Air conditioning condenser
If an air conditioning condenser is used it is normally located in front of the radiator on a sucking fan system. The condenser causes a cooling air pressure drop and temperature rise. A condenser in operation may raise the temperature by 3-5 °C (37.4–41 °F).
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
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.
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 ring
• Fan guard
• 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 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 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 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.
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 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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