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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 percent 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.
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