ACC Champion will face a team from either the SEC, the Big 10, or Notre Dame each year.
And so it's been finalized. Starting in 2015 the Orange Bowl will pair the ACC Champion against an opponent from either the SEC or the Big 10 (or Notre Dame, which, you know, is basically an ACC team). ESPN will pay an average of 55 million annually for the bowl, which would be split evenly between the ACC and the opposing conference. If Notre Dame appears, however, the Irish will receive a good deal less of a payout.
The ACC representative will play the highest available ranked team from Notre Dame, the SEC or the Big Ten. However, if the ACC's highest-ranked opponent would create a regular-season rematch, the Orange Bowl has the flexibility to avoid that rematch by taking the next highest-ranked team from Notre Dame, the SEC or Big Ten. The team that was "skipped" over would be placed in an access bowl as long as it meets the minimum ranking requirement.
There's a bunch of other juicy (aka confusing as hell) stuff here at the link about what happens when certain teams do certain things and when certain stars align with certain planets on certain dates. You know. Typical sports stuff.