Man V12-1800 Installation Instructions Manual Download

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Engine room ventilation

Heating of the engine room

During  operation,  each  engine  transfers  heat  from  its  own  hot  surfaces  into  the  air  in  the  engine  room
(convection),  in  a  similar  fashion  to  a  radiator  heating  a  room  in  a  building.  In  addition,  but  to  a  much  lesser
extent,  radiated  heat  dissipates  to  the  surroundings  (radiant  heat).
Both  of  these  effects  can  heat  up  the  engine  room  to  such  an  extent,  that  temperature−sensitive
components  (e.g.  the  electronics)  can  malfunction.

Temperature in the engine room

Caution:

The  following  equation  provides  a  good  rule  of  thumb  for  adequate  engine  room  ventilation:
Engine  room  temperature  =  Ambient  temperature  +  15°C  (max.  20°C)
Measured  at  the  front  and  back  of  the  engine  room  and  at  the  air  filters.
The  max.  permissible  engine  room  temperature  is  60

The temperature in the engine room is essentially dependent on the following boundary conditions:

Outside air temperature

The  outside  air  temperature  depends  on  the  climate  in  the  area  of  operation  of  the  ship  and  the  prevailing
weather  conditions.  In  the  Mediterranean  Sea  area  air  temperatures  of  up  to  40°C  are  to  be  expected  and
in  the  Persian  Golf  up  to  50°C  can  be  reached.

Engine operating conditions

1) Maximum speed / cruising speed of the ship

Naturally,  at  full−load  and  high  power  outputs,  the  temperature  of  critical  components  (charge  air  pipes,
compressor  housing,  exhaust  manifold)  is  at  its  highest  and  thus  the  heat  output  is  at  a  maximum.
However,  this  effect  is  compensated  by  the  high  combustion  air  requirement  of  the  engines  and  that  of
the  associated  high  rate  of  air  exchange  in  the  engine  room.
Example:  Two  engines  V12  −  1800  at  2300  rpm  and  full  load  with  2  x  6300  m

/h demand for combustion

air, corresponding to 3.5 m

/s. A typical engine room air volume of 50 m

is thus replaced every 15

seconds. With adequately dimensioned air inlets and outlets the engine room temperature may not vary
significantly from that of the outside air.

2) Reduction of the maximum speed to crawling speed (e.g. to negotiate canals, waterways with speed

restrictions)

At  low  speeds  and  loads,  the  combustion  air  demand  of  the  engines  and  thus  the  inflow  of  fresh  air  into
the  engine  room  is  very  significantly  reduced.
Example:  Two  engines  V12  −  1800  with  2  x  750  m

/h combustion air requirement, corresponding to

0.20 m

/s at 1000 rpm and operation on the propellor curve.

The  volume  of  air  in  the  engine  room  is  no  longer  replaced  fast  enough  by  external  air  flowing  through
and  can  therefore  quickly  heat  up.  In  addition,  the  hot  engine  components  that  were  under  full  load
(charge  air  pipes,  crankcase,  oil  pan)  give  up  additional  heat  in  the  engine  room.
In  this  operating  phase  it  is  thus  necessary  to  provide  forced  air  ventilation  by  means  of  fans.