Concentration will be higher than inlet & outlet as the oxygen is coming from the gas phase. Looking at the models in Fluent, I’ll have to see where Psat is defined.
You did set the gas as the To Phase didn't you? 23.2.10 https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v231/en/flu_ug/flu_ug_sec_multiphase_setup.html%23flu_ug_sec_mphase_massxfr
You are navigating away from the AIS Discovery experience