MEEN 315, SECTION 503 PRINCIPLES OF THERMODYNAMICS Spring 2013 Homework #4 DUE February 12, 2013 N.B. The online enhancement lecture “Using Tables” may be helpful for this assignment. You can access it on elearning, under the Lectures --> Enhancement Lectures --> Using Thermodynamic Tables folder. 1. The following table lists temperature and specific volumes of ammonia vapor at two pressures: P = 50 psia P = 60 psia T (F) v (ft3/lbm) T (F) v (ft3/lbm) 100 6.836 100 5.659 120 7.110 120 5.891 140 7.380 140 6.120 Data encountered in solving problems often do not fall exactly on the grid of values provided by property tables, and linear interpolation between adjacent table entries becomes necessary. Using the data provided below and the table above, estimate: (a) the specific volume (ft3/lbm) at T = 120F, P = 54 psia. (b) the temperature (F) at P = 60 psia, v = 5.982 ft3/lbm. (c) the specific volume (ft3/lbm) at T = 110F, P = 58 psia. 2. For each case, determine the specific volume at the indicated state. Locate the state on a sketch of the T-v diagram. (a) water at P = 14.7 psia, T = 100F. Find v, in ft3/lbm. (b) water at P = 10 psia, T = 320F. Find v in ft3/lbm. (c) R-134a, T = 15F, x = 0.5. Find v in ft3/lbm. 3. Sketch two constant-pressure curves (500 kPa and 30000 kPa) in a T-v diagram and indicate on the curves where in the water tables you see the properties. Include the saturation dome, and identify the critical point. 4. Identify the missing properties (note: x could be undefined). (a) Water, T = 120°C, x = 0.7, P = ?, v = ?, u = ?, h = ?, s = ? (b) Water, P = 40 psia, u = 1135 Btu/lbm, v = ?, T = ?, x = ?, h = ?, s = ? (c) R-134a, P = 140 kPa, v = 0.1 m3/kg, T = ?, u = ?, x = ?, h = ?, s = ? (d) R-134a, P = 50 psia, v = 1.1 ft3/lbm, T = ?, u = ?, x = ?, h = ?, s = ? 5. A tank who volume is unknown is divided into two parts by a partition. One side of the tank contains 0.01 m3 of refrigerant R-134a that is a saturated liquid at 0.8 MPa, while the other side is evacuated. The partition is now removed, and the refrigerant fills the entire tank. If the final state of the refrigerant is 20°C and 400 kPa, determine the volume of the tank. Do you think this is a reversible or irreversible