How to Arrange Diesel Engine Room
Forced ventilation - 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.
For more:
Comments
Post a Comment