Climacool selection procedures – ClimaCool FLEX SERIES 30, 50, 65 User Manual

Page 14

ClimaCool Selection Procedures

The following information must be known in order to properly select

a ClimaCool

modular chiller:

•

System capacity

•

Entering chilled water temperature

•

Chilled water fl ow rate

•

Leaving condenser temperature

If any three of the fi rst four parameters are supplied, the missing

parameter may be found by the following formula.

Sample Selection

GIVEN: Select a water cooled chiller to cool 691 GPM of water

entering at 54°F and leaving at 44°F when supplied with 832 GPM

of condenser water entering at 85°F and leaving at 95°F leaving.

Solution:

1. Chilled water range (CWTD) = 54°F to 44°F = 10°F

2. Condenser water range = 85°F to 95°F = 10°F

3. Capacity (tons) = (GPM x Chilled Water Range/24 =

691 x 10/24 = 288 tons.

4. Select the closest” project tons” value from the

ClimaCool

Quik Select tables on page 16 and 17 which meets

or exceeds the load of 288 tons. In this case, the closest match

is a Project Tons of “290”, delivering an actual capacity of 293

tons. This selection comprises a total of (4) 65-ton modules

PLUS (1) 30-ton module.

Evaporator water pressure drop and condenser water pressure

drop can be found on separate charts on page 13 of this manual.

If not provided, fl ow rates can be determined from the follow-

ing formulas:

Chilled Water GPM =

(Tons) x24

(

)

Chilled Water delta T(°F)

Condenser =

(Tons+ (0.285

(

x Compressor kW))x24

))

Water GPM

Condenser Water delta T (°F)

Once the GPM is determined, it can be divided by the number of mod-

ules (weighted according to tonnage) to establish GPM per module.

NOTE

: Quik Select Tables (page 16 and 17) are based on a maxi-

mum allowable water fl ow rate of 1000 GPM through each of the 6”

main, water headers serving chiller and condenser sections. This re-

sults in a maximum of fi ve FLEX 65 modules at the customary 10°F

Chilled Water Range, and 10°F Condenser Water Range. Additional

banks of modules can be selected for larger tonnage requirements.

Also, the maximum number of modules which can be controlled by

a single ClimaCom controller is seven. Additional controllers can

be selected for projects requiring more than seven modules.

CHILLER PERFORMANCE WITH GLYCOLS

When analyzing performance data of chillers employing glycol

and water solutions, ﬁ rst derive the chiller performance data

(CAPACITY, KW, GPM & PRESSURE DROP) assuming pure

water ﬂ ow through the chiller. Then you can apply adjustment

factors to the performance data from the pure water case. These

factors are found in Fig. AM-1 through Fig. AM-4 on page 14,

and depend upon the type and percent of glycol used in the chiller

circuit. Fig. AM-1 and Fig. AM-2 provide factors for propylene

glycol. Fig. AM-3 and Fig. AM-4 are for ethylene glycol. The

factors in all Fig’s AM-1 through Fig. AM-4 are based on 10°F

drop in ﬂ uid temperature through the chillers and 85°F entering

condenser water (ECDW), and at 10°F rise through the condenser

(CDTD). Fig. AM-5 is provided for solution freeze temps. of

glycol concentrations. Fig. AM-6 provides adjustment factors for

chiller temp. drops other than 10°F, all assuming a fouling factor

of 0.0001 in the chiller.

Propylene Glycol Selection Example

(Select a FLEX 65 Module)

Determine CAPACITY, KW, GPM and Pressure Drop for a single

FLEX 65 module, given the following Inputs:

CWTD = 10°F

LCWT = 42°F

ECDW = 85°F

CDTD = 10°F.

30% Propylene Glycol/ 70% Water in Chiller

1. Assume a 10°F rise in the condenser, thus 95°F leaving con-

denser water.

2. From the Performance Data Table on page 18:

CAPACITY: 63 TONS;

KW: 46.6

3. First fi nd the chiller water fl ow and pressure drop for pure water

as in the previous example.

GPM = (24)(63)/10 = 151.2 GPM

From page 13, bottom graph - right most curve, read pressure

drop from mid. Curve as:

Pressure drop = 7.0 ft. of water

4. To convert performance data for pure water to data using 30%

Propylene Glycol, record the adjustment multipliers from Fig.

AM-1 & Fig. AM-2 on page 14:

CAPACITY factor:

0.97

KW factor:

0.988

GPM factor:

1.022

Pressure Drop factor:

1.20

5. Calculate chiller performance using 30% Propylene Glycol by

multiplying the chiller performance data for pure water by the

adjustment factors as follows:

CAPACITY:

63 x 0.97 = 61.1 TONS

KW:

46.6 x 0.988 = 46.04 KW

GPM:

151.2 x 1.022 = 154.5 GPM

Pressure Drop:

7.0 x 1.20 = 8.4 ft. of water