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I always wonder in directional flow which fan would send colder.air and cool better. I am biased toward table fan as it throws fresh air while ceiling fan throws stale hot air accumaled at top. Please tell which is better according to aerodynamic?

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There are far too many factors involved to definitively state that a table fan cools more than a ceiling fan or vice versa. For starters, there are different styles of both. It also depends highly on what you consider "cools better". For example, if you were to come inside and are sweaty, and are looking to cool down quickly, standing in front of a small fan will largely work better because the air volume being moved can be concentrated directly on you. It will, therefore, provide a more efficient means of removing latent heat.

I think the confusion here is actually regarding what a fan does. In general, a fan is a fan, so a ceiling fan and table fan that are designed to move the same amount of air will perform equally well. Neither one of them is cooling the air. While you are correct that air near the ceiling will possibly be warmer and "more stale" this is not due to the performance of the fan. If you have a supply outlet for an HVAC system right above a ceiling fan, for instance, you will now be blowing cold air down from that outlet (I'm not saying that is the correct placement of an air outlet, just using an example). Open air fans like you are talking about are really designed for mixing air more than anything. All of the heat sources in a closed room will seek to equalize when the air is mixed.

As for the last part of your question regarding aerodynamics, I'm not really sure what you mean. There are different blade styles available for both fan types, but I'm not sure what it is you're actually trying to figure out here since you have also tagged the question with "experimental physics".

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  • $\begingroup$ stated the situation clearly - well done. $\endgroup$
    – Solar Mike
    Jun 28 '17 at 21:10
  • $\begingroup$ A good thing about the ceiling fans is that they caused a forced convection current in the vertical direction. If for some reason you're in a situation where it's much cooler near the floor, a ceiling fan could help circulate the cold air instead of letting it stagnate. The thing is; that seems like a pretty rare situation, as there are usually moderate heat sources near the ground (such as people's legs and just the floor heating from light). Basically my biggest point is that stagnation can occur vertically; so in situations where you may expect it, ceiling is a good call. $\endgroup$
    – JMac
    Jun 29 '17 at 10:47

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