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I have seen from a video and a website where they said that, temperature can be reduced by reducing the area where the air passes. But what theory can explain it more precisely? I guess this could be an example of Bernoulli's principle, but I failed to related the temperature with it. Will the process work always ? I mean is there any drawback?


marked as duplicate by John Rennie, user36790, CuriousOne, Wolphram jonny, ACuriousMind Jun 12 '16 at 17:33

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  • $\begingroup$ It works by letting air flow trough the house without adding additional heat load (which an ordinary window would). OTOH, simple window shutters would probably do the same. It would be even better is there was thermal insulation in the roof of these dwellings, that, however, would roughly double the material budget for the roof construction (it would require a second layer of roofing material), which to most people in the developing world is not affordable. The question has been asked before, by the way, I just can't find the post. $\endgroup$ – CuriousOne Jun 11 '16 at 14:21
  • $\begingroup$ Does this mean you heat your house by inverting the device? ;-) $\endgroup$ – Gert Jun 11 '16 at 16:52

It is similar to how the Chinook winds work, where wind from a high altitude at low pressure falls down a mountain into a region of higher pressure. Much the same can happen with moving air through a restricted volume. Moving air enters a region of reduced volume and by natural gas law its temperature increases. If in this narrow region you have some heat exchange system, even just passive vanes and the like, the heat can be dissipated to the outside. Then once the air passes this restricted region it will have a lower temperature than when it entered.

  • $\begingroup$ I would like to see a thermodynamic calculation of that, better still, an experimental confirmation. Chinook winds can reach velocities of up to 120km/h while falling 3000m, which, per $m^3$ of air, constitutes a potential energy change of over 30kJ. $\endgroup$ – CuriousOne Jun 11 '16 at 14:28

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