Examining a Power Plant Consider a power plant. At point 1 the working gas has a temperature of T = 25oC. The pressure is 1bar and the mass flow is m. = 2kg/s.
After point 1, the air enters a compressor, at which the pressure is increased to 6 bar. (This is point 2.) After this, the flow is heated to T3 = 700oC. (This is stage 3.) Afterwards, the flow goes through a turbine, at which the pressure is decreased to 1bar again. (This is stage 4.) The flow is then cooled to T1 = 25oC. We're now back in stage 1.
We assume that: 1. air behaves like a thermally and calorically perfect gas with Cp = 1004J/kg K, R = 287J/kg K and γ = 1.4. 2. the isentropic efficiency of the compressor is 0.88. 3. the polytropic efficiency of the turbine is 0.85.
Answer the following questions.
1. Depict the evolution of the cycle in the T - s plane.
2. Determine the net power.
3. Determine the heat received from the hot source.
4. Determine the thermal efficiency of the power plant.
5. Determine the Carnot efficiency associated with the present power plant and compare it with the previous result.
6. Verify the first principle.