Alain Sepeda <alain.sep...@gmail.com> wrote: - one way to be wrong would be to make a temperature error. since power in > in T^4, error is 5^1/4, about 1.5, thus +50%/-33%, assuming no convection. >
Yes, temperature measurement is critical. That is why they checked the surface temperature with a thermocouple to confirm the IR camera is set correctly. In the previous test, they just assumed emissivity is 1, meaning as bad as it can be. It makes no sense to assume no convection. There has to be convection. Also, as you see in Fig. 10, the flange is large and it must be radiating and convecting a lot of heat. They did not try to measure that. On p. 20 they say unaccounted for heat losses were 58 W out of 810 W during the calibration with joule heating. 7%. Actually, that is remarkably good accounting for a system like this. > Am I reasoning well ? > is COP<=1 ruled out ? > I think so, but actually even if the COP was exactly 1, that would indicate excess heat. You would not expect it to be better than 0.93 as shown by the 7% loss during calibration. - Jed
