Room temperature 2

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Hi,

Iam working on the ventilation design for a Electric switch board room

When the ventilation system is working, the inside condition is to be maintained at 35 deg C.

My client want know that incase of failure of the ventilation system, In how much time the inside temperature will reach 45 deg C.

Can someone guide on the procedure for doing this calculations.

Design Info is like this

Room Volume : 240 M3
Normal Temperature when ventilation is running : 35 deg C
Maximum temp rise if ventilation fails : 10 deg C
Cooling Load from Load Calculations: 7.5 Kw (This take into account external and internal loads)


Thanks

 

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240 m[sup]3[/sup] is 8469 cu.ft. 7.5kW is 25591 btu/hr.

Considering purely sensible load and using the equation

Q = 1.08 x cfm x dT or cfm = Q/(1.08 x dT) = 25591/(1.08 x 18) = 1316. That means the given load can raise temperature of 1316 cu.ft of air by 10[sup]0[/sup]C with in a minute time. For 8469 cu.ft, it takes 8469/1316 = 6.43 minutes.

PS: dT in the above equation is in deg.F