# Capturing heat exhaust

Given a natural gas fired industrial heater dryer which gives off 70,000 CFM of 190F air at 1.1 atm air pressure, is it practicably possible to capture 24 hours worth of this heated air exhaust into a compressed storage tank?

How would I calculate the theoretical maximum compression ratios and tank volume requirements?

Mech_Engineer
Gold Member
Given a natural gas fired industrial heater dryer which gives off 70,000 CFM of 190F air at 1.1 atm air pressure, is it practicably possible to capture 24 hours worth of this heated air exhaust into a compressed storage tank?

How would I calculate the theoretical maximum compression ratios and tank volume requirements?

There's no way you could store that kind of volume in a single tank, and doing so would be a losing proposition anyway. http://www.wolframalpha.com/input/?i=70000+cfm+*+24+hours".

I'm getting the feeling you're actually interested in capturing/utilizing/storing the energy in the exhaust from the dryer, which could possibly be done with some sort of http://en.wikipedia.org/wiki/Brayton_cycle" [Broken], which assuming atmospheric temperature is 75 F will be 17.5% (but if it's "free" energy, who cares? Run a generator and pipe that energy back into the dryer...)

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Thank you. Actually, our goal is ultimately to filter the air to remove suspended Nox or VOC particulate matter but the air filtration system cannot handle 70,000 CFM so we were considering compressing and storing the air so we can filter it later at a metered, controlled rate. But alas, it seems that won't work either. Any ideas??

Mech_Engineer
Gold Member
Get a filtering system that can keep up with the flow rate, or look into additives or secondary processes that reduce NOx?

AlephZero