Carleton MAAE 3400 Final Exam Prep:
310 Solved Exam Q&As & Expert
Solutions updated 2026-2027
Master Carleton University's MAAE 3400 (Applied Thermodynamics) with this ultimate final exam
preparation bundle. Features 310 highly targeted, conceptual, and calculative multiple-choice
questions complete with expert solutions and detailed rationale explanations. Covers essential
course topics including Vapour Power Cycles (Rankine), Gas-Turbine Cycles (Brayton),
Psychrometrics, and Combustion Balance Matrix equations. Perfect for securing an A+ and passing
the strict 50% exam threshold.
Part 1: Vapour Power Cycles (Questions 1–15)
1. In an ideal Rankine cycle, which thermodynamic process occurs within the steam
turbine?
A) Isothermal expansion
B) Isentropic expansion
C) Isobaric expansion
D) Isenthalpic expansion
Rationale: An ideal turbine is modeled as an adiabatic and reversible device. An
adiabatic and reversible process is isentropic, meaning the entropy of the fluid
remains constant from the inlet to the exit.
2. What is the primary purpose of adding a reheat stage to a vapor power cycle?
A) To reduce the moisture content of the steam at the low-pressure turbine exit
B) To increase the pressure of the fluid entering the condenser
C) To eliminate the need for a high-pressure feedwater pump
D) To drop the average temperature at which heat is added to the system
Rationale: Reheating allows the steam to expand through a high-pressure turbine,
get reheated at constant pressure, and expand again. This shifts the expansion line
on a T-s diagram to the right, significantly decreasing the liquid moisture content at
the turbine exhaust to prevent blade erosion.
3. How does lowering the condenser pressure below atmospheric pressure affect a
Rankine cycle?
A) It increases the temperature of heat rejection, lowering thermal efficiency.
B) It lowers the net work output of the cycle by requiring more pump work.
C) It increases the net work output and increases the overall thermal
efficiency.
D) It converts the cycle into an open loop system that does not require a cooling
tower.
Rationale: Lowering the condenser pressure drops the temperature at which heat is
rejected. This increases the enclosed area on the T-s diagram, which represents an
increase in net work output and thermal efficiency.
4. In a regenerative Rankine cycle with an open feedwater heater (OFWH), what
physical process takes place inside the OFWH?
A) Liquid water is evaporated using heat from combustion exhaust gases.
B) Extracted steam is condensed on the outside of tubes while feedwater flows
inside them without mixing.
C) Extracted steam from the turbine mixes directly with subcooled feedwater
, from the low-pressure pump.
D) High-pressure steam is throttled to lower its enthalpy before entering the boiler.
Rationale: An open feedwater heater is a direct-contact heat exchanger where bled
steam and compressed liquid water mix directly to leave as a saturated liquid at the
heater pressure.
5. Why is a closed feedwater heater (CFWH) often chosen over an open feedwater
heater despite being less efficient at heat transfer?
A) A CFWH does not require a separate pump for every single heating stage.
B) A CFWH allows for direct contact mixing which speeds up fluid transit.
C) A CFWH eliminates the need for traps or condensate pumps.
D) A CFWH must operate at a pressure significantly higher than the boiler pressure.
Rationale: In a CFWH, fluids do not mix, meaning the feedwater can remain at high
pressure while flowing through tubes. This allows multiple heaters to be chained
together without needing a pump after each stage, unlike an OFWH.
6. What thermodynamic parameter remains constant across an ideal throttling valve
used to drain condensate from a closed feedwater heater?
A) Entropy
B) Enthalpy
C) Temperature
D) Internal energy
Rationale: Throttling valves are modeled as adiabatic, steady-flow devices with no
work output. Applying the first law of thermodynamics reduces the energy balance
equation to h_inlet = h_exit, making it an isenthalpic process.
7. Which modification to a Rankine cycle directly increases the average temperature at
which heat is added without altering the cycle pressures?
A) Decreasing the mass flow rate through the condenser.
B) Increasing the amount of steam bled to the feedwater heaters.
C) Superheating the steam to a higher temperature in the boiler.
D) Increasing the moisture content at the high-pressure turbine inlet.
Rationale: Superheating increases the temperature of the steam before it enters the
turbine while maintaining the same boiler pressure. This raises the average
temperature at which heat is absorbed by the cycle, increasing thermal efficiency.
8. The term "back work ratio" in a vapor power cycle is defined as the ratio of pump
work input to turbine work output. What is its typical value for a standard Rankine
cycle?
A) Less than 1% to 2%
B) Roughly 20% to 30%
C) Exactly 50%
D) Greater than 80%
Rationale: Because the specific volume of liquid water handled by the pump is tiny
compared to the specific volume of the superheated steam handled by the turbine,
the work required by the pump is a very small fraction of the turbine work output.
9. If a steam turbine has an isentropic efficiency of 85%, how does its actual work
output compare to an ideal turbine operating between the same inlet state and exit
pressure?
A) The actual work output is 15% higher than the ideal work output.
B) The actual work output is 85% of the ideal work output.
C) The actual work output is equal, but the exit entropy is lower.
D) The actual work output cannot be determined without knowing the pump
efficiency.
, Rationale: Isentropic turbine efficiency is defined as the ratio of actual work output to
ideal (isentropic) work output: n_t = w_actual / w_ideal. Therefore, w_actual = 0.85 *
w_ideal.
10. What is the phase of the fluid entering the pump of an ideal Rankine cycle?
A) Subcooled liquid
B) Saturated liquid
C) Liquid-vapor mixture with 50% quality
D) Superheated vapor
Rationale: To avoid cavitation inside the pump and minimize the work input required,
the fluid leaving the condenser and entering the pump is assumed to be a saturated
liquid.
11. In a supercritical Rankine cycle, how does the water behave inside the steam
generator?
A) It undergoes a prolonged constant-temperature phase change from liquid to
vapor.
B) It changes from a liquid-like density to a gas-like density continuously
without boiling.
C) It remains a subcooled liquid until it enters the turbine.
D) It splits into two distinct phases that must be separated using a flash tank.
Rationale: Supercritical fluids operate above the critical point pressure and
temperature. At these states, there is no distinct phase change process (no boiling
line); the fluid transitions smoothly from liquid-like to gas-like behavior.
12. How does the presence of irreversibilities (like friction) inside an actual pump affect
the fluid state at the pump exit?
A) It lowers the exit temperature compared to an ideal pump.
B) It increases both the exit temperature and the exit entropy compared to an
ideal pump.
C) It lowers the pressure below the intended boiler operating pressure.
D) It keeps the entropy constant but decreases the enthalpy.
Rationale: Friction and other irreversibilities generate entropy (s_exit > s_inlet). This
internal energy dissipation causes the actual fluid enthalpy and temperature at the
exit to be higher than those of an isentropic process.
13. What limit restricts the maximum temperature to which steam can be superheated or
reheated in a modern utility boiler?
A) The critical temperature of water.
B) The metallurgical limitations of the turbine blades and boiler tubes.
C) The freezing point of the combustion air.
D) The flammability limits of coal or natural gas.
Rationale: Raising the superheat temperature increases efficiency, but it is strictly
limited by the maximum temperature that modern steel alloys and ceramic coatings
can withstand under high pressure without structural failure.
14. In a cogeneration plant utilizing a process-heating loop, what does a utilization factor
of 100% theoretically mean?
A) The plant produces no electricity and only outputs process heat.
B) All energy rejected by the cycle is perfectly utilized as useful process heat,
with zero unutilized thermal losses.
C) The turbine operates with zero internal friction or entropy generation.
D) The boiler operates with zero fuel consumption.
Rationale: The utilization factor is defined as (Net Work Output + Process Heat
, Output) / Heat Input. A factor of 100% implies that all thermal energy added by the
fuel is recovered either as electricity or as useful process heat.
15. What happens to the cycle parameters if a designer adds an ideal regenerator to a
vapor cycle without changing boiler or condenser settings?
A) The net work output decreases dramatically.
B) The total heat rejected in the condenser increases.
C) The heat input required in the boiler decreases, raising the efficiency.
D) The mass flow rate through the turbine drops to zero.
Rationale: Regeneration uses thermal energy harvested internally from the cycle to
preheat the feedwater before it hits the boiler. This directly reduces the quantity of
external heat input required from the fuel.
Part 2: Gas-Turbine Cycles (Questions 16–30)
16. Which cycle serves as the ideal model for simple gas-turbine power plants?
A) Rankine cycle
B) Brayton cycle
C) Otto cycle
D) Diesel cycle
Rationale: The Brayton cycle is the standard thermodynamic model for gas-turbine
engines, featuring isentropic compression, constant-pressure heat addition,
isentropic expansion, and constant-pressure heat rejection.
17. In an air-standard Brayton cycle, how is the combustion process modeled?
A) As a constant-volume heat addition process.
B) As an isothermal heat addition process.
C) As a constant-pressure heat addition from an external source.
D) As an instantaneous isenthalpic chemical reaction.
Rationale: Under air-standard assumptions, the actual combustion process is
replaced by a simplified constant-pressure (isobaric) heat transfer process from an
external source.
18. How does an increase in the compressor pressure ratio affect the back work ratio of
an ideal Brayton cycle?
A) It increases the back work ratio because compressor work grows faster
than turbine work.
B) It eliminates the back work ratio entirely.
C) It keeps the back work ratio locked at exactly 5%.
D) It decreases the back work ratio to less than 1%.
Rationale: As the pressure ratio increases, the temperature rise across the
compressor grows, requiring significantly more work input per unit mass, which
raises the ratio of compressor work to turbine work.
19. Under what structural condition can an ideal regenerator be successfully added to a
Brayton cycle to improve its thermal efficiency?
A) The compressor exit temperature must equal the turbine inlet temperature.
B) The turbine exit temperature must be higher than the compressor exit
310 Solved Exam Q&As & Expert
Solutions updated 2026-2027
Master Carleton University's MAAE 3400 (Applied Thermodynamics) with this ultimate final exam
preparation bundle. Features 310 highly targeted, conceptual, and calculative multiple-choice
questions complete with expert solutions and detailed rationale explanations. Covers essential
course topics including Vapour Power Cycles (Rankine), Gas-Turbine Cycles (Brayton),
Psychrometrics, and Combustion Balance Matrix equations. Perfect for securing an A+ and passing
the strict 50% exam threshold.
Part 1: Vapour Power Cycles (Questions 1–15)
1. In an ideal Rankine cycle, which thermodynamic process occurs within the steam
turbine?
A) Isothermal expansion
B) Isentropic expansion
C) Isobaric expansion
D) Isenthalpic expansion
Rationale: An ideal turbine is modeled as an adiabatic and reversible device. An
adiabatic and reversible process is isentropic, meaning the entropy of the fluid
remains constant from the inlet to the exit.
2. What is the primary purpose of adding a reheat stage to a vapor power cycle?
A) To reduce the moisture content of the steam at the low-pressure turbine exit
B) To increase the pressure of the fluid entering the condenser
C) To eliminate the need for a high-pressure feedwater pump
D) To drop the average temperature at which heat is added to the system
Rationale: Reheating allows the steam to expand through a high-pressure turbine,
get reheated at constant pressure, and expand again. This shifts the expansion line
on a T-s diagram to the right, significantly decreasing the liquid moisture content at
the turbine exhaust to prevent blade erosion.
3. How does lowering the condenser pressure below atmospheric pressure affect a
Rankine cycle?
A) It increases the temperature of heat rejection, lowering thermal efficiency.
B) It lowers the net work output of the cycle by requiring more pump work.
C) It increases the net work output and increases the overall thermal
efficiency.
D) It converts the cycle into an open loop system that does not require a cooling
tower.
Rationale: Lowering the condenser pressure drops the temperature at which heat is
rejected. This increases the enclosed area on the T-s diagram, which represents an
increase in net work output and thermal efficiency.
4. In a regenerative Rankine cycle with an open feedwater heater (OFWH), what
physical process takes place inside the OFWH?
A) Liquid water is evaporated using heat from combustion exhaust gases.
B) Extracted steam is condensed on the outside of tubes while feedwater flows
inside them without mixing.
C) Extracted steam from the turbine mixes directly with subcooled feedwater
, from the low-pressure pump.
D) High-pressure steam is throttled to lower its enthalpy before entering the boiler.
Rationale: An open feedwater heater is a direct-contact heat exchanger where bled
steam and compressed liquid water mix directly to leave as a saturated liquid at the
heater pressure.
5. Why is a closed feedwater heater (CFWH) often chosen over an open feedwater
heater despite being less efficient at heat transfer?
A) A CFWH does not require a separate pump for every single heating stage.
B) A CFWH allows for direct contact mixing which speeds up fluid transit.
C) A CFWH eliminates the need for traps or condensate pumps.
D) A CFWH must operate at a pressure significantly higher than the boiler pressure.
Rationale: In a CFWH, fluids do not mix, meaning the feedwater can remain at high
pressure while flowing through tubes. This allows multiple heaters to be chained
together without needing a pump after each stage, unlike an OFWH.
6. What thermodynamic parameter remains constant across an ideal throttling valve
used to drain condensate from a closed feedwater heater?
A) Entropy
B) Enthalpy
C) Temperature
D) Internal energy
Rationale: Throttling valves are modeled as adiabatic, steady-flow devices with no
work output. Applying the first law of thermodynamics reduces the energy balance
equation to h_inlet = h_exit, making it an isenthalpic process.
7. Which modification to a Rankine cycle directly increases the average temperature at
which heat is added without altering the cycle pressures?
A) Decreasing the mass flow rate through the condenser.
B) Increasing the amount of steam bled to the feedwater heaters.
C) Superheating the steam to a higher temperature in the boiler.
D) Increasing the moisture content at the high-pressure turbine inlet.
Rationale: Superheating increases the temperature of the steam before it enters the
turbine while maintaining the same boiler pressure. This raises the average
temperature at which heat is absorbed by the cycle, increasing thermal efficiency.
8. The term "back work ratio" in a vapor power cycle is defined as the ratio of pump
work input to turbine work output. What is its typical value for a standard Rankine
cycle?
A) Less than 1% to 2%
B) Roughly 20% to 30%
C) Exactly 50%
D) Greater than 80%
Rationale: Because the specific volume of liquid water handled by the pump is tiny
compared to the specific volume of the superheated steam handled by the turbine,
the work required by the pump is a very small fraction of the turbine work output.
9. If a steam turbine has an isentropic efficiency of 85%, how does its actual work
output compare to an ideal turbine operating between the same inlet state and exit
pressure?
A) The actual work output is 15% higher than the ideal work output.
B) The actual work output is 85% of the ideal work output.
C) The actual work output is equal, but the exit entropy is lower.
D) The actual work output cannot be determined without knowing the pump
efficiency.
, Rationale: Isentropic turbine efficiency is defined as the ratio of actual work output to
ideal (isentropic) work output: n_t = w_actual / w_ideal. Therefore, w_actual = 0.85 *
w_ideal.
10. What is the phase of the fluid entering the pump of an ideal Rankine cycle?
A) Subcooled liquid
B) Saturated liquid
C) Liquid-vapor mixture with 50% quality
D) Superheated vapor
Rationale: To avoid cavitation inside the pump and minimize the work input required,
the fluid leaving the condenser and entering the pump is assumed to be a saturated
liquid.
11. In a supercritical Rankine cycle, how does the water behave inside the steam
generator?
A) It undergoes a prolonged constant-temperature phase change from liquid to
vapor.
B) It changes from a liquid-like density to a gas-like density continuously
without boiling.
C) It remains a subcooled liquid until it enters the turbine.
D) It splits into two distinct phases that must be separated using a flash tank.
Rationale: Supercritical fluids operate above the critical point pressure and
temperature. At these states, there is no distinct phase change process (no boiling
line); the fluid transitions smoothly from liquid-like to gas-like behavior.
12. How does the presence of irreversibilities (like friction) inside an actual pump affect
the fluid state at the pump exit?
A) It lowers the exit temperature compared to an ideal pump.
B) It increases both the exit temperature and the exit entropy compared to an
ideal pump.
C) It lowers the pressure below the intended boiler operating pressure.
D) It keeps the entropy constant but decreases the enthalpy.
Rationale: Friction and other irreversibilities generate entropy (s_exit > s_inlet). This
internal energy dissipation causes the actual fluid enthalpy and temperature at the
exit to be higher than those of an isentropic process.
13. What limit restricts the maximum temperature to which steam can be superheated or
reheated in a modern utility boiler?
A) The critical temperature of water.
B) The metallurgical limitations of the turbine blades and boiler tubes.
C) The freezing point of the combustion air.
D) The flammability limits of coal or natural gas.
Rationale: Raising the superheat temperature increases efficiency, but it is strictly
limited by the maximum temperature that modern steel alloys and ceramic coatings
can withstand under high pressure without structural failure.
14. In a cogeneration plant utilizing a process-heating loop, what does a utilization factor
of 100% theoretically mean?
A) The plant produces no electricity and only outputs process heat.
B) All energy rejected by the cycle is perfectly utilized as useful process heat,
with zero unutilized thermal losses.
C) The turbine operates with zero internal friction or entropy generation.
D) The boiler operates with zero fuel consumption.
Rationale: The utilization factor is defined as (Net Work Output + Process Heat
, Output) / Heat Input. A factor of 100% implies that all thermal energy added by the
fuel is recovered either as electricity or as useful process heat.
15. What happens to the cycle parameters if a designer adds an ideal regenerator to a
vapor cycle without changing boiler or condenser settings?
A) The net work output decreases dramatically.
B) The total heat rejected in the condenser increases.
C) The heat input required in the boiler decreases, raising the efficiency.
D) The mass flow rate through the turbine drops to zero.
Rationale: Regeneration uses thermal energy harvested internally from the cycle to
preheat the feedwater before it hits the boiler. This directly reduces the quantity of
external heat input required from the fuel.
Part 2: Gas-Turbine Cycles (Questions 16–30)
16. Which cycle serves as the ideal model for simple gas-turbine power plants?
A) Rankine cycle
B) Brayton cycle
C) Otto cycle
D) Diesel cycle
Rationale: The Brayton cycle is the standard thermodynamic model for gas-turbine
engines, featuring isentropic compression, constant-pressure heat addition,
isentropic expansion, and constant-pressure heat rejection.
17. In an air-standard Brayton cycle, how is the combustion process modeled?
A) As a constant-volume heat addition process.
B) As an isothermal heat addition process.
C) As a constant-pressure heat addition from an external source.
D) As an instantaneous isenthalpic chemical reaction.
Rationale: Under air-standard assumptions, the actual combustion process is
replaced by a simplified constant-pressure (isobaric) heat transfer process from an
external source.
18. How does an increase in the compressor pressure ratio affect the back work ratio of
an ideal Brayton cycle?
A) It increases the back work ratio because compressor work grows faster
than turbine work.
B) It eliminates the back work ratio entirely.
C) It keeps the back work ratio locked at exactly 5%.
D) It decreases the back work ratio to less than 1%.
Rationale: As the pressure ratio increases, the temperature rise across the
compressor grows, requiring significantly more work input per unit mass, which
raises the ratio of compressor work to turbine work.
19. Under what structural condition can an ideal regenerator be successfully added to a
Brayton cycle to improve its thermal efficiency?
A) The compressor exit temperature must equal the turbine inlet temperature.
B) The turbine exit temperature must be higher than the compressor exit
