Thermo Final Exam Multiple Choice Flashcards
The symbol Δ is always used to denote:
a. Initial value minus final value
b. No change in value
c. Final value minus initial value
d. None of the above
C
What is being transferred to the system if we heat it up?
a. Energy
b. Heat
A
The differential of work, δ W, is said to be an _____ differential.
a. Exact
b. Inexact
B
What direction is the net energy transfer by work for a refrigeration or heat pump cycle:
a. In
b. Out
A
What direction is the net energy transfer by heat for a refrigeration or heat pump cycle:
a. In
b. Out
B
The coefficient of performance of an irreversible heat pump cycle is always ______ the coefficient of performance of a reversible heat pump cycle when each operates between the same two thermal reservoirs.
a. Equal to
b. Greater than
c. Less than
C
An example of an external irreversibility associated with the Rankine cycle is:
a. Expansion of the working fluid through the turbine
b. Frictional effects resulting in pressure drops
c. Combustion of fuel
d. Irreversibilities in the pump
C
Which of the following is not a primary goal of subsystems associated with vapor power plants?
a. Convert electrical power to shaft power.
b. Provide condenser cooling water.
c. Convert shaft power to electrical power.
d. Supply energy to vaporize the power plant working fluid.
A
The value of the back work ratio of a Brayton cycle is typically:
a. Much less than for a Rankine cycle
b. Much greater than for a Rankine cycle
c. About the same as for a Rankine cycle
d. Cannot be determined without more information
B
When a regenerator is introduced in a simple Brayton cycle, the net work developed per unit of mass flow:
a. Increases
b. Decreases
c. Increases or decreases depending on the regenerator effectiveness
d. Remains the same
D
