Honeywell AUTOMATIC CONTROL SI Edition Engineering Manual page 270

AIR HANDLING SYSTEM CONTROL APPLICATIONS
PSYCHROMETRIC ASPECTS
In the following chart it is assumed that:
1. Outdoor air condition is 35 C DB and 26 C WB.
2. RA condition is 24 C DB and 14.5 C WB.
3. Coil leaving air temperature 10 C.
4. 80% OA.
2
SPACE LOAD
3
COIL DISCHARGE
10 C DB, 8 C WB
OA 35 C DB,
26 C WB
COOL
1
15.8 C DB
RA 26 C DB,
4
14 C WB
C3266
The following results are obtained:
Item
No. Explanation
1. RA mixes with 20 percent (minimum position)
outdoor air to obtain mixed air condition.
2. Air entering the coil is cooled along a line of
constant moisture content until saturation is
approached. Near saturation the moisture con-
tent is reduced as the air is cooled. This process
involves both latent and sensible cooling.
3. Mixed air is cooled and dehumidified by
cooling coil to obtain cooling coil leaving air
condition.
4. Reheat coils and/or space heats air to 24 C
DB and 14.5 C WB.
ENGINEERING MANUAL OF AUTOMATIC CONTROL
260