It may come for a surprise for many, but there is no such thing as water boiler that produces a steam with quality much less than 95%, in close to normal pressure. "Very wet steam" just is not stable state, because surface tension makes sure that wetness in steam is quickly converted into liquid water droplets.
—Jouni On Aug 8, 2011 3:30 AM, "Jed Rothwell" <[email protected]> wrote: > Daniel Rocha <[email protected]> wrote: > > NyTeknik maintains that the liquid mass is at most 10% (steam quality at >> least 90%) and because of this there is no significant error in measuring >> the heat output using the steam. > > > Well, this is not NyTeknik's claim. They quote someone else. The article > says: > > > Ny Teknik turned to Professor Björn Palm, Head of the Energy Technology > Division at the Royal Institute of Technology, doing research on heat > transfer by evaporation. Based on the given dimensions and geometry, he gave > his assessment of the situation: > > "Any air in the tube is driven out of the flowing steam. This means that at > the outlet there is pure steam, possibly with a little water droplets that > come with the flow from the liquid surface. However, I cannot imagine that > this would affect the 'effective' enthalpy of vaporization. From other cases > with evaporation in tubes I would guess that the steam quality is at least > 90%." > > > > This is in line with what I have heard from other experts. > > - Jed
