=+3-48.

Conditions in one zone of a dual-duct conditioning system are to be maintained at 75 F (24 ℃)

and 50 percent relative humidity (RH). The cold deck air is at 52 F (11 C) and 90 percent RH.

while the hot deck air is outdoor air at 90 F (32 C) and 20 percent RH. The sensible heat fac-

tor for the zone is 0.65, Assume sea-level pressure. In what proportion must the warm and cold air be mixed to satisfy the space condition? If the total zone load is 50 tons (176 kW), what is the total volume flow rate of air supplied to the zone? Sketch the states and processes on a psy-

chrometric chart. Use

(a) English units and

(b) SI units.