I agree with LOC computer fans will not move enough air to push it out past about 24" of vent pipe. You may be better off using a larger vent pipe then the computer fan just to reduce the backpressure. I still don't think it will work worth a dam but that will at least give you a better chance of the little fan doing you any good.

Active carbon scrubbers are the very best way to deal with odor from growing and flowering plants.