Using iPad so this will be brief. As I said above it is like a TC Vs. TN or NA, it is the lower compression ratio. It has nothing to do with the turbo itself. A TN has the same turbo lets say, but the TC aircraft have lower compression ratios say 7.5:1 compared to 8.5:1 and thus due to less expansion of the end gasses at any given fuel flow if there is less expansion there is higher egt.
Simple thought experiment. Take your BBQ gas bottle, full and lots of pressure....open valve and get LOTS of expansion. Now get another bottle but at a much lower pressure, but same volume. Which one freezes up the most?
The one that does the most expanding of the gas has the lower temp. Same with everything else. Bigger delta P bigger temp drop.
Back to the turbine on the A320, same deal with the lower speed will be less compression, therefore less expansion, so the fuel burns and the gasses have to be a higher egt. They can't not be.
According to Wally who in his old age
must have started a few, it's a bad thing.....so young pups like us should listen and learn
PS anthill, consider the exhaust gases only, immediately after the combustion, the laws then work fine, just like they do on the intake side. You need to examine each component of the process one bit at a time.
my head hurts now, this stuff was too long ago, and I never use it daily, probably got it wrong anyway, and the iPad keyboard and auto spell is doing me in.