Volvo Power Generator Engine Forced Ventilation
by Starlight Generator dieselgeneratortechForced
ventilation – Volvo Penta engine compartment
When a remote radiator is
installed, consideration must be given to engine compartment ventilation. First
of all, the exhaust system in the engine compartment must be efficiently
insulated so that heat radiation is minimal. NOTICE! Because of the risk for
overheating the exhaust manifold and turbocharger may not be insulated, only
the exhaust pipe and silencer. The best forced ventilation systems normally
comprise two electrically-driven fans. One fan forces air into the compartment
and is installed on the wall directly opposite the generator end. The other fan
extracts air hot air from the engine compartment. This fan must be installed on
the wall next to and above the engine. An air duct is required on the inlet
side if the cooling air does not reach the generator/engine. The ducting leads
air to the generator and over the engine to the extraction fan. If no air
ducting is installed when the inlet fan is located high up, inlet cooling air
will pass by the generator set and be drawn out by the extraction fan without
cooling the engine. If there is space in the right place for a large air inlet
opening, no fan is required to force air into the compartment. The extraction
fan must have sufficient extraction capacity to overcome the air resistance
through the inlet and outlet grilles and air ducts, if such are installed.
If an extraction fan is used and
combustion air is drawn from the engine compartment, negative pressure may
occur. Engine compartment negative pressure can be checked using a plastic,
water-filled Ushaped hose. One end is connected to the engine compartment and
the other is exposed to atmospheric pressure (outside the engine compartment).
Allow the engine to run at full throttle for at least 5 minutes in order to
build up a characteristic low pressure in the compartment. Then measure the
pressure difference equivalent to the water's surface differences in mm water
column. The pressure difference must not exceed 10 mm (0.4") (0.8 mm Hg or
1 millibar). A low pressure of 20 mm (0.8") water gauge is acceptable on
engines with remote radiators and without a fan. Crankcase breather Gases from
the engine crank case must be led away from the engine compartment via a
separate duct. The crankcase ventilation pipe may be extended to lead crankcase
gases out of the engine compartment. This is especially important when the
engine has an pusher fan, as the crank case gases would otherwise coat the
radiator which would become dirty and clogged, thus reducing cooling capacity.
Note; where there is a risk of freezing (ice plugs) this pipe must be heated or
insulated.
WARNING
Only start the engine in a
well-ventilated area. If operating the engine in a closed area ensure that
there is exhaust ventilation leading out of the work area to remove exhaust
gases and crankcase ventilation emissions.
NOTICE! Some engines are equipped
with closed crankcase ventilation that does not require additional ventilation.
Calculating required engine
compartment ventilation When calculating engine compartment ventilation,
consideration must be given to the following important factors:
• Max engine
compartment air temperature is 60 °C (140 °F), given that combustion air is
drawn from outside the engine compartment.
• The entire
exhaust system and silencer in the engine compartment should preferably be
insulated.
• The exhaust
manifold and turbocharger may not be insulated.
• Max input
air for the radiator cooling system. Refer to Sales Support Tool, Partner
Network.
The large volume of air moved by
an engine-mounted cooling fan is usually sufficient to ventilate the engine
compartment. When a remote radiator or water-cooled heat exchanger is
installed, consideration must be given to engine compartment ventilation. The
volume of air required to provide a given temperature increase in the engine
compartment can be calculated as follows:
Total heat
transfer to air
Airflow requirement =––––––––– +
Required combustion air
Air density
x Tincrease x Constant
Total heat transfer to air: Heat
transfer from engine + generator and other heat-emitting equipment in the
engine compartment( kW).
Air density: Air density at
different temperatures shown in the table below in kg/m3. Tincrease: Max. air
temperature increase in the engine compartment, above ambient temperature.
Constant: = 0.0167
Required combustion air: Engine
air consumption in m3/min according to data in the Sales Support Tool,
Partner Network.
Air density
°C 0 5 10 15
20 25 30 35 40 45 50 55
kg/m3 1.30 1.27 1.25 1.22 1.20
1.19 1.17 1.16 1.14 1.12 1.09 1.08
A Microsoft Excel application for
calculating both engine compartment ventilation and exhaust system back
pressure is available from AB Volvo Penta, Sales Engineering Industrial.
Multi-engine installations In
general, the same installation instructions apply to multi-engine installations
as for single installations, and each unit must have its own engine bed and
exhaust system.
IMPORTANT!
Exhaust gases from multi-engine
installations may not be led together in a common system, as this can be very
dangerous and cause engine damage. If the exhaust system in a multi-engine
installation must be led together in a combined exhaust system, each engine
must be equipped with a separate exhaust shut-off valve, so that exhaust gases
are not able to enter an engine that may not be running. Also refer to
“Multiple exhaust outlets” in the chapter Exhaust System page 75.
Engine
Mountings for Stationary and Semi-mobile Installation
Frame-mounted
engines
The simplest mounting method is
to bolt the engine and driven unit directly to the frame. It is necessary for
the engine and driven component mounting inserts on the frame to be flat,
square and parallel to one another. The frame must be designed so that the
mounting inserts cannot be twisted in any way. The quality of the installation
is greatly affected by the appearance of the frame. Vibration levels from the
engine and its components can be influenced by changing the design of the
frame. Engine bed types.
The engine support/bed to which
the frame is attached is of great importance as it must be able to:
• support the
units' static weight and dynamic loads from balance forces in the engine.
• be
sufficiently stiff and stable so as not to distort and thereby affect engine
and driven unit alignment。
• absorb
vibrations from driven units and prevent vibrations from being propagated to
the engine bed and walls. Refer to the chapter about noise and sound dampening.
The engine must be aligned to the
driven unit within specific recommendations with the aid of shims between the
engine, the driven unit's attachment devices and the frame. The dimension of
the shims (or packing) must not be less than the mating surface between the
engine and driven unit's mounting devices. At least two bolts must be used in
both the engine and driven unit mounting devices.
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Created on Jul 24th 2018 04:03. Viewed 320 times.