2. Thermodynamics

Power Cycles — Quiz

Test your understanding of power cycles with 5 practice questions.

Practice Questions

Question 1

An ideal Carnot engine operates between a hot reservoir at $T_H=600\ \mathrm{K}$ and a cold reservoir at $T_C=300\ \mathrm{K}$. If $Q_H=1200\ \mathrm{kJ}$ is absorbed per cycle, what are the cycle’s thermal efficiency and net work output in kJ?

Question 2

For an ideal Brayton cycle with pressure ratio $r_p=12$ and specific heat ratio $\gamma=1.3$, what is the approximate thermal efficiency $\eta$?

Question 3

In a Brayton cycle with two-stage compression and ideal intercooling to the initial temperature, assuming fixed turbine inlet temperature, which effect does intercooling have?

Question 4

A Rankine cycle has boiler exit enthalpy $h_1=3500\ \mathrm{kJ/kg}$, ideal turbine exit $h_{2s}=2500\ \mathrm{kJ/kg}$, condenser outlet enthalpy $h_3=200\ \mathrm{kJ/kg}$, negligible pump work, and turbine isentropic efficiency $\eta_t=85\%$. What is the actual cycle thermal efficiency?

Question 5

Which thermodynamic rationale explains the use of reheat between turbine stages in a practical Rankine cycle?