Right but if this is the kind of question they're asking, you gotta wonder how high the bar is... https://pkteerium.xyz/media/fe07dcf5e1736c4088fb2f5a3c2ec031cb42335047f6d7bfbede95b38bea7cc0.png

I’m curious what the correct answer is

> A better question would be: under what conditions would a co-flow exchanger be preferred over a counterflow? that's probably the answer they're looking for tbh "which one is better?" "that depends, what are you trying to accomplish?" (explains pros and cons of each)

Then I assume my anser below was wrong. But it seemed not too eacy for my brain to figure it out. But I now see, that the argument for the counterflow is that at the exit of the liquid, the highest airtemperature is provided. So it can heat up the exiting liquid to the highest temperature.