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ME 104 Thermodynamics [F23]

Homework Assignment 3

[Due MON 9/18]

Text: Thermodynamics: An Engineering Approach, Y. Çengel and M. Boles, McGraw-Hill, 10th Edition, 2024. The link to the book is provided on the course site.

1. Problem 3-34: 10 kg of R-134a fill a 1.115-m³ rigid container at an initial temperature of −30°C. The container is then heated until the pressure is 200 kPa. Determine the final temperature and the initial pressure.

2. Problem 3-47: Water initially at 200 kPa and 300°C is contained in a piston–cylinder device fitted with stops. The water is allowed to cool at constant pressure until it exists as a saturated vapor and the piston rests on the stops. Then the water continues to cool until the pressure is 100 kPa. On the T-v diagram, sketch, with respect to the saturation lines, the process curves passing through the initial, intermediate, and final states of the water. Label the T, P, and v values for end states on the process curves. Find the overall change in internal energy between the initial and final states per unit mass of water.

3. Problem 3-54: A piston–cylinder device contains 0.005 m³ of liquid water and 0.9 m³ of water vapor in equilibrium at 600 kPa. Heat is transferred at constant pressure until the temperature reaches 200°C.

(a) What is the initial temperature of the water?

(b) Determine the total mass of the water.

(c) Calculate the final volume.

(d) Show the process on a P-v diagram with respect to saturation lines.

4. Problem 3-81: A rigid tank whose volume is unknown is divided into two parts by a partition. One side of the tank contains an ideal gas at 927°C. The other side is evacuated and has a volume twice the size of the part containing the gas. The partition is now removed and the gas expands to fill the entire tank. Heat is now transferred to the gas until the pressure equals the initial pressure. Determine the final temperature of the gas.