Unfortunately I couldn't find anything on axial fan efficiency or whatnot, compared to centrifugal fans. In general, though, if I had to pick one I'd go with the centrifugal fan for cooling purposes; they seem to move air much better than axial fans.
They do make direct-drive centrifugal fans, but I am not sure if they exist in large versions for home cooling systems. They are made for use in computers, as well as for smaller (but still large) units like blowers for drying and for things like "air curtains" and smaller blowers for small air-conditioning systems.
It depends. They each have their pros and cons:
https://en.wikipedia.org/wiki/Centrifugal_fan
http://www.pelonistechnologies.com/blog/axial-vs.-centrifuga... (might be somewhat biased)
https://en.wikipedia.org/wiki/Fan_(machine)
Unfortunately I couldn't find anything on axial fan efficiency or whatnot, compared to centrifugal fans. In general, though, if I had to pick one I'd go with the centrifugal fan for cooling purposes; they seem to move air much better than axial fans.
They do make direct-drive centrifugal fans, but I am not sure if they exist in large versions for home cooling systems. They are made for use in computers, as well as for smaller (but still large) units like blowers for drying and for things like "air curtains" and smaller blowers for small air-conditioning systems.