Steam properties and phase diagram

Steam tables are defined as the thermodynamic data that contain the properties of water or steam. ... Property tables list the properties from saturated water to steam

1. Properties of Pure Substances Presented By: Ankit Kumar Singhal Assistant Professor Mech. Engg . Deptt .

2. Pure Substance A substance that has a constant chemical composition throughout its mass is called a pure substance. It is one component system. It may exist in one or more phases. e.g. Water, Air Phases of a Pure Substances: Solid Liquid Gas or Vapour

3. 4’ 4’’ 1’’ 2’’ 3’’ 1’ 2’ 3’ 2 3 4 5 6 1 Phase Diagram P v 5’ 6’ 5’’ 6’’ Solid Solid starts melting Solid changes into liquid Liquid starts vapourizing Liquid changes into vapour

4. 6’’’ 5’’’ 4’’’ 3’’’ 2’’’ 6’’ 5’’ 4’’ 3’’ 2’’ 6’ 5’ 4’ 3’ 6 2’ 5 4 3 2 S S + L L L + V V Saturated Solid Line Saturated Liquid Line Saturated Vapor Line p v Triple Point Line S V Critical Point Sublimation Phase Diagram

5. Phase Diagram 4’ 1’ 2’ 3’ 2 3 4 5 6 1 5’ 6’ 4’’ 1’’ 2’’ 3’’ 5’’ 6’’ T S

6. 4’’ 2’’ 3’’ 5’’ 4’ 2’ 3’ 5’ 2 3 4 5 S S + L L L + V V Triple Point Line S V Critical Point Phase Diagram T S

7. Property Tables Saturated Liquid and Saturated Vapour State: f = properties of saturated liquid g = properties of saturated vapour v f = Specific volume of saturated liquid v g = Specific volume of saturated vapour v fg = Difference between v f and v g

8. Property Tables Saturated Liquid – Vapour Mixture: Dryness Fraction ;  

9. Property Tables Superheated Vapour : Compare to saturated vapour , superheated vapour is characterized by Higher temperature (T> T sat , at a given pressure)

10. 11 Critical point - the temperature and pressure above which there is no distinction between the liquid and vapor phases. Triple point - the temperature and pressure at which all three phases can exist in equilibrium. Sublimation - change of phase from solid to vapor. Vaporization - change of phase from liquid to vapor. Condensation - change of phase from vapor to liquid. Fusion or melting - change of phase from solid to liquid. Important Definition

11. 12 Saturation is defined as a condition in which a mixture of vapor and liquid can exist together at a given temperature and pressure. Saturation pressure is the pressure at which the liquid and vapor phases are in equilibrium at a given temperature For a pure substance there is a definite relationship between saturation pressure and saturation temperature. The higher the pressure, the higher the saturation temperature

12. 13 Latent heat : The amount of energy absorbed or released during a phase-change process. Latent heat of fusion : The amount of energy absorbed during melting. It is equivalent to the amount of energy released during freezing. Latent heat of vaporization : The amount of energy absorbed during vaporization and it is equivalent to the energy released during condensation. At 1 atm pressure, the latent heat of fusion of water is 333.7 kJ/kg and the latent heat of vaporization is 2256.5 kJ/kg.

13. 14 When a substance exists as part liquid and part vapor at saturation conditions, its quality (x) is defined as the ratio of the mass of the vapor to the total mass of both vapor and liquid. The quality is zero for the saturated liquid and one for the saturated vapor (0 ≤ x ≤ 1) For example, if the mass of vapor is 0.2 g and the mass of the liquid is 0.8 g, then the quality is 0.2 or 20%.

14. 15 Example 1.1 Determine the saturated pressure, specific volume, internal energy and enthalpy for saturated vapor at 45 o C and 50 o C.

15. Example 1.2 Determine the saturated pressure, specific volume, internal energy and enthalpy for saturated water vapor at 47⁰ C .

16. 17 Solution: Extract data from steam table T P sat v u h 45 9.5953 15.251 2436.1 2582.4 47 Ps at v u h 50 12.352 12.026 2442.7 2591.3 Interpolation Scheme for P sat Interpolation for P sat Do the same principal to others!!!!

17. Thank You