Question

Water at 200 kPa with a quality of 25% has its temperature raised 20°C in a constant pressure process. What is the new quality and volume?  

Comments

How the temperature 140°C is marked in graph at constant pressure?The graph given by you varies with temperature but pressure also.

Answer 1

State 1  at 200 kPa

v = v_f + x v_fg = 0.001061 + 0.25 × 0.88467 = 0.22223 m³/kg

State 2  at 200 kPa

T₂ = T_sat + 20 = 120.23 + 20 = 140.23°C

so state is superheated vapor

x = undefined

v = 0.88573 + (0.95964 – 0.88573) 20/150 - 120.23 = 0.9354 m³/kg