PROBLEM 2.48
As shown in Fig. P2.48, an oven wall consists of a 0.635-cm-thick layer of steel (s = 15.1
W/mK) and a layer of brick (b = 0.72 W/mK). At steady state, a temperature decrease of 0.7oC
occurs over the steel layer. The inner temperature of the
PROBLEM 2.69
Steam in a piston-cylinder assembly undergoes a polytropic process. Data for the initial and
final states are given in the accompanying table. Kinetic and potential energy effects are
negligible. For the process, determine the work and heat t
4.86 Three return steam lines in a chemical processing plant enter a collection tank operating at
steady state at 1 bar. Steam enters inlet 1 with flow rate of 0.8 kg/s and quality of 0.9. Steam
enters inlet 2 with flow rate of 2 kg/s at 200oC. Steam ente
Problem 2.85
A concentrating solar collector system, as shown in Fig. P2.85, provides energy by heat transfer
to a power cycle at a rate of 2 MW. The cycle thermal efficiency is 36%. Determine the power
developed by the cycle, in MW. What is the work outp
Midterm
MAE 221 Thermodynamics
Wednesday, 9 November 2005 10:00am 10:50am FC004 Closed Book Closed Notes
Be sure to state all assumptions, and draw and label relevant schematics, processes, etc. 1. A window air conditioner unit consumes 2 kW of elec
PROBLEM 2.70
Air expands adiabatically in a piston-cylinder assembly from an initial state where p1 = 100
lbf/in.2, v1 = 3.704 ft3/lb, and T1 = 1000 oR, to a final state where p2 = 50 lbf/in.2 The process is
polytropic with n = 1.4. The change in specific
4.126 A tank of volume 1.2 m3 initially contains steam at 8 MPa and 400oC. Steam is
withdrawn slowly from the tank until the pressure drops to p. Heat transfer to the tank contents
maintains the temperature at 400oC. Neglecting all kinetic and potential e
PROBLE M 114-3
4.43 Air expands through a turbine from 8 bar, 960 K to 1 bar, 450 K. The inlet velocity is
small compared to the exit velocity of 90 mfs. The turbine operates at steady state and develops
a power output of 2500 kW. Heat transfer between th
PRO§LE M 4. 4-0
4.40 Oxygen gas enters a well-insulated diffuser at 30 lbﬁ’in.2, 440°R, with a velocity of
950 ft/s through a flow area of 2.0 in.2 At the exit, the ﬂow area is 15 times the inlet area,
and the velocity is 25 W3. The potential energy chang
PROBLE M 4-. 4-3
4.45 Steam enters a turbine operating at steady state at 700°F and 450 lbf/in.2 and leaves as a
saturated vapor at 1.2 le‘L/in.2 The turbine develops 12,000 hp, and heat transfer from the turbine
to the surroundings occurs at a rate of2
PRoﬁLEM 4-. S‘l
4.51 Steam at l8001bf/in.2 and 1100°F enters a turbine operating at steady state. As shown in
Fig. P451, 20% of the entering mass ﬂow is extracted at 600 lbf/in.2 and 500013. The rest of the
steam exits as a saturated vapor at l lbf/in.2 T
PROBLEM 4-58
4.58 Air enters a compressor operating at steady state with a pressure of 14.7 lbf/in.2, a
temperature of 80°F, and a volumetric ﬂow rate of 18 ft3/s. The air exits the compressor at a
pressure of 90 lbf/in.2 Heat transfer from the compressor
PROBLEM 4.5?
4.57 At steady state, a well-insulated compressor takes in nitrogen at 60°F, 14.2 lbf/in.2,
with a volumetric ﬂow rate of 1200 ftsfmin. Compressed nitrogen exits at 500°F, 120
lbf/in.2 Kinetic and potential energy changes from inlet to ex
4.62 Air, modeled as an ideal gas, is compressed at steady state from 1 bar, 300 K, to 5 bar, 500
K, with 150 kW of power input. Heat transfer occurs at a rate of 20 kW from the air to cooling
water circulating in a water jacket enclosing the compressor.
4.69 During cardiac surgery, a heart-lung machine achieves extracorporeal circulation of the
patients blood using a pump operating at steady state. Blood enters the well-insulated pump at a
rate of 5 liters/min. The temperature change of the blood is negl
4.41 Air modeled as an ideal gas enters a well-insulated diffuser operating at steady state at 270
K with a velocity of 180 m/s and exits with a velocity of 48.4 m/s. For negligible potential
energy effects, determine the exit temperature, in K.
KNOWN: Ai
PROBLEM 4:35
4.35 Helium gas ﬂows through a well-insulated nozzle at steady state. The temperature
and velocity at the inlet are 550°R and 150 ft/s, respectively. At the exit, the temperature
is 400°R and the pressure is 40 lbf/in.2 The area of the exit i
4.34 Air with a mass flow rate of 2.3 kg/s enters a horizontal nozzle operating at steady state at
450 K, 350 kPa, and velocity of 3 m/s. At the exit, the temperature is 300 K and the velocity is
460 m/s. Using the ideal gas model for air with constant cp
4.13 As shown in Fig. P4.13, river water used to irrigate a field is controlled by a gate. When
the gate is raised, water flows steadily with a velocity of 75 ft/s through an opening 8 ft by 3 ft.
If the gate is raised for 24 hours, determine the volume o
4.16 Air enters a one-inlet, one-exit control volume at 6 bar, 500 K, and 30 m/s through a flow
area of 28 cm2. At the exit, the pressure is 3 bar, the temperature is 456.5 K, and the velocity is
300 m/s. The air behaves as an ideal gas. For steady-state
4.14 Figure P4.14 shows a two-tier fountain operating with basins A and B. Both basins are
initially empty. When the fountain is turned on, water flows with a constant mass flow rate of 10
kg/s into basin A. Water overflows from basin A into basin B. Ther
4.18 Refrigerant 134a enters the evaporator of a refrigeration system operating at steady state at
4oC and quality of 20% at a velocity of 7 m/s. At the exit, the refrigerant is a saturated vapor at
a temperature of 4oC. The evaporator flow channel has co
4.21 Air enters a compressor operating at steady state with a pressure of 14.7 lbf/in.2 and a
volumetric flow rate of 8 ft3/s. The air velocity in the exit pipe is 225 ft/s and the exit pressure is
150 lbf/in.2 If each unit mass of air passing from inlet
4.28 At steady state, air at 200 kPa, 325 K, and mass flow rate of 0.5 kg/s enters an insulated
duct having differing inlet and exit cross-sectional areas. The inlet cross-sectional area is 6 cm2.
At the duct exit, the pressure of the air is 100 kPa and t
PROBLEM +31
4.31 Steam enters a nozzle operating at steady state at 20 bar, 280°C, with a velocity of 80 m/s.
The exit pressure and temperature are 7 bar and 180°C, respectively. The mass ﬂow rate is 1.5
kg/s. Neglecting heat transfer and potential ener
4.70 A pump is used to circulate hot water in a home heating system. Water enters the wellinsulated pump operating at steady state at a rate of 0.42 gal/min. The inlet pressure and
temperature are 14.7 lbf/in.2, and 180oF, respectively; at the exit the pr