Assignment 2
- 1. ASSIGNMENT 2 1. Using steam tables, determine whether water at each of the following states is a compressed water, saturated water, wet steam, dry saturated steam or superheated steam. (a) p = 1.5 bar, h = 2226 kJ/kg; (b) p = 5.5 bar, v = 0.3748 m3 /kg; (c) p = 9 bar, u =2581 kJ/kg; (d) p = 13 bar; t = 171.6 C; (e) p = 20 bar, u = 907 kJ/kg; (f) p = 24 bar, h = 932 kJ/kg. (wet steam, superheated steam, dry saturated steam, compressed water, saturated water, compressed water ) 2. A rigid vessel of volume 3.2 m3 contains 26.5 kg of wet steam at a pressure of 12 bar. Determine its (a) temperature, t; (b) specific volume, v; (c) dryness fraction, x; (d) enthalpy, H; (e) internal energy, U; (188.0 C, 0.1208 m3 /kg, 0.7402, 60103.06 kJ, 56251.55 kJ) 3. Superheated steam at 9.2 bar has a temperature of 225 C. Determine its (a) specific volume, v; (b) specific internal energy, u; (c) specific enthalpy, h. (0.23997 m3 /kg, 2670.2 kJ/kg, 2890.5 kJ/kg) 4. A rigid vessel of volume 2.6 m3 contains dry saturated steam at 15 bar is cooled at constant volume until its pressure becomes 6 bar. Determine: (a) The mass of the steam in the vessel, (b) The final dryness fraction of the steam (c) The change of internal energy during the process, (d) The work energy transferred during the process, (e) The heat energy transferred during the process, (f) Sketch the above process on the p-v diagram. (19.74 kg, 0.4173, -22376.3 kJ, 0 kJ, -22376.3 kJ) 5. In a closed system, 1.25 m3 of wet steam at a pressure of 8 bar and a dryness fraction of 0.75 is heated at constant pressure until it becomes dry saturated steam. Determine: (a) The mass of the steam; (b) The change in internal energy, the work energy and the
- 2. heat energy transferred during the process; (c) Sketch the process on a p-v diagram. (6.936 kg, 3220 kJ, 333.3 kJ, 3553.3 kJ) 6. A rigid vessel of volume 0.3 m3 contains 10 kg of nitrogen at a temperature of 32 C. Calculate the pressure of the nitrogen in the vessel. Take R0 = 8.314 kJ/kmole K and molecular weight of the nitrogen as 28. (30.19 bar) 7. In a closed system, a certain perfect gas of volume 0.1 m3 with an initial pressure of 1.02 bar and temperature of 40 C is compressed to a pressure of 6.5 bar and a temperature of 115 C. Determine the final volume of the gas. (0.01945 m3 ) 8. A rigid vessel contains a certain perfect gas has an initial pressure of 2 bar and the temperature of 28 C is heated to a pressure of 2.6 bar. Determine the final temperature of the gas. (391.3 K) 9. In a closed system, a certain perfect gas having an initial pressure, volume and temperature of 1.4 bar, 0.1 m3 and 25 C respectively is compressed to a final pressure of 7 bar and a temperature of 60C. Take R = 0.29 kJ/kg K. Determine: (a) The mass of the perfect gas, (b) The final volume of the perfect gas. (0.162 kg, 0.02235 m3 ) 10.In a closed system, a certain perfect gas initially has a pressure of 15 bar, volume of 0.05 m3 and temperature of 25 C. is expanded to a volume of 0.08 m3 while the pressure remains constant. Take pc = 0.92 kJ/kg K and vc = 0.657 kJ/kg K. Determine: (a) The mass of the gas in the system, (b) The final temperature of the gas, (c) The change in internal energy during the process, (d) The work energy transferred during the process, (e) The heat energy transferred during the process. (0.957 kg, 476.8 K, 112.4 kJ, 45 kJ, 157.4 kJ) 11.In a closed system, 0.957 kg of a certain perfect gas initially has a pressure of 15 bar, volume of 0.08 m3 is cooled to temperature of 60 C while the volume remains constant. Take pc = 0.92 kJ/kg K and vc = 0.657 kJ/kg K. Determine: (a) The initial temperature of the gas, (b) The final pressure of the gas, (c) The change in internal energy during the process, (d) The work energy transferred during the process, (e) The heat energy transferred during the process. (476.8 K, 10.48 bar, -90.4 kJ, 0 kJ, -90.4 kJ)