Heating continuously moving air

[mishandle]

I need to keep equipment and personnel relatively warm in a structure having continuous air exchanges from outside the equipment housing, where temperatures can fall below freezing. The structure is approximately 24'x12'x10'. I have some flexibility regarding intake and exhaust quantities and locations.

 

[tombmech]

This should probably be posted in the HVAC/R group, but here's a couple of points:

If you have continuous air exchanges, heating that airflow is a simple mathematical relationship (assuming typical altitude, air, and temperatures):

Q = 1.08 x CFM x (T2-T1), where

Q is heat addition in Btuh,
CFM is airflow rate in cubic feet per minute
T2 is the desired supply temperature in deg. F. (or deg. R), and
T1 is your worst case outside temperature.

Except for extremely high air exchange rates, that heat addition will not be enough to offset the heat loss given up by the space through heat transfer to the outside. In most cases, you must calculate the anticipated "heating load" and supply air at a much higher temperature to compensate.

Since you still have the air exchanges, you would calculate to find T2, the supply temperature, given all the other parameters.

 

[TXiceman]

WHy not use an air to air exchanger to gain some of the heat from the air leaving the room. ie, cross exchange and contrl the air leaving the room.

Ken

TXiceman

http://www.rae-corp.com