Difficulty: Easy
Correct Answer: In the closed cycle gas turbine, the pressure range depends upon the atmospheric pressure.
Explanation:
Introduction / Context:Gas turbine plants are implemented as open (Brayton with atmospheric intake and exhaust) or closed cycles (recirculated working fluid through external heat addition and rejection). Distinguishing their characteristics is vital for plant design and performance analysis.
Given Data / Assumptions:
Concept / Approach:
The incorrect statement is the one tying closed-cycle pressure range to atmospheric pressure. In closed cycles, absolute pressure levels and ratios are chosen independently (within mechanical limits) since the working fluid is contained. In contrast, open cycles usually have compressor inlet near atmospheric pressure, so their absolute levels depend on ambient conditions.
Step-by-Step Solution:
Evaluate (a): true—heat is added externally to the working fluid in heaters.Evaluate (b): false—closed-cycle pressures are not constrained by atmosphere.Evaluate (c): acceptable phrasing—combustion is external with associated heat-exchanger surfaces.Evaluate (d): true—open cycle exhausts to atmosphere acting as the sink.Include (e) to clarify true closed-cycle feature.Verification / Alternative check:
Textbook schematics show a closed Brayton loop pressurized to several bars for compactness and efficiency, independent of ambient pressure.
Why Other Options Are Wrong:
Options (a), (d), and (e) reflect standard definitions; (c) is a qualitative statement about external surfaces and does not claim false dependencies.
Common Pitfalls:
Assuming all gas turbines must inhale/exhaust to atmosphere; forgetting that pressurizing a closed loop improves heat-exchanger effectiveness and specific power.
Final Answer:
In the closed cycle gas turbine, the pressure range depends upon the atmospheric pressure.
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