McQuay MDS030AR Applications Manual page 62

Design & installation Guide For McQuay MDS Multi System
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Acceptable (CO ) density
2
Room type
Place where people stay for a long time
Place where children and patients stay
Place where people stay
regularly (government agency)
Place where people stay for a short time
In actual practice, the fresh air volume is generally 30m
much room space a person occupies.
For densely populated buildings, such as air conditioned gymnasiums and meeting rooms,
as the room space per capita is less and every one stays shorter, the fresh air volume can
be calculated on a basis of 7-15m
way will count for 30% to 40% of the total air volume and it will greatly affect the cooling
capacity, you must be careful in deciding it.
Supplementary of air discharge
When the air conditioned room has an exhaust system, the air conditioning system must
have corresponding fresh air volume to complement the exhaust volume. Generally, it is
recommended to use an exhaust volume that is 80% of the fresh air volume for
comfortable air conditioning.
Keeping the air conditioned room in
To prevent outside air (those from outdoor and adjacent rooms with less strict air
conditioning requirements) from penetrating the room and affecting the temperature/
humidity or the cleanness of the air conditioned room, the air conditioning system needs
to use a certain volume of fresh air to keep the room in positive pressure , that is, the
atmospheric pressure of the room is higher than that of outside). Generally, the indoor
positive pressure is 5~10Pa. Too high positive pressure not only is a waste, but also
makes the system run less cost-effectively. In actual engineering design, the fresh air
flow should count for 10% or more of the total inlet to guarantee the air is healthy and
comfortable.
Introduction of fresh air
The inlet of fresh air should be at a clean place outdoor. It should be away from the
air discharge outlet and leeward to smoke, dust, and other harmful and toxic sources.
To avoid dust, the fresh air inlet should be at least 2m above the ground, or 1m above
the ground if it is placed in a green belt.
To introduce less hot air from outdoor in the summer, the inlet should be placed at the
shade side of the building.Generally, it is placed on the northern wall, not at the roof
or on the west wall.
Configure waterproof shutters, metal web, and air flow adjustment valves to fresh air
inlet if necessary.
To guarantee the quality of the introduced fresh air and the ambient temperature, do
not place the fresh air inlet near to the outdoor unit which has a condenser or put it near
to the exhaust outlet.
Generally, the size of the fresh air inlet depends on the air volume and air speed. For
the air speed, refer to Annex 4.
Note
For heat pump unit, you should consider the effects of layer height to the air conditioning effects.
When the layer height is 3m or more, you should select an appropriate air inlet to improve the air
flow pattern and the blown-in air flow.
Acceptable CO
L/m 3
1
0.7
1.25
2
2 /h person or more, no matter how
2 /h.person. However, as the fresh air volume got by this
positive pressure
density
2
g/kg
1.5
1.0
1.75
3.0