Hi Trillian!! Nice to hear from you!
Have you seen Zaphod?
I think this is going to be one of those 'sounds better in theory' kind of things. Still give it a go and report back with pics of your crazy creation, of course! I suspect that the restriction of flow from the pipe head alone will cancel out most of the hot buoyant air effect you are trying to exploit. I would confidently say that it WILL have some airflow but the question becomes "is it sufficient?".
Yes, the last question is the right point.
One of the properties of the Venturis effect is exactly the thermal properties of the low pressure and air flow acceleration.
In short, by accelerating the air on the constriction, the pressure drops making it more permeable to absorb heat.
You see this effect exactly on any Kelvin's refrigeration cycle where you compress the gas (R14, R15, R134a, etc) before it reaches the condenser pressurized, absorbing the heat inside the chamber. When it expands it cools down but the thermal energy is still the same, so we need the radiator.
Since I'm going to use air, the properties are quite a lot different, specially on the Thermal Capacitance side, but the principle remains.
So that's the correct question: is it sufficient? (for a sneak peak, see the link in end of this post :p)
I am not sure about the H-chimney design, I think the two 90 degree bends the flow would have to make would limit the momentum and flow rate of the rising air. I would almost bet BTC that a single straight tube of constant diameter would be better.
The H is to be put in the house exterior.
We use them quite a lot here in our houses chimneys because it has two advantages: the Venturi effect (again) sucking the flow from inside the pipe and no water in.
The H is mounted vertically.
The one I showed is for vertical mount but there are others for wall mount.
EDIT: I re-read your idea about putting the fan on it too. I was thinking you meant it would work passively. I suspect you will still find that having this contraption with the fan(s) on top will still be worse than just having the fan next to the heat sink as normal.
The fan is just to accelerate the air flow, somehow, not sure if in the intake or in the exhaust.
Where are all the process engineers / industrial chemists to model this scenario for us??? Do we have to bribe them with BTC lol?
I never finished university in Mechanics Engineering but it was a problem with maths and some Vapor Pressure charts in Thermodynamics :-p But hey! Here I am!! Just don't ask me to put some math on this.. I'd fail providing reliable numbers... :-(
No, it wasn't, but nice to acknowledge something new!
My motivation was this:http://www.extremetech.com/extreme/144731-the-wind-tunnel-computer-that-hopes-to-conquer-cancer
This is horizontal and I want to have it vertical.