04.09 Turbine calculations
Book navigation
- Chapter 1 - Basic concepts
- Chapter 2 - The energy balance
- Chapter 3 - Energy balances for composite systems.
- Chapter 4 - Entropy
- Chapter 5 - Thermodynamics of Processes
- Chapter 6 - Classical Thermodynamics - Generalization to any Fluid
- Chapter 7 - Engineering Equations of State for PVT Properties
- Chapter 8 - Departure functions
- Chapter 9 - Phase Equlibrium in a Pure Fluid
- Chapter 10 - Introduction to Multicomponent Systems
- Chapter 11 - An Introduction to Activity Models
- Chapter 12 - Van der Waals Activity Models
- Chapter 13 - Local Composition Activity Models
- Chapter 14 - Liquid-liquid and solid-liquid equilibria
- Chapter 16 - Advanced Phase Diagrams
- Chapter 15 - Phase Equilibria in Mixtures by an Equation of State
- Chapter 17 - Reaction Equilibria
- Chapter 18 - Electrolyte Solutions
General Procedure of Solving for Turbine Efficiency
General procedure to solve for steam turbine efficiency. (LearnChemE.com, 5min) This video outlines the procedure without actually solving any specific problem. It shows how inefficiency affects the T-S diagram and how to compute the actual temperature at the turbine outlet.
Comprehension Questions:
1. In this video, the entropy at the outlet of the actual turbine is to the right of the entropy for the reversible turbine. Suppose we were interested in the T-S diagram for a 75% efficient compressor. Would the outlet entropy of the actual compressor be to the right of the entropy for the reversible turbine, to the left, or about the same? Explain.
2. In the video, Prof. Falconer states that the outlet entropy must be the same as the inlet entropy because the process is reversible and one other property. What is the other requirement for the turbine to be isentropic? Explain.
3. Will inefficiency in the turbine always cause the temperature at the outlet to be higher than the inlet? Explain.
Sample Calculation of Solving for Turbine Efficiency
Entropy Balances: Solving for Turbine Efficiency Sample Calculation. (uakron.edu, 10min) Steam turbines are very common in power generation cycles. Knowing how to compute the actual work, reversible work, and compare them is an elementary part of any engineering thermodynamics course.
Comprehension Questions:
1. An adiabatic turbine is supplied with steam at 2.0 MPa and 600°C and it exhausts at 98% quality and 24°C. (a) Compute the work output per kg of steam.(b) Compute the efficiency of the turbine.
2. A Rankine cycle operates on steam exiting the boiler at 7 MPa and 550°C and expanding to 60°C and 98% quality. Compute the efficiency of the turbine.
Turbine Efficiency Calculations with Steam.xls
Turbine calculations using Steam.xlsx (uakron.edu, 15min) Using the Steam.xlsx spreadsheet can facilitate computations by eliminating the need for interpolation. You may have seen this video before, but it is convenient to link it here too since turbines often operate on steam.
Comprehension Questions: Solve the following using Steam.xlsx for the vapor properties.
1. An adiabatic turbine is supplied with steam at 2.0 MPa and 600°C and it exhausts at 98% quality and 24°C. (a) Compute the work output per kg of steam.(b) Compute the efficiency of the turbine.
2. A Rankine cycle operates on steam exiting the boiler at 7 MPa and 550°C and expanding to 60°C and 98% quality. Compute the efficiency of the turbine.