What are the air flow patterns in ASHRAE and industry standards?
ROOM
MIXING FACTORS
A recent conversation with a hospital engineer brought to mind a need
to talk about air flow patterns and ASHRAE tests documented in the
fundamentals handbook:
The standard room has a possibility of having supply air registers
either:
- 1 - Blowing out horizontally from the interior wall,
- 2 - Blowing up past an exterior window or,
- 3 - Blowing four ways out from the middle of the room at the ceiling.
All three of these tend to stagnate air in the center of the space
approximately at chest or at head height. This reduces the mixing
effect and increases the mixing factor to higher than 1.
When introducing the air flow patterns of a free standing unit with
top air discharge into these rooms, the patented high air velocity
coming from the top of the NQ unit will divert and mix with the low
velocity airflow from the building supply registers. The NQ high velocity
will bring the low velocity air with it and continue across the room
where intended.
There will be a certain amount of turbulence at the point of contact
of the two air streams. This turbulence is good. The basic rooms mentioned
above, will therefore now have the central stagnant air, in the space,
mixed so as to keep the mix factor at or close to a value of 1.
The air from the building system, which is thought to hurt the air
flow patterns because of the nataural stagnation set up, actually
helps the mix factor stay at the prime rate of 1, when both systems
are used together in any room.
