Tom,
You stated, <A modern aircraft taxiing by itself at DFW in the the summer, has no way of activly cooling air i.e. through refridgeration?>
Yes it does. As I stated in my previous post
'These packs contain heat exchangers(utilising ram air in flight and air drawn through them by a fan on the ground) and an aircycle machine operating on a boot-stap cycle.'
Air conditioning of the aircraft on the ground is essential, particularly in high ambient temperature conditions, hence the fan drawing air over the heat exchangers and the air cycle machine.
Regards
Exeng