Question

(4). (10 points) Phases. Determine the phases of the following substances under given conditions, and sketch the corresponding points on both T-v and P-v diagrams:
(4a). (2p) H2O at 5.0 MPa and 300 °C.
(4b). (2p) R-134a at 10 °C and 0.5 MPa.
(4c). (2p) H2O of specific enthalpy 1.6 MJ / kg at 330 °C.
(4d). (2p) R-134a of specific volume 0.1 m3/ kg at 0.1 MPa.
(4e). (2p) H2O of specific internal energy 2.7 MJ / kg at 0.7 MPa.

Answer 1

(a) H_2O at 5.0MPa and 300 degree C from saturated water tables P_sat = 85.81 bal = 8.581 MPa > P. So we can say that H_2O in at super heated vapor. T_sat = 179.9 degree C < T State is super heated vapor. (d) R-134a of specific volume 0.1 m^3/kg at 0.1MPa We know that V_f = 0.7258 times 10^-3 m^3/kg V_g = 0.1917 m^3/kg Therefore V_g V > V_f It is in a state of vapor and liquid mixture. (e) H_2O of specific internal energy 2.7 MJ/kg at 0.7 MPa from saturated water tables we know that h_g = 2763.5 KJ/kg, h_f = 697.22 KJ/kg h_g > h > h_f This is in a state of vapor and liquid mixture.