ME 3322 Section E, Spring 2024
Homework 9 – Due April 18, 12:30 pm
Problem 1: At the beginning of the compression process of an air-standard Otto cycle, 𝑝1 = 1
bar, 𝑇1 = 290 K, 𝑉1 = 400 cm3 . The maximum temperature in the cycle is 2200 K and the
compression ratio is 8. Determine:
a. the heat addition, in kJ.
b. the net work, in kJ.
c. the thermal efficiency.
d. the mean effective pressure, in bar.
Problem 2: The pressure-specific volume diagram of the air-standard Lenoir cycle is shown
below. The cycle consists of constant-volume heat addition, isentropic expansion, and constant
pressure compression. For the cycle, 𝑝1 = 14.7 psi and 𝑇1 = 540°R. The mass of air is 4.24 × 10-3
lb, and the maximum cycle temperature is 1600°R. Assuming 𝑐𝜐 = 0.171 Btu/lb⋅°R, determine
for the cycle
a. the net work, in Btu.
b. the thermal efficiency.
Problem 3: Consider an air-standard Diesel cycle. Operating data at principal states in the cycle
are given in the table below. The states are numbered as in Fig. 9.5 (in the book). Determine
a. the cutoff ratio.
b. the heat addition per unit mass, in Btu/lb.
c. the net work per unit mass, in Btu/lb.
d. the thermal efficiency.
Problem 4: Air enters the compressor of a simple gas turbine at 𝑝1 = 14 psi, 𝑇1 = 520°R, and a
volumetric flow rate of 10,000 ft 3 /min. The isentropic efficiencies of the compressor and
turbine are 83% and 87%, respectively. The compressor pressure ratio is 14 and the temperature
at the turbine inlet is 2500°R. On the basis of an air-standard analysis, calculate
a. the thermal efficiency of the cycle.
b. the net power developed, in hp.
Problem 5: Solve Problem 5 on a cold air-standard basis with specific heats evaluated at 520°R.
Problem 6: An ideal air-standard regenerative Brayton cycle produces 10 MW of power.
Operating data at principal states in the cycle are given in the table below. The states are
numbered as in Fig. 9.14 (in the book).
Sketch the T–s diagram, and determine:
a. the mass flow rate of air, in kg/s.
b. the rate of heat transfer, in kW, to the working fluid passing
through the combustor.
c. the thermal efficiency.
Problem 7: Air enters a two-stage compressor operating at steady state at 1 bar, 290 K. The
overall pressure ratio across the stages is 16 and each stage operates isentropically. Intercooling
occurs at 4 bar. Air exits the intercooler at 290 K. Assuming ideal gas behavior with k = 1.4,
determine:
a. the intercooler pressure, in bar, and the heat transfer, in kJ per
kg of air flowing.
b. the work required for each compressor stage, in kJ per kg of
air flowing.