Conversion between water and water vapor
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What is the volume of 1 kg of water when it turns into steam at 0.1 MPa?
This post was last edited by ylb913 on 2015-6-2 09:04. With such low pressure, I use PV=nRT. P=1 (absolute pressure), V=nRT. n=1kg/18=0.0556 (kmol) R=0.082 What is the temperature? An absolute pressure of 1 kg/cm2 corresponds to 100 degrees, or 373 K. Using the formula 0.0556*0.082*373, the value obtained is 1.7 m3/kg; however, according to the thermodynamic parameters table for saturated water and saturated steam, the corresponding value is 1.6937 m3/kg. P=2 (gauge pressure of 1), V=nRT/2. n=1 kg/18=0.0556 (kmol); R=0.082. The temperature is 120 degrees, which is 393 K. 0.0556*0.082*393/2=0.895 m3/h. According to the tables of thermodynamic properties for saturated water and saturated steam, the value is 0.88544 m3/kg.
The density of saturated water vapor at 0.1 MPa is 0.58961 kg/m3; therefore, the volume occupied by 1 kg of water when it turns into vapor is 1/0.58961 = 1.696 m3.
What about the temperature? At 0.1 MPa, the volume must be different at 20°C and 200°C, right?