A new parabolic dish solar concentrator is being developed to supply electricity to a small remote community. The system operates with a Stirling engine connected to two heat reservoirs HR₁ and HR₂ as shown in Fig. Concentrated solar radiation Q˙ₛᵤₙ=200kW maintains HR₁ at constant temperature Tₕᵣ,₁=700℃, and a high performance heat sink device maintains HR₂ at temperature Tₕᵣ,₂=25℃. After some time of operation, an engineer working on the project realizes that the engine power output is performing below design specifications and only provides a power output of 120kW. After inspecting the system, they discover a contact resistance that causes the thermal communication between the two heat reservoirs and the engine to be imperfect in the sense that a finite temperature difference is required to establish heat transfer between each of the heat reservoirs and the engine.
Sketch the cycle on a T-s diagram and include the temperatures of the heat reservoirs in your sketch. Calculate the engine efficiency and compare it to the efficiency of an ideal Stirling engine with perfect thermal communication with the heat reservoirs.
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