November 26 – Happy Birthday, Willis Carrier

nPostednon November 26, 2016

nWhennI typed “Carrier” into Google, the first thing that came up wasnCarrier Air Conditioning.

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nAndnthat’s all well and good, because today’s birthday boy inventednmodern air conditioning!

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Bornnin New York on this date in 1876, Willis Carrier grew up to be annengineer. He invented the first air conditioning unit in 1902 andnstarted Carrier Corporation in 1915. Carrier advertises that it isnstill a world leader in HVAC (Heating, Ventilation, and AirnConditioning).

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nOfncourse, even before Carrier’s invention, people had been coolingntheir homes and work places since prehistoric times, often using snownand ice – even storing ice for use during summer. Some people usednshade or moist cloths or reeds hung in windows so that breezes wouldnbring in cooler, moister air. Even ancient people used waterncirculating in pipes inside walls to cool particular rooms, and earlyncivilizations utilized things such as wind towers and cisterns toncool the air. Ancient peoples also invented human- or animal-powerednrotary fans to move air around.

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nButnCarrier’s air conditioning unit used electricity to do four importantnthings:

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ncontroln temperature

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ncontroln humidity (how much moisture is in the air)

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ncontroln air circulation, or movement, and ventilation

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ncleansen the air

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nBasically,nCarrier’s invention heated water in order to put more humidity intonthe air, and it cooled water in order to take humidity out of thenair.

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nCarrierntied together the ideas of absolute humidity, relative humidity, andndew-point temperature in a document sometimes referred to as the mostnimportant document ever written on HVAC stuff.

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nLet’snsee what these three ideas mean:

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nAbsolutenhumidity – a measure of the water vapor in air no matter what thentemperature is, expressed in grams of water per cubic meter of air.

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nRelativenhumidity – a measure of water vapor in the air relative to thentemperature of the air, expressed as a percentage of the total amountnof water vapor that could be held by air at that temperature.

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n Warmnair can hold a lot more water vapor than can cold air. n

n Relativenhumidity is important because it affects how we experiencentemperature. If the air is really moist and 90 degrees, we feel a LOTnhotter and more uncomfortable than if the air is quite dry and 90ndegrees.

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nDew-pointntemperature – when relative humidity reaches 100%, the air isncalled “saturated” – which means it is holding as much waternvapor as it can possibly hold at that temperature. Some water vapornis condensing (forming drops of liquid water) on solid surfaces ornparticles, but some drops of water are also evaporating and becomingnwater vapor…Because of this steady condensation and evaporation,nthe amount of water vapor stays the same.

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Butnwhen the temperature drops a smidge (or a lot) below the dew-pointntemperature, the water vapor condenses at a higher rate than liquidnwater evaporates. And dew begins to form on leaves and blades ofngrass and cars and other objects. Or drops of water condense onnparticles of dirt or sand in the air, causing the formation of eithernfog or clouds, depending on how high the drops are located.

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