EGN 3343 – THERMODYNAMICS Abtahi FINAL EXAM SUMMER 2021 Name_______________________ SHARING INFORMATION WITH OTHER STUDENTS WHILE WORKING ON THIS EXAM OR COPYING SOLUTIONS FROM “CHEGG OR OTHER SOLUTION PROVIDERS WILL RESULT IN A GRADE OF “0” FOR THE EXAM AND POSSIBLY A GRADE OF “F” FOR THE CLASS

EGN 3343 – THERMODYNAMICS Abtahi FINAL EXAM SUMMER 2021 Name_______________________ SHARING INFORMATION WITH OTHER STUDENTS WHILE WORKING ON THIS EXAM OR COPYING SOLUTIONS FROM “CHEGG OR OTHER SOLUTION PROVIDERS WILL RESULT IN A GRADE OF “0” FOR THE EXAM AND POSSIBLY A GRADE OF “F” FOR THE CLASS. THIS IS AN OPEN BOOK EXAM AND YOU CAN USE THE TABLES OF OUR REFERENCE TEXTBOOK OR INTERNET SOURCES FOR DATA AS LONG AS YOU CITE THE source. Problem # 1 -50 points A mass of 3 kg of air at 800 K and 2500 kPa contained in a cylinder expands in a reversible isothermal process to 5 times its original volume. Determine the heat transfer from/to the cylinder and the change of entropy of air inside the cylinder. (You need to apply the first law and change of entropy as a function of heat transfer.) Problem # 2-50 points A cylinder fitted with a piston initially contains water at 100°C, 80% quality. Heat is transferred from the cylinder at a constant temperature, until the volume is 50% of the initial condition Write the first law of thermodynamics for this process, and determine the heat loss and the work. Answers should be in kJ/kg. Draw a sketch of this process on Pv diagram with respect to a water property dome. Problem # 3 -50 points The owner of a property with farm animals is thinking of using the water wells on his property as a source of heat for the stables in the winter. The minimum safe temperature for the stables is 13oC. He will start his project with his smallest stable that loses 30 kW when the outside temperature is -20oC. a. (10 points) What is the COP of a heat pump that uses the well water to maintain the desired temperature in this stable. b. (20 points) How much heat should the well water provide? c. (20 points)(This is a heat exchanger question): If the design requires to re-inject the water into a nearby well at 10oC for a maximum loss of 3oC, how much flow (kg/s) is required to achieve the necessary heat input to the heat pump? Cp of water is 4.18 kJ/kg-oC