mass flow rate calculation

[coatepequense]

I'm an engineering at UGA and I was wondering if anyone can help me out with some tips on how to calculate the mass flow rate for a building with 2020 ft^a and 9 ft tall, with a heating load of 66489.11 Btu/hr, a cooling load of 86820.14 Btu/hr and 3.57 air changes per hour. The outside temperature is at 20°F and the inside temp is at 70°F. Do I use the formula m = Q/(Cp*deltaT), this souds really easy or do I multiply the air changes per hour times the volume of the room.

 

[quark]

There are three things to consider.

1. Air flow rate required to take care of heating load.
2. Air flow rate required to take care of cooling load.
3. Air flow rate required to take care of required air changes per hour.

Your final figure will be the maximum value of the above three cases.

With respect to no. of ACPH I got a volume flow rate of (2020x9x3.57/60)= 1082 cfm.

Based on your heating load (without humidification),

66489.11 = 1.08 x cfm x 50 (use the formula Q = 1.08xcfmxdT)

Therefore, air flow rate is 1232 cfm.

This is a rough calculation in the absence of some important data.

1. Whether your system is once through or recirculatory?
2. Do you have a requirement for humidification during heating?
3. Do you have to dehumidify the air during cooling?
4. What are the design conditions during cooling season?

Regards,


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