Question

Water vapor initially at 10 bara and 400°C is contained within a piston-cylinder assembly. The water is cooled at constant volume until its temperature is 150°C. The water is then condensed isothermally to saturated liquid. Sketch the process in T-v coordinates. Clearly label the three states. For the water as the system, (a) write the symbolic equation for the specific work (and simplify), w; and (b) evaluate the specific work, in kJ/kg.

Answer 1

solution P= lotar T = 400 a . . water state L it is given that P = 10 bar = 1 MPa T= 400c from steam table [ CATT-] U; 2..3066 m2/kg m = 2957 kJ /kg for state-2 it is given that it cooled - until volume since temperature become at constant 1 So's + 4 y = 0.3066 12 = 1500 be scaunggubala for this 4 - y = 2135 KJ/kg P = 0.4759 MPa How for state - 3 it is given that it is condensed isothermally to ico saturated liquid-

for this we have 7 = 150°C = ∞ = 0.00109 m2/ky & P = b = 0.4749 MPa 00103 -3064 vu (a) work for process 1-2 Wire - sear since duo I constant volume] » Ki-2 =0 f work for procen 2-3 Warz span since process 2-3 is y for this press wre isothermal condensation also remains constant > Wizz = por

(b) specific work hazz POV = P(ų") E 0.4759x10^x [00109 - 0.30663 = -0.145392 X106 Illy - - 145.392X16 = - 145.392 KJlk * Total specific work W = = @ Wirat Wang 0.+ 1-145.392) wlly I wrz = - 145.392 kJ/14)