8.2.2 Ideal Rankine CycleIf the working fluid passes through the various components of the simple vapor power cy- cle without irreversibilities, frictional pressure drops would be absent from the boiler and condenser, and the working fluid would flow through these components at constant pressure. Also, in the absence of irreversibilities and heat transfer with the surroundings, the processes through the turbine and pump would be isentropic. A cycle adhering to these idealizations is the ideal Rankine cycle shown in Fig. 8.3.Referring to Fig. 8.3, we see that the working fluid undergoes the following series of in- ternally reversible processes:Process 1–2: Isentropic expansion of the working fluid through the turbine from saturated vapor at state 1 to the condenser pressure.Process 2–3: Heat transfer from the working fluid as it flows at constant pressure through the condenser with saturated liquid at state 3.Process 3 – 4: Isentropic compression in the pump to state 4 in the compressed liquid region.Process 4 –1: Heat transfer to the working fluid as it flows at constant pressure through the boiler to complete the cycle.The ideal Rankine cycle also includes the possibility of superheating the vapor, as in cycle1 –2 –3– 4 –1 . The importance of superheating is discussed in Sec. 8.3.Since the ideal Rankine cycle consists of internally reversible processes, areas under the process lines of Fig. 8.3 can be interpreted as heat transfers per unit of mass flowing. Ap- plying Eq. 7.40, area 1-b-c-4-a-1 represents the heat transfer to the working fluid passing through the boiler and area 2-b-c-3-2 is the heat transfer from the working fluid passing through the condenser, each per unit of mass flowing. The enclosed area 1-2-3-4-a-1 can be interpreted as the net heat input or, equivalently, the net work output, each per unit of mass flowing.ideal Rankine cycleT1′1 a43 2 2′c b sFigure 8.3 Temperature – entropy diagram of the
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