Selection Procedure - Carrier 30GTN Product Data

Selection procedure — English (with 30GTN example)
NOTE: The Carrier electronic catalog provides quick, easy
computer selection of Carrier chillers. The catalog is
available from your local Carrier representative.
I Determine unit size and operating conditions
required to provide specified capacity at given
conditions:
Capacity required . . . . . . . . . . . . . . . . . . ...112 tons
Leaving chilled water temperature (LCWT) . . . 45 F
Chilled water temperature rise . . . . . . . . . . . 14° F
Condenser entering-air temperature (CEAT) . . 95 F
Loop volume . . . . . . . . . . . . . . . . . . . . . . 350 gal.
Ratings are based on 10° F rise and are suitable for a
temperature rise range from 5° to 15° F without
adjustment. In this case, however, greater accuracy is
desired.
II Correct LCWT for 14° F cooler water temperature
rise.
Enter LCWT correction curve (below) at 14° F and
read a correction of 0.3 F. Corrected LCWT is,
therefore, 45 + 0.3 = 45.3 F.
III Determine capacity, unit size, and power input.
Enter Cooling Capacities table at given CEAT and
LCWT — 95 F and 45 F, respectively.
Read down capacity column until the capacity nearest to
but higher than specified required capacity is reached. In
this case, 113 tons is delivered by a 30GTN110.
Selection procedure — SI (with 30GTN example)
I Determine unit size and operating conditions required
to provide specified capacity at given conditions:
Capacity required . . . . . . . . . . . . . . . . . . . 380 kW
Leaving chilled water temperature (LCWT) . . . . 6 C
Chilled water temperature rise . . . . . . . . . . . 7.8° C
Condenser entering air temperature (CEAT) . . 35 C
Loop volume . . . . . . . . . . . . . . . . . . . . . . 1400 L
Ratings are based on 6 C rise and are suitable for a
temperature rise range from 2.8° to 8.3° C without
adjustment. In this case, however, greater accuracy is
desired.
II Correct LCWT for 7.8° C cooler water temperature
rise.
Enter LCWT correction curve (below) at 7.8° C and
read a correction of 0.14 C. Corrected LCWT is,
therefore, 6 + 0.14 = 6.1 C.
III Determine capacity, unit size, and power input.
Enter Cooling Capacities table at given CEAT and
LCWT — 35 C and 6 C, respectively.
Read down the capacity column until the capacity nearest
to but higher than the specified required capacity is
Interpolate between 45 F and 46 F to find determined capacity
and power input at corrected LCWT (45.3 F). Values are:
Capacity . . . . . . . . . . . . . . . . . . . . . . . 113.6 tons
Power input . . . . . . . . . . . . . . . . . . . . . 136 kW
IV Calculate corrected cooler water flow.
Water flow = 24 x corr cap. in tons = U.S. gpm
temperature rise °F
=24 x 113.6 = 194.8 U.S. gpm
14
V Calculate the cooler pressure drop.
Enter cooler pressure drop curve (page 32) at the corrected
flow rate (194.8 U.S. gpm) and read, for the 30GTN110, a
pressure drop of 10.4 ft of water.
VI Check loop volume and cooler water flow rate.
Minimum loop volume, from application data, is 333 gal. for
30GTN110. Therefore, given volume of 350 gal. is
satisfactory. Minimum water flow rate, from application data,
is 73 gpm for 30GTN110. Flow rate of 194.8 gpm is well
above minimum required.
reached. In this case, 381.7 kW is delivered by a 30GTN110.
Interpolate between 6 C and 7 C to find the determined
capacity and power input at corrected LCWT
(6.1 C).
Values are:
Capacity . . . . . . . . . . . . . . . . . . . . . . . . 383 kW
Power input . . . . . . . . . . . . . . . . . . . . . 132.6 kW
IV Calculate corrected cooler water flow.
Water flow = 0.239 x corr cap. in kW = L/s
= 0.239 x 383 = 11.7 L/s
V Calculate cooler pressure drop.
Enter cooler pressure drop curve (page 32) at corrected
flow rate (11.7 L/s) and read, for 30GTN110, a pressure
drop of 26.0 kPa.
VI Check loop volume and cooler water flow rate.
Minimum loop volume, from application data, is 1260 L
for 30GTN110. Therefore, given volume of 1400 L is
satisfactory. Minimum water flow rate, from application
data, is 4.6 L/s for 30GTN110. Flow rate of 11.7 L/s is
well above minimum required.
24
temperature rise °C
7.8