Evaporative cooling

[kilrbee]

This is a turbo-charger problem.

Wanting to inject water into the compressor to reduce compressed air temps. The turbo compresses ambient by 20 (34 absolute) psi, to 450 degrees. My question, is what charts do I use for this compressed product?

Entry conditions: 100 degree ambient air, 10% RH, at 1000 cfm.
Then compressed 20 psi, 450 degrees approx.
How much water do I need to go to 90% RH? Resultant Temp?

Thanks for this forum. It's been a while since I exercised my brain. Was in a coma for a year.

 

[gtsim]

Ambient conditions

Pressure = 14.696 PSI
Temperature = 100F
Relative humidity = 10%
Wet bulb temperature = 63.753F
Airflow rate = 1000 cfm = 70.867 lbs/s

After cooling

Water flow rate (evaporated) = 0.573 lbs/s
Temperature = 65.709F
Relative humidity = 90%
Cooling = 34.291F
Cooling effectiveness = 0.94604

Trust this helps.

Regards,
gtsim

 

[gtsim]

I am sorry. I should have read your question more carefully. You need a hygrometric chart for a given ambient pressure. Alternatively, you can use the questions given in the site:

http://www.srh.noaa.gov/elp/wxcalc/formulas/rhTdFromWetBulb.html

to generate the necessary chart.

I think your other sources which gives spreadsheets that does this (try the HVAC forum).

Regards,
gtsim

 

[kilrbee]

Thanks for the reply gtsim. I may not have made myself clear. Lets do it this way. The entry conditons are:

air at 70 lb/min, 450 degrees, 34 psia, 10% RH.

How much water flow rate to go to 90% RH, and what is the resultant temp?

 

[kilrbee]

I would settle for a 2 bar or 3 bar psychrometric chart.

Where can I see one?

 

[kilrbee]

A high temp one at that...

 

[insult2injury]

You can create your own psych charts based on tabular data and the proper equations found in any thermo book.

I2I