Summary of Volvo Cooling System Design
Summary of System Design
The following points must be given extra thorough consideration when designing a cooling system:
• The maximum ambient temperature the engine must operate in.
• Cooling air flow direction, i.e. if a puller or pusher fan is to be used. A pusher fan is recommended for generator sets to avoid generator overheating. On mobile applications, consideration must be give to any slipstream.
• Engine heat radiation causes a rise in cooling air temperature in pusher fan systems.
• Generator heat contribution is 7-10 % of net engine power.
• Additional coolers in front of the radiator (puller fan) or behind the radiator (pusher fan) will
cause a rise in cooling air temperature and a reduction in airflow.
• The radiator may become clogged in dusty environments, which will impair cooling capacity.
The radiator must be installed so that it can easily be cleaned. Grilles / filters are available
as options.
• There must be as few obstacles to cooling air flow as possible. The design of air ducts, grille
and engine compartment is important.
• Hot air recirculation will impair cooling capacity significantly and must be prevented by sealing.
• Where accessory components such as a torque converter oil cooler are connected to the coolant system, it is necessary to know the cooling requirement for such components.
• Consideration must be given to the altitude above sea level at the location where the engine
will be used, as ATB is reduced by around 1.4 °C (34.5 °F) at 300 m (984 ft.)
• If it is necessary to increase cooling capacity, it must be done in the first instance by using a
larger radiator and improving cooling air flow.
Important to bear in mind regarding the coolant circuit
• Coolant flow and external circuit sensitivity to pressure drop. One extremely critical parameter when designing a cooling system is coolant flow. The pressure in the coolant system, which the pump works against, is linear to the amount of coolant that must circulate. When the thermostat opens back pressure increases and flow drops. Therefore, do not increase the external coolant system beyond the permissible maximum volumes specified in the technical data for each individual engine.
Also refer to technical data/cooling system
• Cooling effect and maximum cooling temperature. Refer to technical data/cooling system
“heat rejection from engine” and “Maximum top tank temperature”
• Static main pressure. Refer to technical data/cooling system
“maximum static main pressure” and “minimum static main pressure”
• Expansion tank volume. The total amount of coolant used in the system affects the appropriate size of the expansion tank. Minimum expansion tank size is 18 % of the total coolant volume.
Refer to the expansion tank chapter
• Venting.
Refer to the venting, nipples, pipes and hoses chapter
• Pipe and hose quality Refer to the radiator, pipes and hoses chapter.
Important to bear in mind regarding the charge air circuit
• Charge air temperature and cooling capacity. Engine charge air temperature should be as low
as possible. This is beneficial for fuel consumption and increases total engine service life. (lower stress effects from heat at maximum load points). Therefore pay attention to the need for effective cooling.
• Pressure drop across the charge air system. Refer to technical data/cooling system/charge
air system
• Load take-up. Be aware that the increase in air volume created by extending the charge air pipes will have a drastically negative effect on load take-up.
• Pipe runs and installation (clamps). Refer to the charge air cooler chapter
Induction System
General
The air inlet system is one of the most important parts of the engine installation as it is able to directly affect engine power, fuel consumption, exhaust emissions and engine service life. Bearing this in mind the air inlet system must be designed so that it is able to provide the engine with clean, dry, cold air with the smallest possible flow limitation. The system must also be designed to cope with the shock loads and operating conditions that occur during use. It must also provide reliable sealing and durability.
Air Inlet System
The air inlet system consists of three main components:
- Air inlet - before filter
- Air cleaner
- Air inlet - after filter
Inlet pipe, before filter
The air inlet must be installed in a location
- that has the lowest possible dust concentration
- where the temperature is as close to ambient air temperature as possible
- and which is protected from water splashes
The inlet must be protected against rain and snow. Make sure it is not possible for exhaust gases to be drawn in to the air inlet system. The air inlet pipe must be designed so that pressure drop is minimized. A small pressure drop extends filter service life. The basic guidelines for achieving a low pressure drop involve using large pipes with as few short-radius bends as possible. A water lock must be designed in the lower section of the pipe and/or where it bends upwards. The water lock must be drainable. The filter housing must also be drainable. Installation, Induction System
Cleaner Type
Air cleaner
Air cleaners protect engines against airborne contaminants that cause serious engine wear through their abrasive effect. Air cleaners can be divided into three basic types:
- pre-cleaner
- primary cleaner
- secondary element
Pre-cleaner
The function of the pre-cleaner is to remove the major part of airborne dirt from inlet air and to extend primary element service life. Pre-cleaners work by forcing air to rotate thus separating
the dust from the air. There are two main types of pre-cleaner:
- multi-cyclone filters installed in the air inlet
- stators installed in the filter housing
Volvo Penta recommends the use of pre-cleaners in dusty environments.
Primary cleaner
Primary cleaners can be divided into two types:
- oil bath type
- paper type
Paper type primary cleaners can be divided into:
- dry type
- oil-treated type
The cleaning efficiency of oil bath type cleaners is usually 70-90 %.
Dry type cleaning efficiency is 95-99.8 %.
Oil-treated type cleaning efficiency is 95-98 %.
Oil bath type
Air filters of the oil bath type must be accurately adapted to engine type and operating speed for them to work correctly. If the filter is not adapted to the engine, filtration may be poor and/or the oil can be transferred from the filter to the engine. Oil bath filters also have a limit regarding incline, i.e. the angle at which the installation may slope before oil begins to be transferred to the engine. For this reason Volvo Penta recommends that oil bath filters not be used.
Dry paper type
Filtration in a dry filter improves during filter service life. The filter is at its most effective when the pressure drop indicator indicates that the filter must be changed. Because of this, the filter should not be touched before it is changed.
IMPORTANT!
Dry filters may never be cleaned with compressed air, washed in fluids or knocked against the floor to empty out dirt. If dry filters are cleaned small leaks occur that cannot be seen with the naked eye. There is also a risk of dust being transferred to the clean side while the filter is removed.