## Name:_____________________________ ENGR 381 Homework #3: Chapter 4 part 1 Due Oct. 7th at the beginning of class. Show your work! Practice problems that should be done but are NOT HANDED IN: 4-4E (answer: -5.14 Btu), 4-9 (answer: 1.355×105 kJ), 4-22 (answer: 25.3 kJ), 4-30E (answers: 40.23 °F, 47.73 lbm, 4167 Btu), 4-34, 4- 35, 4-37. Problems to be handed in: 1. (5 points) A piston/cylinder system contains 1.5 kg of water at 50 kPa and a quality factor of 0.4. Heat transfer occurs to the system until a temperature of 400 °C is achieved. Determine: a. The initial volume of liquid and the initial volume of vapor, both in m3; b. The boundary work out (Wb,out) of the system in kJ; c. The heat transfer in kJ. 2. (5 points) Solve using EES. A gas grill tank (i.e. rigid tank) contains 20 lbm of propane at 70 °F and has a quality factor of 0.001. The tank is left outside during the winter and reaches a temperature of -10°F. Determine: a. The tank volume; b. The initial pressure in psia; c. The final pressure in psia; d. The final quality factor; e. The heat transfer in Btu; Hint: You’ll want to switch the unit system to English units, under Options/Unit System. 3. (5 points) A mass of 3 kg of R-134a undergoes a polytropic process (PVn = constant) from a pressure of 400 kPa and temperature of 70 °C to a final pressure of 800 kPa. The polytropic exponent n is 1.15. Determine: a. The initial volume in m3; b. The final volume in m3; c. The final temperature in °C; d. The boundary work out (Wb,out) in kJ; e. The heat transfer in kJ; f. +1 Extra credit (solve the problem in EES in addition to the hand calculations) 4. (5 points) A piston/cylinder system contains 0.5 kg of saturated solid water (i.e. ice) at -12 °C. Heat transfer occurs to the system until the system contains only saturated vapor. a. What is the boundary work out (Wb,out) in kJ? b. What is the heat transfer in kJ? For EES problems, print the equation and solution windows.

Name:_____________________________ ENGR 381 Homework #3: Chapter 4 part 1 Due … Read More...