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Jules June 10, 2002 14:41

effect of ventilation on particles problem
Dear All,

I am doing a study on the spread of dust particles in an air-conditioned room.

To simplify the model, the room consists of one exhaust, two vents for return of air from the room to the air-con system, and 4 vents for the air from air-con and the environment back into the room.

I was given the values of the flow rate of air thru the exhaust (entirely and directly out into the environment), the 2 vents where air is recirculated back into the air-con system, and the flow rate of circulated air+fresh air into the 4 vents into the room

I thought of two ways of doing the model. Since I need to model the spread of particles in the room, plus how the particles were removed thru the exhaust and the filters in the air-con system,

i need to either : 1)draw ducts from the vents that are created at the ceiling of the room and include perhaps a "porous wall" in the ducts such that it represents the filter in the air-con system. However depending on the volume of the ducts created, I may alter the values of the air flow rate at each vents

2)just a room with openings at the ceiling with the specification of boundary types and the flow rate at the outlets and inlets. Regarding the return of particles into the room, if for example, n amount of particles is being "sucked" back into the air-con, then 0.2*n is being returned into the room assuming filters of 80% efficiency of trapping the particles.However, how should i "tell" fluent that 0.2*n percent of particles are to be released into the room thru the 4 inlet vents?

Another thing is the consideration that it is a transient problem, and a DPM problem.Obviously, the concentration of particles in the room will be reduced with time.

I have not tried anything yet with the model, I am just really unsure of what to do and how I should model my problem. Any help regarding the modelling of air-conditioning is greatly appreciated!

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