Supply Air Flow Rate
The ventilation supply air rate is taken from table B2.3 and is given as 8 air changes per hour; the mass flow rate can be calculated.
Volume flow rate (m3/h) = Volume of room (m3) x air change rate (ac/h)
Volume of room (m3) = 40 x 20 x 8 = 6400 m3
Volume flow rate (m3/h) = 6400 (m3) x 8 (ac/h)
Volume flow rate (m3/h) = 51,200 m3/h
Volume flow rate (m3/s) = 51,200 / 3600 = 14.22 m3/s.
Mass flow rate = Volume flow rate / specific volume
The specific volume at the supply condition may be approximated at this stage from a psychrometric chart. It can be taken as 0.834 m3/kg.
Mass flow rate (Supply Air) = 14.22 / 0.834 = 17.05 kg/s.