Power Cycle Thermal Efficiency – Impossible, Reversible, or Irreversible?

To calculate the thermal efficiency of a system that undergoes a power cycle, you may first want to determine whether the cycle operates reversibly, irreversibly, or is impossible.

These reversible, irreversible, impossible type problems are found in the 2nd Law aspects of power cycles interacting with two reservoirs section in Fundamentals of Engineering Thermodynamics Moran chapter 5. They often start with the phrase “an inventor claims to have developed a power cycle” and you are tasked with finding the maximum performance measures for cycles operating between two reservoirs, then checking whether the claimed performance is lower, equal, or higher than the Carnot maximum.

Thermodynamics chapter 5 covers refrigeration cycles, heat pump cycles, and a power cycle operating between hot and cold reservoirs. This video only addresses the power cycle, but refrigeration and heat pump analysis is nearly identical, just swapping out the appropriate efficiency equation.

TIMECODES
0:00 2nd Law of Thermodynamics
1:30 Irreversible vs Reversible vs Impossible
5:00 Use efficiency to find minimum Qc

[learnandteach]

Very good explanation sir. All concepts are clear. I want to ask one thing "Heat rejected from the system is taken as negative in thermodynamics. Why we do not take this sign convention here?"

[emine]

this helped me a lot thank you and I'm waiting for new videos!