On Sun, Jun 26, 2011 at 3:41 AM, Mark Iverson <[email protected]> wrote:
> ** > > You stated: > "But steam at 100C and 1 atmosphere pressure has a density of 0.6 kg / > m^3. It can't be 10 g/m^3." > > I thought it would have been clear by how I worded it, but apparently not, > so let me be perfectly clear; I was NOT saying that the output vapor content > was 10g/m^3. I specifically state in step#1: > " ***can't remember*** but say its 10g/sec" > > The inlet water flow rate has varied for each demo, so I wasn't referring > to an actual flow rate. All I was trying to establish in this step was that > we know the mass of water going in... WHATEVER IT IS... so forget I even > mentioned the 10g/sec for now... let's just go with this and see where it > leads. > It doesn't matter what the input flow rate is. Your measurement will always give the same answer, so how can you get anything from it. I don't think I misread anything you wrote. I think your reasoning is wrong. > > Do you see the very first word in step #2??? > "ASSUME" > It means just that... for this scenario, just accept that all the mass of > incoming water is vaporized. I'm not asking you to admit that that is > what's really happening, so relax and follow the reasoning... > Fine, but if that's your assumption (and it's possible of course), the follow through. What value of RH would indicate dry steam. You say, 10g/m^3, but first that's not possible, and second it doesn't indicate that the output steam carries all the mass. There is only one inlet and one outlet on this 'box', so the mass of water > in MUST equal the total mass of water out, in whatever forms (i.e., liquid + > vapor), **IF** the pressure does not start to build up inside the box! > We agree on this point It's a trivial one. It's when you try to find what fraction the vapor is carrying that your argument falls apart. > > > Let's stop there for tonight as I need to get some rest... we'll pick-up > the step-by-step analysis tomorrow or monday. > There is no step by step analysis that is going to make the humidity of steam at 100C and atmospheric pressure without droplets, which is always the same, tell you what mass fraction is carried by the steam. Consider the actual flow rate of close to 2 g/s. If the output is 100% steam, then it is carrying 0.6 kg/m^3. If the output is 50% steam by mass, then the steam is also carrying 0.6 kg/m^3. If it is 10% steam by mass, the steam is also carrying 0.6 kg/m^3. So how does that measurement tell you which of those fractions is the right one?
