How to determine the flow?

[ashwininventech]

Hello,

I am trying to design cooling system for an electronic heat load of the 2.5 kW in a chamber.

I need to supply air at 17 deg C to maintain the temperature of the air in the chamber at 20 deg C. (As per the specifications)

The chamber is insulated.

In this case how to determine the Air Flow?

[Brian_UK]

We need a few more details, as usual.

Ambient air temperature
Size of room
Air Change Rate
etc

[ashwininventech]

Thanks for the reply.

Ambient air temp is 45 deg C (max)
Size of the chamber is 520 mm (width) x 520 mm (Length) x 900 mm (Height)

[MilosBog]

Q=V*cp*ro*DT/3600
From that
V(air flow)=Q*3600/cp*DT*ro [m3/h]
cp heat capacity of air
ro density
DT-your case 3K
you allready have a Q=2.5kW so just change the units and that is it.
And also you can do it according to the desired air change rate.

[dougheret0]

KW = air flow * delta T*specific heat of air *density of air*conversion constants
KW = L/s * ˚C * cal/gm˚C *gm/L* kw-hr/cal * s/hr
for air, cal/gm˚C = .25, density gm/L =1.25
s/hr = 3600, kw-hr/cal =1.163*10^-6

so L/s = KW/(˚C * cal/gm˚C *gm/L* kw-hr/cal * s/hr )
= 2.5/(3*.25*1.25*1.163*10^-6*3600)
= 640 L/s

This is the minimum air flow needed to absorb 2.5KW with a temperature rise of 3˚C. Any higher air flow will result in a chamber colder than 20˚C, ultimately approaching the 17˚C supply air temperature.