Carrier 50AH - Manual (Page 6)

6
I Determine cooling requirements at design
conditions.
Given:
Gross Cooling Capacity
Required (TC) . . . . . . . . . . . . . . . . . .39,000 Btuh
Sensible Heat Capacity (SHC) . . . . . .30,500 Btuh
Temperature of Air Entering Condenser . . . . .95 F
Temperature of Air Entering
Evaporator . . . . . . . . . . . . . . . 80 F edb/67 F ewb
Evaporator Air Quantity. . . . . . . . . . . . 1,200 cfm
External Static Pressure:
Condenser . . . . . . . . . . . . . . . . . . .0.50 in. wg
Evaporator (includes static pressure
drop of factory-supplied filter
of 0.06 in. wg) . . . . . . . . . . . . . . .0.20 in. wg
II Select unit based upon required cooling
capacity.
Enter cooling capacity table at temperature of air
entering condenser of 95 F. The 50AH036 unit at
1200 cfm and 67 F ewb will provide a Total
Capacity (TC) of 44,200 Btuh and a Sensible Heat
Capacity (SHC) of 31,300 Btuh. Since the entering
air is 80 F edb, an SHC correction is not required.
III Determine evaporator fan performance.
Enter Evaporator Fan Performance table at
1200 cfm and 50AH036 data. The external static
pressure shown (0.23 in. wg) will exceed the
0.20 in. wg required. The fan motor will require
0.52 kW.
IV Determine condenser fan performance and
motor pulley setting requirements.
Enter Condenser Fan Performance table at
the selected cfm and required static pressure of
0.50 in. wg. The fan motor will require 0.73 kW
and the motor pulley should be set at 2 turns open
at 1350 cfm of condenser air required.
NOTE: Unit 50AH024 contains a direct-drive con-
denser fan assembly.
Performance data
GROSS COOLING CAPACITIES
See Legend on page 7.
50AH024
Temp
Air Ent
Condenser
(F)
Evaporator Air Quantity — Cfm/BF
600/0.02 800/0.03 1000/0.04
Evaporator Air Ewb Temp (F)
72 67 62 72 67 62 72 67 62
85
TC 27.1 25.3 23.0 27.7 26.4 24.6 27.8 26.9 25.8
SHC 13.5 17.0 20.2 14.7 19.4 23.7 15.6 21.5 25.8
kW 1.64 1.62 1.61 1.65 1.63 1.62 1.65 1.64 1.63
95
TC 26.6 24.5 20.8 27.4 25.8 22.9 28.0 26.5 25.2
SHC 13.4 16.7 19.1 14.7 19.4 22.8 16.0 21.7 25.2
kW 1.85 1.84 1.80 1.86 1.85 1.82 1.87 1.85 1.84
105
TC 25.8 22.3 18.4 27.1 24.5 21.2 27.7 25.6 23.6
SHC 13.1 15.8 17.9 14.7 18.9 21.2 16.2 21.5 23.6
kW 2.09 2.05 1.99 2.11 2.08 2.04 2.12 2.10 2.07
115
TC 24.6 19.9 16.5 26.1 22.0 19.8 26.8 23.6 22.3
SHC 12.7 14.8 16.5 14.4 17.9 19.8 16.0 20.7 22.3
kW 2.36 2.29 2.22 2.39 2.33 2.29 2.39 2.35 2.33
50AH036
Temp
Air Ent
Condenser
(F)
Evaporator Air Quantity — Cfm/BF
900/0.01 1050/0.01 1200/0.02
Evaporator Air Ewb Temp (F)
72 67 62 72 67 62 72 67 62
85
TC 45.0 41.1 37.3 45.8 42.3 38.6 46.5 43.4 39.8
SHC 22.5 27.7 32.6 23.6 29.9 35.6 24.6 32.0 38.3
kW 3.19 3.07 2.96 3.22 3.11 3.00 3.25 3.14 3.04
95
TC 43.0 38.8 34.3 44.1 40.1 35.8 45.0 44.2 37.4
SHC 21.8 26.8 31.1 23.1 29.1 34.1 24.4 31.3 36.8
kW 3.42 3.28 3.15 3.46 3.33 3.20 3.49 3.37 3.25
105
TC 40.4 35.8 29.6 41.6 37.1 31.3 42.6 38.2 33.2
SHC 20.9 25.6 28.5 22.3 27.9 30.8 23.7 30.2 33.2
kW 3.63 3.48 3.38 3.68 3.53 3.44 3.73 3.58 3.49
115
TC 37.7 30.6 25.8 38.7 31.6 37.8 39.7 32.8 29.7
SHC 19.9 23.3 25.8 21.3 25.5 27.8 22.7 27.8 29.7
kW 3.85 3.71 3.59 3.90 3.76 3.67 3.94 3.80 3.73
Selection procedure (with example)