Specific volume of steam

elements of mechanical

1. Elements of Mechnical Engineering Name : Vishvesh M Prajapati Branch : Chemical Technology En. No : 130990136047 Batch : A 3

2. Specific Volume Of Steam The specific volume is the volume occupied by the unit mass of a substance . It is expressed in m³/kg . The volume of water and steam increase with the increase in temperature.

3. Specific Volume Of saturated water( v f ): It is define as the volume occupied by 1 kg of water at the saturation temperature at a given pressure. Specific Volume Of dry saturated water( v g ): It is define as the volume occupied by 1 kg of dry saturated steam at a given pressure. Specific Volume Of wet steam: Consider 1 kg of wet steam with dryness fraction x. This steam contains ( i ) x kg of dry steam (ii) (1-x) kg of water molecules in suspension

4. (Specific Volume of wet steam) = Volume of dry steam at given pressure + Volume of water molecules in suspension V= xV g + (1-x) V f Generally, (1-x) V f is very low and is often neglected V= xV g m³/kg

5. Specific Volume Of Superheated steam: It is the volume occupied by 1 kg of superheated steam at a given pressure and superheated temperature, and is denoted as v sup . The superheated steam behaves like a perfect gas, therefor its specific volume is determined approximately applying charle’s law. v g / t s = v sup / t sup v sup = v g ( t sup / t s )

6. Vg = Specific volume of dry saturated steam at pressure P. Ts = Saturation temperature at pressure P. Tsup = Superheated temperature. Vsup = Specific volume of superheated steam at pressure P.

7. Internal Energy Of Steam Defition : It is define as the difference between the enthalpy of steam and external work of evaporation. Mathematically, Internal energy of dry steam : u g = h g – p v g Internal energy of wet steam : u = h f + x h fg - px v g

8. Intenal energy of superheated steam: u sup = h sup – p v sup Internal latent heat: It is the algebraic difference between the enthalpy of evaporation at given pressure and work of evaporation. Internal latent heat = h fg – pv Where, h fg = enthalpy of evaporation at given pressure p = pressure of steam v = specific volume of steam

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