TER 201E 2019-2020 SPRING TERM DISTANCE EDUCATION TERM HOMEWORK 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." Date: Name Surname: Student number: Course Code: TER 201E CRN: Signature: Good luck. PROBLEMS 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 1 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 m/s, 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 2 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 3