Intercoolers are usually only seen in cars with superchargers installed. Because intercoolers are actually a supporting part of turbocharging, their function is to reduce the temperature of high-temperature air after supercharging, reduce the heat load of the engine, increase the intake volume, and thus increase the power of the engine. For supercharged engines, intercoolers are an important component of the supercharging system. Whether it is a mechanical supercharged engine or a turbocharged engine, an intercooler needs to be installed between the supercharger and the intake manifold. The following is a brief introduction to intercoolers using a turbocharged engine as an example.
Why do turbocharged engines have greater power than ordinary engines? One of the reasons is that their ventilation efficiency is higher than the natural intake of ordinary engines. When air enters the turbocharger, its temperature will increase 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 no intercooler and the high-temperature air after supercharging enters the engine directly, the engine will detonate or even be damaged and stalled due to the high air temperature.
Intercoolers are usually found in cars with turbochargers installed. Because the intercooler is actually a supporting part of the turbocharger, and its function is to improve the ventilation efficiency of the turbocharged engine.
The function of the intercooler is to reduce the intake temperature of the engine. So why do we need to reduce the intake temperature?
Function
The function of the intercooler is to reduce the intake temperature of the engine. So why do we need to reduce the intake temperature?
(1) The temperature of the exhaust gas discharged by the engine is very high, and the heat conduction through the supercharger will increase the temperature of the intake air. In addition, the density of the air will increase during the compression process, which will also cause the temperature of the air discharged by the supercharger to increase. As the air pressure increases, the oxygen density decreases, thereby affecting the effective charging efficiency of the engine. If you want to further improve the charging efficiency, you must reduce the intake temperature. Data show that under the same air-fuel ratio conditions, the engine power can be increased by 3% to 5% for every 10°C drop in the temperature of the supercharged air.
(2) If the uncooled supercharged air enters the combustion chamber, in addition to affecting the engine's charging efficiency, it is also easy to cause the engine combustion temperature to be too high, causing faults such as knocking, and increasing the NOx content in the engine exhaust gas, causing air pollution.
In order to solve the adverse effects caused by the temperature rise of the air after supercharging, it is necessary to install an intercooler to reduce the intake temperature. .
(3) Reduce engine fuel consumption.
(4) Improve adaptability to altitude. In high-altitude areas, the use of intercoolers can use compressors with higher pressure ratios, which enables the engine to obtain greater power and improves the adaptability of the car.
(5) Improve the matching and adaptability of the supercharger.
Classification
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.
Maintenance method
The air-to-air cooling intercooler is installed together with the water tank radiator, installed in front of the engine, and cooled by the suction fan and the wind 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 checked and maintained regularly. The main contents are:
External cleaning
Since the intercooler is installed at the front, the intercooler radiator channel is often blocked by leaves, sludge (hydraulic oil overflowed from the steering tank), etc., which hinders the heat dissipation of the intercooler. Therefore, it should be cleaned regularly. The cleaning method is to use a water gun with a pressure that is not too high to slowly flush from top to bottom or from bottom to top at an angle perpendicular to the plane of the intercooler, but never flush obliquely to prevent damage to the intercooler.
Internal cleaning and inspection
The internal pipes of the intercooler are often attached with dirt such as sludge and colloid, which not only narrows the air flow channel, but also reduces the cooling heat exchange capacity. For this reason, maintenance and cleaning are also required. Generally, the interior of the intercooler should be cleaned and inspected every year or when the engine is overhauled or the water tank is welded.
Cleaning method: add a 2% aqueous solution of soda ash (temperature should be 70-80℃) into the intercooler, fill it up, wait for 15 minutes, and see if there is any water leakage in the intercooler. If there is, it should be disassembled and inspected, and welded and repaired (same as repairing the water tank); if there is no water leakage, shake it back and forth, repeat several times, pour out the washing liquid, and then fill it with a clean aqueous solution containing 2% soda ash to rinse until it is relatively clean, and then add clean hot water (80-90℃) to clean 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 oily part in the alkaline solution and use a brush to clean it until it is clean. After cleaning, use compressed air to blow dry the water in the intercooler or dry it naturally, or when installing the intercooler, do not connect the intercooler and the engine connecting pipe first, start the engine, and when there is no water at the intercooler outlet, connect the engine intake pipe. If the intercooler core is found to be seriously dirty, the air filter and the intake pipes should be carefully checked for leaks and the faults should be eliminated.
The biggest problem with the turbocharger is that the air intake for fresh air is very close to the high-temperature exhaust, and the temperature of the fresh air sucked in will increase a lot after being compressed, so even a supercharged engine without the influence of high exhaust temperature needs to cool the intake air through the intercooler. The temperature of air will increase when it is compressed. The simplest example is the air pump that inflates the tire. 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 know from the knowledge of chemistry and physics that the lower the temperature, the higher the oxygen content in the air. Some people may ask: What does this have to do with it? You know, what fuel combustion needs is oxygen in the air. The more oxygen, the more fuel can be burned, thus generating more power. Friends who want to know more can refer to the relevant introduction in "Intake System". The intercooler is an efficient radiator, and its main function is to cool the fresh air before it enters the engine. You can imagine that the intercooler is located in front of the radiator, so it can be directly impacted by the cold air blowing from the front, and it must also be located behind the air filter, turbocharger or supercharger. The actual situation is indeed like this. Most cars are equipped with intercoolers located in front of the radiator, and the cooling effect is indeed better than some top-mounted intercoolers. However, this will more or less affect the airflow blowing to the radiator, so in some extreme cases, such as on the track, the radiator must be upgraded at the same time to control the engine temperature.
Working principle
Using a well-designed intercooler can get an additional 5%-10% power.
Some cars also use top-mounted intercoolers, which get cooling air through the openings on 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, the intake temperature will increase under such circumstances, so the fuel consumption of the engine will decrease a lot, which also indirectly reduces the working efficiency of the engine. However, for powerful supercharged cars, the unstable start caused by excessive power will be alleviated in this case. Subaru's Impreza series is a typical top-mounted intercooler. In addition, the biggest advantage of the top-mounted intercooler layout is that it can effectively shorten the journey of compressed gas to the engine.