Thermal power of the air extracted from a building

[ricardo46]

Good afternoon.
I need to know if the thermal power of the air extracted from a building is greater than 80kW.
I know the flows entering and leaving the building. Also, I know the temperature of the air inside and outside the building.
How do I calculate the power of the air extracted?
thank you

 

[SteamKing]

Good afternoon.
I need to know if the thermal power of the air extracted from a building is greater than 80kW.
I know the flows entering and leaving the building. Also, I know the temperature of the air inside and outside the building.
How do I calculate the power of the air extracted?
thank you

You'll need to know either the specific heat of the air at the temperatures encountered or know the enthalpy of the air. The latter will depend on temperature and humidity.

 

[ricardo46]

You'll need to know either the specific heat of the air at the temperatures encountered or know the enthalpy of the air. The latter will depend on temperature and humidity.

Ok. I know the specific heat. I have solved problems like this in the past. I am just a bit rusty.

I think I have found the solution:
P = Cp·flow·DeltaT

I am just not sure about the units:
P- power (W)
flow- m3/sec
DeltaT- temperature diference between the inside and the outside of the building
Cp- specific heat (J / (kg . ºK))

Is this correct?

 

[SteamKing]

Ok. I know the specific heat. I have solved problems like this in the past. I am just a bit rusty.

I think I have found the solution:
P = Cp·flow·DeltaT

I am just not sure about the units:
P- power (W)
flow- m3/sec
DeltaT- temperature diference between the inside and the outside of the building
Cp- specific heat (J / (kg . ºK))

Is this correct?

Seems to be.

 

[ricardo46]

Seems to be.

I think I can't use the flow like this. If i use it like this i won't get the power in watts but this W.m3/kg.
What should i do to get watts?

 

[SteamKing]

I think I can't use the flow like this. If i use it like this i won't get the power in watts but this W.m3/kg.
What should i do to get watts?

You can convert the volumetric flow to a mass flow, using the temperature of the air to find its density.