On Sat, Jun 25, 2011 at 9:11 PM, Jeff Driscoll <[email protected]> wrote:
> On Sat, Jun 25, 2011 at 8:58 PM, <[email protected]> wrote: > > In reply to Joshua Cude's message of Fri, 24 Jun 2011 16:20:48 -0500: > > Hi, > > [snip] > >>I was talking about running it above boiling, but way below the level > needed > >>to boil it all. Different thing. And it's easy. The power can range > within a > >>factor of 7. In this case, anywhere between 600W and about 5 kW. > > > > BTW (the latent heat of steam) / (the heat energy required to bring water > to the > > boil) is a factor of about 6.7 (depending on starting temperature of > water), and > > curiously close to the COP Rossi claims to be aiming for. > > In short, if virtually none of the water were converted to steam, and he > was > > assuming that it all was, then it would neatly explain the conversion > factor he > > is claiming. > > > > You might be thinking of another scenario - but if I'm guessing what > you are saying then the best anyone could do is about 1.86 to 1 ratio. > But this assumes that any liquid hot water needed to cool water vapor > in a heat exchanger is included in the calculation (otherwise the > ratio would be worse, less than 1.86 to 1). I did this calculation, > shown below, weeks ago. [...] > > There is no need for heat exchangers to arrive at the ratio of around 7. The argument goes, that if the water starts at 10C, then the amount of heat required to vaporize 1 g is 90 + 540 = 630 cal. The amount of heat required to bring it to the bp is 90 cal, and the ratio is 630/90 = 7. (Different starting temperatures give slightly different ratios) These two scenarios result in the same quantitative data reported in one of Rossi's steam producing demos, because he only reports temperature, and input flow rate. So the same data is consistent (in Krivit's run) with 600W and with 5 kW. Rossi does not provide quantitative evidence that it should be closer to, or at, the high end of that range. He only makes pronouncements based on things like visual inspections, or unreported RH measurements, which indicate nothing. Now, of course, the fact that there is some steam, means it is not at the bottom of the range either, but in the videos where he shows the steam, it is not impressive.
