Harry Veeder <hveeder...@gmail.com> wrote: how does he determine the ouput ? >
Briefly: The abstract says that at the lab they have a precision flow calorimeter. Here they are using crude thermometry in an uncontrolled environment. That is, a room full of people crowded around the machine, with currents of air and so on. Not a constant temperature incubator. That is obviously inaccurate but you cannot transport a flow calorimeter. The cell is equipped with two wires. One for calibration which I think is nichrome. It is gray, anyway. The other, working wire is constantan (Isotan 44) treated by Celani to be a lot more porous and absorbent. By "thermometry" I mean they turn on the 48 W heater or the working wire and watch the temperature stabilize at 120 deg C. That is the minimum temperature below which this material will not load, and no effect can be seen. This is straight DC power coming from a high quality power supply. As you would expect when there is no excess the temperature is very stable. The temperature stabilizes for a while even with the working wire. This morning it was flat. No indication of excess heat. When excess heat begins it fluctuates considerably, climbing and falling, from one minute to the next. With this kind of gas calorimeter, the increase in temperature is proportional to the excess heat, although not linear. When I did similar calorimetry years ago with Mizuno I found the response was stable, repeatable and predictable, and the fact that it is not linear is unimportant. (With something like LabView you can just tell it to be linear anyway. Throw in a fudge factor, or probably nowadays tell it to figure out the fudge factor.) Rob Duncan told me that the major problem with this arrangement would be changes in heat loss because of changes in convection. Convection dominates. If anything, he expects convection would increase as the gas moves faster, and this would lower the temperature. There is one thing that might raise the temperature slightly. The cell has a leak. It is initially pressurized to 20 atm. It loses 1 atm over 8 hours. That could not explain the anomalous temperature increase for two reasons: 1. The temperature rise happens too soon. 2. A leak is probably fairly steady, causing a steady, linear increase in temperature. It would never decrease. It would not fluctuate rapidly. When they brought the cell to Texas it had a variety of different instrument types attached, with LabView software written by various physicists and other non-experts. The people at NI looked at it -- actually, Truchard, the president and CEO himself looked at it, I gather -- and said "let's get rid of everything but the cell." They replaced all instruments, computers, the interface box etc.; they put in the latest version of LabView and rewrote the code. So now it is as good as any instrument I have ever seen. It looks like a product brochure illustration. Except the method is still crude. At one point Truchard said, "what this needs is an IR sensor for the surface temperature." He jumped in his car, drove to an electronics store and came back with a handheld IR sensor. He said: "This was on sale. I got a great deal on it!" The IR sensor is sitting on the table. That's the way the NI engineer told me the story, anyway. They say it is typical of Truchard. Input power is steady at 48 W both in Texas and here. Anomalous output was 5 W and climbing when I last saw it. In Texas it peaked at 21 W. I think Celani said that is a typical result. In other words, 48 + 21 = 69 W. I think that even crude thermometry should be adequate to measure a difference as large as this. I would call this a trade-show demonstration. That is, not something perfectly convincing in itself, but something that gives you feel for what the product is like. I doubt that the ENEA labs are incapable of measuring the difference between 48 and 69 W. - Jed
