{\mathrm{i}}} +
        \sum^n_{j=1}\frac{1}{\lambda _j}\,
        \ln \frac{r_{\mathrm{a},j}}{r_{\mathrm{i},j}} +
        \frac{1}{\alpha _{\mathrm{a}}\,
          r_{\mathrm{a}}}\right] \cdot r_{\mathrm{reference}}
    \end{equation}%
    \nomenclature[ga]{$\alpha$}{convection heat transfer
      coefficient}{\watt\per(\square\meter\kelvin)}{}%
    \nomenclature[zi]{i}{in}{}{}%
    \nomenclature[gl]{$\lambda$}{thermal conductivity}{\watt\per\kelvin}{}%
    \nomenclature[za]{a}{out}{}{}%
    \nomenclature[zn]{$n$}{number of walls}{}{}%
    \nomenclature[zj]{$j$}{running parameter}{}{}%

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