ASSIGNMENT 2 CHE 3473

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1 DUE: May 21 ASSIGNMENT 2 CHE 3473 #Problem 1 Read Chapter 3. ALL OF IT. Time yourself and report the time. #Problem 2: 3.2 #Problem 3: 3.3 #Problem 4: 3.5 #Problem 5: 3.6 #Problem 6: 3.7 #Problem 7: 3.8 #Problem 8: 3.11 #Problem 9: 3.15 #Problem 10: 3.22 #Problem 11: 3.32 #Problem 12: A piston-cylinder assembly contains 6kg of steam at a pressure of 100 bar and a temperature of 400 o C. It undergoes a process whereby it expands against a constant pressure of 20 bar, until the forces balance. During the process, the piston generates J of work. Steam is not an ideal gas under these conditions. Determine the final temperature and the heat transferred during the process.

2 #Problem 13: An insulated vessel has two compartments separated by a membrane. On one side is 2kg of steam at 500 o C and 200 bar. The other side is evacuated. The membrane ruptures, filling the entire volume. The final pressure is 100 bar. Determine the final temperature of the steam and the volume of the vessel. #Problem 14: Consider a piston-cylinder assembly containing 10kg of steam. Initially the gas has a pressure of 20 bar and occupies a volume of 1.0 m 3. Under these conditions, steam does not behave as an ideal gas. A)The system now undergoes a compression process in which it is compressed to 100 bar, the external pressure is slightly larger than and could be assumed to be equal to internal pressure. The pressure-volume relationship is given by. What is the final temperature and internal energy of the system? Calculate the work done during this process. How much heat was exchanged? B) Consider a different process by which the system gets to the same final state as in part (A). In this case, a large block is placed on the piston, forcing it to compress. Calculate the work done during this process. How much heat was exchanged? #Problem 15: You wish to measure the temperature of steam flowing in a pipe at pressure of 9MPa. To do this task you connect a well-insulated tank

3 of volume 0.4m 3 to this pipe through a valve. This tank initially is at vacuum. The valve is opened, and the tank fills with steam until the pressure is 9 MPa. At this point the pressure of the pipe and tank are equal, and no more steam flows through the valve. The valve is then closed. The temperature right after the valve is closed is measured to be 800 o C. The process takes place adiabatically. Determine the temperature of the steam flowing in the pipe. You may assume the steam in the pipe stays at the same temperature and pressure throughout this process.

4 #Problem 16: Refrigerant 12 flows steadily through a 40 mm diameter horizontal pipe. At a point where the velocity is 40m/s the temperature and pressure of the refrigerant are 40 o C and 300kPa, respectively. As a result of heat transfer from the surroundings, the temperature at a point downstream reaches 50 o C. a) Assuming a negligible pressure drop, determine the heattransfer rate to the refrigerant 12. Specific volumes of inlet and outlet streams are m 3 /kg and m 3 /kg. Specific enthalpy of inlet and outlet streams are kj/kg and kj/kg. b) do part (a) with consideration of 50kPa of pressure drop. Specific volume and specific enthalpy of outlet stream now are m 3 /kg and kj/kg. Mass flow rate in pipe is constant. #Problem 17: An air compressor is designed to compress atmospheric air (assumed to be at 100 kpa, 20 o C) to a pressure of 1 MPa. The heat transfer rate to the environment is anticipated to be about equal to 10% of the power input to the compressor. The air enters at 50 m/s where the inlet area is 9x10-3 m 2 and leaves at 120m/s through an area 5x10-4 m 2. Determine the exit-air temperature and the power input to the compressor. The compressor is working at steady state, and air could be assumed to be an ideal gas.

Ideal gas properties of air #Problem 18: Steam enters

and 600 o C and leaves at 100kPa as a saturated vapor.

5 Ideal gas properties of air #Problem 18: Steam enters a turbine with a pressure and temperature of 15 MPa and 600 o C and leaves at 100kPa as a saturated vapor. The flow area at the turbine inlet is 0.045m 2 and at the exit it is 0.31 m 2. The steam flows steadily through the turbine at a mass flow rate of 30kg/s. Calculate the

power that can be produced by the turbine, assuming negligible heat transfer from the system. Specific volume and specific enthalpy of inlet air are 0.0249 m 3 /kg and 3581.5 kj/kg.

6 power that can be produced by the turbine, assuming negligible heat transfer from the system. Specific volume and specific enthalpy of inlet air are m 3 /kg and kj/kg. #Problem 19: Air at 1atm and 20 o C occupies an initial volume of 1000 cm 3 in a cylinder. The air is confined by a piston which has a constant restraining force so the gas pressure always remains constant. Heat is added to the air until its temperature reaches 260 o C. Calculate the heat added, the work the gas does on the piston, and the change in internal energy of the gas. Air could be assumed to be ideal gas with c p = x 10 3 J/kg o C

ASSIGNMENT 2 CHE 3473

DUE: May 23 ASSIGNMENT 2 CHE 3473 #Problem 1: 3.3 #Problem 2: 3.4 #Problem 3: 3.5 #Problem 4: 3.6 #Problem 5: 3.7 #Problem 6: 3.8 #Problem 7: 3.11 #Problem 8: 3.15 #Problem 9: 3.22 #Problem 10: 3.32 #Problem