Which limit impacts the efficiency of a Carnot heat engine using supercritical carbon dioxide?

💡 Explanation

When supercritical CO2 is used near its critical point in a Carnot engine, large property changes (density, heat capacity) for small temperature changes impact heat transfer optimization because maintaining isothermal conditions is difficult. Therefore, critical point proximity causes efficiency limits, rather than irreversibility effects, turbine strength or compressor friction which are separate considerations.

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