Trantham_M5.3

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Apr 3, 2024

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Course: Thermal Measurements Lab Section: Module 5 Instructor Name: Dr. Pashayi Name(s): Carlton Trantham __________________________________________________________________________ Title : In this lab, we calculated the Carnot steam plant efficiency and compared that to real steam cycle efficiency. We also discussed factors that cause the differences in the two values. __________________________________________________________________________ Abstract: Operators must understand that their actions play a large part in the efficiency of the power plant. Maintaining a high power output while minimizing fuel burnout will maintain the plant operational for as long as possible and reduce refueling times. There are also other variables like the weather that will affect cooling water temperature and further improve or reduce the plant efficiency. Operators can mitigate these effects on efficiency if they understand what portions of the steam cycle process they will impact. __________________________________________________________________________ Introduction: Calculating steam plant efficiency is a vital process for operators to see what their efficiency goal should be while they operate the plant. Evolutions that lower the plant efficiency should be minimized to maintain the efficiency as high as possible. There are also outside factors that will directly impact the efficiency of the steam cycle since the heat sink is generally not a closed system. In this lab, we will record the required values to calculate a Carnot cycle efficiency and a real steam cycle efficiency. After comparing the two values, we will discuss why there is such a large disparity between the two. __________________________________________________________________________ Methods: Begin by selecting ‘Lesson 02 - IC002 100 MOL’. After starting the simulation, navigate to the Circulating Water System page, CWS1. Locate and record the Circulating Water Inlet temperature from this page.

Then navigate back to the Reactor Coolant System page, RCS1. On this page, you will record the values for the two steam generator pressures after converting them to absolute pressure. Find and record the saturation temperature of the steam utilizing the absolute pressure of the steam generators. Next calculate the Carnot efficiency with the base equation ƞ = 1 - (T C / T H ) using the recorded seawater inlet temperature as the T C , and the saturated steam temperature as the T H . Finally, record the Generator Power value, and the R. T. Power values. Set them up as a ratio totaling less than one, and after multiplying by 100%, record the true overall plant efficiency. ________________________________________________________________________ Results: 6. a. 60.1 F 9. a. 1053.3 psia 12. a. 550.99 F 15. a. ƞ = 1 - (519.77 R / 1010.66 R) x 100% = 48.57%

17. During the winter months, you would drastically reduce the temperature of the inlet circulating water system. This would affect the system efficiency equation by lowering the T C temperature making the plant more efficient. It would also make the plant more efficient by lowering the vacuum in the main condenser, allowing more enthalpy to be extracted within the turbine. During the summer months, the plant would see a large reduction in efficiency. Plants using seawater would most likely experience a smaller change between the two time periods since the seawater temperature will change less drastically than a river’s temperature. 20. Overall Efficiency = (1408.5 MW / 3983.0 MW) x 100% = 35.36% 21. The calculated steam plant efficiency, or real steam plant efficiency, shows the factors that are unaccounted for in the ideal steam cycle. Condensate depression is a prime example since we have to sub-cool the condensate before pumping it out of the hotwell. If we were able to pump saturated liquids with no fear of cavitation, this designed inefficiency wouldn’t exist. The real steam cycle also accounts for the headloss within the system, as the steam and liquid flow within the piping. There are also multiple forms of turbine losses that lower their efficiency, and the pumps experience mechanical friction as well. _________________________________________________________________________ Discussion : As you can see from the results of our steam plant efficiency calculations, the efficiency of the real steam cycle is significantly lower than the Carnot efficiency. The Carnot efficiency assumes many portions of the steam cycle are isentropic processes, but in the real steam cycle, those processes create an increase in entropy. The processes that raise entropy create a large difference between the Carnot and real cycle efficiencies. As operators of steam plants, we should understand how different plant evolutions will raise or lower the steam plant efficiency. For example, in the winter months with a lower circulating water inlet temperature, you may need to reduce the amount of circulating water cooling flow to reduce the amount of condensate depression within the main condenser. __________________________________________________________________________ Conclusion: There is a significant difference between the efficiency of a Carnot steam cycle and a real steam cycle due to the entropy increases within feed and steam expansion processes. The Carnot cycle treats these processes as isentropic when there is an entropy increase within both in the real steam cycle. Operators must understand how to calculate overall steam plant efficiency and understand that their actions will directly affect the efficiency of their steam plant. __________________________________________________________________________

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References: 3 Key Student, (n.d.) PWR Simulator. https://www.3keystudent.com/ Engineering Fundamentals, (n.d.). Saturated Steam Table. https://www.efunda.com/materials/water/steamtable_sat.cfm