# Connecting heat engines

What is the smallest number of identical heat engines of efficiency $$\eta _{0}=0.3$$ that should be connected in series in order to get an effective efficiency $$\eta _{eff}>0.8$$?

Details and Assumptions:

• Efficiency of a system is defined as the ratio of total work done by the system to the heat delivered to the system.
• Connecting engines in series means that the heat rejected by one of the engines is completely transferred the one next to it, and so on.
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