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Thread: Please help!!
01-17-2012, 08:12 PM #27
01-18-2012, 07:25 AM #28
Air's ability to hold more moisture has more to do with the higher activity of the water molecules supended in the air. Cooling air slows the speed of the water vapor to the point of condensation. Therefore cold air holds less moisture than warm air.
This is my understanding. We all go through this process as we improve our understanding of the problem. Sometimes not quite perfect. Maybe we will get a PHD in here to give us the "real story".
Regards TBBear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"
01-18-2012, 07:33 AM #29
Thank you TB. I am learning every day.
Apologies to ryanl for speed bumping your thread with a side issue. Gotta go to work.
01-18-2012, 08:04 AM #30
01-18-2012, 08:50 AM #31
RH can be applied to any two-phase substance, since any liquid substance has an associated vapor pressure. It isn't uncommon to see RH used in the context of refrigerant vapor. For instance, in a closed cylinder of R22 the steady state pressure is the saturated pressure, found on the P/T chart. If at the same temperature the vapor pressure is found to be half of that value, then the RH of the refrigerant vapor would be 50% in that case, and would obviously be in a superheated state. IOW, RH of a refrigerant is an indicator of how close the vapor is to saturation.
Water is also classified as a refrigerant, R718. As with all of the other refrigerants, as the temperature is increased, the saturation pressure increases. The vapor above the liquid surface will not only be at a higher pressure, but also at a higher mass density as well. This is why it is said that "air at a higher temperature can hold more moisture". It really has nothing to do with the air, it has to do only with the temperature in the space, i.e., the temperature of the water vapor. IOW, as the temperature of water vapor is increased, its saturation pressure increases, and thus its maximum density before condensation will begin.