Overview Of Cooling System Engineering Essay
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Published: Mon, 5 Dec 2016
In order to reducing fuel consumption and meet the emission standards, many improvements has been made. The examples of the improvements are combustion strategies, fuel injection system, exhaust emission and fuel quality.
There are four possible sources of atmospheric pollution from the automobile. Without emission controls, a carburetor and fuel tank emits vapors, the crankcase emits blowby gases and the tailpipe emits exhaust gases that contain pollutants. The main regulated pollutant in engine exhaust are nitrogen oxides (NOx), carbon monoxide (CO), unburned hydrocarbon (HC) and smoke. These air pollutants are harmful to human beings as well as plants and animals. The law now requires automotive manufacturers to install emission controls.
Car that gives off excessive amount of air pollutants may not be allowed on the streets someday. Stronger laws limiting automotive air pollution and mandatory inspection and maintenance has been proposed. These laws are part of the government policy that cars must contribute as little as possible to the problem of air pollution. Each car already have three major systems for controlling pollutants from these sources that is positive crankcase ventilation (PVC), evaporative emission control and exhaust emission control. But in this study we want to focus more on engine cooling system and its effects to the emission reduction, fuel consumption and engine performance. Now, we will through about the components of engine cooling system and its functions.
Engine cooling system is a system that responsible for cooling the engine by releasing heat through the cooling fins so that the carâ€™s engine is not too hot or not too cold. This system helps to bring the engine up at to normal operating temperatures as quickly as possible and maintain the operating temperature for efficient function of the car engine. It is very important to keep the engine at its most operating temperature at all speeds and operating conditions. Burning fuel in the engine produces heat. Some of the heat must be taken away before it damages the engine parts. This is one of the jobs that performed by the cooling system. If the engine temperature is too low, fuel consumption will rise and if the temperature is too hot for too long, the engine will overheat.
1.2 TYPES OF COOLING SYSTEM
There are two types of car cooling system which is the air cooling system and liquid cooling system. Air cooling system is a system that uses air as a cooling agent. It is commonly used in single cylinder engines such as motorcycles while liquid cooling system is known as the radiator system. It a system that uses liquid as a cooling agent and is used in a multi-cylinder engine such as cars and trucks. Radiator is the crucial components in the car cooling system. It ensures the engine is not overheating.
Figure 1.1 : Cooling System Components 
1.3 COMPONENTS OF COOLING SYSTEM
1.3.1 WATER JACKET
For operation of the cooling systems, it uses five basic parts or components to do the job in controlling the engine temperature that is water jackets, water pump, thermostat, radiator and fan. Water jackets are open spaces between the cylinder walls and the outside shell of the block and head. Coolant from the water pump flows first through the block water jackets. Then, the coolant flows up through the cylinder head water jackets and back to the radiator.
1.3.2 WATER PUMP
Water pump usually known as impeller pumps. It is attached to the front of the engine and are driven by a belt from crankshaft pulley. The pump circulates as much as 28 390 L of coolant an hour. As the impeller rotates, the curved blades draw coolant from the bottom of the radiator. It forces the coolant from the pump outlet to the water jackets. The impeller shaft is supported on sealed bearings which never need lubrication. The seals prevent the coolant from leaking past the bearings.
Radiator is a heat exchanger that removes heat from engine coolant that passing through it. The heat transfer from the hot coolant to the cooler outside air. It has three main parts that is radiator core, inlet and outlet tanks. The core consists of set of tubes and set of fins that attached to the tubes.
Figure 1.2 : Coolant Flow Inside Engine Cooling System C:UsersFaisal Mamat.FaisalMamat-PCDesktopCapture.PNG
For thermostat, it is a heat operated valve that regulates the coolant temperatures. It does this by controlling the coolant flow from the engine to the radiator. The thermostat is in the coolant passage between the cylinder head and the radiator. The valve in thermostat stay open and close as coolant temperature changes. As long as the coolant temperature is below the thermostat set point, the thermostat remains closed. Once the temperature arrives at the set point, the thermostat starts to open, sending heated coolant through the radiator. The radiator then cools the heated engine coolant and the water pump forces the coolant back through the engine. The passage to the radiator is closed when the engine is cold so the engine can warms up more quickly. Engine heat stays in the engine instead of being carried to the radiator.
Figure 1.3 : Closed Position of Thermostat  Figure 1.4 : Open Position of Thermostat 
1.3.5 ELECTRIC FAN
An electric fan is turned on by thermostatic switch only when needed. For example, it turns on when the coolant temperature reach 93Â°C and turn off back the fan if the coolant drops below this temperature. But on vehicles with air conditioning, turning on the air conditioner bypass the thermostatic switch. The fans run all the time when air conditioner is on. The fan is controlled by electronic control module (ECM) in many vehicles with an electronic engine control system.
1.4 PROPERTIES OF COOLANT
1.4.1 TAP WATER
Tap water is potable water supplied to a tap inside the household or workplace. The application of technologies involved in providing clean water to homes, businesses and public buildings is a major subfield of sanitary engineering. Specific chemical compounds are often added to tap water during the treatment process to adjust the pH or remove contaminants, as well as chlorine to kill biological toxins. The use of tap water adversely affect the car cooling system. Tap water contains magnesium and calcium ions that will form the yellow precipitate (rust) when the water becomes hot. The yellow precipitate will be attached to the car engine after long time period and this will reduce the absorption of heat from the engine. If this rust become denser, it can interfere the passage of cooling liquid in the car cooling system.
1.4.2 ETHYLENE GLYCOL (EG)
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid. Ethylene glycol is toxic, and ingestion can result in death. Ethylene glycol is produced from ethylene via the intermediate ethylene oxide. The major use of ethylene glycol is as a medium for convective heat transfer. For example, automobiles and liquid cooled computers. Pure ethylene glycol has a specific heat capacity about one half that of water. So, while providing freeze protection and an increased boiling point, ethylene glycol lowers the specific heat capacity of water mixtures relative to pure water. A 50/50 mix by mass has a specific heat capacity of about 0.75 BTU/lb F, thus requiring increased flow rates in same system comparisons with water.
Gasoline is a transparent, petroleum derived liquid that is used primarily as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasoline also contain ethanol as an alternative fuel. A good gasoline quality should have :
Proper volatility, which determines how easily the gasoline vaporizes.
Resistance to spark knock or detonation.
Oxidation inhibitors, which prevent formation of gum in the fuel system.
Antirust agents, which prevent rusting of metal parts in the fuel system.
Detergents, which keep help keep the carburetor or fuel injectors clean.
Dye for identification, such as red eye which gives leaded gasoline a rust or orange colour.
Volatility is the ease with which a gasoline vaporizes. Gasoline must vaporize quickly after it is mixed with air in the throttle body or intake manifold. Otherwise, drops of liquid gasoline enter the cylinder walls. This increases wear of the cylinder walls, pistons and rings. Gasoline that does not vaporize will not burn. It leaves the cylinder in the exhaust gas and pollutes the air. This wastes gasoline and reduces fuel economy. Volatility determines how quickly a gasoline can vaporizes. A high volatility gasoline can vaporizes quickly while a low volatility gasoline vaporizes slowly. Gasoline must have the right volatility for the climate in which it is used.
1.5.2 ANTIKNOCK QUALITY
Antiknock is known as octane rating. It measure the gasoline ability to resist knock during combustion. The higher the octane rating, the greater the engine’s resistance to knock. The knocking in your engine occurs when the air fuel mixture detonates prematurely. Since it is the gasoline vapor that ignites, the air fuel mixture must be correct to burn smoothly. Some of the problems associated with knock are overheating of engine parts such as valves, pistons and spark plugs.
Then we will go for the explanation about the combustion in the engine and how it resulting emission. Automotive fuels such as gasoline are made mostly of two elements that hydrogen and carbon. They have chemical symbols H and C. This type of fuel is hydrocarbon (HC). During complete combustion in the engine, these two elements unite with other element, the gas oxygen. Oxygen, usually in the form of free oxygen (O2), makes up about 20 percent of the earth atmosphere. This is the air that we breathe.
During combustion process, each atom of oxygen will unites with two hydrogen atoms. Each carbon atom unites with two oxygen atoms. Oxygen uniting with hydrogen produces water (H2O). Carbon uniting with oxygen produces gas carbon dioxide (CO2). During combustion, the burning of air fuel mixture in the engine cylinder may reach 2200oC or higher. This high temperature produces pressure in the engine that makes it run and produces power. With perfect combustion, all the hydrogen and carbon in gasoline would unite with the oxygen. The exhaust would contain only harmless H2O and CO2. But combustion is not perfect in the engine. Some of the gasoline (HC) does not burn. Also, some of it only partly burns. This produces carbon monoxide (CO). This lack of oxygen prevents the formation of carbon dioxide. The unburned gasoline and partly burned gasoline (CO) exit from the engine through the tailpipe. Once in the air, it will cause atmospheric pollution. Another group of atmospheric pollutants the engine is nitrogen oxide (NOx). About 80 percent of the atmosphere is gas nitrogen (N). High temperatures in the combustion chamber cause some of the nitrogen and oxygen to unite and form nitrogen oxide (NOx).
1.7 PROBLEM STATEMENT
Nowadays the rate of fuel consumption currently going on throughout the world is quite alarming. Fuel consumption and emission rates are off the chart. This will give negative impact to the environment and increase the pollution rate. Basically the power to move a motor vehicle comes from the burning of air fuel mixture in an engine. Air pollutants from vehicles comes from the products of this combustion process. With perfect combustion process, the emission would be water (H2O) and carbon dioxide (CO2). Both of these are harmless gases. But combustion is not perfect in an engine. Some of the gasoline (HC) does not burn and some of it only partly burns. This produces carbon monoxide (CO) and nitrogen oxide (NOx). Both of these gases are air pollutants and breathing polluted air is very bad for human and animals. Then the demand for low cost car from customer that has good performance with low fuel consumption and emission also increase. Usually car that has good performance will have high fuel consumption and emission rate. In order to solve these problems, the study about engine cooling system and its effects towards engine performance, fuel consumption and emission reduction will be conducted. Two types of liquid cooling such as tap water and ethylene glycol will be used and its temperature will be checked in order to investigate the influenced to these 3 outputs.
1.8 OBJECTIVES OF THE RESEARCH
To study the effect of engine cooling system and its components to the engine performance, fuel consumption and emission.
To investigate the influence of percentage of ethylene glycol in the coolant and coolant temperature set point to the engine performance, fuel usage and emission rate.
1.9 SCOPE OF THE RESEARCH
The scope of this researched is mainly about the variations percentage of coolant (ethylene glycol) mixed with water and its temperature effects towards engine performance, fuel consumption and emission. The percentage that will be used for ethylene glycol are 30%, 50% and 70%. For every percentage, the coolant temperature set point will be controlled using two kind of thermostat with temperature set point 80oC and 100oC. The increasing temperature in cylinder block by increasing the coolant temperature results in fuel savings and emission reduction.
Ethylene Glycol solution
(% by volume)
Table 1.1 : Boiling Point of Ethylene Glycol Solutions 
Car model that will be used is Perodua Kancil 660cc (4 stroke and 3 cylinder). Then for the fuel, petrol RON 95 will be used. Three test will be conducted in investigate the engine performance, fuel consumption and emission rate. The test for engine performance is dynamometer test. A dynamometer is a device that is used for measuring force, moment of force (torque), and power. For example, the power produced by an engine, motor or other rotating prime mover can be calculated by simultaneously measuring torque and rotational speed (RPM).
For the fuel consumption, we will conducted a fuel test by using a new tank provided by automotive lab. Unit to measure the fuel test is in liter/km. To measuring the emission rate, gas analyzer is used and the measurement unit is in concentration of gas which is parts per million (ppm).
1.10 SIGNIFICANT OF THE RESEARCH
This study will give better understanding and exposure about the operation in the engine cooling system and how it will effects the engine performance, fuel consumption and emission.
Reducing the fuel expenses by car users as the rate of fuel consumption reduced.
The expected output to reducing the emission will result in increased the air quality that is harmful to humans. It also will lead in reducing the air pollution rate and provide more safer environment for people.
The low cost car with good performance and low on fuel and emission rate also will be develop.
2.0 LITERATURE REVIEW
2.1 COOLING SYSTEM OPERATION
A huge amount of heat is generated in the internal combustion engines. It is created when the air fuel mixture is ignited inside the combustion chamber. The explosion that occur will causes the piston to be forced down inside the cylinder, levering the connecting rods and turning the crankshaft. The temperatures of the metal parts around the cylinder can exceed 2500oC. To prevent the components such as engine oil, cylinder walls, pistons, and valves from overheating, it is necessary to effectively dispose the heat. Approximately 30% of heat in the combustion process is lost into the atmosphere through the exhaust system, 35% is converted into power to drive the vehicle and the remaining 35% lost as heat through the cylinder walls .
Water pump is attached at the front of the engine and driven by a belt from crankshaft pulley. The impeller rotates and the curved blades draw liquid cooling from the bottom of the radiator and force it to flow through pump outlets and water jackets. The liquid cooling will flow through passageways in the engine block and cylinder head. Temperature in the combustion chamber can around 2500oC, so cooling around this area is critical to prevent overheat.
The areas around exhaust valve are especially crucial and almost all space inside the cylinder head around the valve that is not needed for structure filled with coolant. But when the engine is still cold, thermostat still close and the liquid cooling is circulated back to the engine. By closing the passage through radiator when engine is cold, the engine warms up more quickly. Engine heat stays in the engine instead of being carried to the radiator. This shortens warms up time, wastes less fuel and reduces exhaust emissions . After engine already heat up, the thermostat keeps the engine running at a higher temperature than it would without a thermostat. The higher operating temperature improves engines efficiency and reduces exhaust emissions .
2.1.1 EFFECT OF RADIATOR
A radiator usually known as heat exchanger. The hot coolant that flows through it will transfer the heat by the air blown through the aluminium fins by fan. Nowadays modern cars use aluminium radiators. It usually made by brazing thin aluminium fins to flattened aluminium tubes. Flow of the coolant is from inlet to the outlet through many tubes that mounted in parallel arrangement. These fins will conduct the heat from the coolant inside the tubes and transfer it through the air that flowing through the radiator.
A type of fin is inserted into the tube called turbulator. Its function is to increases the turbulence of the fluid flowing through the tubes. If the flowing of the fluid through the tubes is smooth, only the fluid that touching the tubes would be cool directly. The amount of heat transferred from the fluid to the tubes depends on the difference in the temperature between the tube and the fluid touching it. Therefore, less heat will be transferred if the fluid that is in contact with the tube cools down quickly. To prevent that, turbulence is created inside the tube and all of fluid mixes together. Keeping the temperature of the fluid touching the tubes up so that more heat can be extracted and all of the fluid inside the tube is used effectively.
2.1.2 EFFECT OF RADIATOR FAN
The function of radiator fan is to draw the air towards the radiator and helps to cool the hot coolant that flowing through the tubes. It usually has four or more blades that spin rapidly to provide sufficient air to that would cool the engine. The fan will be mounted between the radiator and the engine so that the air can easily flowing through the radiator. There are also additional fan in front of the radiator in some cars in order to draw more cool air to the engine especially when vehicle is not moving fast enough, very little cool air reaches the radiator and the engine is not cooled properly.
2.1.3 EFFECT OF PRESSURE CAP
The radiator cap or also known as pressure cap actually increases the boiling point of your coolant by about 25oC. The cap is a pressure release valve and usually is set to 15 psi. When the coolant is placed under pressure, its boiling point will increase. As the engine running, the cooling system will be heated up and increase the pressure. The only place where the pressure can escape is at the pressure cap. Therefore, the setting of the spring on the cap determines the maximum pressure in the cooling system.
If the pressure reaches 15 psi, it will push the valve open and allowing the coolant to escape from the cooling system. The flowing of the coolant is from overflow tube to into the bottom of the overflow tank. This kind of arrangement will keep air out of the system. After the radiator is already cools back down, a vacuum is created in the cooling system that pulls open another spring loaded valve while sucking the water back in from the bottom of the overflow tank to replace the water that was expelled.
2.1.4 EFFECT OF WATER PUMP
Water pumps are impeller pumps. They attached to the front of the engine and driven by a belt from the crankshaft pulley. As the impeller rotates, the curved blades draw coolant from the bottom of the radiator. The water pump only thrust to drive the circular flow of the coolant within the engine cooling system, so the inlet is the point of lowest pressure in the system and the exit point is the highest pressure. The pressure drops sharply at the inlet/outlet of the water pump during the operational of the water engines and this pressure drop will vary in proportion to the rotational speed. Water pumps in engines are prone to cavitation and air bubbles are likely to permeate in to antifreeze and will severely reducing the performance, reliability and service life of the engines. Cavitation means the cavities or bubbles are forming in the liquid that have been are pumping. These cavities form at the low pressure or suction side of the pump. For the well design engine cooling system, cavitation is less likely to take occur as the temperature of the coolant declines. But when the cavitation temperature is reached, the pressure of the water pumps drops abruptly and all the cooling system loses its functionality.
2.1.5 EFFECT OF THERMOSTAT
The main function of the thermostat is to allow the engine to heat up quickly and keep it at its efficient temperature. It control this by regulating the amount of water that goes through the radiator. The coolant in the cooling system starts to initiate by picking up heat at the water jackets. In the coolant circuit, the pressure gradient exist and causing the hot coolant flows out from the engine to the radiator or to coolant bypass passage . Once the temperatures of the coolant rises to 80oC, the thermostat starts to open. Different thermostat open at different temperatures and allowing fluid to flow through the radiator. The secret of the thermostat lies in the small cylinder located on the engine side of the device. Actually this cylinder is filled with wax that starts to melt at temperatures 80oC (depends on the thermostat). Then, a rod that is connected to the valve press into this wax. As the wax melts. It will expands and pushing the rod out of the cylinder and opening the valve.
2.2 EFFECT OF COOLANT
Coolant is the mixture of antifreeze and water in the cooling system. The commonly used antifreeze is Ethylene Glycol. This coolant will circulate through the cooling system. It will remove the waste heat from the engine and delivers the heat through the radiator hose to the radiator. It is not recommended to use only water as a liquid cooling because it would freeze if the temperature drop below 0oC. This would stop the circulation and the engine would overheat. As the water would expand 9% as it freezes, it would crack the cylinder block and head, split the radiator . By controlling the engine cooling system in a flexible way as compare to the conventional cooling system, it will improve the fuel consumption rate of spark ignition (SI) engines .
It is known from the cold start research that the coolant and inlet charge temperature are key parameters to reduce pollutant emissions and guarantee smooth engine operation. Cold start experiment were performed with coolant temperatures of 15oC and 80oC. In the steady state operation reached after the start, the piston surface temperature was respectively 110oC and 150oC. The HC emissions were 25% lower and the NOx emissions 7% higher with the higher coolant temperature. It seems to indicate that there is an influence of the coolant temperature on the emissions through the cylinder wall temperatures .
In the search for greater fuel economy and reduced emission output, the engine cooling system is being targeted for further improvements to engine performance through its effects on engine frictional losses. Fuel economy improvements from the changes to the engine cooling system are derived mainly from reduced engine frictional losses with increased oil temperature by raising the engine operating temperature indirectly through the step increase in the coolant temperature. Hydrocarbon (HC) and carbon monoxide (CO) output are also shown to decrease with the increase in operating temperature . There are also suggestion that higher cylinder block temperatures will reduce the frictional losses with the piston and ring pack and will lead to reducing fuel consumption .
But the increasing of operating temperature has a negative effect on nitrogen oxide (NOx) output as the formation of NOx in the combustion chamber can be highly sensitive to temperature changes .
There are some previous works in the engine cooling area focuses on to the fuel economy benefit to IC engines through the reduction engine frictional losses by raising the coolant temperature. As the coolant temperature increases, the cylinder block wall temperaturs also increases and will result in reducing the HC emissions . It concentrates mainly on gasoline engines where oil temperature is relatively lower and the tailpipe emissions are HC and CO. Fuel efficiency improvements about 10% are achieved in part load conditions by raising coolant temperature .
In this chapter, we will discuss about the procedures and entire activities to carry out in this whole project. The flow chart below will describe the steps that should be followed during this project. Basically there are 3 test that will be conducted that is dynamometer test, fuel test and emission test.
3.2 FLOW CHART
Select the type of liquid cooling and thermostat that will be used.
Preparation and Setup
Select the type of liquid cooling and thermostat that will be used.
Run the experiment
The experiment will be conducted to the conventional and modified cooling system.
TYPES OF METHODS
3.3.1 DYNAMOMETER TEST
Dynamometer is actually a device use to measuring force, moment of force (torque) and power produced by an engine or motor. We can see the example from the power produced by an engine, motor or other rotating prime mover can be calculated by simultaneously measuring torque and rotational speed (RPM). Nowadays dyno test become more easier to operate with the advance of the modern computer and produce more accurate results. A dyno that paired with the computer will display the power rating of a given machine as a figure below.
Figure 3.1 : Example Graph of Dynamometer Test
Actually dyno test is used for various applications but the most common one is automobile testing. Automobile manufacturers will measure the performance of a car or truck in order to market its power. Sports car will modified their vehicles with aftermarket parts in order to achieve higher power output and then run the dyno test to evaluate their modifications.
Dyno tests can be run in a couple of different ways which is chassis and engine dyno. When running a chassis dyno test, the vehicle to be tested is driven onto the dyno platform that simulates resistance through the use of automated wheels. For an engine dyno test, the engine to be tested is mounted to the dyno device. These different methods produce different measurements such as brake horse power and torque from a chassis dyno and flywheel horse power and torque from an engine dyno. Power is often lost through the drive train of a vehicle so the brake measurement will typically less than the flywheel measurement.
The model that will be used for dynamometer testing is Dynapack 3000. The components of Dynapack 3000 consists of computer, sensors hub adaptors controller and power absorption units. This test is a bit from other dyno test because of the elimination of the tire to roller interface on a conventional roller dyno. It eliminates this variable by using a hub adaptor that provides a direct coupling to our power absorption units. There will be no tire slip, no rolling resistance and no chance of the vehicle coming off from the dyno at high speeds.
For the theory of operation. Firstly the hubs of the vehicle are directly attached to hydraulic pumps. A variable load can be applied with all of the potential holding power that hydraulic possess. Figure below show that the wheels are removed from the vehicle and the variable fit hub adaptors are bolted to the vehicle axle. The hub adaptor is then directly attached to a hydraulic absorption unit.
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Figure 3.2 : Hub adaptor bolted to vehicle Figure 3.3 : Monitor of Dynapack 3000
3.3.2 FUEL TEST
For the fuel test, a new fuel tank is used to replace with the existing tank. The problem with the existing tank is the fuel consumption cannot be measured correctly. The new fuel tank will be connected using the hose from the fuel pump to the series of injectors at cylinder head. Gasoline or RON 95 will used in this fuel test. The example for the new fuel tank is shown in figure below and the fuel pump is already attached on top of it.
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Figure 3.4 : The new fuel tank
The test will be conducted according to the gears and revolution per minutes (RPM) that already been set. It is done to control the speed of the engine to get the accurate result of the fuel consumption without affected by the changing of gear on each test. The RPM and gears can be referred in the table below.
Table 3.1 : RPM for each of the gear
3.3.3 EMISSION TEST
Hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxide (NOx) are measured in parts per million (ppm). For this emission test, the device that will be used is the gas analyzer 95/3. The gun of this device will be placed into the tailpipe to measure the exhaust rate. The data will be taken during the various RPM that already been set up which is 2000 rpm, 3000 rpm and 4000 rpm. The result of this test will be recorded in this device.
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Figure 3.5 : Gas Analyzer 95/3
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