Air Change Rate (Ventilation System)
Air Change Rate (Ventilation System)
(OP)
Dear expert,
I want to size ventilation fans in a chiller machinery room. The heat gain by the room is 136 kW and the volume of room is 1830 m3. Temperature must be maintained between 35 to 40 deg.C. After calculation, the ACH required is 47, which is insanely high. I read in literature that the typical ACH for chiller room is less than 15, and of course it does not tally with my calculation due to the size of the room. So, what figure should I take and why?
Thanks
Isaac
I want to size ventilation fans in a chiller machinery room. The heat gain by the room is 136 kW and the volume of room is 1830 m3. Temperature must be maintained between 35 to 40 deg.C. After calculation, the ACH required is 47, which is insanely high. I read in literature that the typical ACH for chiller room is less than 15, and of course it does not tally with my calculation due to the size of the room. So, what figure should I take and why?
Thanks
Isaac





RE: Air Change Rate (Ventilation System)
Best to you,
Goober Dave
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RE: Air Change Rate (Ventilation System)
RE: Air Change Rate (Ventilation System)
RE: Air Change Rate (Ventilation System)
Otherwise we're just guessing.
RE: Air Change Rate (Ventilation System)
RE: Air Change Rate (Ventilation System)
Room load is about 50 tons, set point is between 95 to 104F. if this is the outside conditions too, then we consider your equipment as they are installed in outside under a shade.
RE: Air Change Rate (Ventilation System)
RE: Air Change Rate (Ventilation System)
RE: Air Change Rate (Ventilation System)
RE: Air Change Rate (Ventilation System)
RE: Air Change Rate (Ventilation System)
Good luck
RE: Air Change Rate (Ventilation System)
RE: Air Change Rate (Ventilation System)
thx
RE: Air Change Rate (Ventilation System)
I would like to thank you all of you who posted very insightful comments, and my special thanks to chicopee for providing me his calculation.
My calculation is as follows:
Machinery room ventilation air required for chillers can be estimated by using the formula:
V = H/(ρ×C_p×∆T)
= 136/(1.099×0.017×11)
= 661.8 m^3/min
Where
V = Ventilating air (m3/min)
H = heat radiation by 3 chillers (kW) – data given by GEA
ρ = Density of air at 38oC (1.099 kg/m3)
Cp = Specific heat of air (0.017 kW.min/kg.oC)
ΔT = Permissible temperature rise in machine room (oC)
The ventilation air required is 661.8 m3/min or 39,708 m3/h
Since the volume of room is 1,830 m3
ACH = 39,708/1,830
= 21.7 ACH
Maybe something wrong that I got a very high figure. Please help.
Best regards
RE: Air Change Rate (Ventilation System)