First, here is my conclusion based on the methodology and resoning below: "If certain conditions are present, one can reduce this to a mass-in, mass out problem, and you don't need to measure the volume of steam exiting in order to estimate dryness"
I don't think anyone here was suggesting that the instrument used by Galantini could measure steam quality directly. What I am attempting to do is ascertain if there is a way to make an indirect measurement with what variables we DO have, and I think I may have the answer. Let's discuss whether this method will work, and under what conditions... 1) we know the flow-rate of water going in; can't remember but say its 10g/sec. 2) assume the entire mass of water IS vaporized; 3) we can easily calculate the volume of steam that would be generated each second; 4) *IF* the pressure inside the chimney is ambient, then the entire volume of steam is exiting the chimney each second, else pressure would build up inside; 5) assume that overall the process is relatively stable, with constant flow of steam out the chimney and only minor fluctuations in temp and pressure inside; 6) Given the above, the mass on the instrument's display of mass of water in the steam MUST equal the mass of water going in. If the instrument is reading 10g/m^3, then ALL the inlet water is being converted to vapor, and the steam is dry. Volume is irrelevent *IF* the pressure inside the chimney is ambient. This also assumes the instrument's humidity sensor isn't getting bombarded by liquid water, as we have discussed recently in our postings about how the polymer/capacitive sensor works. The only critical elements here are #4 and #5. I propose that it is REASONABLE to accept these assumptions because of these FACTS: 1) There is only one place for the water vapor to go... Out the chimney! 2) The pressure inside the chimney is the same as ambient as measured by the instrument in question. If pressure was higher in the chimney then this would not be a valid methodology. As I said very early on, there is a specific reason why both Rossi and Galantini always specified the temperature AND pressure when being asked about how they measured the steam quality. I've explained why the pressure is important, and I assume that the temperature is important for the reasons stated by Finlay McNab, "If the temperature of the vapor is above 100C and the pressure is 1 atm, then an examination of the phase diagram of water suggests that no liquid water can be entrained in the vapor." CONCLUSION: If certain conditions are present, one can reduce this to a mass-in, mass out problem, and you don't need to know the volume of steam exiting in order to estimate dryness... -Mark
