SELECTION PROCEDURE (with example)
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
of 0.06 in. wg) . . . . . . . . . . . . . . . . . . . . . . 0.20 in. wg
IISELECT UNIT BASED UPON REQUIRED COOLING CAPACITY.
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.
IIIDETERMINE EVAPORATOR FAN PERFORMANCE.
Enter Evaporator Fan Performance table at 1200 cfm and 502A036 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 502A024 contains a
Enter cooling capacity table at temperature of air entering condenser of 95 F. The 502A036 unit at 1200 cfm and
PERFORMANCE DATA
GROSS COOLING CAPACITIES
502A024
Temp |
| Evaporator Air Quantity — Cfm/BF |
| ||||||||
Air Ent | 600/0.02 | 800/0.03 | 1000/0.04 | ||||||||
Condenser |
|
| Evaporator Air Ewb Temp (F) |
|
| ||||||
| (F) |
|
|
|
|
|
|
|
|
| |
| 72 | 67 | 62 | 72 | 67 | 62 | 72 | 67 | 62 | ||
|
|
| |||||||||
|
| TC | 27.1 | 25.3 | 23.0 | 27.7 | 26.4 | 24.6 | 27.8 | 26.9 | 25.8 |
85 |
| 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 |
|
| TC | 26.6 | 24.5 | 20.8 | 27.4 | 25.8 | 22.9 | 28.0 | 26.5 | 25.2 |
95 |
| 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 |
|
| TC | 25.8 | 22.3 | 18.4 | 27.1 | 24.5 | 21.2 | 27.7 | 25.6 | 23.6 |
105 |
| 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 |
|
| TC | 24.6 | 19.9 | 16.5 | 26.1 | 22.0 | 19.8 | 26.8 | 23.6 | 22.3 |
115 |
| 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 |
See Legend on page 7.
502A036
Temp |
| Evaporator Air Quantity — Cfm/BF |
| ||||||||
Air Ent | 900/0.01 | 1050/0.01 | 1200/0.02 | ||||||||
Condenser |
|
| Evaporator Air Ewb Temp (F) |
|
| ||||||
| (F) |
|
|
|
|
|
|
|
|
| |
| 72 | 67 | 62 | 72 | 67 | 62 | 72 | 67 | 62 | ||
|
|
| |||||||||
|
| TC | 45.0 | 41.1 | 37.3 | 45.8 | 42.3 | 38.6 | 46.5 | 43.4 | 39.8 |
85 |
| 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 |
|
| TC | 43.0 | 38.8 | 34.3 | 44.1 | 40.1 | 35.8 | 45.0 | 44.2 | 37.4 |
95 |
| 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 |
|
| TC | 40.4 | 35.8 | 29.6 | 41.6 | 37.1 | 31.3 | 42.6 | 38.2 | 33.2 |
105 |
| 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 |
|
| TC | 37.7 | 30.6 | 25.8 | 38.7 | 31.6 | 37.8 | 39.7 | 32.8 | 29.7 |
115 |
| 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 |
6
