SPX Cooling Technologies Recold / JW Series Fluid Cooler / Selection Procedure, Load Btuh =

Recold / JW Series Fluid Cooler / Selection Procedure

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Closed circuit cooler selections can easily be made by using the information on pages 6 through 11. The examples below demonstrate proper procedures for water and ethylene glycol solutions. Other fluids can be cooled, but since their heat transfer and flow characteristics may vary, please contact your local Recold sales representative for assistance.

WATER SELECTION EXAMPLE

Select a unit to cool 225 GPM of water from 102°F to 90°F at 76°F wet bulb temperature.

1. Determine Range:

102°F - 90°F = 12°F Range

2. Determine Approach:

90°F - 76°F = 14°F Approach

3.Select Load Factor — Enter Unit Load FactorTable 2 for 76°F wet bulb. Select load factor based on 12°F range and 14°F approach. Load factor in this example equals 3.3. When wet bulb temperature is an odd number interpolate between appropriate tables to determine the load factor.

4.Select Unit Model — Table 3, the load factor determined in step 3 falls between 3.0 and 3.5. Enter the 3.0 column and read down to the smallest unit flow rating which is greater than or equal to 225 GPM. For the Model JWL35B, interpolate between 245 and 190 GPM to determine the

flow rating at the 3.3 load factor. Interpolation gives a rating of 212 GPM which is less than the design requirement. Select a Model JWL35C and again interpolate between load factor columns to determine flow rating. The second selection provides a flow rating of 245 GPM which exceeds the design requirement. The correct unit size is, therefore, a Model 35C

5.Determine Flow Limitations — Enter Table 3 at unit size determined in Step 4 to select a JWL low flow or JW standard flow unit. The Model 35C with 225 GPM design flow falls within the standard coil flow limitations. The correct unit selection is, therefore, a JW35C.

6.Determine Coil Pressure Drop — Enter the Coil Pressure Drop Table at 225 GPM and read across to the unit model column to select pressure drop reading. In this example, pressure drop equals 4.8 PSI.

ETHYLENE GLYCOL EXAMPLE

Select a unit to cool 75 GPM of 40% by volume ethylene glycol from 107°F to 85°F with 78°F wet bulb.

1. Determine Range:

107°F - 85°F = 22°F Range

2. Determine Approach:

85°F - 78°F = 7°F Approach

3.Select Load Factor — Enter Table 2 for 78°F wet bulb and select load factor at design range and approach. Select 6.0 factor.

4.Select Test Unit Model — Enter the Unit Rating Table 3 at the 6.0 load factor and read down to the smallest unit flow rating greater than or equal to the design 75 GPM. Select the test model JWL35C

5.Correct Flow for Ethylene Glycol — The flow correction factor obtained from Table 1 is 1.04. 75 GPM x 1.04 = 78 GPM

6.Adjust Model Selection — Re-enter Table 3 at the 6.0 load factor and make selection based on corrected flow of 78 GPM. The adjusted unit selection is the Model JWL50A indicating an 80 GPM rating

7.Determine Flow Limitations — Enter Table 3 at unit size determined in Step 6 to select a JWL low flow or JW standard flow unit. The Model 50A with

75 GPM design flow falls within the low flow coil limitations. The correct unit selection is, therefore, a JWL50A.

8.Determine Coil Pressure Drop — For ethylene glycol pressure drop calculation, the conversion factor from Table 5 must be applied to design flow before entering Table 4. 75 GPM x 1.05 = 79 GPM.

The coil pressure drop for 79 GPM is 2.4 PSI

DEFINITIONS

Range: the difference between the entering and leaving water temperatures (WT in – WT out).

Approach: the difference between the leaving water temperature and the web bulb temperature (WT out

– WB).

Load BTUH =

GPM x 500 x Sp. Gr. x Sp. Ht. x (T1 – T2) where Sp. Gr. = specific gravity at average temperature Sp. Ht. = specific heat at average temperature T1 = entering temperature

T2 = leaving temperature