The automobile radiator is composed of three parts: inlet chamber, outlet chamber and radiator core. The coolant flows inside the radiator core and the air passes outside the radiator. The hot coolant cools as it dissipates heat to the air, while the cold air heats up by absorbing the heat emitted by the coolant.
summarize
The radiator belongs to the automobile cooling system, and the radiator in the engine water cooling system is composed of three parts: inlet chamber, outlet chamber, main plate and radiator core.
The radiator cools the coolant that has reached high temperature. When the tubes and fins of the radiator are exposed to the airflow generated by the cooling fan and the airflow generated by the movement of the vehicle, the coolant in the radiator becomes cold.
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According to the direction of coolant flow in the radiator, the radiator can be divided into two types: longitudinal flow and cross-flow.
The structure of the radiator core is mainly divided into two categories: tube plate type and tube belt type
material
There are two main types of car radiators: aluminum and copper, the former for general passenger cars, the latter for large commercial vehicles
Automotive radiator materials and manufacturing technology are developing rapidly. Aluminum radiator with its obvious advantages in material lightweight, in the field of cars and light vehicles gradually replace the copper radiator at the same time, copper radiator manufacturing technology and process has been greatly developed, copper brazed radiator in passenger cars, construction machinery, heavy trucks and other engine radiator advantages are obvious. The radiators of foreign cars are mostly aluminum radiators, mainly from the perspective of protecting the environment (especially in Europe and the United States). In new European cars, the proportion of aluminum radiators is an average of 64%. From the perspective of the development of automobile radiator production in China, the aluminum radiator produced by brazing is gradually increasing. Brazed copper radiators are also used in buses, trucks and other engineering equipment.
structure
Automobile radiator is an indispensable part of automobile water-cooled engine cooling system, which is developing towards light, efficient and economical. The automobile radiator structure is also constantly adapting to new developments.
The most common structural forms of automotive radiators can be divided into DC type and cross-flow type.
The structure of the radiator core is mainly divided into two categories: tube plate type and tube belt type. The core of the tubular radiator is composed of many thin cooling tubes and heat sinks, and the cooling tubes mostly adopt flat and circular sections to reduce the air resistance and increase the heat transfer area.
The core of the radiator should have a sufficient flow area for the coolant to pass through, and it should also have a sufficient air flow area for a sufficient amount of air to pass through to take away the heat transferred by the coolant to the radiator. [1]
At the same time, it must also have sufficient heat dissipation area to complete the heat exchange between the coolant, air and heat sink.
The tubular belt radiator is composed of corrugated heat distribution and cooling pipe interarranged by welding.
Compared with the tubular radiator, the tubular radiator can increase the heat dissipation area by about 12% under the same conditions, and the heat dissipation belt is opened with a similar window shutter hole with disturbed air flow to destroy the adhesion layer of the flowing air on the surface of the dispersion zone and improve the heat dissipation capacity.
Car radiators are generally divided into water cooling and air cooling. The heat dissipation of air-cooled engines relies on the circulation of air to take away heat to achieve the effect of heat dissipation. The outside of the cylinder block of the air-cooled engine is designed and manufactured into a dense sheet structure, thereby increasing the heat dissipation area to meet the heat dissipation requirements of the engine. Compared with the most used water-cooled engine, the air-cooled engine has the advantages of light weight and easy maintenance.
Water cooling is the radiator radiator is responsible for cooling the coolant with the high temperature of the engine; The task of the pump is to circulate the coolant throughout the cooling system; The operation of the fan uses the ambient temperature to blow directly to the radiator, so that the high-temperature coolant in the radiator is cooled; A state storage tank that controls the circulation of the coolant is used to store the coolant.
When the vehicle is driving, dust, leaves, and debris are easy to accumulate on the surface of the radiator, blocking the cooling blade and causing the performance of the radiator to decline. In this case, we can use a brush to clean up, or we can use a high-pressure air pump to blow away the debris on the radiator.
The working principle is explained in detail
The main job of the cooling system is to dissipate heat into the air to prevent the engine from overheating, but the cooling system also has other important roles. The engine in a car works best at the right high temperature. If the engine gets cold, it will accelerate the wear and tear of the components, making the engine less efficient and emitting more pollutants. Therefore, another important role of the cooling system is to heat up the engine as quickly as possible and keep it at a constant temperature.
There are two types of automotive cooling systems:
Liquid cooling and air cooling. Liquid cooling The cooling system of a liquid cooled vehicle circulates liquid through pipes and channels in the engine. When the liquid flows through the hot engine, it absorbs heat, which reduces the temperature of the engine. After the liquid flows through the engine, it flows to the heat exchanger (or radiator), and the heat in the liquid is dissipated into the air through the heat exchanger. Air cooling Some early cars used air cooling technology, but modern cars hardly use this method anymore. Instead of circulating liquid through the engine, this cooling method dissipates heat from the cylinder through an aluminum sheet attached to the surface of the engine block. A powerful fan blows the aluminum sheets into the air to cool the engine. Because most cars use liquid cooling, there are a lot of pipes in the cooling system in the car.
After the pump delivers the liquid to the engine block, the liquid begins to flow in the engine channels around the cylinder. The fluid is then returned through the engine's cylinder head to the thermostat at the point where the fluid flows out of the engine. If the thermostat is turned off, the liquid will flow directly back to the pump through the pipes around the thermostat. If the thermostat is turned on, the liquid will first flow into the radiator and then back into the pump.
The heating system also has a separate cycle process. This cycle starts with the cylinder head and sends the liquid through the heater bellows and back to the pump. For cars equipped with an automatic transmission, there is usually a separate cycle process to cool the transmission fluid built into the radiator. Transmission fluid is drawn by the transmission through another heat exchanger in the radiator. Liquid cars can operate in a wide temperature range from well below zero degrees Celsius to well above 38 degrees Celsius.
Therefore, no matter what liquid is used to cool the engine, it must have a very low freezing point, a very high boiling point, and can absorb a lot of heat. Water is one of the most efficient liquids for absorbing heat, but its freezing point is too high for use in a car engine. The liquid used in most cars is a mixture of water and ethylene glycol (c2h6o2), also known as antifreeze. By adding ethylene glycol to water, the boiling point can be significantly increased and the freezing point reduced.
Whenever the engine is running, the water pump circulates the liquid. Similar to centrifugal pumps used in cars, the pump operates by centrifugal force to transport the liquid outside and continuously sucks the liquid from the middle. The inlet of the pump is located close to the center, so the liquid returning from the radiator can reach the pump blades. The pump blade sends the liquid to the outside of the pump, where it enters the engine. The fluid from the pump flows first through the engine block and cylinder head, then into the radiator, and finally back to the pump. The engine block and cylinder head have a number of channels that are cast or machined to facilitate liquid flow.
If the flow of liquid in these pipes is smooth, only the liquid in contact with the pipe will be cooled directly. The amount of heat transferred from the liquid flowing through the pipe to the pipe depends on the temperature difference between the pipe and the liquid touching the pipe. Therefore, if the liquid in contact with the pipe is cooled quickly, less heat will be transferred. By creating turbulence in the pipe, mixing all the liquids, keeping the liquids in contact with the pipe high to absorb more heat, so that all the liquids in the pipe can be used efficiently.
The transmission cooler is very similar to the radiator inside the radiator, except that instead of exchanging heat with the air, the oil exchanges heat with the coolant inside the radiator. Pressure tank cover The pressure tank cover can increase the boiling point of the coolant by 25 ° C.
The main function of the thermostat is to heat up the engine quickly and maintain a constant temperature. It is achieved by regulating the amount of water flowing through the radiator. At low temperatures, the outlet of the radiator will be completely blocked, that is, all the coolant will be recirculated through the engine. Once the temperature of the coolant rises to between 82 and 91 ° C, the thermostat opens, allowing the liquid to flow through the radiator. When the temperature of the coolant reaches 93-103 ° C, the thermostat will remain open.
The cooling fan is similar to a thermostat and must be controlled to keep the engine at a constant temperature. Front wheel drive cars are equipped with fans because the engine is usually mounted transversally, that is, the output of the engine faces one side of the car.
Fans can be controlled by thermostatic switches or engine computers, and these fans will turn on when the temperature rises above the set point. When the temperature drops below the set point, these fans will shut down. Rear-wheel drive cars with longitudinal engines are usually equipped with engine-driven cooling fans. These fans have thermostatically controlled viscous clutches. The clutch is located in the center of the fan and is surrounded by the air flow out of the radiator. This particular type of viscous clutch is sometimes more like a viscous coupler for an all-wheel drive car. When the car overheats, open all Windows and run the heater while the fan is running at full speed. This is because the heating system is actually a secondary cooling system, which can reflect the situation of the main cooling system on the car.
The heater duct system located in the dashboard of the car's heating bellows is actually a small radiator. The heater fan allows air to flow through the heating bellows before entering the passenger compartment of the car. The heater bellows are similar to a small radiator. The heater bellows draw hot coolant from the cylinder head and then return it to the pump, so the heater can operate with the thermostat on or off.
