Mary Yugo <[email protected]> wrote:
> I found some heat exchangers -- anyone know if one of these is identical > or equivalent to Rossi's? If so, I will consider sending one to Jed. What > may hold me back is that however the T out thermocouple placement issue > resolves, it doesn't help that much with verifying that Rossi's October 6 > test was legitimate. I think you could test for this more easily and more directly by putting a large resistance heater around a copper pipe, and measuring the pipe temperature ~20 cm downstream. I do not know if that is far enough, but someone more skilled in physics than I can model it. I think the effect of the water convection should be far greater than heat conducted by the pipe from the hot spot. Of course that depends on where you put the TC, and how hot you make it. A blowtorch would probably reach the TC a good distance away. You have to put the TC downstream. The flowing water will be heated. The TC should agree with the temperature of the fluid coming out of the pipe. The heat exchanger itself is not the issue. It is whether conduction by metal or convection by water dominates. Most of the other questions that have been raised about the placement & performance of the TC can be tested with the kind of simple tests I have done over the last few days. If anyone would like me to do something else, such as clipping some wire insulating material from the TC wire and putting it between the TC and the hot surface I would be happy to do that. It is a piece of cake to do stuff like this, especially with a dual input meter. I think all of these problems are imaginary. I think that rather than fretting about them or waving your hands, you should get a TC and try it. Bear in mind that they make these things to be used in the real world by busy engineers, workmen, mechanics, cooks who are roasting turkeys, and others who do not have time to conduct careful tests. If a piece of adhesive tape could throw the reading off by several degrees, people would have huge problems repairing equipment and installing HVAC ducts. The thing is, when people measure the temperature of the fluid in a pipe they know damn well they are supposed to cover up the TC with insulation. That is how it is shown in every manual. They sell kits with surface mounted TCs and insulating material. Nobody who does this for a living does it the wrong way. Rossi does this for a living. To take another example, when you measure the temperature of a roasting turkey you are not supposed to let the TC touch the bone. Every cook knows this, so they never make that mistake. Heck even I know it. Although I tried touching the bone and did not find much difference in temperature. I have always been in favor of trying things, doing things and finding out directly. Don't fret, wonder, or raise questions -- do it! Make an air pocket and see if it affects the TC. Be careful not to do some unrelated test, such such as exposing the TC to ambient air. Rossi did not do that, so it is pointless to test for it. Perhaps I am prone to testing these things rather than simply looking up the conductivity of copper, or speculating, because I do not understand theory beyond what they taught undergraduates at Cornell in 1974 in mid-level physics. I have discovered to my dismay that is what they teach high school kids nowadays. Also I am no good at math. I am not capable of the kinds of modelling Higgins and Houkes have kindly uploaded. - Jed
