The intercooler is generally only seen on cars equipped with a supercharger. Because the intercooler is actually a component of the turbocharger, its function is to reduce the temperature of the high-temperature air after supercharging, so as to reduce the thermal load of the engine, increase the air intake volume, and thereby increase the power of the engine. For supercharged engines, the intercooler is an important component of the supercharger system. Whether it is a supercharged engine or a turbocharged engine, an intercooler needs to be installed between the supercharger and the intake manifold. The following takes a turbocharged engine as an example to give a brief introduction to the intercooler.
One of the reasons why a turbocharged engine has more power than a normal engine is that its air exchange efficiency is higher than the natural intake of a normal engine. When the air enters the turbocharger, its temperature will rise significantly and its density will decrease accordingly. The intercooler plays the role of cooling the air. The high-temperature air is cooled by the intercooler and then enters the engine. If there is a lack of intercooler and the supercharged high-temperature air directly enters the engine, the engine will knock or even be damaged and stalled due to excessive air temperature.
Intercoolers are usually found on cars equipped with turbochargers. Because the intercooler is actually a supporting part of the turbocharger, and its function is to improve the ventilation efficiency of the turbocharger engine.
The function of the intercooler is to reduce the intake air temperature of the engine. So why should we lower the intake air temperature?
(1) The temperature of the exhaust gas discharged from the engine is very high, and the heat conduction through the supercharger will increase the temperature of the intake air. Moreover, the density of air will increase during the process of being compressed, which will also cause the temperature of the air discharged from the supercharger to increase. As the air pressure increases, the oxygen density decreases, thus affecting the effective charging efficiency of the engine. If you want to further improve the charging efficiency, you need to lower the intake air temperature. Some data show that under the same air-fuel ratio, engine power can increase by 3% to 5% for every 10°C drop in the temperature of the supercharged air.
(2) If uncooled supercharged air enters the combustion chamber, in addition to affecting the engine's charging efficiency, it can easily cause the engine combustion temperature to be too high, causing knocking and other failures, and it will also increase the NOx content in the engine exhaust gas. , causing air pollution.
In order to solve the adverse effects caused by the heating of the supercharged air, an intercooler needs to be installed to reduce the intake air temperature. .
(3) Reduce engine fuel consumption.
(4) Improve adaptability to altitude. In high-altitude areas, intercooling can use a compressor with a higher pressure ratio, which allows the engine to obtain more power and improves the adaptability of the car.
(5) Improve supercharger matching and adaptability.
Intercoolers are generally made of aluminum alloy materials. According to the different cooling media, common intercoolers can be divided into two types: air-cooled and water-cooled.
The air-to-air intercooler is installed together with the water tank radiator and is installed in front of the engine. It is cooled by the suction fan and the surface air of the car. If the intercooler is not cooled well, it will lead to insufficient engine power and increased fuel consumption. Therefore, , the intercooler should be inspected and maintained regularly. The main contents are:
exterior cleaning
Since the intercooler is installed at the front, the radiator channel of the intercooler is often blocked by leaves, sludge (hydraulic oil overflowing from the steering oil tank), etc., which blocks the heat dissipation of the intercooler, so this area should be cleaned regularly. The cleaning method is to use a water gun with a not too high pressure to flush slowly from top to bottom or bottom to top at an angle perpendicular to the plane of the intercooler, but never flush it at an angle to prevent damage to the intercooler. [1]
Internal cleaning and inspection
The internal pipes of the intercooler are often filled with sludge, colloid and other dirt, which not only narrows the air flow channel, but also reduces the cooling and heat exchange capacity. For this reason, maintenance and cleaning are also necessary. Generally, the inside of the intercooler should be cleaned and inspected every year or at the same time as the engine is overhauled or the water tank is welded and repaired.
Cleaning method: Add an aqueous solution containing 2% soda ash (the temperature should be 70-80°C) into the intercooler, fill it up, wait 15 minutes, and check whether there is any water leakage in the intercooler. If there is any, it should be dismantled, inspected, and repaired by welding (the same as repairing the water tank); if there is no water leakage, shake it back and forth several times, pour out the washing liquid, and then fill it with a clean aqueous solution containing 2% soda ash for flushing. Until it is relatively clean, add clean hot water (80-90℃) for cleaning until the released water is clean. If the outside of the intercooler is stained with oil, it can also be cleaned with alkaline water. The method is: soak the oil stain in the alkali solution and remove it with a brush until it is clean. After cleaning, use compressed air to blow dry the water in the intercooler or let it dry naturally, or when installing the intercooler, do not connect the connecting pipe between the intercooler and the engine, start the engine, and wait until there is no moisture in the air outlet of the intercooler. , and then connect the engine intake pipe. If serious dirt is found in the intercooler core, you should carefully check for leaks in the air filter and air intake pipelines, and eliminate the fault.
The biggest problem with the turbocharger is that the distance between the air inlet for sucking in fresh air and the high-temperature exhaust is very close, and the temperature of the fresh air sucked in will rise a lot after being compressed, so even if there is no high-temperature exhaust The affected supercharged engine also needs an intercooler to cool the intake air. The temperature of air will increase when it is compressed. The simplest example is the air pump that inflates tires. If you don't believe it, you can touch the air pump that is inflating and you will know how terrible the heat accumulated by air compression is. In addition, we can know from chemistry and physics knowledge that the lower the temperature, the higher the oxygen content in the air. Some people may ask: What does this have to do with? You know, fuel burning requires oxygen in the air. The more oxygen, the more oxygen it will have. More fuel is burned, resulting in more power. Friends who want to know more can refer to the relevant introduction in "Inhalation System". The intercooler is an efficient radiator whose main function is to cool fresh air before it enters the engine. You can imagine that the intercooler is located in front of the radiator tank, so it can be directly impacted by the cold air blowing from the head, and it is also located behind the air filter, turbocharger or supercharger. The actual situation is indeed like this. Most cars are equipped with an intercooler located in front of the radiator tank, and the cooling effect is indeed better than some overhead intercoolers. However, this will affect the heat dissipation to some extent. The airflow of the water tank is limited, so in some extreme situations, such as on the track, the water tank must be upgraded at the same time to control the engine temperature.
Using a well-designed intercooler can get an additional 5%-10% of power.
Some cars also use overhead intercoolers to obtain cooling air through the openings in the engine cover. Therefore, before the car starts, the intercooler will only be blown by some hot air blowing from the engine compartment, although the heat dissipation efficiency is affected. Impact, but because the intake air temperature will increase under such circumstances, the engine's fuel consumption will drop a lot, which also indirectly reduces the engine's working efficiency. However, for a powerful supercharged vehicle, too much power The unstable start caused by this situation will be alleviated in this case. Subaru's Impreza car series is a typical example of an overhead intercooler. In addition, the biggest advantage of the overhead intercooler layout is that it can effectively shorten the stroke of compressed gas to reach the engine.