How much condensate when 90F 80%RH air dropped to 40F? 1

[shane21]

Per cubic foot of hot 90F humid 80%RH air, how much water is released when that air temp is dropped to 40F?

Thank you for any comments.

 

[MFJewell]

I think you need one more parameter on the outlet. Then use a psychrometric chart.

 

[shane21]

I've been looking at one, think I need to figure out water content of 90F 80%RH air - 40F 100%RH air, and that would give me answer, working on that now.

 

[Latexman]

A psychometric chart makes short work of this problem. About 0.0246 - 0.0052 = 0.0194 Grains/lb of dry air. The 90F/80%RH air is 14.4 ft^3/lb of dry air. So, 0.00135 Grains/ft^3 of dry air. 1 lb = 7000 Grains. So, 1.92x10^-7 lbs of H2O/ft^3 of dry air.

Psychometric Chart

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[Latexman]

Can you follow my previous post, or should I explain in detail?

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[shane21]

I just now came up with 0.02192 ounces of condensate water per cubic foot by using this chart...

http://www.process-heating.com/ext/resources/PH/2001/05/Files/PDFs/0501PHhartzell-tables1and2.pdf

where I took the water content of 90F 80%RH air and subtracted water content of 40F 100%RH air.
Not sure if correct, yet, double checking it...

 

[Latexman]

Your 0.02192 oz/ft³ looks right to me.

The chart I gave a link to has an error in their moisture content numbers. It should be lb/lb dry air for the numbers I used, not Grains/lb of dry air. My redo is:

About 0.0246 - 0.0052 = 0.0194 lbs H2O/lbs dry air. The 90F/80%RH air is 14.4 ft³/lb of dry air. So, 0.00135 lbs H2O/ft³ of dry air, and 0.0216 oz H2O/ft³ of dry air.

Both our numbers round to 0.022 oz/ft³ of dry air.

You are good to go!

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[shane21]

Latexman, many thanks, having our numbers jive is very reassuring here.

 

[Caloooomi]

FYI, I use this website quite a lot for work:

http://daytonashrae.org/psychrometrics_si.html#start

Quite handy just to plug in and pull the values off

 

[shane21]

Thanks, Caloooomi, that's a keeper.