=+3-54. Outdoor air is mixed with room return air to reduce the refrigeration load on a cooling coil.

(a) For a space condition of 77 F (25 ℃) db and 68 F (20 C) wb, describe the maximum wet bulb and dry bulb temperatures that will reduce the coil load.

(b) Suppose a system is designed to supply 10,500 cfm (5 m /s) at 64 F (18 C) db and 63 F (17 C) wb to a space maintained at the conditions given in part

(a) above. What amount of outdoor air at 68 F (20 C) db and 90 per-

cent relative humidity can be mixed with the return air if the coil SHF is 0.67

(c) What is the apparatus dew point in part

(b) above?

(d) Compare the coil refrigeration load in part

(b) above with the outdoor air to that without outdoor air. Assume sea-level pressure.