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on heavy fuel, but strongly recommended also for engines that operate exclusively on marine
diesel fuel.
The energy required for preheating of the HT cooling water can be supplied by a separate
source or by a running engine, often a combination of both. In all cases a separate circulating
pump must be used. It is common to use the heat from running auxiliary engines for preheating
of main engines. In installations with several main engines the capacity of the separate heat
source can be dimensioned for preheating of two engines, provided that this is acceptable
for the operation of the ship. If the cooling water circuits are separated from each other, the
energy is transferred over a heat exchanger.
Heater (4E05)
The energy source of the heater can be electric power, steam or thermal oil.
It is recommended to heat the HT water to a temperature near the normal operating
temperature. The heating power determines the required time to heat up the engine from cold
condition.
The minimum required heating power is 12 kW/cyl, which makes it possible to warm up the
engine from 20 ºC to 60...70 ºC in 10-15 hours. The required heating power for shorter heating
time can be estimated with the formula below. About 6 kW/cyl is required to keep a hot engine
warm.
Design data:
min. 60°C
Preheating temperature
12 kW/cyl
Required heating power
6 kW/cyl
Heating power to keep hot engine warm
Required heating power to heat up the engine, see formula below:
where:
Preheater output [kW]
P =
Preheating temperature = 60...70 °C
T
1
=
Ambient temperature [°C]
T
0 =
Engine weight [ton]
m
eng
=
HT water volume [m
3
]
V
FW
=
Preheating time [h]
t =
Engine specific coefficient = 3 kW
k
eng
=
Number of cylinders
n
cyl
=
P < 10 kW/cyl
The formula above should not be used for
Circulation pump for preheater (4P04)
Design data:
1.6 m
3
/h per cylinder
Capacity
80...100 kPa (0.8...1.0 bar)
Delivery pressure
Preheating unit (4N01)
A complete preheating unit can be supplied. The unit comprises:
9-20
Wärtsilä 50DF Product Guide - a16 - 9 September 2016
Wärtsilä 50DF Product Guide
9. Cooling Water System
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