In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 minutes and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is:

Concept:

Dryness fraction is defined as the ratio of the mass of dry steam and the combined mass of dry steam & mass of water vapour in the mixture. It is denoted by x.

\(Dryness\;fraction\;\left( x \right) = \frac{{mass\;of\;vapour\;\left( {{m_v}} \right)}}{{mass\;of\;vapour\;\left( {{m_v}} \right) ~+~ mass\;of\;liquid\;\left( {{m_l}} \right)}}\)

For saturated liquid x = 0

For saturated vapour = 1

The value of dryness fraction lies between 0 and 1.

Calculation:

Given:

m_v = 4.8 kg, m_l = 1.2 kg

\(x=\frac{4.8}{4.8~+~1.2}=0.8\)