Intercoolers

Intercoolers Abstract Intercoolers use the same principle used in the heat exchanger experiment. Intercoolers have a similar shape with a radiator, but it has a different function. The cooling process will be explained, as well as the advantages and disadvantages of the system. I will also discuss about how it can be improved. 1.0 Introduction: 1.1 What is an intercooler' Intercoolers are basically used in internal combustion engines which uses a turbocharger. A turbocharger consists of two main parts, the turbine (driven by the exhaust gasses of the engine), and the compressor (compresses the intake air of the engine). The intercooler is used to cool down the compressed air created by the compressor, which became hot due to the compression. Compression of the air is required to deliver more energy to the engine, since compressed air contains more oxygen molecules, thus, increasing the amount of fuel completely combusted, meaning more energy delivered. But the problem with compressed air is that it is hot, and may cause auto-ignition of the air fuel mixture, causing heat build-up in the engine, and also causing engine knock, leading to engine damage. The intercooler is then created and connected to the compressor of a turbocharger in order to cool the compressed air using the flow of air through the intercooler. This uses the same principle with the heat exchanger experiment as well as the free and forced convection experiment, using air as the moving fluid. 1.2 Convection Heat is exchanged between two flowing fluids in the intercooler’s system, the ambient air and the compressed engine intake air. The temperature difference between the ambient air and the compressed air causes heat transfer to occur. For intercoolers in fast moving cars, the air is cooled by forced convection, since the car is moving against the ambient air, and the compressed air is forced to move through the intercooler by the compressor. Heat transferred can be calculated using the following equation, which is according to the Newton’s Law of cooling: q= h. A. (Ts-T∞) The q signifies the amount of heat transferred, the h is the convection coefficient(depends on type of medium, speed of flow, and other factors), Ts is the temperature of the surface, and T∞ is the ambient temperature. Engineers designed the intercooler to have a large area to maximize the amount of heat transferred, thus providing cooler air for the engine. 1.3 Applications Most intercoolers are used in tuned racing cars, to maximize its performance. Performance is an important aspect of a car, but it has its limits. Before the intercooler was introduced, turbocharged cars face problems related with the high temperature compressed intake air, causing auto-ignitions of the air-fuel mixture, leading engine knocks, and worse, overheating. Once an engine overheats, the internal components are damaged permanently, for example melted pistons, causing the engine to be jammed. They figured out a way to remove heat from the compressed air, which is by cooling the intake air using intercoolers. Intercoolers not only improve the engine performance, it also reduces the engine’s temperature significantly. There are different types of intercoolers that exist, which are the front mounted intercoolers and the top mounted intercoolers. Front mounted intercoolers are mounted at the front of the bumper of the car, to maximize the airflow on the intercooler, but debris from the road is a main problem where it usually causes damage on the intercooler. The solution to this is the top mounted intercooler, where it is placed on top of the engine of a car, and hood scoops are created to force the airflow towards the intercooler. Not only in cars, marine engines like boat engines also uses intercoolers, where it is directly submerged inside the water, maximizing heat transfer from the intercooler. 2.0 Discussions Intercoolers play an important role in keeping the engine temperature low for turbocharged cars. However they have their own advantages as well as disadvantages. Advantages: * Prevent overheating of engine due to turbocharger. * Maximize the potential performance of an engine. * Less pollution since combustion is more complete (more oxygen molecules) * Increase the efficiency of the engine. Disadvantages: * More weight added to the car. * Cosmetic values (large intercoolers at the front bumper is not a nice view) * Higher maintenance cost. * Less engine space. 3.0 Recommendation There is still room for improvements for existing intercoolers: 1)Airflow: Since a better airflow would provide a better heat transfer, the best step to improve an intercooler is by increasing its airflow. Restricted airflow will cause choking in the air movement, thus decreasing the efficiency of an intercooler. 2) Fluid (coolant): Since air is usually used to cool compressed intake air, I think water could be used to remove heat from the intake air since water has a better convective coefficient, thus increasing heat transfer. However, we need to sacrifice and add a little more weight to the car, since we need to have pumps, and reservoirs inside the car to use this system. 3) Material: Most standard intercoolers are made of steel, but using materials that conduct heat better could make some difference, for example, using aluminum alloy to construct the intercooler. Not only that, aluminum also weighs lighter compared to steel, thus reducing weight of the car. 4) Cosmetic values: Large intercoolers at the front of the car maybe cool for some cars, but how about sporty European cars like a Ferrari' I am sure it would be such a disastrous look to have your Ferrari fitted with a big fat intercooler in front. For this, I think engineers could design ducts on the car that could scoop the air and lead them to a hidden compartment where the intercooler is placed. This way, the car would have increased performance without sacrificing its cosmetic values. 5) Shape of intercooler: Connected to the above topic, in order to fit a hidden intercooler inside a car, it cannot be shaped like the normal boxy intercoolers. Instead, we should try and fabricate a different shape that could fit easily inside the desired compartment, and still function properly as an intercooler. 6) Internal design of an intercooler Intercoolers usually have tubes inside them that channel the hot intake air, further breaking down into smaller tubes, to increase the area of convection. If the air flow inside the intercooler is slow, the air would flow in a laminar condition, making heat dissipation less, since only the air in contact with the surface would transfer heat. In order to prevent this, a layer of metal should be placed inside the tubes, to cause the air flow to flow turbulently, causing more air to make contact with the surface of the tubes, increasing heat transfer. 4.0 Conclusions Intercooler is an important part in a car that uses a turbocharger. The main function is to remove unwanted heat from the compressed intake air that could possibly damage the engine, using some principles that we learned from our laboratory experiments, which are the heat exchanger and the forced and free convection. The principles are simple yet interesting to see it applied in something that we use in our daily lives. Before this I did not even bothered to know why an intercooler is fitted on a car, but now, I know why it is fitted there. Knowing that it has something to do with what I learn in college makes it more interesting.