Question

Answer: W/m=20.94kJ/kg

Q/m=1705 kJ/kg

Applying the Energy Balance Referring to Fig. P3.71, water contained in a piston-cylinder assembly, initially at 1.5 bar and a quality of 20%, is heated at constant pressure until the piston hits the stops. Heating then continues until the water is saturated vapor. Show the processes of the water in series on a sketch of the 7-vdiagram. For the overall process of the water, evaluate the work and heat transfer, each in kJ/kg. Kinetic and potential effects are negligible. Walkthrous for probler

Answer 1

AND Given . P = 1.5 bar x, = 0.2 P, =Pq. Using the saturated tables and x =0.2 at p=1.5bar The fpecific volume at the enitial state & = 4 + x Ufg 19,- (0.00105273) +0.-) (1.15824727) =>. U, = 0.2327 m3 lkg The specific enthalpy of water at the initial etate & " his hft a hag - (467.13) + (0.2362226:0) he = 912.33 kilig As the flow man of water is content the may rate at initial and final state ů equal mi .ant V = (V, (0.08) 0-05)

V = (0.2327 m3lkg). (0.08m) 0.05m V2 = 0.37232 milig The work transfor å W = Wing + Wo-3 - [W₂-s=0 since 83=0.] = P(02-0,) to "... = (150 kPa) (0.37232 - 0.2327 m3/kg) TW = 20.95 kilkg At the final state, Ug= Ug = 0.31232 milky and water i saturated vapour The specific enthalphy at final state wing saturated table is ng= 2596.39 lei/kg the heat trauter i 9 = hz- hitw Q = | 2596.34 - 912. 33) + 20.95 g. 1684.06+ 20.95 - 1705.01 kJ/kg Q = 1705 ks/89

The TV diagram for the procen is shown below plecye rate it ;