Thank you very much for the reply, Desmond. I’ve downloaded the paper. It’s 165 pages long, so it’s going to take me some time to work through it in detail, so I appreciate your summary.
On casual inspection, I found, “Figure 1 which shows the variation in turbine exhaust pressure vs. ambient temperature for a range of wind speeds.” The author makes the point that at “ambient temperatures above 100°F, the difference between no wind or low wind and high winds (above 20 mph) can be 1.5 to 2.inches Hga with a correspondingly significant effect on turbine output.”
That’s just one example of variables over which the operator has no control (ambient temperature and wind speed) that greatly impact the efficiency of the ACC.
And I think your impression is correct, based on my reading to date, that there is no magic gauge showing efficiency per se. I think that’s true of water-cooled condensers too. A lot of people watch backpressure, cleanliness factor and TTD, but none of those values, alone, give a complete picture of what’s happening in the condenser. A little detective work is always necessary to diagnose a performance issue (or, in some cases, to determine if a performance issue actually exists).