Most APUs are installed in the rear, see the above image of an Airbus A380 as an example. On the An-225, no APU exhaust is visible at the rear of the aircraft.
So does the An-225 have an APU, and if yes, where is it located?
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Sign up to join this communityThey are located close to the main landing gears. From An-225 Mriya is the world’s largest aircraft (English version):
Auxiliary power plant consisting of two TA-12 turbofans installed in the left and right chassis fairings provides independent power to all systems and starts the engines.
I think "turbofans" is not the proper term here. Actually the TA-12 is (just) a gas turbine (Wiki (Russian), Google translation).
The location of the APUs being much closer to the tarmac might be a reason why Copenhagen airport has (or had) special regulations for its operation on an An-225 (source):
Special regulations for AN124 and AN225.
Aeroplane type AN124 and AN225 must not operate their APU unless the pavement underneath is protected against heat and blast effects from the exhaust.
I couldn't find a better picture but the exhaust pipe is quite visible here (red circle):
(Source)
I'm not perfectly sure whether the green circle marks the intake, but I guess so.