Tuesday, August 15, 2023

Addendum to the DIY A/C addendum

 It's been awhile but after reading my post regarding the use of an indirect-cooled evaporative cooler that's running a pseudo M-cycle scheme, I thought it good to mention that if the incoming water is below the ambient dew point (house interior), at least SOME parts of the system will likely have water condensation on them.  Hoses, any parts of the heat exchanger that isn't getting much, if any, air flow around it, etc.

One reason for re-visiting the subject is, of course, our current heat wave.  It got to 105 yesterday, and probably will get close to that today.  The day after it will "just" get up to 100.

The current outside air is at 77F/25C and 64% relative humidity.  According to my trusty psychrometric chart the wet bulb temperature is about 20C (68F) and the dewpoint is about 17.5C(~64F).  I have observed that the current air conditions are such that the wet bulb and dewpoint temperatures remain the same, as the air heats up.  That means that the humidity ratio (water/air mass) remains the same -- everything is so dry that there's little evaporation occurring!

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