Exergy analysis of a power plant

Assume that the surroundings are at 298 K and the kinetic and potential energy changes are negligible 

Because this is an isentropic process S3 = S4 and. S, = S2. We estimate the quality of the discharged wet steam (S3 V , S4V) after passing through the turbine  

The exergy losses or the work losses are 79% and 21% in the boiler and condenser, respectively. In a Rankine cycle, exergy losses are due to irreversibilities occurring during heat transfer with finite temperature differences in the boiler and condenser. In order to decrease exergy losses, the temperature differences should be made smaller. Regeneration may help to decrease the temperature differences. 

Some modifications to improve the efficiency of steam power production are  

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Example 4.12 Exergy analysis of a power plant A steam power plant operates on a simple ideal Rankine cycle (see Figure 4.18). The turbine receives steam at 698.15 K and 4200 kPa, while the discharged steam is at 40 kPa. The mass flow rate of steam is 3.0 kg/s. In the boiler, heat is transferred into the steam from a source at 1500 K. In the condenser, heat is discharged to the surroundings at 298 K. Determine the energy dissipated at each state. 

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