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oil/air- coolerfluid/air - cooler

[[OOLLKK..]]standard-range

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General Description

Combinations

The type OLK oil cooler series is designed for re-cooling oil in hydraulic, lubricating and cooling oilcircuits by means of air. Eight different sizes areavailable with a cooling capacity of up to approx80kW (Dte = 40°C). Fan drive and speed arevariable, meaning that the oil coolers can beadapted to the official noise-level specificationsapplicable at the site.

Function

The oil is passed through the oil cooler, part of itsheat thus being absorbed by the air flow. The oilcan be cooled to 5°C above ambient temperaturedifference is not practical for economic reason.

Special version

The air direction and sense of rotation of the fanare altered for air temperatures above 40°C.Should this measure be inadequate, a 3-phasemotor of Insulation material class F is installed.If an auxiliary drive is used, the fans can beoperated at a maximum tip speed of approx.70m/s and a maximum air temperature of 70°C. Ifthese values are higher, a different fan type isused.

Operating version

Maximum oil inlet temperature:Te1 = 120°C

Maximum static working pressure (DIN 50104):pmax = 16 bar

A special version can be supplied for otheroperating conditions.

The standard version of the 3-phase motors areapproved for air temperatures of 40°C and sitealtitudes of 1000m above sea level rated output.

The modular design principle allows a combination of typeOLK oil coolers for greater thermal outputs.

Figure 1

Series connection Parallel connectionFigure 2

Advantages of the concept SLB

compact constructionpowerfullow weightlow noisemaintenance-freecombinable by module SLB technologyvariable in the drivecheap

universal connection possibilities

the same class also with copper block to thecooling of water available (Pmax= 4,0 bar)

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Order DataOrder Number Type OLK

OLK 6 W 4 D

Type:OLK = oil/air - coolerWLK = water/air - cooler

Cooler size:Watch data sheet

Connection type: W = Angle connection with internal thread F = SAE- Flange connection with internal thread

Drive: D = 3-phase motor G = DC motor H = Hydraulic motor K = V-belt W = AC motor OM = without drive (only cooler block)

Fan speed:2 = 2-polig = 3000 rpm4 = 4-polig = 1500 rpm6 = 6-polig = 1000 rpm

8 = 8-polig = 750 rpm

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Specific thermal outputs as a function of oil throughput(cooling system with D, H, K, W fan drive)

Diagram 1(true for the material pair Oil SAE 30, DIN 51511 (teOil =60°C) and dry air (teL = 20°C))

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Specific thermal outputs as a function of air throughput(cooler with DC fan)

Diagram 1A(true fort he material pair Oil SAE 30, DIN 51511 (teOil = 60°C) and dry air (teL= 20°C))

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Oil-side pressure loss, correction curves

Diagram 2 Oil-side pressure loss Dp1 [kN/m²] as a function of oil

throughput G1 [kg/s].(true for the Oil SAE 30, DIN 51511 tm1 = 60°C (kinematicviscosity ca. 45 · 10-6 m2/s))

Diagram 3 Correction factor as a function of the mean

temperature tm1 [°C]. (true for the Oil SAE 30, DIN 51511)

Diagram 4Correction factor as a function of the kinematicviscosity g x 10-6 [m²/s].

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Data sheetComplete Cooler Type OLK-W & OLK-F with AC motor

BG A A2 B1 C DØ fan

E Fangle

G Hangle

HFlange

J1 Öil.Liter

port weightkg

OLK 1 180 380 315 359 255 395 405 270 460 355 68 3,0 G 1 27OLK 2 245 445 315 359 280 395 405 270 460 355 68 3,5 G 1 30OLK 3 315 515 348 392 315 428 438 270 493 387 68 4,5 G 1 36OLK 4 365 565 412 456 355 492 502 270 557 452 68 6,0 G 1 44OLK 5 480 710 444 488 400 524 554 320 624 514 75 8,5 G 1½ 56OLK 6 530 760 540 584 500 620 650 320 720 609 75 11,0 G 1½ 65OLK 7 615 845 653 697 600 733 763 320 833 723 75 14,5 G 1½ 82OLK 8 775 1005 717 761 680 797 827 320 897 786 75 18,5 G 1½ 100

750 rpm 1000 rpm 1500 rpm 3000 rpmBG N

mmPkW

LdB (A)

GKg/s

Nmm

PkW

L dB(A)

GKg/s

Nmm

PkW

LdB(A)

GKg/s

Nmm

PkW

LdB(A)

GKg/s

OLK1 448 0,10 50 0,058 432 0,09 57 0,09 448 0,18 77 0,18OLK 2 448 0,10 52 1,105 432 0,09 58 0,16 448 0,25 79 0,32OLK 3 448 0,10 54 0,15 432 0,09 61 0,225 466 0,37 82 0,4OLK 4 448 0,10 55 0,23 432 0,09 63 0,35 492 0,75 86 0,7OLK 5 493 0,10 64 0,37 493 0,12 70 0,55 537 1,1 89 0,1OLK 6 511 0,09 61 0,54 511 0,18 68 0,72 537 0,55 79 1,08OLK 7 537 0,125 67 0,95 537 0,37 74 1,27 553 1,1 86 1,9

max. pressure DIN 50104,16 bar

max. oiltemperature120 °C

TYPE W

TYPE F

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Data sheetComplete Cooler Type OLK-W & OLK-F with DC motor

BG A A2 B1 C DØ fan

E Fangle

G Hangle

Hflange

J1 OilLiter

port weightkg

OLK 1 180 380 315 359 190 395 405 270 460 355 68 3,0 G 1 22OLK 2 245 445 315 359 190 395 405 270 460 355 68 3,5 G 1 24OLK 3 315 515 348 392 280 428 438 270 493 387 68 4,5 G 1 29OLK 4 365 565 412 456 280 492 502 270 557 452 68 6,0 G 1 33OLK 5 480 710 444 488 366 524 554 320 624 514 75 8,5 G 1½ 46

BG 12VJ (A)

24VJ (A)

LDb (A)

speedU/min

OLK 1 5,3 2,6 76 3000OLK 2 5,3 2,6 76 3000OLK 3 9,0 3,8 79 3000OLK 4 9,0 3,8 79 3000OLK 5 16,5 8,4 87 3000

More possible drives

Hydraulic gear motorWith and without leakage oilconnection

V-beltDIN 2211, profile SPA 12,5

Determination of the quantity of heat to be dissipated

max. pressure DIN 50104,16 bar

max. oiltemperature120 °C

TYPE W

TYPE F

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Introduction

Losses (e.g. fluid friction and bearing friction) resultin heating of the oil and of all system components inany hydraulic system. The oil temperature tcontinues to rise until the quantity of heat input (Qv)is equal to the quantity of heat dissipated by freeconvection and radiation (Qk).If the steady-state temperature occurring afterlengthy period of operation is no longer permissible,the oil must be cooled.Figure 3 shows the oil temperature as a function oftime in a circuit with and without a cooler.

Figure 3Determination of the heat loss from the temperatureincrease

In existing systems, the quantity of heat to bedissipated can be calculated with sufficient accuracyfrom the temperature increase in the system.The oil temperature curve as a function of operatingtime is determined in accordance with Fig. 4; thetemperature increase Dto occurring ion a fixed periodof time DT before and after the desired operatingtemperature can be taken from the curve. This valuecan be used to determine the quantity of heat whichmust be removed from the oil circuit by means of acooler in order to maintain the desired operatingtemperature of the oil at a constant level.

Figure 4

Calculation example

Oil contents: G0 = 260 kgPermissible oil operatingTemperature: t0 = 50 °C (= 323 K)Temperature differencein test period DT: Dt0 = 20 °C (= 20 K)Specific thermal capacity: cÖl = 2000 Ws/kg KTest duration: DT = 1 h

Quantity of heat to be dissipated:

Designations:

Q [W] = Quantity of heat to be dissipatedQV [W] = Heat loss occurring in the systemQK [W] = Quantity of heat dissipated by

convection an radiation G0 [kg] = Oil contents of circuit

toil [°C] = Permissible oil operating temp.coil [Ws/kg K] = Specific thermal capacity of the oilT[h] = Operating timeG1 [kg/s] = Oil throughputG2 [kg/s] = Air throughputte2 [°C] = Air inlet temperaturete1 [°C] =Oil inlet temperatureDte [°C] =Inlet temperature difference

(Oil inlet temperature Air inlet temperature)G0 · c

Öl · Dt

0

3600 · DT260 · 2000 · 20

3600 · 1 »2900W

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Example to destinate the cooler sizeSelection of the type OLK oil cooler

The following data are required for selection of theoil cooler size:

Quantity of heat to be dissipated: Q [W]Oil throughput: G1 [kg/s]Specific thermal capacity: c1 [Ws/kg K]Oil inlet temperature: te1 [°C]Air inlet temperature: te2 [°C]

Formula

Quantity of heat to be dissipated:

Q [W] = G1 · c1 (te1 - ta1) (ta1 = Ölaustrittstemperatur [°C])

First calculate the inlet temperature difference Dte:

Dte = (te1 - te2)

And use this to obtain the ratio

Q/Dte [W/K]

Which is plotted as the specific thermal output onthe vertical axis in the diagrams. The calculationmethod is explained on the basis of two examples..

Calculation example 1:

Given:Thermal output: Q = 11200 WOil throughput: G1 = 1,0 kg/sOil grade: ISO VG 46Specific thermal capacity: c1 = 1996 Ws/kg KOil inlet temperature: te1 = 50 °CAir inlet temperature: te2 = 20 °CPermissible noise level: L = 61 dB (A)Drive: 3-phase motor

Inlet temperature difference:

Dte = te1 - te2 = 50 - 20 = 30 °C (= 30 K)

Specific thermal output:

Q/Dte = 11200/30 = 373 W/K

To allow for contamination, it is advisable to add a10% safety margin, this making the specific thermalcapacity:

Q/Dte = 373 · 1,1 = 410 W/K

With the calculated value of Q/Dte = 410 W/K fort hespecific thermal output and the given oil throughputof G1 = 1,0 kg/s, Diagram No.1 has to be consulted(see Diagram No. 1A foc coolers with DC blower).The oil/air cooler OLK4-2D, OLK6-8D and OLK5-4Dare found in the vicinity of the intersection of the twodefinition lines.Therefore, three different sizes are available to solvethe task at hand. They only differ as regards theirsize, noise level and pressure loss on the oil side.

Calculation example 2: Determination of the oil-side pressure loss

According to Diagram No.3, an oil throughput ofG1 = 1,0 kg/s and a mean temperature of tm1 = 60 °Cresults in a pressure loss of Dp1 = 77 kN/m².

The mean oil temperature fort the ISO VG 46 oil inthe calculation example is:

tm1 = 0,5 (te1 + ta1) = 0,5 (50 °C + 44 °C) = 47 °C (= 320 K)

As this temperature, the kinematic viscosity is

g = 20 cst (mm²/s)

However, since oil grade SAE10W is used incalculation example 2, Dp1 must be corrected withthe correction factors fT und fV as a function of themean temperature and the kinematic viscosity.Using this information, the correction factors fT = 1,7and fV = 0,6 are taken from Diagram Nos. 3 & 4.

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This results in an effective pressure loss of

Dp1 eff = p1 · fT · fV (kN/m2) = 77 · 1,7 · 0,6 » 78 kN/m2.

The addition of a 5% contamination surcharge yields

Dp1 eff » 83 kN/m2

It is thus possible to select suitable oil cooler size.type OLK6*-8D is selected for noise reasons.

Calculating of oil cooling

The cooling of the oil is calculated in accordancewith the following equation:

Q = G1 · c1 (te1 - ta1) [W]

te1 - ta1 = = » 6 K (= 6 °C)

The specific thermal capacity fort the ISO VG 46 oilis c1 = 1996 Ws/kg K. If no precise values areavailable from the oil manufacturer, a mean value ofc1 = 2000 Ws/kg K can be used in the calculations.

Calculating of air heating

The heating of the air is calculated in accordancewith the following equation:

Q = G2 · c2 (ta2 - te2) [W]

ta2 - te2 = = = 21 K

The specific thermal capacity of dry air is c2 = 1000 Ws/kg K. The air throughput

G2 = 0,54 kg/s for type OLK6-8D is taken from thedata sheet on page 5.

Conversion of units:

0 °C = 273 K 1 kcal/h = 1,16 kW 1 bar = 100 kN/m² 1 mm WS = 9,81 N/m² 1 cSt = 10-6 m²/s

Noise emission

Q(G1 · c1)

11200(1,0 · 1996)

Q(G2 · c2)

11200(0,54 · 1000)

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Sound levels

The fan noise can only be stated accurately wheninstalled under the prevailing local conditions, sincethe room acoustics, duct connections, naturalfrequencies, reflection, etc., influence the sound level.The variations can be in the region of ± 4 dB (A) (DIN45632 section 9).

Volume increase by several noise source

If several cooling aggregates run at the same time, thewhole noise level increases. In case of thisconsideration it plays an essential role whether thenoise source have the same or different single levels.

Increase in noise level with several identicalcooling units

Number of noise sources 2 3 4 Noise increase in dB(A) 3 5 6

5 10 15

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2

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Zunahme des Pegels[dB(A)]

Pegeldifferenz[dB(A)]

Diagram 5 Variation in the sound level dB(A) as a function of the

level difference of two noise sources.

Calculation example 3:

Calculation of the sound level increase of twonoise sources with different sound levels:

given:

Oil/air cooler type OLK6W-8D L = 61 dB(A)Oil/air cooler type OLK7W-8D L = 67 dB(A)

Level difference:

67 - 61 = 6 dB (A)

Diagram No.5 shows that this difference results ina level increase of approx. 1dB(A). As a result, theoverall level increase:

Leff = 67 + 1 = 68 dB(A)

1,0 1,5 2 3 4 5 6 8 10 20 40 60 80 100

0

10

20

30

Entfernung von der Schallquelle[m]

Änderung der Lautstärke[dB(A)]

Diagram 8 Variation in sound level dB(A) as a function of

distance.