Answered step by step
Verified Expert Solution
Question
1 Approved Answer
Problem 3 Using the data in problem 1 when the quality at the exit of the turbine is 92%, please answer the following for
Problem 3 Using the data in problem 1 when the quality at the exit of the turbine is 92%, please answer the following for parts a, b, c, and d. a. Compute the change in entropy per unit mass for the water as it enters and leaves the pump. Assume that the temperature of the water did not change. Based on your results, would you conclude that the process is reversible? What condition needs to happen to make it reversible? b. The temperature of the water when it exits the pump has increased by 0.94C. Based on your results, assuming that no heat is transferred to the surroundings, would you conclude that the process is reversible? If not, what is it, why? c. For the adiabatic turbine, based on your results, would you conclude that the process is isentropic? Why? d. On a T-s diagram represents the processes that correspond to a cycle that includes the conditions in parts (b) and (c). 1-2: pump, 2-3: boiler, 3-4: turbine, 4-1: condenser e. Next, assume that the pressure in the boiler is 8 MPa and steam leaves the boiler as saturated vapor and enters the turbine. For an adiabatic reversible process in the turbine, compute the work per unit mass produced in the turbine, in kJ/kg. Problem 1 As you learned in chapter 6 while understanding the basics of the Second Law of Thermodynamics, a steam power plant can be represented as a heat engine by assembling the devices shown in the figure on the right, where qin is supplied from a source and qout is rejected to a sink. Please answer the following questions. - Wpump,in " Pump 0-1 9in Boiler Turbine Condenser Yout Wturb,out a. Assume that all devices shown in the figure are adiabatic and reversible. Water enters the pump as saturated liquid and leaves the pump at 1 MPa and approximately at the same temperature it entered, leaves the boiler as saturated vapor, enters the turbine and leaves the turbine as a saturated mixture with quality 85% and a pressure equal to 20 kPa. Also changes in kinetic and potential energy on any device may be assumed to be negligible compared to changes in other properties, and there are no fluid pressure losses as it passes through the boiler and the condenser, or as it travels from one device to the next. On a T-v and T-s diagrams represent the processes that correspond to each device such that it operates as a cycle; do not include any property values except for pressures that correspond to the boiler and condenser and temperatures. Label your states with numbers and do not omit including the process lines. In your diagram, is there any change in entropy for the water as it passes through the pump and turbine? Explain. b. In part (a) you were told that the boiler and the condenser were adiabatic and reversible. What condition needs to happen to make the statement true? c. Next, you want to determine if the cycle as given to you could be a real cycle, reversible cycle or impossible cycle. Support your answer with computations using concepts learned in chapter 7. List your assumptions. d. Next, you decide to compute the thermal efficiency of the cycle to verify that your conclusion in part (c) is correct. Support your answer with computations using concepts learned in chapter 6. List your assumptions. e. You as an engineer realized that you want to have a cycle with better thermal efficiency for the same boiler and condenser pressures. You realize by looking at your governing equations for each device and for the efficiency of the heat engine that decreasing the value for qout may bring benefit to your goal however you do not know by how much. Thus, you decided to investigate how cycle efficiency changes with qout for better of for worse. What parameter would you change at the exit of the turbine if you wish to increase or decrease qout? Support your answer with an equation and appropriate explanations. List your assumptions. Note that no computations are required beyond understanding the expressions that you wrote.
Step by Step Solution
There are 3 Steps involved in it
Step: 1
Get Instant Access to Expert-Tailored Solutions
See step-by-step solutions with expert insights and AI powered tools for academic success
Step: 2
Step: 3
Ace Your Homework with AI
Get the answers you need in no time with our AI-driven, step-by-step assistance
Get Started