On Thu, Jun 23, 2011 at 2:04 AM, Harry Veeder <[email protected]> wrote:
> Joshua Cude wrote: > > > >On Wed, Jun 22, 2011 at 9:38 PM, Daniel Rocha <[email protected]> > wrote: > > > >Do you expect water droplets above 100C? This is like expecting > >>microscopic ice to not immediately melt above 0C. > >> > >>You don't expect water droplets above the boiling point. The temperature > of the > >>mixture of steam and droplets will be *at* the boiling point. > >> > >The actual boiling point inside the conduit will be slightly elevated > because of > >a slight increase in pressure. Rossi emphasizes that the pressure is at > >atmosphere inside the reactor, but in fact it must be slightly higher, or > there > >would be no flow of the fluid. The pressure difference, flow rate, and > tube > >geometry are related by a simple formula, and reasonable estimates > indicate an > >elevation in the bp of a degree or so is easily plausible. > > If the boiling point goes up by degree or two that makes no difference to > the implausibility of water drops existing in the beginning of > the plume which has a temperature just above the boiling point. > > I don't follow. If the bp goes up, then the temperature of the plume is not just above the boiling point; it is at the boiling point. And so water drops are entirely plausible. What's not plausible is that at the moment it hits the bp, which requires 750 W, it immediately begins to vaporize all the water, which requires 5 kW. A 7-fold increase in power requires a 7-fold increase in the temperature difference between the reactor walls and the fluid. How can that happen so fast?
