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Assignment No. 1

Applied Thermodynamics
Course Instructor: Dr. Abdullah A. AlZahrani
Assignment # 1
UQU-Mechanical Engineering Department
Fall 2021
Due date: Tuesday September 2021
Solve problems 1-4 (4 points): (You must do it).
Problems 5 and 6 are bounce (+1 point). (Optional).
Try to solve by yourself (copy + past = 0 point).
The submission is through the blackboard + hardcopy.
Problem # 1
Consider a double-fluid manometer attached to an air pipe shown in the figure below. If the specific gravity of one
fluid is 13.55, determine the specific gravity of the other fluid for the indicated absolute pressure of air. Take the
atmospheric pressure to be 100 kPa.
Problem # 2
In a hydroelectric power plant, 65 m3/s of water flows from an elevation of 90 m to a turbine, where electric power is
generated. The overall efficiency of the turbine–generator is 84 percent. Disregarding frictional losses in piping,
estimate the electric power output of this plant.
Problem # 3
One ton (1000 kg) of liquid water at 50 ℃ is brought into a well-insulated and well-sealed 4 𝑚 × 5 𝑚 × 6 𝑚 room
initially at 15 ℃ and 95 kPa. Assuming constant specific heats for both air and water at room temperature, determine
the final equilibrium temperature in the room.
Problem # 4
Refrigerant-134a enters a diffuser steadily as saturated vapor at 600 kPa with a velocity of 160 m/s, and it leaves at
700 kPa and 40°C. The refrigerant is gaining heat at a rate of 2 kJ/s as it passes through the diffuser. If the exit area is
80 percent greater than the inlet area, determine
(a) the exit velocity and
(b) the mass flow rate of the refrigerant.
Problem # 5 (Bounce)
An insulated piston-cylinder device initially contains 1.8-kg saturated liquid water at 120C. Now an electric resistor
placed in the tank is turned on for 10 min until the volume quadruples. Determine (a) the volume of the tank, (b) the
final temperature, and (c) the electrical power rating of the resistor.
Problem # 6 (Bounce)
Steam is to be condensed in the condenser of a steam power plant at a temperature of 50°C with cooling water from
a nearby lake, which enters the tubes of the condenser at 18°C at a rate of 101 kg/s and leaves at 27°C. Determine
the rate of condensation of the steam in the condenser.