Air in a piston-cylinder assembly undergoes a Carnot power cycle. For the process numbers used in this problem refer to Figure 5.13 in the textbook and the figure below for a T-s diagram. The isothermal expansion and compression occur at 853 K and 295 K respectively. The pressures at the beginning and the end of the cycle are p₁ = 315 kPa and P4 = 100 kPa, respectively. Assuming the ideal gas model with constant heat capacity, Cp = 1.005 kJ/kg-K and k = 1.40 determine: T a) the pressures p2 and p3. b) the heat transfer and work for each process. c) the thermal efficiency. 2 1. 3 4 S Đ

Air (Rair = 0.287 ) as an ideal gas flows through the turbine and heat exchanger arrangement kg-K, shown below. Steady-state data are given on the figure. Stray heat transfer and kinetic and potential energy effects can be ignored. Sketch a T - s diagram of processes 1-4 and determine: (a) The entropy production of turbine 1 [3.2 kW /K] (b) The isentropic efficiency of turbine 1 [75%] (c) The exit temperature of turbine 2 if its isentropic efficiency is nr, = 0.85 [960 K] (d) The entropy production within the intermediate heat exchanger [3.2 kW/K] W1 = 10,000 kW Wn= ? Turbine Turbine P3= 4.5 bar T3 = ? T = 1100 K P2=5 bar P4 = 1 bar Air wwww www 2 4 T = 1400 K Pi = 20 bar Ts = 1480 K 5 Ps = 1.35 bar ms = 1200 kg/min Heat exchanger V T = 1200 K P6 =1 bar %3D Air in

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3. Air occupies a 0.3 m³ piston-cylinder at 150 kPa and 278 K. The piston-cylinder operates on a three-process cycle where from state 1 to state 2 the pressure is constant and V2 = 1.4 V1. From state 2 to 3 the compression is reversible adiabatic until V3 = V1, and the temperature at state 3 is 450 K. A constant-volume process completes the cycle. Sketch the cycle on a p-V diagram and determine the network and heat flows for the cycle.