Comments for AC Burst Noise
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Barry Kort
May 22, 2019
The mathematical analysis presented here was first worked out and communicated in late 2010 and early 2011. The version published here was uploaded and edited in late October and early November 2014.
Barry Kort
May 12, 2019
Follow-Up ...
Evidently, there was a bit of a scandal regarding McKubre at SRI that took place in 2010, whereupon his CF project was abruptly shut down. He stayed on for 6 more years at SRI, resigning in 2016 and moving back to New Zealand.
Barry Kort
Oct 24, 2014
To date, only one person with credentials in AC circuit analysis has bothered to examine the observation that time-varying fluctuations in resistance would indeed introduce an RMS power term into the energy budget model. Dieter Britz independently confirmed[1] my closed form analysis of the AC power term, under a handful of convenient simplifying assumptions. He also took it one step further to compute the contribution of AC power for a more realistic model of the exponentially modeled slew rate of a regulated constant current power supply, using numerical integration methods.
Britz confirmed the observation, from basic AC circuit theory, that a fluctuating ohmic resistance of R±r, yields an AC power contribution PAC ≈ α²PDC, where α = r/R.
This term only manifests itself under the experimental conditions where the palladium lattice is fully loaded (so that there arises fluctuations in the fraction of the surface area of the electrodes occluded by bubbles), and even then, only when the Faradaic drive current is elevated to unusually high levels. Under more moderate conditions, the AC power term contributes less than 1% additional energy over and above the DC baseline.
[1] "Electrolysis Power Calculation," Dieter Britz, February 25, 2011. http://www.dieterbritz.dk/fusweb/powercalc.pdf
Barry Kort
In the paper by Dieter Britz, the first three tables present the instantaneous and cumulative average power at successive time increments. However, all three tables have two entries for t=3, with different values for those entries.
I cannot figure out precisely what's wrong with those three tables, but something is amiss. This appears to be some kind of error that neither of us noticed at the time.
There is also something weird in Figure 7, where the total power is at all times less than the average DC power. The only way I can think of that happening is if the AC transients are being transmitted back up the line, escaping from the cell and delivering their power to the sink within the power supply. But if that's what's happening, then the power supply isn't doing its job.
The only computation that appears to be without error is the one for the sinusoidally varying resistance (Figure 8), where it is easy to see that there is an RMS contribution of 0.5% above the average DC power, consistent with the mathematical model.
Nov 3, 2014