=+3-43.

A variable-air-volume (VAV) cooling system is a type where the quantity of air supplied and the supply air temperature are controlled. The space is to be maintained at 75 F (24 C) db and 63 F (17 C) wb. Under design conditions, the total cooling load is 15.0 tons (53.0 kW) with a sensible heat factor of 0.6, and the supply air temperature is 60 F (16 C) db. At minimum load, about 1.8 tons (6.3 kW) with SHF of 0.8, the air quantity may be reduced no more than 80 per-

cent by volume of the full load design value. Determine the supply air conditions for minimum load. Show all the conditions on a psychrometric chart for

(a) English units and

(b) SI units.

Assume sea-level pressure.