Consider the following statements regarding effects of...

Name: Problem 10, Chapter 4: Thermal Engineering
Uploaded: 2021-12-03T09:45:53-08:00
Duration: 1 min 1 s
Channel: Hunza Gilgit
Description: Consider the following statements regarding effects of reheating of steam in a steam turbine: I. It increases the specific output of the turbine. II. It decreases cycle efficiency. III. It increases blade erosion. IV. It improves the quality of exit steam. Which of these statements are correct? (a) I and II (b) II and III (c) III and IV (d) I and IV

Consider the following statements regarding effects of reheating of steam in a steam turbine: I. It increases the specific output of the turbine. II. It decreases cycle efficiency. III. It increases blade erosion. IV. It improves the quality of exit steam. Which of these statements are correct? (a) I and II (b) II and III (c) III and IV (d) I and IV

Consider the following statements regarding effects of reheating of steam in a steam turbine:
I. It increases the specific output of the turbine.
II. It decreases cycle efficiency.
III. It increases blade erosion. IV. It improves the quality of exit steam. Which of these statements are correct?
(a) I and II
(b) II and III
(c) III and IV
(d) I and IV

Key Concepts

Reheat Cycle

The reheat cycle is a thermodynamic technique used in steam turbine systems in which partially expanded steam is returned to the boiler to be reheated before further expansion in the turbine. This process helps maintain a higher average temperature during expansion, improves the overall thermal efficiency of the cycle, and allows for a higher specific work output from the turbine.

Specific Output

Specific output refers to the work produced per unit mass flow of the working fluid. In the context of a reheat cycle, reheating the steam allows the turbine to extract more work from each unit of steam, thereby increasing the specific output. This enhancement is achieved by reducing moisture content and ensuring that the steam remains at a higher temperature during further expansion.

Cycle Efficiency

Cycle efficiency in a steam power plant is a measure of how effectively the thermal energy from the fuel is converted into useful work. The incorporation of reheat into the cycle generally improves efficiency by raising the average temperature at which heat addition occurs, thereby increasing the overall thermodynamic efficiency of the system rather than decreasing it.

Exit Steam Quality and Blade Erosion

Exit steam quality pertains to the state of the steam leaving the turbine, particularly its dryness or moisture content. Reheating improves this quality by reducing the moisture content attained during expansion, which in turn minimizes blade erosion. Moisture droplets can cause physical damage to turbine blades, so an improvement in exit steam quality helps extend the life of these components.

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