Improving Thermal Efficiency with a 2-Stage Rankine Modification (uakron.edu, 15min) Power is to be generated between temperatures of 500 C and 65 C (0.025MPa) with the steam quality not to drop below 100%. This coursecast compares a simple Rankine cycle and one modification in which the single turbine expansion is replaced with two turbine stages. The thermal efficiency increases from 27% to 39% as a result of this modification. Such an increase could equate to millions of dollars per year at a decent sized electric power plant. These considerations motivate careful analysis of thermal efficiency under multiple permutations of modifications. Ultimately, the Carnot efficiency cannot be surpassed, however. Also, the optimal configuration for a particular facility (like cogeneration at a chemical plant) will depend on other demands like the need for medium pressure steam dedicated to other purposes.
Comprehension Questions:
1. Do you think that turning this process into a 3-stage Rankine cycle would increase the thermal efficiency another 12%, from 39% to 51%? Explain.
2. Suppose the turbines were 85% efficient. How would you approach this problem in that case?

Organizing your calculations in a spreadsheet (uakron, 18min) Scratching numbers on a crude process flow diagram (PFD) may be convenient for a rough calculation, but it is not the kind of document that would want to submit for a project report or even for homework. Organizing your calculations can make them easier to convey and defend, and you may even catch a typo or two relative to your rough calculation. Did you ever wonder, "How can I show how I did my calculations so I can get some partial credit? Just hand in the spreadsheet? But this lame prof wants a hard copy...?" Then you definitely need to watch this video. If you are indeed writing a project report, you might like to review howto construct your PFDs using a process simulator.

Comprehension Questions:

1. Create a spreadsheet version of the Table associated with Example 5.3 in the textbook. Add a column to indicate the order in which the calculations were performed. Add another column to indicate the variables that specified each state in the table. Use the space under this table to indicate how the work, heat, and efficiency were computed.

## Comments

Lira replied on Permalink

## Improving Thermal Efficiency

Improving Thermal Efficiency with a 2-Stage Rankine Modification (uakron.edu, 15min) Power is to be generated between temperatures of 500 C and 65 C (0.025MPa) with the steam quality not to drop below 100%. This coursecast compares a simple Rankine cycle and one modification in which the single turbine expansion is replaced with two turbine stages. The thermal efficiency increases from 27% to 39% as a result of this modification. Such an increase could equate to millions of dollars per year at a decent sized electric power plant. These considerations motivate careful analysis of thermal efficiency under multiple permutations of modifications. Ultimately, the Carnot efficiency cannot be surpassed, however. Also, the optimal configuration for a particular facility (like cogeneration at a chemical plant) will depend on other demands like the need for medium pressure steam dedicated to other purposes.

Comprehension Questions:

1. Do you think that turning this process into a 3-stage Rankine cycle would increase the thermal efficiency another 12%, from 39% to 51%? Explain.

2. Suppose the turbines were 85% efficient. How would you approach this problem in that case?

Elliott replied on Permalink

## Process Reporting

Organizing your calculations in a spreadsheet (uakron, 18min) Scratching numbers on a crude process flow diagram (PFD) may be convenient for a rough calculation, but it is not the kind of document that would want to submit for a project report or even for homework. Organizing your calculations can make them easier to convey and defend, and you may even catch a typo or two relative to your rough calculation. Did you ever wonder, "How can I show how I did my calculations so I can get some partial credit? Just hand in the spreadsheet? But this lame prof wants a hard copy...?" Then you definitely need to watch this video. If you are indeed writing a project report, you might like to review how to construct your PFDs using a process simulator.

Comprehension Questions:

1. Create a spreadsheet version of the Table associated with Example 5.3 in the textbook. Add a column to indicate the order in which the calculations were performed. Add another column to indicate the variables that specified each state in the table. Use the space under this table to indicate how the work, heat, and efficiency were computed.