Assignment # 2 Petroleum Engineering Thermodynamic
1.

PCB/PDB 1043

A piston–cylinder device initially contains 0.07 m3 of nitrogen gas at 130 kPa and

120°C. The nitrogen is now expanded to a pressure of 100 kPa polytropically with a polytropic exponent whose value is equal to the specific heat ratio (called isentropic expansion). Determine the final temperature and the boundary work done during this process. 2. A frictionless piston–cylinder device contains 2 kg of nitrogen at 100 kPa and 300 K. Nitrogen is now compressed slowly according to the relation PV1.4 =constant until it reaches a final temperature of 360 K. Calculate the work input during this process. 3. Complete the table below on the basis of the conservation of energy principle for a

closed system. Qm kJ 350 350 130 260 -500 -50 Wout kJ E1 kJ 1020 550 600 1400 1000 900 E2 kJ 860 M kg 3 5 2 7 3 -200 150 e2-e1 kJ/kg

4. A well-insulated rigid tank contains 2 kg of a saturated liquid-vapor mixture of water at 150 kPa. Initially, three-quarters of the mass is in the liquid phase. An electric resistor placed in the tank is connected to a 110-V source, and a current of 8 A flows through the resistor when the switch is turned on. Determine how long it will take to vaporize all the liquid in the tank. Also, show the process on a T-V diagram with respect to saturation lines. 5. An 80-L vessel contains 4 kg of refrigerant -134a at a pressure of 160 kPa. With the help of Pressure Table for saturated refrigerant-134a (given in Table A-12) calculate a) The enthalpy of the refrigerant b) the specific volume and temperature.

6. A 1 m3 rigid vessel contains steam at 6 bar and 600oC is cooled by transferring heat from the system to the surroundings. a. Determine the temperature and pressure at which the steam starts to condense. b. Calculate the mass of the liquid at the end of the cooling process when