Thermal Transfer Systems AOC Series - Manual (Page 3)

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[email protected] 262.554.8330 www.thermaltransfer.com
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OIL FLOW - G.P.M.
HORSEPOWER REMOVED IN COOLER
AOC-19
AOC-22
AOC-24
AOC-33
AOC-37
AOC-50
AOC-54
AOC-57
AOC-70
Oil ▲P
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= 5 PSI
■ = 10 PSI
▲ = 20 PSI
✛ = 40 PSI
50 60 80 100 150 300 400 500
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OIL
 P MULTIPLIER
OIL VISCOSITY - SSU
OIL

P CORRECTION CURVE
Performance Curves
Selection Procedure
Performance Curves are based on 50SSU oil leaving the cooler 40°F higher
than the ambient air temperature used for cooling.This is also referred to as
a 40°F approach temperature.
STEP 1 Determine the Heat Load.This will vary with different systems,
but typically coolers are sized to remove 25 to 50% of the input
nameplate horsepower.
(Example: 100 HP Power Unit x .33 = 33 HP Heat load.)
If BTU/Hr. is known: HP = BTU/Hr
2545
STEP 2 Determine Approach Temperature. Desired oil leaving cooler
°F – Ambient air temp. °F = Actual Approach
STEP 3 Determine Curve Horsepower Heat Load. Enter the
information from above:
Horsepower heat load x 40 x Cv = Curve Horsepower
Actual Approach
STEP 4 Enter curves at oil flow through cooler and curve horsepower.
Any curve above the intersecting point will work.
STEP 5 Determine Oil Pressure Drop from Curves:
l
= 5 PSI; n = 10 PSI; s = 20 PSI; ; = 40 PSI. Multiply
pressure drop from curve by correction factor found in oil P
correction curve.
Desired Reservoir Temperature
Return Line Cooling: Desired temperature is the oil temperature leaving the
cooler. This will be the same temperature that will be found in the reservoir.
Off-Line Recirculation Cooling Loop: Desired temperature is the oil tem-
perature entering the cooler. In this case, the oil temperature change must be
determined so that the actual oil leaving temperature can be found.
Calculate the oil temperature change (oil T) with this formula:
Oil T = (BTU’s/Hr.) / (GPM Oil Flow x 210).
To calculate the oil leaving temperature from the cooler, use this formula:
Oil Leaving Temp. = Oil Entering Temp – Oil T.
This formula may also be used in any application where the only temperature
available is the entering oil temperature.
Oil Pressure Drop: Most systems can tolerate a pressure drop through the
heat exchanger of 20 to 30 PSI. Excessive pressure drop should be avoided.
Care should be taken to limit pressure drop to 5 PSI or less for case drain
applications where high back pressure may damage the pump shaft seals.
Oil Temperature
Typical operating temperature ranges are:
Hydraulic Motor Oil 110° - 130°F
Hydrostatic Drive Oil 130° - 180°F
Bearing Lube Oil 120° - 160°F
Lube Oil Circuits 110° - 130°F
De-rate cooler performance by 10%
when used in 50Hz service.
50 100 0 0 2 0 0 3 500
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OIL
P MULTIPLIER
OIL VISCOSITY - SSU
OIL P CORRECTION CURVE
400