On Sat, Nov 19, 2011 at 9:55 AM, David Roberson <dlrober...@aol.com> wrote:
> > > >If you claim the heating elements are submerged, then I completely agree > that if the steam were dry, fluctuations in power in the ecats would be > accommodated by fluctuations in output flow rate, and variations in the > water level. In this case, the steam has to be at >the boiling point, > because there is nothing to heat the steam after it is formed. If you > agree that the measured output temperature is at the boiling point though, > then the question about why it's so stable is not necessary. Because that's > what I was trying to establish >in the first place. If the output were 1% > steam, it would also be at the boiling point. Since the temperature is the > only thing measured, it does not constitute evidence for dry steam. > > I think we both think that the system operates as you described above. > The heater is submerged and the dry steam exits the output check valve > heading toward the dissipaters. > No. I don't think that at all. That operation is consistent with the temperature being at the boiling point, but it is not by any means necessary. And in fact the 8-fold increase in power required makes it completely implausible. The thing we agree on is that the output is at the boiling point. > We are beginning to make a lot of progress. > Polite debate is fine, but please don't get patronizing. You have not understood my argument yet. And it's not that complicated. I think progress is minimal, so far. > >The reason I asked the question about the stable temperature, was to > counter the claim that the temperature was above the boiling point, and > therefore the steam must be dry. I think F. made that claim in his > interview with Lewan, or at least implied it. If the steam is >above the > boiling point, then part of the heaters must be exposed to heat the steam. > And in that case the level would be regulated pretty tightly by the need to > balance the ecat power with the output power, since the power transfer > would depend strongly on the >amount of the heater submerged. With the > level relatively stable, the output flow rate would be pretty constant, and > then fluctuations in power would result in fluctuations in steam > temperature. An increase in the power would cause a brief increase in the > boiling rate, >but that would reduce the level, causing the boiling rate > to decrease, restoring the level, so the increased power would have to be > removed by hotter steam. It is undoubtedly not as simple as the formula I > gave, but if the steam is already a few degrees above the >boiling point, > it seems pretty reasonable that power fluctuations would result in > significant temperature fluctuations. > > Super heating is not in the cards in my opinion. The system design did > not suggest that to me so I have never really thought about it in any > detail. > If the power exceeded the power necessary for complete vaporization, superheating would be the only way to remove the heat faster. At the flow rate given, 470 kW is the power you get for complete vaporization. So, imagine if the power was 670 kW. The only way to remove 670 kW at the given flow rate, would be if the steam heated above the boiling point. In fact way, way above it. > >So, the relatively stable output temperature indicates that it is at > the boiling point (including in your scenario), or the power is stable to > 1% (in the second scenario). > > Yes, I agree that the boiling of the water within the ECAT devices is > linked to the output via the check valve and thus the temperature is > controlled to a reasonable degree. The interactions among the various > ECATs can get very interesting with the non linear behavior associated with > the valve performance. > You're complicating matters with something we don't know anything about. If the heating elements are submerged or at least wetted, then the steam has to be at the local boiling point. Full stop. > > But to me the fact that the steam must exit through a small aperture > that sits above the water level suggests that it will be pretty dry. > Here's where we differ. And this is the crux of the matter. We have no evidence that the water level is below the top, or for that matter any idea of what is going on inside the ecat. All we know is that the output is at the boiling point, so there is some steam present. Try to think what would happen if the power were say 235 kW. Then, you'd have half the water vaporized at the heating elements. Now steam is 1700 times as voluminous as water (at atmosphere), so you'd have enormous turbulence going on. And the mixture would be more than 99% gas (by volume). And yet, since only half of the water (by mass) gets vaporized the other half has to leave as liquid, or stay behind. At equilibrium, the most likely scenario is it leaves as a mist formed from the turbulence and entrained in the gas. In that case, you'd get a mist leaving at the boiling point. The temperature would be at the boiling point, just as was measured. Now, if you claim that the liquid stays behind, and only dry steam exits, well, then the output mass flow rate would be 1/2 of the input mass flow rate. And then the calculation of the power has to use this reduced flow rate. But Rossi uses the input flow rate for his calculation of the power. Either way, the same temperature measurement would be consistent with 235 kW as it is with 470 kW. If the liquid did escape as a mist, which is more likely, it would not be trapped by their liquid trap (think mist from a mister), especially if the valve was closed, and so again the measurements are completely consistent with 235 kW. Likewise they are also consistent with 100 kW and 70 kW. > And, the lack of water collection in the capture vessel suggests pretty > dry steam. > Again, it suggests no such thing. Even if the valve was open, it would not have trapped liquid from a mist. You can get real steam traps that drain liquid condensate without losing steam, but they do nothing for entrained drops. For that, you can get a steam separator/ steam trap combination, but Rossi clearly used nothing like that. So, I have no confidence that Rossi removed the liquid from the output. The layout of the piping for the steam path was arranged to allow the HVAC > engineer to capture any significant water that flows inside these pipes. > No, it clearly wasn't. At the very least, there should be a U-shaped pipe with a steam trap at the bottom, but as I said, to capture droplets, you also need a steam separator. > I have to assume that he is experienced in this type of testing and > would understand any mechanism that demonstrates low quality vapor. > You certainly don't have to assume that. The report that claims 470 kW should provide evidence to support it. And claiming that liquid was captured is not evidence that it was. If he ran the system with 235 kW (electric), and showed that half the output was liquid using his trap, that would be evidence. If he at least used a steam separator, and a real steam trap, it might be somewhat plausible. As it is, there is no evidence at all. And that leaves out the observations that (1) the valve to the trap looked closed in Lewan's video, and (2) there is another huge pipe to carry fluid with no trap at all. All he would really need is something to measure the velocity of the output steam. That would indicate the degree of vaporization pretty well. > This is the type of trick one learns on the job. > This is the type of argument that does nothing for me. > > I suspect that we can agree on another factor after this discussion. In > your earlier posts, you seemed to insist that the actual power output was > 70 kW or in that ball park. > What I'm insisting is that the evidence is consistent with power as low as 70 kW. > I have not made the calculation yet, so I will accept your figure at > this time. But, now I assume that you would allow that the output must be > somewhat greater since we can see that a lot of vapor is generated by the > ECATs. Do you agree that the output is heading toward the 480 kW range now? > No. We don't see a lot of vapor generated. We see no vapor at all. We just see the temperature. And based on considerations of thermal inertia, I suspect the power was not much above 70 kW, at least for a considerable length of time after the onset of boiling. But the point is we don't know anything beyond that.
