Carrier 30XW325-400 사용자 설명서

15

Carrier’s packaged selection program provides quick,
easy selection of Carrier’s water-cooled chillers. The pro-
gram considers specific temperature, fluid and flow
requirements among other factors such as fouling and alti-
tude corrections.

Before selecting a chiller, consider the following points:

Leaving water (fluid) temperature (LWT)
• The LWT must be at least 40 F (4.4 C) or greater.
• If the LWT requirement is greater than 60 F (15.5 C), a

mixing loop is required.

Entering water (fluid) temperature (EWT)
• If the EWT requirement is greater than 70 F (21.1 C), a

mixing loop is required. The EWT should not exceed
70 F (21.1 C) for extended operation. Pulldown can be
accomplished from 95 F (35 C).

Evaporator flow rate or evaporator delta-T:
• The evaporator delta-T (EWT – LWT) must fall between

5 and 20° F (2.8 and 11.1° C) while still meeting the
maximum entering requirements.

• For larger or smaller delta-T applications, a mixing loop

is required.

 If the evaporator flow is variable, the rate of

change of flow should not exceed 10% per minute.
The loop volume in circulation must equal or exceed
3 gallons per nominal ton (3.2 L per kW) of cooling for
temperature stability and accuracy in normal air condi-
tioning applications. In process cooling applications,
there should be 6 to 10 gallons per ton (6.5 to 10.8 L
per kW). To achieve this loop volume, it is often neces-
sary to install a tank in the loop. The tank should be baf-
fled to ensure there is no stratification, and that water
(or brine) entering the tank is adequately mixed with liq-
uid in the tank. See Water Loop Volume in the Applica-
tion Data section.

Evaporator pressure drop:
• A high evaporator pressure drop can be expected when

the evaporator delta-T is low. A mixing loop can help to
alleviate this situation.

• The three-pass evaporator option is recommended to

increase performance when the evaporator delta T is
high. This is particularly helpful with brine applications.

Condenser pressure drop:
• A high condenser pressure drop can be expected when

the condenser delta-T is low. A one-pass condenser can
help lower pressure drop.

Series chillers:
• One-pass heat exchangers can help lower pressure

drop when heat exchangers are placed in series.

Water quality, fouling factor:
• Poor water quality can increase the required evaporator

fouling factor.

• Higher than standard fouling factors lead to lower

capacity and higher input kW from a given chiller size
compared to running the same application with better
water quality (and lower fouling factors).

Temperature reset:
• Return water (standard)
• Outside air temperature (standard)
• Space temperature (accessory sensor required)
• 4 to 20 mA (requires an energy management module)
Demand limit:
• 2-step (requires an energy management module)
• 4 to 20 mA (requires an energy management module)
• CCN Loadshed

*Maximum condenser fluid temperature shown for standard condensing
option. Heat machine option may have leaving fluid temperatures up to
140 F (60 C).

411

25.9

1481

93.4

494

31.1

1974

124.5

790

49.8

987

62.3

790

49.8

3126

197.2

987

62.3

3290

207.6

790

49.8

987

62.3

247

15.6

987

62.3

—

—

—

—

790

49.8

—

—

433

27.3

1557

98.2

519

32.7

2076

131.0

830

52.4

1038

65.5

830

52.4

3287

207.4

1038

65.5

3460

218.3

830

52.4

1038

65.5

260

16.4

1038

65.5

—

—

—

—

830

52.4

—

—

486

30.7

1751

110.4

584

36.8

2334

147.3

934

58.9

1167

73.6

934

58.9

3696

233.1

1167

73.6

3890

245.4

934

58.9

1167

73.6

292

18.4

1167

73.6

—

—

—

—

934

58.9

—

—