I wrote:
> Another thing I forgot to mention is that they ignore heat from the ends > of the cylinder and from the large flange. I'll bet those two would add > ~100 W. > Okay, unaccounted for losses during the calibration at 810 W were 58 W. Not ~100 W. The calibration was stepped up through various power levels, including 810 W. (Maybe they went higher, but this was the closest step to the output during the test with powder.) The output during the run with powder was estimated at 816 W, conservatively, which is close to 810 W. They comment that the surface temperatures and temperature distribution were remarkably close to what was seen during the calibration. So that means losses unaccounted for were ~58 W. Actual output was more like ~868 W. A realistic COP would be 868 / 322 = 2.7. The same as Eq. 36. In any real-world scenario, if there was no excess heat, the COP would have been less than 1. You can never recover all the heat. Using conservative estimates as they did, you never get close. As I said, the COP would be about 0.93 based on the calibration. There is no way these measurements could be off by a factor of 3. That is, 290% too high. I would be surprised if they were too high by more than 10%. Too low by 10% would not surprise me at all. This method is somewhat crude but it is based on first principles and it is reliable. People have been using emissivity and IR cameras to estimate heat output for a long time. It is well established engineering physics. - Jed
