DESIGN IV MACHINERY

DEPARTMENT OF MARINE
ENGINEERING

CALCULATION AND
SPESIFICATION OF ENGINE
COOLING SYSTEM
Doc.No. 08 - 42 19 MA029- CO

Prepared by Approved by
Rev. Date Remark Muzami Thahir Dr. I Made Ariana S.T.,
M.T.
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I. INTRODUCTION
Cooling system is a system that consist of some components which is
used as cooling for main engine and auxiliary engine. In this design, its concern
how to design the appropriate engine cooling system from the requirement of the
needed equipments by Product Guide from engine manufacturer MAN B&W
L27/38.

II. OBJECTIVES
1. Understand the CO system for the engine.
2. Calculate and determine pump and pipe for CO system
3. Choosing the pipe and pump which match to the calculation above.
4. Drawing the cooling system for engine.

III. REFERENCES
1. NK Class
2. Project Guide MAN B&W L27 38
3. Japanese Industrial Standards (JIS) G3455 2004 Carbon Steel Pipes for
Ordinary Piping.

IV. LIST OF ABBREVATIONS

N Symbo
Definition
o l
1 Lpp Length between perpendiculars
2 B Breadht of ship
3 H Height of ship
4 T Draught of ship
5 Q Minimum capacity of pump
6 A Pipe Area
7 V Velocity of water in pipe
8 hs Head static of bilge pump
9 hp Head of pressure difference
10 hv Head of velocity difference
11 Rn Reynould number
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12 u kinematic viscocity
13 λ Friction loss coefficient
14 L Length of pipe
15 D Diameter of pipe
16 HTOTAL Total head

V. SYSTEM DESCRIPTION
The engine is designed for freshwater cooling only. Therefore the cooling water
system has to be arranged as a centralised or closed cooling water system. All
recommendable types are described in the following.
The engine design is almost pipeless, i.e. the water flows through internal cavities inside
the front-end box and the cylinder units. The front-end box contains all large pipe
connections. On the aft-end, the water to the gear oil cooler has to be connected by the
yard.
The engine is equipped with built-on freshwater pumps for both the high
and low temperature cooling water systems. To facilitate automatic start-up of
stand-by pumps, non-return valves are standard. Thermostatic valve elements,
which control the high and low temperature cooling water system, are also
integrated parts of the front-end box. In case the HT cooler as alternative is a part
of the LT cooling water system the LT thermostatic valves are to be replaced by
“dummies” inside the front-end box and an external thermostatic valve housing is
required to be placed in the LT circuit just after the HT freshwater cooler.
The engine is equipped with a two stage charge air cooler. The first stage
is placed in the high temperature cooling water system. The charging air
temperature after the turbocharger is at its maximum, making a higher degree of
heat recovery possible, when the heat is dissipated to the high temperature cooling
water. The second stage of the charge air cooler is placed in the low temperature
system. It will cool the charging air further down before entering the combustion
chamber.
For special applications i.e. sailing in arctic waters with low air
temperatures and direct air intake from deck, a regulating system can be applied to
control the water flow to the second stage of the charge air cooler in order to
increase the charging air temperature, at low load.
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VI. DESIGN REQUIREMENTS

No
Key Equipment Reference Parameter Design
.
1 Capacity: Determined by the cooler
manufacturer. Approx 100 - 175% of
Project Guide
fresh water flow in the cooler,
Sea Water Pump MAN B&W
depending on the central cooler.
L27/38
Pressure: 1.8 - 2.0 bar Sea water
temperature: Max 32°C
2 The minimum water level in the
expansion tank should be no less than 6
m above the centre line of the
crankshaft. This will ensure sufficient
Project Guide
suction head to the freshwater pump
Expansion Tank MAN B&W
and reduce the possibility of cavitation,
L27/38
as well as local “hot spots” in the
engine.
Volume: Min 10% of water volume,
however, min 100 litres.
3 Preheater Project Guide Preheating temperature MDO engine:
MAN B&W Min 40°C Preheating temperature HFO
L27/38 engine: 60-70°C
The heating power required for
electrical preheating is stated below:
Engine type Heating power 8L27/38 12
kW .
The figures are based on raising the
engine temperature to 40°C (20-60°C)
for a period of 10 hours including the
cooling water contained within the
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engine.
4 Velocity recommendations for
freshwater and sea water pipes:
Project Guide
Velocity FW and Freshwater: Suction pipe: 2.0 - 2.5 m/s
MAN B&W
SW Delivery pipe: 2.0 - 2.5 m/s
L27/38
Sea water: Suction pipe: 1.0 - 1.5 m/s
Delivery pipe: 1.5 - 2.5 m/s

Table 1.1. Design Requirements

VII. SUMMARY OF CALCULATION

SYMBO RESUL
NO CALCULATION   L T  
1 Q Sea Water Pump   Q 0.03 m3/s
2 Preheater Unit   V 12.99 m3

Pipe selection according to JIS G3452    

Inside diameter (dm) = 154.2 mm
Thickness = 5.5 mm
Outside diameter = 165.2 mm
Nominal
size   = 150A  

Sea Water Pump : Ma nufa cture : Desmi Pump

Type : Centrifuga l Pump SLV 1 2 5 -2 6 5
RPM : 1 4 5 0 rpm
3
Ca pa city : 160 m / h
Hea d : 20 m
Power : 1 4 .3 kw
MaFrequency
nufa cture : Desmi
5 0 Pump
Hz
Type : Centrifuga l Pump SLV 1 2 5 -2 1 5
Fresh Water Pump :
RPM : 1 4 5 0 rpm
3
Ca pa city : 150 m /h
Hea d : 15 m
Power : 6 .8 kw
Frequency : 50 Hz
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VIII. DETAIL OF CALCULATION

a. Calculation of the Fresh Water Cooling Pump Capacity
The engine is designed for freshwater cooling only. Therefore the cooling water
system has to be arranged as a centralised or closed cooling water system. All

Q = qLT + ((3,6 x Φ) /(4,15 x (Tout-Tin))

Where, (based on project guide)
Q = total fresh water flow m3/h
qLT = nominal of LT pump capacity 70 m3/h
Φ = heat dissipated to HT water 804 kW
T out = HT water temperature after engine 79 °C
T in = HT water temperature after cooler 38 °C

Q = 87.011 m3/h
= 0.024 m3/s
The diameter can be calculated by,
velocity of freshwater inside
Q = Axv pipe
= 1/4 x P x D2 x v 2.5 m/s (max)
D = √Q/(1/4 x P x v)
= 0.111 m
= 111 mm
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Specifica tion of selected pipe :

Ga lva nized Ca rbon steel pipes for ordina ry Piping (ga lva nized) by JIS G 3 4 5 4
Inside dia meter (dm) = 1 5 4 .2 mm
thickness (sch 2 0 ) = 5 .5 mm
Outside dia meter = 1 6 5 .2 mm
Nomina l Dia meter = 150A
Ma teria l = Ca rbon Steel Ga lva nized
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2. Head Loss In Discharge Line

Major Losses Discharge Side (hf)

hf = λ x (L / d) x (v^2 / 2g)

Rn = (Dxv)/υ υ= 0,84931 x 10-6

= 385018.4267 = 0.000000849

3. Head Static, Head Pressure, and Head Velocity

Hs = Distance from suction to overboard

= 6.75 m

Hp = Pressure Differene in Suction side and Discharge Side

= 2 bar
= 20 m

Hv = Different flow velocity in suction side and discharge side

= 0 (the velocity is similar)

Hs + Hp + Hv + Total Head
Head Total = Loss
= 29.17 m

So, the pump requirement for the Fresh Water Cooling Pump is,

Capacity = 87.011 m3/h

Head = 29.17 m
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4. Pump Selection

Pump
Brand = Desmi Pump
Pump
Type = SLV 125-215
Capacity = 150 m3/h
Head = 15 m
RP
RPM = 1450 M
Power = 6.8 kW

b. Calculation of the Capacity of Sea Water Circulating Pump

The capacity of the sea water pump is approximately 100 to 175 %
of fresh water flow in the cooler. The value is taken 175% of the
fresh water pump capacity as written below,

Q sw = 1,5 x Q fw
= 130.5 m3/h
Head is approximately 1,8 to 2 bar

Head = 2 bar
= 20.4 bar

Pump
Brand = Desmi Pump
Pump
Type = SLV 125-265
Capacity = 160 m3/h
Head = 20 m
RPM = 1450 RP
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M
Power = 14.3 kW

c. Calculation of the Capacity of Preheater Pump

The capacity of Preheater Pump can be calculated by,
Pressure = 2 bar
= 20.4 m
Heating Power = 12 kW
Preheating Temperature = 12000 watt
= min max
Specific Heat 40 85
Pressure Drop = 4.187 kJ/kgC
= 5 C
Capacity = 57.32 m3/h
Pump Brand = Evergush
Pump Type = XA80/26
Capacity = 63 m3/h
Head = 24 m
RPM = 1450 RPM
Power = 7.5 kW

d. Calculation of Capacity of High Temperature Diameter Pipe Standby Pump

Capacity is based on the fresh water pump, so the data will be,
Capacity = 87.01 m3/h
= 0.024 m3/s
Head = 29.17 m
Temperature = 95 C (max)
Fluid Velocity = 2.5 m/s
A = Q/v
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= 0.0097 m2
A = π x d²/(4 x v)
D = √((4 x A) / 3,14)
= 0.111 m
= 111 mm

Nominal Pipe
5
Size =
Inside Diameter = 139.8 mm
Outside
Diameter = 139.8 mm
Material = Galvanized Pipe
Thickness = 4.5 mm

e. Calculation of Capacity of Low Temperature Diameter Pipe Standby Pump

Capacity is based on the fresh water pump, so the data will be,

Capacity = 87.01 m3/h

= 0.02 m3/s
Head = 29.17 m
Temperature = 95.00 C (max)
Fluid Velocity = 2.50 m/s

Pump Brand = Evergush

Pump Type = XA65/16B
A = Q/ v
Capacity = 89 m3/h
2
Head == 0 .0 1
24.7 m m
A = π x d² / (4 x v)
D = √((4 x A) / 3,14)
= 0 .1 1 1 m
= 111 mm

Nomina l Pipe Size = 5

Inside Dia meter = 1 3 9 .8 mm
Outside Dia meter = 1 3 9 .8 mm
Ma teria l = Ga lva nized Pipe
Thickness = 4 .5 mm
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f. Ca lcula tion of Pre He a te r

P = ሺ் ି் ᇲሻሺெ ௫଴ǡଵସା௏௟௢ ௫଴ǡସ଼ ା௏௪

௙௪ ௫ଵǡଵ଺ሻ
௧
൅ Heating power

P = Preheater output [kW]

o
T1 = Preheating temperature = 60 C
o
T0 = Ambient temperature [° C] = 20 C
m e ng = Engine weight [ton] = 38.7 ton
3 3
VLO = Lubricating oil volume [m ] = 2 m
3 3
VFW = HT water volume [m ] = 0.51 m
t = Preheating time [h] = 10 h
Heating Power = Heating power for engine = 12 kW

P = 39.8784 kW
Preheater Unit
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e . Ca lcula tion of Expa ns ion Ta nk

Sepa ra te expa nsion ta nks for the LT a nd HT system should be insta lled to a ccommoda te
for cha nges of volume due to varying tempera tures a nd possible lea kage in the LT a nd HT
systems. The separa ted HT a nd LT systems fa cilitates trouble shooting. Volume: Min 1 0 %
of wa ter volume, however, min 10 0 litres.
Design da ta :
Volume : min. 10% of the total system volume
3
Total Volume = 1 .1 5 m
Volume = 1 0 % x 1 .1 5
3
= 0 .1 2 m
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f. Calcula tion of Dra in Ta nk

Ba sed on the project guide MAN B&W L2 7 / 38 . It is recommended to collect the cooling
wa ter with a dditives in a dra in ta nk, when the system ha s to be dra ined for ma intena nce
work. A pump should be provided so tha t the cooling wa ter ca n be pumped ba ck into the
system a nd reused. Concerning the wa ter volume in the engine, see cha pter Technica l
da ta . The wa ter volume in the LT circuit of the engine is sma ll.

V dra in ta nk = volume wa ter in engine

= 1 .1 5 m3

IX. SPECIFICATION OF EQUIPMENTS

See attachment of Doc. No. 08 - 42 19 MA029 – CO
X. DRAWING OF SYSTEM
See attachment of Dwg. No. 08 - 42 19 MA029 – CO