Uploaded by Emin Karagöz

TER 201E Homework 2019-2020 Spring

TER 201E
2019-2020 SPRING TERM
MAY 30, 2020 – JUNE 6, 2020
In the following there is a homework which is prepared in the context of distance education
for the 2019-2020 Spring semester. A total of 5 problems were presented and each problem
has equal weight (20 pts × 5 = 100 pts). After solving the homework problems with your own
handwriting and taking a photo of them, you need to scan and upload them to the Ninova
system (and your own class) in PDF format within the given time. The time given for the
assignment was determined between 30.05.2020-00.00 and 06.06.2020- 08.00. It is also
important that you enter the statement below and your personal information in the following
order at the beginning of the paper you will make your solutions:
"I prepared the homework in accordance with ethical rules without any help from anyone."
Name Surname:
Student number:
Course Code: TER 201E
Good luck.
P 1/5. Air is contained in a vertical piston-cylinder assembly by a piston of mass 50 kg and
having a face area of 0.01 m2. The mass of the air is 5 g, and initially the air occupies a volume
of 5 liters. The atmosphere exerts a pressure of 100 kPa on the top of the piston. The volume of
the air slowly decreases to 0.002 m3 as the specific internal energy of the air decreases by 260
kJ/kg. Neglecting friction between the piston and the cylinder wall, determine the heat transfer
to the air, in kJ.
P 2/5. One kilogram of air, initially at 5 bar, 350 K, and 3 kg of carbon dioxide (CO2), initially
at 2 bar, 450 K, are confined to opposite sides of a rigid, well-insulated container, as illustrated
in Figure below. The partition is free to move and allows conduction from one gas to the other
without energy storage in the partition itself. The air and carbon dioxide each behave as ideal
gases. Determine the final equilibrium temperature, in K, and the final pressure, in bar,
assuming constant specific heats.
Figure for P 2/5
P 3/5. A well-insulated turbine operating at steady state is sketched in Figure below. Steam
enters at 3 MPa, 400ºC, with a volumetric flow rate of 85 m3/min. Some steam is extracted
from the turbine at a pressure of 0.5 MPa and a temperature of 180ºC. The rest expands to a
pressure of 6 kPa and a quality of 90%. The total power developed by the turbine is 11,400
kW. Kinetic and potential energy effects can be neglected. Determine
a) the mass flow rate of the steam at each of the two exits, in kg/h,
b) the diameter, in m, of the duct through which steam is extracted, if the velocity there is 20
c) sketch the P-v diagram for the problem.
Figure for P 3/5
P 4/5. A compressor operates at steady state with Refrigerant 22 as the working fluid. The
refrigerant enters at 5 bar, 10ºC, with a volumetric flow rate of 0.8 m3/min. The diameters of
the inlet and exit pipes are 4 and 2 cm, respectively. At the exit, the pressure is 14 bar and the
temperature is 90ºC. If the magnitude of the heat transfer rate from the compressor to its
surroundings is 5% of the compressor power input, determine the power input, in kW.
P 5/5. A refrigeration cycle having a coefficient of performance (COP) of 3 maintains a
computer laboratory at 18ºC on a day when the outside temperature is 30ºC (see the Figure
below). The thermal load at steady state consists of energy entering through the walls and
windows at a rate of 30,000 kJ/h and from the occupants, computers, and lighting at a rate of
6000 kJ/h. Determine the power required by this cycle and compare with the minimum
theoretical power required for any refrigeration cycle operating under these conditions,
each in kW.
Figure for P 5/5