I like your idea and look forward to your results. What Frogwatch says makes sense and I especially like the idea of a black tube inside a clear tube. As I imagine the system, I think your biggest hurdle will be that it works too well, and the induced convection of air (the stated goal) will produce convective cooling of the tube itself, thus slowing the desired airflow.
How about a black tube inside a white tube with water in-between? Think sun shower (bag of water with one clear side and one black side). Water has an extraordinary specific heat capacity and won't be easily cooled by the air moving through the tube. You could even add hot water to kick-start it, though based on my experience with sun-showers it wouldn't take long to get it started. Also, if you make the inside tube longer than the outside tube, and sized it to fit a standard deck-plate hole, you'd have an easy way to stick it on the deck.
Keep us posed!
PS. Apparently this idea is quite ancient: