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<li class="toctree-l1"><a class="reference internal" href="chap1_balanceEquations_Chap.html">1. Balance equations</a></li>
<li class="toctree-l1"><a class="reference internal" href="chap2_thermMachinesBasics_Chap.html">2. Thermal machines: Basics</a></li>
<li class="toctree-l1"><a class="reference internal" href="chap3_CompExpGas_Chap.html">3. Compression / Expansion of Gas and vapors</a></li>
<li class="toctree-l1 current"><a class="reference internal" href="chap4_ThermalEngines_Chap.html">4. Heat engines</a><ul class="current">
<li class="toctree-l2"><a class="reference internal" href="chap4_1RICE.html">4.1. Reciprocating internal combustion engine</a></li>
<li class="toctree-l2"><a class="reference internal" href="chap4_3GasTurbines.html">4.2. Gas Turbines</a></li>
<li class="toctree-l2"><a class="reference internal" href="chap4_4SteamTurbines.html">4.3. Steam turbines</a></li>
<li class="toctree-l2 current"><a class="current reference internal" href="#">4.4. Combined cycles / Cogeneration</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#combined-cycles">4.4.1. Combined cycles</a></li>
<li class="toctree-l3"><a class="reference internal" href="#cogeneration">4.4.2. Cogeneration</a></li>
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<div class="section" id="combined-cycles-cogeneration">
<h1><span class="section-number">4.4. </span>Combined cycles / Cogeneration<a class="headerlink" href="#combined-cycles-cogeneration" title="Permalink to this headline">¶</a></h1>
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<h2><span class="section-number">4.4.1. </span>Combined cycles<a class="headerlink" href="#combined-cycles" title="Permalink to this headline">¶</a></h2>
<p>In Gas turbine, an important part of energy is loss with exhausted combustion gases. This energy can possibly used as hot source for a vapor turbine. We then talk about <strong>combined cycle</strong>.</p>
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<div class="section" id="cogeneration">
<h2><span class="section-number">4.4.2. </span>Cogeneration<a class="headerlink" href="#cogeneration" title="Permalink to this headline">¶</a></h2>
<p>Finally, whatever the heat engine is, thermal energy is provided to a cold sink. <strong>Cogeneration</strong> consists in using these residual energy for a heating system. By the way, the installation produces mechanical work and heat. The global efficiency of a cogenerative installation may be evaluated by:</p>
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<p><img src="_images/math/af6669740b63997523e70a7a3b573715d7be737c.svg" alt="\eta_{cogen} = \frac{-\dot{W}_t + |\dot{Q}_{recup}|}{\dot{Q}_C}"/></p>
</div><p>With <img class="math" src="_images/math/a276beba81664b10199d46525a184ecd0188bf53.svg" alt="|\dot{Q}_{recup}|\leq \dot{Q}_C" style="vertical-align: -5px"/>.</p>
<p>These installation may reach 70 to 80% or efficiency.</p>
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