h a l f b a k e r yBirth of a Notion.
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I have this installed in my car.
All you need is to purchase a standard indoor/outdoor thermometer [link] from your local electronics shop, and place "outdoor" sensor in your wheel arches. |
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Why wheel arches?? You won't be measuring your engine bay temperature, and you won't have the skin effect (if it was exposed to the moving air). |
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A friend of mine from uni has actually bought the extension kits for this and measures the temperature inside, outside, in the air intakes and inside the outlet from his turbo. |
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Baked in higher-end Buicks I've seen and most cars with digital temp controls. |
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Mm, yeah, pretty Baked, both for cars and for houses. |
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[reap] actually there would be no skin effect at all unless the sensor were wet. Wind-chill only effects things that are wet. Actually there would be a very tiny temperature increase due to the friction of the wind, but that couldn't really be a factor unless you're car goes _way_ faster than mine. |
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"It does help to know how to dress in the mornings" |
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The transparent parts of your walls let you "see" outside and they can be opened to also let you "feel" outside. |
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// Wind-chill only effects things that are wet. // |
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It also affects things that are heated. That's why computers have fans, despite not usually being wet. |
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That's not wind-chill though. The computer fan will only cool the heatsink to air temperature, not below. |
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Check out how a Psychrometer works, it measures the difference between the air temperature and the wind-chill factor. |
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// That's not wind-chill though. // |
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"Wind-chill" is an estimation of an equivalent stil-air temperature given an object is above ambient and in a moving airstream. |
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As you point out, thanks to the Second Law of Thermodynamics, the gas stream - no matter how cold - cannot cool the object below its own temperature. |
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But it is a crude approximation, depending on the pressure, specific heat and conductivity of the gas, the surface area of the object, and the velocity of the flow. |
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The typical model is for a human-sized object in air at 1 nominal atmosphere. |
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The wet bulb/dry bulb temperature is linked to absolute humidity which itself is a function purely of temperature, pressure and the gas composition - velocity has no influence, unless by Bernoulli's Principle a change in pressure results. |
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//velocity has no influence// that can't be quite right, otherwise you wouldn't have to whirl it round your head. |
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The velocity only needs to be "non-zero" i.e. no "dead air" around the device. If the air is moving, then the velocity doesn't matter until frictional heating starts to become a significant factor. That's fairly fast in normal air - certainly supersonic. If it were more significant, airframe icing wouldn't be anything like the problem it is. |
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