Air-cooled
torque converter oil cooler
This type of torque converter oil
cooler (1) may also be located in front of the radiator (2) and thus cause a
cooling air pressure drop and temperature rise. The ATB reduction depends on
the radiator type and the torque converter cooling requirement.
1 Oil cooler
2 Radiator
3 Condenser
4 Air flow
5 Sucking fan
Cooling air
ducts
When an engine is installed in a
building it is necessary to lead cooling air out of the building to prevent
recirculation. On gen set engines with pusher fans the warm air from the
radiator must be carried in a duct from the front of the radiator to an opening
in the wall. The air outlet opening may have a grille or noise baffles and the
free flow area in the opening must be 25 % greater than the radiator core
surface area. The air inlet opening in the wall must be as large as the outlet
opening. The pressure drop across the inlet, ducts and outlet must be minimized
to achieve the best possible cooling capacity. The pressure drop across these
components may not exceed the external flow limitation for the required cooling
performance. The external flow limitation for each engine is specified in the
Sales Support Tool, Partner Network. Refer to the chapter: Arrangement and
Planning page 14.
Recirculation
Warm air recirculation is a
problem that can significantly impair cooling capacity. It is therefore
necessary to prevent recirculation in all installations. Warm air from the fan
outlet in a sucking fan system tends to recirculate back to the radiator inlet
(or charge air cooler). In a pusher fan system the warm air recirculates from
the radiator outlet to the fan inlet. Recirculation is caused by the air
pressure differential between the front and the back of the fan. Air always
seeks to flow from a higher pressure to a lower pressure. Recirculation occurs
chiefly in covered installations and engine compartments. The installation must
be carried out so that recirculation is prevented, especially in mobile
applications and generator sets in engine compartments. Recirculation can be
prevented on generator sets by installing cooling air ducts and sealing. Refer
to the chapter: Engine Mounting and Engine Room Layout page 30. All surfaces
where air can recirculate must be thoroughly sealed on mobile applications. The
ATB value may be reduced by 3–5 °C (37.4–41 °F) through improved circulation.
Cooling Air
System
The function of the cooling air
system is to cool and carry heat away from the radiator (and air-to-air type
charge air cooler). The fan causes a pressure increase that forces cooling air
through the radiator and other components.
There is a pressure drop across
each component in the system, and the total system pressure drop must be
minimized to achieve the best possible cooling capacity. Cooling air may even
be heated by components in the air flow, such as the generator, and this
impairs system cooling capacity.
The cooling air system comprises
the following components:
• Fan
• Fan ring
• Fan guard
• Radiator
• Charge air cooler (TAD engines)
The system can be extended with
extra components:
• Air
conditioning condenser
• Air-cooled
torque converter oil cooler
• Grille and
cooling air ducting
Cooling air
Cooling air temperature can vary
greatly and may also contain different kinds of dust, moisture and oil mists.
Ambient temperature, and the temperature of the air that enters the radiator
(or charge air cooler) are often different, as the air may be heated by various
components before it reaches the radiator. The amount and type of dust in the
air is an important factor in selecting the type of radiator. If a system using
a pusher fan is used, crankcase blow-by gases may give rise to an oil coating
on the radiator and charge air cooler cores (especially gases from crank case
ventilation). Dust particles in the air stick more easily to the oil, and this
reduces heat transfer. Methods of reducing this effect are to use a closed
crank case ventilation system or to lead crank case gases away from the cooling
air flow (separate pipe outside the room). Refer to the Engine Mounting and
Engine Room Layout page 30 chapter.
Pressure
drop
Pressure drop across the cooling
system depends on the pressure drop across all the system components, both
upstream and downstream of the fan.
The following components affect
total pressure drop:
• Engine Room
• Fan guard
• Fan
location
• Charge air
cooler, air-to-air type
• Radiator
• Radiator
guard
• Air
conditioning condenser
• Air-cooled
oil cooler
• Air ducting
• Radiator
grille, noise insulation
Cooling air airflow must have as
few obstacles as possible to minimize pressure drop. Total system pressure drop
must be minimized to ensure good cooling capacity. It is not always correct to
calculate total pressure drop by adding together component pressure drops, as
the components themselves influence each other's air flow conditions. External
flow limitations for different AOT temperatures are specified in the Sales
Support Tool, Partner Network. Pressure drop from accessory components outside
engines using the standard Volvo Penta cooling assembly may not exceed the
external flow limitation, as cooling capacity may be affected.
Engine
Heater
There are different types of
electrical engine block heaters available for 220–240V AC.
Engine heater installed in engine
block It is only designed for intermittent use. Remove the engine thermostat
before using the heater. The heater is designed to be used with a timer, and to
be switched on for shorter periods, maximum 3 hours per occasion. The heater
can be installed in one of the plugs on the left side of the engine block.
Separately
installed engine heater
This heater is especially
suitable for continuous heating for e.g. standby gen set engines. Heater output
must be adapted to the specific coolant quantity depending on engine size and
ambient temperature. The heater must be installed separately in a protected location,
but at the same time the shortest possible connection hoses must be used. The
heater may be installed as illustrated in figure 3, adjacent. For more details
in heater options, refer to Sales Support Tool, Partner Network. Contact Volvo Penta regarding engines running in extremely low temperatures, < -20 °C (-4
°F).
Cab Heater
Cab heaters use engine coolant to
heat the cab via a heat exchanger. Cab heaters must be dimensioned so that they
do not take too much heat from the coolant. If this occurs, the engine will not
reach the correct operating temperature and engine wear will increase. Pipes
and hoses must be of a diameter sufficient to provide correct circulation. The
system must be fitted with a drain tap at its lowest point, and a venting
nipple at its highest point. If the heater matrix is located higher than the
engine, the expansion tank must be located higher than the heater matrix.
Heater hoses and pipes must be connected to the engine according to the
dimensional drawing for the engine concerned. Refer to Sales Support Tool,
Partner Network.
Torque Convertor
Oil Cooler
If a torque converter is
connected to the engine (mobile applications), heat from the converter can be
cooled by cooling water or cooling air. If cooling water is used, a torque
converter oil cooler must be installed in the engine cooling water system. The
oil cooler (1) can be connected between the radiator and the water pump inlet.
The cooling system (especially the radiator) must be dimensioned to withstand
the extreme heat that is generated by the torque converter. Pressure losses from
the oil cooler, coolant pipes and hoses must be kept to a minimum. The shortest
possible pipes and hoses must be used for coolant. It is better to use longer
pipes for the oil. A narrow pipe or hose (2) with an internal diameter of max.
10 mm (0.4") must be connected between the oil cooler and the engine
block. This is done to safeguard coolant supply to the oil cooler when the
engine thermostat is closed.
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