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Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 1.Combustion engines main principles and definitions.

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Presentation on theme: "Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 1.Combustion engines main principles and definitions."— Presentation transcript:

1 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 1.Combustion engines main principles and definitions 2.Reciprocating combustion engines architecture 3.Reciprocating engines dynamic properties 4.Engine components and systems 5.The engine management system for gasoline and Diesel engines 6.The emission Requirements & Technology 7.Engine vehicle integration 8. 7.1 Engine layout and mounting 7.2 Engine-vehicle cooling system 7.3 Intake system 7.4 Exhaust system Light and heavy vehicle technology (Malcolm James Nunney - Elsevier)

2 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Cooling system System Targets To extract from the engine the heat quantity necessary to maintain the working temperature of every engine components below the safety limit in any vehicle operating condition. To assure the thermal balance between the heat extracted from the engine hardware and the heat released to external ambient through the heat exchanger (radiator) even in the most severe vehicle operating conditions. 2

3 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Critical engine components Combustion chamber walls Cylinder wall Cylinder head Piston Exhaust valve Spark plug Gasoline / Diesel injector Engine lubricants Cooling system 3

4 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Centrifugal pump Cooling fluid Radiator Fan Thermostat System componentsFunction Cooling fluid circulation Heat transfer Heat exchange with the ambient Air through the radiator at low vehicle speed Engine temperature stabilization Cooling system 4

5 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Expansion tank (nourice) Filler pressure cap Passenger compartment radiator Lubricant radiator EGR cooling radiator (Diesel) Fluid expansion and gas release Cooling circuit pressure Passenger compartment heating Engine lubricant cooling Exhaust gas cooling System componentsFunction Cooling system 5

6 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Heat transfer fluid Etilene glycol mixture in water (30 –60% concentration) Water High specific heat Low viscosity High heat of vaporization Constant characteristics vs time and temperature Etilene glycol High thermal capacity Low pressure drop Low gas formation Low freezing point Cooling system 6

7 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 7 EG Weight Percent (%) Freezing Point (deg F) Freezing Point (deg C) 0320 1025-4 20 -7 305-15 40-10-23 50-30-34 60-55-48 70-60-51 80-50-45 90-20-29 10010-12 Ethylene glycol freezing point vs concentration in water Cooling system

8 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Cooling circuit scheme Cooling system 8

9 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Engine-Vehicle cooling system LEGENDA 1 RADIATORE CON CONVOGLIATORE E VENTOLE 2 VASCHETTA DI ESPANSIONE 3 MANICOTTO DA RADIATORE A POMPA 4 MANICOTTO DA RISCALDATORE A POMPA 5 RISCALDATORE ABITACOLO 6 MANICOTTO DA TERMOSTATO A RISCALDATORE 7 POMPA 8 MANICOTTO DA RADIATORE A TURBO 9 MANICOTTO DA TERMOSTATO A RADIATORE 10 MANICOTTO DA TURBO A POMPA 11 TERMOSTATO Cooling system 9

10 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Thermal balance equations 1/6 = heat introduced into the engine through the fuel combustion = work equivalent heat at the engine shaft = heat realeased to the engine cooling system = heat rejected to the exhaust gases = lost heat for radiance where: General equation for engine thermal balance Cooling system 10

11 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science H i = net calorific or lower heating value (KJ/Kg) m f = fuel consumption (Kg/h) Heat released to the engine Heat released to the cooling fluid K= heat transfer coefficient (KJ/m 2° Kh) A eq = heat transfer equivalent surface area (m 2 ) = average difference in temperature between the exhaust gas and the coolant (°K) where: Thermal balance equations 2/6 Cooling system 11

12 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science c w = (KJ/Kg°K) water calorific value (4.1868 KJ/KgK) m w = (Kg/h) coolant flow rate T wu = (°K) coolant temperature at the engine outlet T we = (°K) coolant temperature at the engine inlet c l = (KJ/Kg°K) lubricant calorific value m l = (Kg/h) lubricant flow rate through the water-lubricant heat exchanger T lu = (°K) lubricant temperature at the outlet of the heat exchanger T le = (°K) lubricant temperature at the inlet of the heat exchanger where: Heat released to the cooling fluid from the engine where: Heat released to the cooling fluid from the engine and the water-lubricant heat exchanger Thermal balance equations 3/6 Cooling system 12

13 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science K r = (KJ/m 2 °Kh) heat transfer coefficient of the cooling radiator A r = (m 2 ) radiator frontal area T rm = (°K) average tempearture of the coolant inside the radiator Heat released to the external ambient through the cooling radiator T ae = (°K) air temperature at the radiator inlet which differs from the ambient temperature T a when the condenser radiator of air conditioning system is installed ahead where: Thermal balance equations 4/6 Cooling system 13

14 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science T a = (°K) ambient temperature T boil = (°K) boiling temperature of the coolant at the pressure of the circuit T re = (°K) temperature of the coolant at the radiator inlet Air Temperature to Boil index (ATB): it defines the ambient temperature boiling point of the cooling fluid ( It represents an equilibrium condition between the heat rejected from the combustion gases to the cooling fluid and the heat rejected from the fluid to the external air for a specific vehicle operation mode. Thermal balance equations 5/6 where: Cooling system 14

15 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science ATB index vs Q w ATB index could be expressed as function of the heat to be rejected from the engine into the coolant and of the radiator exchanging performances. Without air conditioning system (T ae = T a ) With air conditioning system ATB index expresses an equilibrium condition determined by the engineering design of the cooling system. ATB index expresses an equilibrium condition determined by the engineering design of the cooling system. Practically some ATB values are defined for some severe operating vehicle modes that represents the project targets. Thermal balance equations 6/6 where K r [Kw/m 2 ·°K] is a performance exchanger parameter of the radiator Cooling system 15

16 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 16 The water pump provides circulation of the engine coolant (antifreeze) through the cooling system: it pushes the coolant through the passages (water jackets) in the engine cylinder block and cylinder head and then out into the radiator. The hot coolant passes through the radiator where it cools down and then returns back to the engine. Centrifugal pump is the most used:it is a rotodynamic pump that uses a rotating impeller to increase the pressure and flow rate of a fluid. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward or axially into a diffuser or volute chamber, from where it exits into the downstream piping system. A water pump is usually driven by the engine through the driving belt and only sometimes by a timing belt. A water pump consists of the housing with the shaft rotating on the bearing pressed inside. At the outer side there is a pulley mounted on the shaft. At the inner side there is a seal to keep the coolant from leaking out and the impeller. Cooling system Component – Water pump 1/5

17 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Impeller diameter ( = 60 75 mm) Impeller height (h = 12 20 mm) Paddles number and design (z = 5 10) Axial and radial impeller clearance Drive ratio = 1.3 1.6 Main design characteristics Component – Water pump 2/5 Cooling system 17

18 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Typical values T w = 8 – 10°C / P m = 0.030 – 0.043 Kg/sKw for gasoline engines 0.025 – 0.035 Kg/sKw for Diesel engines Typical system back pressure 0.5 2.5 bar Setting of the coolant flow rate The coolant pressure at the pump inlet must not be negative to avoid cavitations phenomena and therefore the inlet speed shall be limited, generally lower than 3 m/s. Component – Water pump 3/5 Cooling system 18

19 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 19 Hydrodynamic cavitation describes the process of vaporization, bubble generation and bubble implosion which occurs in a flowing liquid as a result of a decrease and subsequent increase in pressure. Cavitation will only occur if the pressure declines to some point below the saturated vapor pressure of the liquid. In pipe systems, cavitation typically occurs either as the result of an increase in the kinetic energy (through an area constriction) or an increase in the pipe elevation. Hydrodynamic cavitation can be produced by passing a liquid through a constricted channel at a specific velocity or by mechanical rotation through a liquid. In the case of the constricted channel and based on the specific (or unique) geometry of the system, the combination of pressure and kinetic energy can be created when the hydrodynamic cavitation cavern downstream of the local constriction generating high energy cavitation bubbles. The process of bubble generation, subsequent growth and collapse of the cavitation bubbles results in very high energy densities, resulting in very high temperatures and pressures at the surface of the bubbles for a very short time. The overall liquid medium environment, therefore, remains at ambient conditions. When uncontrolled, cavitation is damaging; however, by controlling the flow of the cavitation the power is harnessed and non-destructive. Controlled cavitation can be used to enhance chemical reactions or propagate certain unexpected reactions because free radicals are generated in the process due to disassociation of vapors trapped in the cavitating bubbles. Component – Water pump 4/5 Cooling system

20 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Typical water pump characteristic (63.5mm impeller diameter, 8 paddles of 13.5mm height, axial clearance of 0.6mm, engine drive ratio 1/1.39) 5450 Component – Water pump 5/5 Cooling system 20

21 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 21 Target - In internal combustion engines a thermostat is used to maintain the engine at its optimum operating temperature by regulating the flow of coolant to the external air cooled radiator. It must balance the heat rejected from the engine to the coolant and the heat rejected from the radiator to the ambient in any operating vehicle mode. This type of thermostat operates mechanically: it makes use of a wax pellet inside a sealed chamber. The wax is solid at low temperatures but as the engine heats up the wax melts and expands. The sealed chamber has an expansion provision that operates a rod which opens a valve when the operating temperature is exceeded. The operating temperature is fixed, but is determined by the specific composition of the wax, so thermostats of this type are available to maintain different temperatures, typically in the range of 70 to 90°C. Modern engines run hot, that is, over 80°C, in order to run more efficiently and to reduce the emission of pollutants. Most thermostats have a small bypass hole to vent any gas that might get into the system, e.g., air introduced during coolant replacement, which also allows a small flow of coolant past the thermostat when it is closed. This bypass flow ensures that the thermostat experiences the temperature change in the coolant as the engine heats up; without it a stagnant region of coolant around the thermostat could shield it from temperature changes in the coolant adjacent to the combustion chambers and cylinder bores. Wax thermostatic elements permit the transforming of thermal energy into mechanical energy. Their working principle is based on the large increase in the thermal expansion of waxes when they pass from the solid to the liquid state Cooling system Component – Thermostat 1/4

22 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 22 While the thermostat is closed, the flow of coolant in the loop is greatly slowed, allowing coolant surrounding the combustion chambers to warm up rapidly. The thermostat stays closed until the coolant temperature reaches the nominal thermostat opening temperature. The thermostat then progressively opens as the coolant temperature increases to the optimum operating temperature, increasing the coolant flow to the radiator. Once the optimum operating temperature is reached, the thermostat progressively increases or decreases its opening in response to temperature changes, dynamically balancing the coolant recirculation flow and coolant flow to the radiator to maintain the engine temperature in the optimum range as engine heat output, vehicle speed, and outside ambient temperature change. If the load on the engine increases, increasing the heat input to the cooling system, or the vehicle speed decreases or air temperature increases, decreasing the radiator heat output, the thermostat will open further to increase the flow of coolant to the radiator, preventing the engine from overheating. If the conditions reverse, the thermostat will reduce its opening to maintain the coolant temperature. Cooling system Component – Thermostat 2/4

23 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 23 Under normal operating conditions the thermostat is open to about half of its stroke travel, so that it can open further or reduce its opening to react to changes in operating conditions. A correctly designed thermostat will never be fully open or fully closed while the engine is operating normally, or overheating or overcooling would occur. For instance, If more cooling is required, e.g., in response to an increase in engine heat output which causes the coolant temperature to rise, the thermostat will increase its opening to allow more coolant to flow through the radiator and increase engine cooling. If the thermostat were already fully open, then it would not be able to increase the flow of coolant to the radiator, hence there would be no more cooling capacity available, and the increase in heat output by the engine would result in overheating. If less cooling is required, e.g., in response to decrease in ambient temperature which causes the coolant temperature to fall, the thermostat will decrease its opening to restrict the coolant flow through the radiator and reduce engine cooling. If the thermostat were already fully closed, then it would not be able to reduce cooling in response to the fall in coolant temperature, and the engine temperature would fall below the optimum operating range. Modern cooling systems contain a relief valve in the form of a spring-loaded radiator pressure cap, with a tube leading to a partially filled expansion reservoir (most recent applications use to have the pressure cap directly on the expansion reservoir – see slides 25/26). Owing to the high temperature, the cooling system will become pressurized to a maximum set by the relief valve. The additional pressure increases the boiling point of the coolant above that which it would be at atmospheric pressure. The wax product used within the thermostat requires a specific process to produce. Unlike a standard paraffin wax, which has a relatively wide range of carbon chain lengths, a wax used in the thermostat application has a very narrow range of carbon molecule chains. The extent of the chains is usually determined by the melting characteristics demanded by the specific end application. To manufacture a product in this manner requires very precise levels of distillation, which is difficult or impossible for most wax refineries. Cooling system Component – Thermostat 3/4

24 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Typical thermostat characteristic Opening temperature 88 2 °C Valve stroke of 9.5mm at 101 105 °C 1-Cooling system Component – Thermostat 4/4 24

25 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 25 Main target To absorb the expansion of the coolant as it gradually increases into full operating temperature. To generate pressure at the pump inlet to avoid cavitations phenomena. To remove bubbles from the entire cooling system to absorb heat much faster. To assure a coolant reservoir sufficient for the maintenance-free target To fit the filler neck (the mouth of the header tank) covered with a pressure cap, which forms an air-tight joint due to which the coolant is maintained at some pressure higher than the atmospheric (generally 1.4-1.6 bar). Using the pressure cap brings about the following advantages in the cooling system: Elevating the boiling point: the engine can operate at higher temperatures without boiling the liquid coolant within. Allows for the usage of smaller tanks for the same engine sizes. Prevents any coolant to be wasted or drained away and maintains a self regulated system that can go maintenance free. Component – E Component – Expansion reservoir and pressure cap 1/5 1-Cooling system

26 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 26 The reservoir is connected to the radiator that it receives the excess coolant as the engine temperature increases. When the liquid cools down, its volume decreases and the coolant in the reservoir returns to the reservoir to keep the coolant level in the cooling system optimal. This system is also known as coolant recovery system and it helps to prevent loss of coolant, doesnt allow air to come into the system and allows for a smaller header tank. The expansion tank is a see-through plastic container that has to be mounted into the overflow tube from the radiator. With a properly working expansion bottle, radiator is always full even if the coolant inside it rises and falls. As a general rule, standard expansion tank volume is approximately 20 to 30-percent of the estimated volume of the specific thermal fluid of the system circuit. A pressure cap contains a pressure valve and a vacuum valve. If in severe operating conditions, the coolant starts to boil or to vaporize, the pressure in the system builds up and exceeds a certain pre-determined value, the pressure blow-off value, which operates against a pre-tensioned spring, opens releasing the excess pressure to the atmosphere through the over flow pipe. Component – E Component – Expansion reservoir and pressure cap 2/5 1-Cooling system

27 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science The expansion tank should be located about the level of the radiator header tank. Component – E Component – Expansion reservoir and pressure cap 3/5 1-Cooling system 27

28 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Typical installation of the expansion reservoir inside a complex layout of the engine bay for a small segment vehicle Component – E Component – Expansion reservoir and pressure cap 4/5 1-Cooling system 28

29 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 3 Control functions 1-Filler neck sealing 2-Max pressure control 3-Min pressure control (vacuum valve) Pressure cap Component – E Component – Expansion reservoir and pressure cap 5/5 1-Cooling system 29

30 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Air liquid heat exchanger (radiator) composition Coreheat exchange Two tankscooling collection & release Heat exchange core made by stacked layers of pipes Material (high thermal conductivity) brass aluminum Technology mechanical expansion & interference brazing 1-Cooling system Component – Radiator 30

31 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 31 A radiator is a type of heat exchanger. It is designed to transfer heat from the hot coolant that flows through it to the air blown through it by the fan. A typical radiator consists of a header tank, the core and the lower tank: both of these tanks have water outlets. The water coolant mixture is cooled while it flows into the radiators core which is made of thin, flattened aluminum small tubes with aluminum fins outside which are present only to help increase the rate of heat transfer (secondary heat transfer surfaces). The tubes sometimes have a type of fin inserted into them called a turbulator, which increases the turbulence of the fluid flowing through the tubes. The core is usually made of stacked layers of metal sheet, pressed to form channels and soldered or brazed together. For many years radiators were made from brass or copper cores soldered to brass headers. Modern radiators save money and weight by using plastic headers and may use aluminum cores. This construction is less easily repaired than traditional materials. 1-Cooling system Component – Radiator

32 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Typical main and secondary (louvers) fins of a aluminum brass radiator Fins of an aluminum mechanical built radiator (oval and elyptical tubes) Twin row brazed radiator 1-Cooling system Component – Radiator 32

33 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Automotive cooling radiators with horizontal tanks and with vertical tanks Tank material -PA 66 glass reinforced 1-Cooling system Component – Radiator 33

34 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Radiator thermal performance per surface unit depend on Material Construction technology Radiator thickness Tubes and fins passo/technology brass brazing 18 – 34 mm mechanical techn. 18 – 40 mm brazed techn. Manufacture patents Air velocity (flow rate) Coolant velocity (flow rate) Air velocity (flow rate) Coolant velocity (flow rate) Heat exchanged per surface area unit Air pressure drop Coolant pressure drop Air flow rate Coolant flow rate 1-Cooling system Component – Radiator 34

35 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Construction Technology Radiator thickness [mm] Heat exchange capacity [W/dm2 °C] Interference mech. 18 40.2 Interference mech. 3246.4 Brazed 1341.6 Brazed1846.0 Brazed2764.1 Brazed4070.8 Heat Transfer Capacity in Kalories (W) per dm2 and per °C of temperature difference between coolant and air 1-Cooling system Component – Radiator 35

36 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Specific heat transfer of an aluminum interf. mech. radiator (Alm) 580x317x18 (LxHxP) Specific heat transfer of an aluminum brazed radiator (Alm) 580x305x18 (LxHxP) 1-Cooling system Component – Radiator 36

37 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Air pressure drop of some radiatorsCoolant pressure drop of some radiators 1-Cooling system Component – Radiator 37

38 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 38 The primary task of the fan is to generate sufficient air flow rate at low engine speed or more generally when the coolant temperature exceeds a set point. Front-wheel drive cars have electric fans (150-600W) because the engine is usually mounted transversely, meaning the output of the engine points toward the side of the car. The fans are controlled either with a thermostatic switch or by the engine electronic system (ECU), and they turn on when the temperature of the coolant goes above a set point, they turn back off when the temperature drops below that point. Rear-wheel drive cars with longitudinal engines usually have engine-driven cooling fans. These fans have a thermostatically controlled viscous clutch. This clutch is positioned at the hub of the fan, in the airflow coming through the radiator. 1-Cooling system Component – Fan

39 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 39 Core face to fan distance is the distance from the fan blade face and the next cooling component inline, typically the radiator core. This distance is critical to proper airflow and to the durability to the fan. If the distance is too close the air flow will focus on only that portion of the core that is covered by the fan blades, rendering the core section covered by the center hub section of the fan useless. If the fan is too close there will also be a constant flexing of the fan blades due to the proximity of the core face and some air pressure gradient problems. For more efficient use of the whole radiator core surface, the fan is shrouded in the most severe applications. Typical engine-driven cooling fan application for a longitudinal engine installation 1-Cooling system Component – Fan

40 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Electrical fan stationary efficiency (ca.40%) Air flow power [W] where: Electrical power absorbed by the fan [W] Air flow rate[kg/s] Air density [kg/m3] Back pressure [Pa] Electrical motor voltage [V] Current adsorbed by electrical motor [A] P el = V I V I DPa 1-Cooling system Component – Fan 40

41 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Coooling air Shrouded mono and twin fan 1-Cooling system Component – Fan Coooling air Up front fan 41

42 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 500W fan typical performance (380mm blade diameter) 1-Cooling system Component – Fan Optimal working area 42

43 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 43 Engine oil lubricates and cleans moving / rotating metallic surfaces. As metallic surface rub on each other, that causes friction, thus creating heat. Heat is the enemy to motor oil. As motor oil heats up it loses its ability to lubricate and the surfaces requiring lubrication begin to wear. Continued use at elevated temperatures can result in premature engine wear and eventual failure. Engine oil coolers are commonly used on higher performance engines, heavy duty commercial vehicles, vehicles with increased trailer towing capacity, and most high speed diesel engines. As engines become more efficient engine oil coolers will become common on most motor vehicles. The general target is to avoid oil temperature exceeding 160-180°C in the most severe operating conditions, but generally the cooling system is design and set to keep a constant temperature around 120-130°C. Component – Oil cooler 1-Cooling system

44 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 44 Filter Mounted Engine Oil Cooler This type of engine oil cooler is designed to be mounted onto the engine block with a hollow bolt and uses the engine water as cooling fluid. The oil flow is as follows: engine oil leaves engine and enters the oil cooler, circulates through the oil cooler, exits oil cooler and enters oil filter, oil is filtered and returns to engine through the hollow mounting bolt. The cold fluid comes from the radiator circuit. Optimal performance will be achieved if the cold fluid can be taken from the exit side of the radiator (cooled water/glycol). Engine Mounted Engine Oil Coolers This type of engine oil cooler is designed to be mounted directly onto the engine block. The oil flow is as follow: engine oil leaves the engine and enters the oil cooler, circulates through the oil cooler, exits oil cooler and re-enters the engine. The cold fluid can either be routed to the heat exchanger in 2 ways: 1) fed from the radiator circuit through flexible lines or, 2) fed directly into the heat exchanger from the engine block, eliminating the need for additional lines. Optimal performance will be achieved when the hot oil and cold fluid (glycol/water mixture) have the greatest inlet temperature difference. Component – Oil cooler 1-Cooling system

45 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 45 Remote Mounted Engine Oil Cooler This type of design is normally mounted remotely from the engine block. This design is well suited to applications where additional engine oil cooling is required over the original design intent of the vehicle (I.e. increased trailer tow, large engine displacements and racing applications).There are 2 types of designs and mounting strategies in this class of engine oil coolers. Mounted directly in an air stream (most often in front of the radiators). Cooling occurs by passing hot oil through the cooler via fluid lines coming from the engine and ambient air passing through the core of the oil cooler. Liquid-to-liquid remote oil cooler. Engine oil and coolant are both fed to the oil cooler via fluid lines coming from the engine and coolant circuit respectively. This design can be mounted anywhere there is room to package under the hood. Optimal performance will be achieved when the hot oil and cold fluid (glycol/water mixture or air) have the greatest inlet temperature difference. Most common applications for this design can be found on heavy-duty trucks, large displacement engines and racing or high speed applications. Component – Oil cooler 1-Cooling system

46 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 46 Component – Oil cooler

47 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Filter Mounted Engine Oil Cooler – Thermal performances 80x140mm e 12 layers (oil 140 °C, coolant 82 °C) Component – Oil cooler 1-Cooling system 47

48 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Remote Mounted Engine Oil Cooler – Thermal performances 200x150x30 mm (oil 100 °C, air 20°C) Component – Oil cooler 1-Cooling system 48

49 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 49 An intercooler (original UK term, sometimes aftercooler in US practice), or charge air cooler, is an air-to-air or air-to-liquid heat exchange device used on turbocharged and supercharged (forced induction) internal combustion engines to improve their volumetric efficiency by increasing intake air charge density through nearly isobaric (constant pressure) cooling. The general target is to cool the compressed air down to below 60°C at the engine intake. - Air temperature at intercooler inlet - Air temperature at intercooler outlet - Temperature of the ambient cooling air where: Component – Intercooler 1-Cooling system

50 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science 50 T ai T ao TURBOCHARGER ENGINE Brick type air to air intercooler Full Face air to air intercooler Component – Intercooler 1-Cooling system

51 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Intercooler performance characteristic (280x130x50). Charge air temperature 140°C, ambient air temperature 30°C (ETD external temperature difference = 110°C) Component – Intercooler 1-Cooling system 51

52 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Cooling system design Engine protection Reduced packaging of the radiator/fan module Minimized system cost ATB index Vehicle design & aerodynamic penetration Product competitivity Design targets 1-Cooling system 52

53 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science In the most severe vehicle operating modes the engine outlet temperature must not exceed 100° - 105°C for long time 110° - 115°C for limited time V=30 Km/h 1° gear 9% slope with trailer equal to the vehicle weight V=140 Km/h Longest gear Max engine power ATB = T a + T boil - T re Low vehicle speed ATB = 40°C High vehicle speed ATB = 60°C Engine protection targets Two severe conditions ATB design target Cooling system design 1-Cooling system 53

54 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Radiator performance characteristic Heat to be rejected at the high speed severe driving mode with Tru calculated from the the temperature drop through the radiator by Design target K r [Kw/m 2 ·°K] T r [°K] Q w [Kw] ATB The radiator frontal area can be calculated by: In theory, being knowed: _ Cooling system design Cooling module design 1-Cooling system 54

55 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Radiator size defined by the layout constraints In real practice: A value of air flow rate trough the radiator is estimated at the vehicle speed of the high speed ATB target By iterative approach, type and thickness of the radiator are selected so that the K r coefficient can satisfy the following equation: Cooling module design Cooling system design 1-Cooling system 55

56 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Exchanged heat coefficient Kr vs air flow rate of a typical automotive cooling radiator Cooling module design Cooling system design 1-Cooling system 56

57 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Through the radiator performance characteristic by Qw heat to be rejected at the low speed mode it can be defined Fan selection and design (Low speed ATB) The necessary air flow rate Electrical fan is selected from a catalogue suitable for the specific layout and able to deliver the necessary air flow rate at maximum fan efficiency Cooling system design 1-Cooling system 57

58 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Rejected heat vs air flow rate for a typical radiatorPerformance characterisric of a typical electric fan Cooling system design 1-Cooling system 58

59 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Design criticities during the project development Difficult estimation of the air flow rate through the radiator Different power train to be installed on the same vehicle (different Qw) Continuous evolution of the engine compartment layout during development Optimized process for the project design development Design phase Approximate calculation Mono-dimensional analysis Mono-dimensional analysis Experimental check Three-dimensional analysis Three-dimensional analysis Design concept Design development Design validation Cooling system design 1-Cooling system 59

60 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Input data Output Coolant flow rate, rejected engine and oil cooler heats, exchange heat and perssure drop radiator characteristics….engine power and torque curve, vehicle features and front end design and air permeability, total gear ratio… CAD file: Vehicle extrenal design Cooling module installation Engine bay layout for the major components Coolant flow rate, rejected engine and oil cooler heats, exchange heat and perssure drop radiator characteristics….engine power and torque curve, vehicle features and front end design and air permeability, total gear ratio… CAD file: Vehicle extrenal design Cooling module installation Engine bay layout for the major components Air speed distribution through the radiator surfacea rea ATB index Coolant temperature at the engine outlet Air speed distribution through the radiator surfacea rea ATB index Coolant temperature at the engine outlet Accurate estimation of the air speed distribution High work load and long time Advantages Disadavantages Three-dimensional analysis Cooling system design 1-Cooling system 60

61 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science CFD analysis: examples of calculation output. Under bonnet air speed and temperature map at two different vehicle speeds Cooling system design 1-Cooling system 61

62 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science CFD analysis: examples of calculation output. Air speed and temperature distribution through radiator at two different vehicle speeds Cooling system design 1-Cooling system 62

63 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science CFD and test results comparison ATB exp. test 1° gear at 30 km/h 9% slope with trailer A/C OFF 5° gear at140 km/h full load A/C ON Testing data 3D simulation Heat to be rejected [kW] Air T [°C] ATB [°C] 22.5 30.1 29.7 30.7 60 75.3 101 84.8 61.2 77.1 Rad inlet temperature 102.3 87.9 Rad inlet temperature Cooling system design 1-Cooling system 63

64 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Heat (Qw) rejected to the coolant Test equipment Engine test bench Temperature, flow meter, engine parameters …. Test equipment Engine test bench Temperature, flow meter, engine parameters …. Prerequisites Engine design conformity Coolant flow rates representative of the vehicle configuration Prerequisites Engine design conformity Coolant flow rates representative of the vehicle configuration Measurement of Coolant temperature at the engine inlet (T we ) and outlet (T wu ) Coolant flow rate (m w ) Engine speed Engine torque At ATB operating conditions Measurement of Coolant temperature at the engine inlet (T we ) and outlet (T wu ) Coolant flow rate (m w ) Engine speed Engine torque At ATB operating conditions ° ° Q w = C w · m w · (T wu -T we ) 64 Cooling system design 1-Cooling system

65 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Heat rejected to the coolant as % of the engine power measured on the test bench (gasoline engine 1242cc 16v 80 CV, diesel engine 1910cc 8v 105 CV 65 Heat (Qw) rejected to the coolant Cooling system design 1-Cooling system

66 Engine Vehicle Integration Scuola di Dottorato di Ricerca 2010 - Road vehicle and engine engineering science Test equipment Chassis dynomometer inside climatic chamber Tempertaure and pressure measure devices Test equipment Chassis dynomometer inside climatic chamber Tempertaure and pressure measure devices ATB test measurement Procedure When engine temperature is stabilized at the vehicle load & speed defined by ATB targets, it has to be measured the ambient and radiator inlet temperatures Procedure When engine temperature is stabilized at the vehicle load & speed defined by ATB targets, it has to be measured the ambient and radiator inlet temperatures Prerequisite - Conformity of Engine and electronic management system Vehicle and vehicle system, particularly front end and engine bay layout Cooling module (radiator and fan) Pressure cap Prerequisite - Conformity of Engine and electronic management system Vehicle and vehicle system, particularly front end and engine bay layout Cooling module (radiator and fan) Pressure cap ATB = T a + T boil - T re Cooling system design 1-Cooling system 66


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