Check the lines of the alternator sometimes it gets corrosives
Check the tension on the drive belt, bearings, brushes...
Take the current alternator and test it with the new one and check the voltage in the store where you purchased.
check for shorts.
check that gets enough ground.
Also, just because its new does not mean its good special if it's refurbished that I don't know where you purchase it.

I remember a time that I replaced my refurbish steering power pump 6 times. pump was defected took me 6 times. it could be the Alternator regulator to be faulty.

how you can tell if your alternator is faulty. the lights on inside your car will blink go off, when you change station on your radio go off and on, dim, fuses blowing, head lights bulb blowing... check it out.
Test the alternator both the one you have now and a new one,
get second opinion to another place.

If is refurbished and keeps dying try to get the genuine for your car.

Good luck