# MECE 2335 FINAL EXAM FALL 2009 Name SID# _________________

Mechanics

Oct 27, 2013 (4 years and 8 months ago)

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MECE 2335

FINAL EXAM

FALL 2009

Name
___
____
___________
_____

S
ID#

_________________

All answers must be placed in the underlined answer space and entered in the response system. Your work will only be graded
on
select pr
oblems as indicated on each problem so calculate values carefully.

Mark each of the following true (T) or false (F).

1.

____
Pressure is an in
tensive property.

2.

S
pecific volume is an
ex
tensive property.

3.

C
lassical t
hermodynamics is considered

a ma
croscopic approach.

4.

_

Work is

a thermodynamic property.

5.

_

The zeroth law of
thermodynamics is about thermal

equilibrium.

An electric generator coupled to a windmill produces an electric power output of 10kW. The power is used
to charge
a battery. Heat transfer from the battery to the surroundings occurs at a rate of 1.5kW. Determine
the rate at which energy is being stored on the battery.

6.

dE/dt
=__________kW

Determine the specified property for water at each defined state.

7.

h=_
_________kJ/kg given T=25°C and x=0.7

8.

v=__________m
3
/kg given
a saturated liquid at
T=25°C

9.

u
=__________kJ/kg given T=25°C

and P
=
0.06 bar

10.

s
=__________kJ/kg
-
K

given T=270
°C

and P
=
1.0 MPa

Two

k
ilograms

of
a gas

is compressed in a pis
ton
-
cyli
nder assembly from P
1
=106

kPa and V
1
=
0.200

m
3

to a
specific volume
of V
2
=0.
100

m
3
. The p
rocess is polytropic where n=1.5
0. Determine the

final pressure and
the

work for the compression process.

11.

P=____________kPa

12.

W=____________kJ

Determine the
compre
ssibility factor and
specific

volume of Butane where P=76 bar

and T=489 K.

Note: For Butane Pc=38 bar, Tc=425K, and MW=58.12 kg/kmol
.

13.

Z=__

________

14.

v=____________m
3
/kg

Steam

at
1.0

M
Pa,
54
0
o
C enters a well insulated valve. The exit pressur
e of the valve is
0.5 MPa. T
he exit
velocity equals the inlet velocity.
Det
ermine the
enthalpy of the steam at the exit of the valve.

15.

h=__________kJ/kg

Cooling water in a heat exchanger receives energy at the rate of 2500 kW. Determine the mass flo
w rate of
the cooling water if the water experiences a temperature rise of 10
o
C
.

Note:
The specific heat of the
water is 4.2 kJ/kg
-
K.

16.

=__________kg/min

A wa
ter tank, initially containing 1
00 kg of water, is being filled
through pipe 1 above the tank. Water is
leaving the tank through pipes 2 and 3. The flow rate
(kg/s)
through each pipe
is given
as a function of time
(seconds)

below. Determine the tim
e it takes to reach a mass of 200

kg in the tank.

17.

t=____________seconds

An oil pump delivers 2

k
g/s of oil (density=1350 kg/m3)
. The pressure rise from inlet to exit is

4
00 kPa.
Determine the required power for the pump

in kW
.

18.

=____________kW

Steam

enters a well

insulated nozzle
with an enthalpy of 3213.6 kJ/kg and

a steady velocity of 10 m/s. At the
exit the
enthalpy is 2992.5 kJ/kg. Determine the velocity of the steam at the exit.

19.

V=______________m/s

Steam enters a turbine at 12 MPa and 560
o
C at a rate o
f 5kg/s. The steam exits at 4 MPa and 400
o
C. The
steam is losing heat to the surro
undings at a rate of 2
00kW. The surface temperature of the turbine is 300
o
C.

Determine the power output of the turbine.

20.

=____________kW

D
etermine the rate of entropy generation within the turbine.

21.

=____________kW
/K

Determine the efficiency of a Carnot heat engine if the heat source is at 900
o
C and the environment is

at 25
o
C.

22.

=____________ (do not give as a percent)

Two kilograms of air at 25
o
C and 100 kPa is compressed in a reversible adiabatic process in a piston cylinder
assembly to a pressure of 400 kPa. Determine the temperature of the air at the end of the compression
process and the work output during the process. Assume constant specific heats where Cv=0.718 kJ/kg
-
K,
Cp=1.005 kJ/kg
-
K, and k=1.4.

Your work on this
problem will also be graded.

23.

T=_______________

o
C

24.

W=______________kJ

An insulated rigid

tank contains 5kg of air at 22
o
C and 101kPa. The tank also contains a 20kg copper block
at 150
o
C. Assume constant specific heats where for air Cv=0.718 kJ/kg
-
k and
for Copper C=0.386 kJ/kg
-
k.

Your work on this
problem will also be graded.

Determine th
e final equilibrium temperature.

25.

T=_______________
o
C

Determine the entropy
generation.

26.

S
gen
=_____________kJ/K

Air as an ideal gas undergoes an isentropic process from P1=100 kPa and T1=3
00K to a final state where
T2=12
00K. Assuming vari
able specific heats determine the final pressure.

Your work on this
problem will also be graded.

27.

P=_____________kPa

Steam at 12 MPa and 560
o
C enters a turbine with an adiabatic efficiency of 90%. Determine the exit
enthalpy if the exit pressu
re is
4 MPa.
Your work on this
problem will also be graded.

28.

h=______________kJ/kg

Sketch the complete cycle on a T
-
v diagram and
label the end states

for a system consisting of water that
undergoes the following processes:

Process 1
-
2: C
onstant pressure from a saturated liquid at T
1
=100
o
C to T
2
=200
o
C.

Process 2
-
3: Constant volume to T
3
=75
o
C.

Process 3
-
4: Constant temperature to a saturated liquid.

Process 4
-
5: Constant pressure to v
5
=v
1
.

29.

v
5
=______________m
3
/kg