Yes, but afdelingen would mean 'departments' rather than 'the department'. But it is still fun to see familiar words in another language!

Not sure if it's what you meant, but here is a video (in Danish) with some words that change their sound if they're at the beginning of a compound noun

Danish sounds/pronounciation continue to blow my mind.

"Afdeling" is a department, "lejlighed" is a flat/apartment, so no, they aren't interchangeable, but I can see where the confusion is coming from

D's at the beginning of the word or the syllable are usually pronounced. But establishing pronounciation rules for Danish would be a daunting task, it appears.