Download Test 1 - Fundamentals of Thermodynamics | ME 3134 and more Exams Thermodynamics in PDF only on Docsity!
I pledge that this work is my own and that I neither gave f
this test.
SS q
Problem 1:(20 pts) A frictionless piston-cylinder device contains 2kg itrogen at 100 kPa and 300+.
Nitrogen is now compressed slowly according to the relation Pv'® = Constant. The final temperature of the
nitrogen is measured as 360 K. Calculate the work done and the heat transfer during this process. (Note:
Heat transfer may occur between the system and the surroundings.)
Problem 2:(10 pts) Power is produced by combusting a fuel at 1000 K and rejecting waste heat to the
atmosphere at 27°C. Determine the maximum efficiency of any heat engine operating under these conditions.
Problem 3:(10 pts’ 0.5 m’ rigid tank containing
hydrogen at 20°C and 600 kPa is connected by a valve
to another 0.5m* rigid tank that holds hydrogen at 30°C
and 150 kPa. Now the valve is opened, and the system
is allowed to reach thermal equilibrium with the 0.5 m3 V=0.502
surroundings which are at 15°C. Determine the final 10°C T=30°C
pressure in the tank P=600 kPa 1} P=150 kPa
© S
Problem 4:(25 pts) Air flows steadily through an adiabatic turbine, entering at 1 MPa, 627°C and
100 m/sec and leaving at 200 kPa, 227°C and 180 m/sec. The inlet area of the turbine is 0.01 m.
a) Determine the mass flow rate of the air.
b) Determine the work output of the turbine per unit mass.
Problem 5:(35 pts) Consider the uninsulated piston-cylinder device shown in the figure. The sealed
device initially contains 0.1 m° of Nitrogen gas
at 100 kPa and 300 K. The gas in the device is
heated by a 100 W electrical resistance
element for 10 minutes while it is being mixed
with a paddle wheel stirrer which adds 15 kJ of
energy to the system. During the process heat
transfer from the system to the surroundings at
300 K equals 25 kJ. At the end of the process
the gas is measured to be at 200 kPa and
700 K. For the system identified by the dashed
line just inside the walls of the piston-cylinder
device answer the following questions.
a) Does the energy input from the
paddle wheel represent heat or work.
b) Does the energy input from the
resistance heater represent heat or work.
c) Determine the mass of Nitrogen in
the system.
d) Determine the final volume of the gas after the process is complete.
e) Determine the boundary work during the process.
f) Briefly describe how the system could be modified to produce more work with the same beginning and
ending states, without changing the power rating or on-time of the resistance heater.
I ha TAv= Rok
ce Tas 20 te
__ Saale nk, mS 3
? ih, alas: 203 =" 5929 e3 ~
mY To toda &
@cWem,Ce Us-T)
eee al. nae) WO)
ee > iced anal
T= 000K sae a). TO?
pe Term = S00 1000 Jae
: Nie. Sm Va=.Sim® Vas \mS
Te aore Ta230°C 5 Ta =
Pi =(oMe Ps = SOR,
2 angaR Een = s7,000098 Ba.
ie = Q3' - (aks i 2
Pal 1)=Caaeas+ .Ovoral(a. vee laa)
Pe: ee ag = i
tls Yi alae ee Cn
ae |COmis Orem
7” Bie .\mn*
Pe CAO TD
ne *
—__ fie __\ap\/eig i
