Page 33 - DJJ20063- Thermodynamics 1

DJJ20063- Thermodynamics 1

2.2.4 Describe steam/water properties and the inter-relationship between the

various properties for unsaturated or saturated water or steam

superheated, saturated or wet.

Properties of a Wet Mixture

Between the saturated liquid and the saturated steam, there exist a mixture of steam plus

liquid (wet steam region). To denote the state of a liquid-steam mixture, it is necessary
to introduce a term describing the relative quantities of liquid and steam in the mixture.

This is called the dryness fraction (symbol x). Thus, in 1 kg of wet mixture, there must be

x kg of saturated steam plus (1 – x) kg of saturated liquid.

x kg of steam
total mass = 1 kg

(1 - x ) kg of liquid

Figure 2.2.4-1 Liquid-steam mixture

The dryness fraction is defined as follows;

mass of dry saturated steam
dryness fraction =
total mass

m
x = steam (2.1)
m total

where mtotal = mliquid + msteam

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