Test Bank for Fundamentals of Power
Plant Engineering, Latest Edition by
George R. Nag - Thermodynamics
Questions and Answers
1. What is the primary function of a power plant?
Answer: To convert energy from a primary source (fuel,
nuclear, solar, etc.) into electrical energy.
Rationale: Power plants transform chemical, nuclear, or
renewable energy into mechanical energy (via turbines) and
then into electricity via generators.
2. Which thermodynamic cycle is the foundation of most
thermal power plants?
Answer: Rankine cycle.
Rationale: The Rankine cycle describes the operation of
steam turbine power plants, including heat addition,
expansion, condensation, and compression.
3. What is a closed thermodynamic system?
Answer: A system where mass does not cross the boundary,
but energy can.
Rationale: Example: a piston-cylinder with a fixed mass of
gas. No mass enters/leaves.
4. Define the Zeroth Law of Thermodynamics.
, Answer: If two systems are in thermal equilibrium with a
third system, they are in thermal equilibrium with each other.
Rationale: This law justifies temperature measurement.
5. What is the difference between intensive and extensive
properties?
Answer: Intensive properties do not depend on mass (e.g.,
temperature, pressure); extensive depend on mass (e.g.,
volume, energy).
Rationale: Important for scaling analysis in power plant
design.
6. What does the First Law of Thermodynamics state?
Answer: Energy cannot be created or destroyed, only
converted from one form to another.
Rationale: For a closed system: ΔU = Q − W.
7. What is a perpetual motion machine of the first kind
(PMM1)?
Answer: A machine that produces work without consuming
energy.
Rationale: It violates the First Law.
8. What does the Second Law of Thermodynamics state about
entropy?
Answer: Entropy of an isolated system increases or remains
constant, never decreases.
Rationale: Defines direction of natural processes.
, 9. Define entropy.
Answer: A measure of molecular disorder or unavailable
energy in a system.
Rationale: Increases with irreversibility.
10. What is a reversible process?
Answer: A process that can be reversed without leaving any
net change in the system and surroundings.
Rationale: Theoretical ideal; requires no friction, no heat
transfer across finite ΔT.
11. What is an isentropic process?
Answer: A process that is both adiabatic and reversible
(constant entropy).
Rationale: Used to model ideal turbines and compressors.
12. Define specific volume.
Answer: Volume per unit mass (m³/kg).
Rationale: Used in steam tables and gas laws.
13. What is the critical point of water?
Answer: 374°C and 22.06 MPa; above this, liquid and vapor
phases are indistinguishable.
Rationale: Important for supercritical power plants.
14. What is enthalpy (h)?
Answer: h = u + Pv (internal energy + flow work).
Rationale: Convenient for open systems (turbines, boilers).
Plant Engineering, Latest Edition by
George R. Nag - Thermodynamics
Questions and Answers
1. What is the primary function of a power plant?
Answer: To convert energy from a primary source (fuel,
nuclear, solar, etc.) into electrical energy.
Rationale: Power plants transform chemical, nuclear, or
renewable energy into mechanical energy (via turbines) and
then into electricity via generators.
2. Which thermodynamic cycle is the foundation of most
thermal power plants?
Answer: Rankine cycle.
Rationale: The Rankine cycle describes the operation of
steam turbine power plants, including heat addition,
expansion, condensation, and compression.
3. What is a closed thermodynamic system?
Answer: A system where mass does not cross the boundary,
but energy can.
Rationale: Example: a piston-cylinder with a fixed mass of
gas. No mass enters/leaves.
4. Define the Zeroth Law of Thermodynamics.
, Answer: If two systems are in thermal equilibrium with a
third system, they are in thermal equilibrium with each other.
Rationale: This law justifies temperature measurement.
5. What is the difference between intensive and extensive
properties?
Answer: Intensive properties do not depend on mass (e.g.,
temperature, pressure); extensive depend on mass (e.g.,
volume, energy).
Rationale: Important for scaling analysis in power plant
design.
6. What does the First Law of Thermodynamics state?
Answer: Energy cannot be created or destroyed, only
converted from one form to another.
Rationale: For a closed system: ΔU = Q − W.
7. What is a perpetual motion machine of the first kind
(PMM1)?
Answer: A machine that produces work without consuming
energy.
Rationale: It violates the First Law.
8. What does the Second Law of Thermodynamics state about
entropy?
Answer: Entropy of an isolated system increases or remains
constant, never decreases.
Rationale: Defines direction of natural processes.
, 9. Define entropy.
Answer: A measure of molecular disorder or unavailable
energy in a system.
Rationale: Increases with irreversibility.
10. What is a reversible process?
Answer: A process that can be reversed without leaving any
net change in the system and surroundings.
Rationale: Theoretical ideal; requires no friction, no heat
transfer across finite ΔT.
11. What is an isentropic process?
Answer: A process that is both adiabatic and reversible
(constant entropy).
Rationale: Used to model ideal turbines and compressors.
12. Define specific volume.
Answer: Volume per unit mass (m³/kg).
Rationale: Used in steam tables and gas laws.
13. What is the critical point of water?
Answer: 374°C and 22.06 MPa; above this, liquid and vapor
phases are indistinguishable.
Rationale: Important for supercritical power plants.
14. What is enthalpy (h)?
Answer: h = u + Pv (internal energy + flow work).
Rationale: Convenient for open systems (turbines, boilers).
