=+3-45. The design condition for a space is 77 F (25 ℃) db and 50 percent relative humidity with SS F

(13 C) db supply air at 90 percent relative humidity. A 50-ton, constant-volume space air-

conditioning system uses face and bypass and water temperature control. Outdoor air is sup-

plied at 95 F (35 C) db, 60 percent relative humidity with a ratio of 1 Ibm (kg) to 5 lbm (kg)

return air. A part-load condition exists where the total space load decreases by 50 percent and the SHF increases to 90 percent. The outdoor air condition changes to 85 F (29 C) db and 70 percent relative humidity. Assume sea-level pressure.

(a) At what temperature must the air be supplied to the space under the part-load condition?

(b) If the air leaving the coil has a dry bulb temperature of 60 F (15 C), what is the ratio of the air bypassed to that flowing through the coil?

(e) What is the apparatus dew point temperature for both the design and part-load condi-

tions?

(d) Show all the processes on a psychrometric chart.