# Thermodynamics / Q = mC⌂T equation in air application

1. Feb 20, 2014

### Phystudent91

1. The problem statement, all variables and given/known data

If you have a radio equipment cabin that has a heat load of 15kW and you wish to stop the temperature becoming more than 15°C hotter than outside, how much 'free air' (outside/atmospheric air) needs to be circulated inside the cabin per hour?

2. Relevant equations

Q = mC⌂T
C = 1.007
⌂T = -15

3. The attempt at a solution

I don't know how to relate the m (usually a mass, right?) to a volume of air, as I assume that is the equations equivalent.
I hope that makes sense...

2. Feb 20, 2014

### BvU

There is an ideal gas law saying pV = nRT which is good enough for this kind of thing. You'll have to make a decent assumption for T and p (p is easy, T is more vague).
But: what's against answering soandsomany kilograms per hour if they ask "how much" ?

3. Feb 20, 2014

### Staff: Mentor

Let m be the amount of air mass that passes through the room in an hour. How much heat does it have to absorb in an hour to remove all the heat generated by the radio equipment?

Chet