ChE 123: LE 1

Question 1

the gas closely follows ideal behavior at what pressure and temperature

Answer 1

low pressure and high temperature

Question 2

a process where fluid undergoes a significant pressure drop without performing work

Answer 2

throttling

Question 3

true or false: according to Clapeyron Equation, in a two-phase system, if the temperature of the system changes, then the pressure must also change given that the two phases coexist in equilibrium

Answer 3

check

Question 4

usual shape of a turbine blade, designated to generate lift or control airflow

Answer 4

airfoil

Question 5

a turbine is a device that

Answer 5

produces work output by expanding a high-pressure fluid

Question 6

what do you call the type of duct with varying cross-sectional area

Answer 6

nozzle

Question 7

after throttling, the fluid temperature

Answer 7

depends on the nature of the fluid

Question 8

true or false: in a two-phase system, the specific volume of the mixture is always between the specific volumes of the saturated liquid and saturated vapor phases

Answer 8

check

Question 9

true or false: the Maxwell relations are derived from the fundamental thermodynamic property relations

Answer 9

true

Question 10

true or false: in a compressor, the ideal work is the maximum work that can be produced by the system

Answer 10

false
in a compressor, the ideal work is the minimum work required by the system

Question 11

a two-phase mixture of liquid water and steam, often characterized by its dryness fraction

Answer 11

wet steam

Question 12

true or false: for a subsonic flow inside the pipe, the velocity increases indefinitely as the fluid flows in x-direction

Answer 12

false
For subsonic flow (Mach number < 1) inside a pipe, velocity does not increase indefinitely as the fluid flows in the x-direction — unless special conditions apply

Question 13

the narrowest part of a converging-diverging nozzle where the flow can reach its crucial state

Answer 13

throat

Question 14

a rotating component in turbines or compressors that helps transfer energy between the fluid and the machine

Answer 14

rotor blade

Question 15

the difference between actual thermodynamic properties and those predicted by an ideal gas model

Answer 15

residual

Question 16

a measure of the proportion of vapor in a saturated liquid-vapor in a saturated liquid-vapor mixture, expressed as a fraction or percentage

Answer 16

quality

Question 17

true or false: for a supersonic flow inside a converging nozzle, both pressure and velocity also decrease

Answer 17

false
only the volume will decrease, while the pressure increases

Question 18

the maximum amount of useful work that can be extracted from a closed system at constant temperature and pressure

Answer 18

decrease in Gibbs free energy

Question 19

true or false: throttling to sufficiently low pressure reduces the quality of a saturated mixture

Answer 19

false
throttling to sufficiently low pressure increases the quality of a saturated mixture since the proportion of vapor increases due to the effect of throttling that causes the mixture to evaporate

Question 20

the Maxwell relation derived from the differential expression internal energy (dU)

Answer 20

(∂T/∂V) S = -(∂P/∂S) V

Question 21

a mechanical device that increases the pressure of a gas by applying work

Answer 21

compressor

Question 22

for incompressible fluid, which of the following is/are true?

Answer 22

Cv - Cp = 0
Cp - Cv = 0

Question 23

the Maxwell relation derived from the differential expression for the Helmholtz free energy (dA) is/are

Answer 23

(∂V/∂S) T = (∂T/∂P) V
​

Question 24

which of the following equation(s) is/are derived when Gibbs Energy was used as a generating function?

Answer 24

U/RT = H/RT - PV/RT

Question 25

true or false: in a turbine, to conserve the total energy, the stator section increases the pressure and temperature while reducing the velocity

Answer 25

false the pressure and temperature should reduce

Question 26

in a converging nozzle, the velocity of a subsonic flow

Answer 26

increases

Question 27

true or false: throttling is an isentropic process

Answer 27

false it is an isenthalpic process where there is no shaft work, and in the absence of heat transfer, therefore process occurs at constant enthalpy

Question 28

a set of thermodynamic relations derived from the second law that expresses partial derivatives of properties in terms of measurable quantities

Answer 28

maxwell

Question 29

true or false: for two phases a and b of pure species, G^a = G^b where G is the specific Gibbs energies of the individual species

Answer 29

false at equilibrium, for two phases a and b of pure species, G^a = G^b where G is the specific Gibbs energies of the individual species