THERMO Flashcards
(14 cards)
A gas initially at 15 psia and 2 ft3 undergoes a process to 90 psia and
0.6 ft3
, during which the enthalpy increases by 15.5 BTU; Cv=2.44
BTU/lb-R. Determine
- ∆U
a. 12.2 BTU c. 13.3 BTU
b. 11.1 BTU d. 10.0 BTU - Cp in BTU/lb-R
a. 3.42 c. 4.01
b. 5.56 d. 2.98 - R in in BTU/lb-R
a. 0.54 c. 0.98
b. 0.61 d. 0.12
b. 11.1 BTU
a. 3.42
c. 0.98
A group of 50 persons attended a secret meeting in a room which is
12 m by 10 m long and a ceiling of 3 m. The room is completely
sealed off and insulated. Each person gives off 150 kcal per hour of
heat and occupies a volume of 0.2 m3
. The room has an initial
pressure of 101.3 kPa and temperature of 160C. Calculate the room
temperature after 10 minutes in 0C.
a. 25 c. 36
b. 33 d. 29
b. 33
Air flows steadily at a rate of 0.5 kg/s through an air compressor,
entering at 7 m/s speed, 100 kPa pressure and. 0.95 m3
/kg specific
volume, and leaving at 5 m/s, 700 kPa, and 0.19 m3
/kg. The internal
energy of the air leaving is 90 kJ/kg greater than of the air entering.
Cooling water in the compressor jackets absorbs heat from the air at
a rate of 58 kW. Compute the work in kW.
a. 211 kW c. 122 kW
b. 112 kW d. 212 kW
c. 122 kW
Air flows steadily and adiabatically through a horizontal straight pipe.
The air enters the pipe at an absolute pressure of 100 psia, a
temperature of 1000F, and a linear velocity of 10 ft/sec. The air leaves
at 2 psia.
- What is the temperature of the leaving air?
a. 60 0F c. 80 0F
b. 70 0F d. 50 0F - What is the velocity of the leaving air?
a. 482 fps c. 345 fps
b. 161 fps d. 229 fps
c. 80 0F
a. 482 fps
One mole of an ideal gas undergoes the following sequence of
mechanically reversible processes in a closed system: from an
initial state of 700C and 1 bar, it is compressed adiabatically to
1500C, it is then cooled from 150 to 700C at constant pressure
and finally, it is expanded isothermally to its original state.
Calculate W for the entire process. Take Cv = 3R/2 and Cp =
5R/2.
a. -168 J c. 168 J
b. 0 J d. 237 J
c. 168 J
Reported values for the virial coefficients of isopropanol vapor at
2000C are: B = -388 cm3
/mol and C = -26000 cm6
/mol2
. Calculate
V and Z for isopropanol vapor at 2000C and 10 bar by:
56. Ideal Gas
a. 1, 3934 cm3/mol
b. 1, 3539 cm3/mol
c. 1, 3488 cm3/mol
d. 1. 3495 cm3/mol
- Virial equation of state
a. 0.91, 3934 cm3/mol
b. 0.95, 3539 cm3/mol
c. 0.89, 3488 cm3/mol
d. 0.80, 3495 cm3/mol
a. 1, 3934 cm3/mol
b. 0.95, 3539 cm3/mol
For liquid acetone at 200C and 1 bar, β = 1.487 x 10-3 0C-, κ = 62x 10-6 bar and V = 1.287 cm3/g.
- The value of (δP/δT)V at 200C and 1 bar is
a. 24 bar/0C c. 26 bar/0C
b. 28 bar/0C d. 30 bar/0C - The pressure generated by heating at constant V from 200C and
1 bar to 300C is
a. 241 c. 242
b. 243 d. 245
a. 24 bar/0C
a. 241
Determine the molar volume of n-butane at 510 K and 25 bar by each
of the following:
- The ideal-gas equation
a. 1696 cm3/mol
b. 1880 cm3/mol
c. 1905 cm3/mol
d. 1758 cm3/mol - The generalized compressibility-factor correlation
a. 1483 cm3/mol
b. 1486 cm3/mol
c. 1480 cm3/mol
d. 1489 cm3/mol - Equation, with the generalized correlation for B
a. 1483 cm3/mol
b. 1486 cm3/mol
c. 1480 cm3/mol
d. 1489 cm3/mol
a. 1696 cm3/mol
c. 1480 cm3/mol
d. 1489 cm3/mol
A nuclear power plant generates 750 MW; the reactor
temperature is 3150C and a river with water temperature of 200C
is available.
- What is the minimum rate at which heat must be discarded to the
river?
a. 680 MW c. 420 MW
b. 330 MW d. 745 MW - If the actual thermal efficiency of the plant is 60% of the
maximum, what is the temperature rise in 0C of the river if it has
a flow of 165 m3 s
-?
a. 4.0 c. 3.6
b. 2.5 d. 1.1
d. 745 MW
b. 2.5
A heat engine operating at a Carnot cycle between 15400F and
400F rejects 250 BTU/lb of working fluid to the sink.
75. What is the work produced by the heat engine?
a. 190 BTU/lb c. 560 BTU/lb
b. 350 BTU/lb d. 750 BTU/lb
d. 750 BTU/lb
At 90 0C, the vapor pressure of acetic acid is 293 mmHg and its
vapor pressure at 100 0C is 417mmHg. Calculate the normal
boiling point of acetic acid.
a. 271.4 K c. 298.2 K
b. 391.3 K d. 303.0 K
b. 391.3 K
Three pounds per second of steam expand in a turbine
isentropically from 300 psia and 7000F to 2000F. Determine the
following:
S1: 1.6758 H1: 1368.9 V1: 2.2263
Sfg: 1.4824 Hfg: 977.9 Vfg: 33.6224
Sg2: 1.7764 Hg2: 1146 Vg2: 33.639
97. Quality of the exit steam.
a. 88% c. 90%
b. 93% d. 85%
98. Steady flow work.
a. 868 BTU/s c. 645 BTU/s
b. 709 BTU/s d. 953 BTU/s
99. Non-flow work.
a. 842 BTU/s c. 698 BTU/s
b. 755 BTU/s d. 904 BTU/s
b. 93%
a. 868 BTU/s
c. 698 BTU/s
Gaseous nitrogen actuates a Carnot power cycle in which
respective volumes at the four corners of the cycle, starting at the
beginning of the isothermal expansion, are V1=10.10 L, V2=14.53
L, V3=226.54 L, and V4=157.73 L. The cycle receives 21.1 kJ of
heat. Calculate the following:
- Work, W
a. 12 kJ c. 8 kJ
b. 17 kJ d. 14 kJ - Mean effective pressure, MEP
a. 65 kPa c. 50 kPa
b. 88 kPa d. 42 kPa
d. 14 kJ
a. 65 kPa
An ideal Diesel engine uses air initially at 200C and 90 kPa at the
beginning of the compression process. If the compression ratio is
15 and the maximum temperature in the cycle is 20000C,
determine the following:
- net work (kJ) produced
a. 812 c. 1010
b. 930 d. 1414 - mean effective pressure (kPa)
a. 812 c. 1010
b. 930 d. 1414 - cut-off ratio
a. 1.3 c. 2.6
b. 2.8 d. 5.7
a. 812
b. 930
c. 2.6
