A radiator is a part of a car that is installed in the engine compartment. It provides constant engine cooling.
How does it work, what is it for, what types of radiators are there, why does it fail, how to care for it and how to choose the best modification? Let's deal with all the nuances in more detail.
General concepts, purpose
During the operation of the vehicle, all its mechanical components heat up. In some compartments, this figure reaches more than one hundred degrees. And the main unit, which will quickly fail due to high temperatures, is the motor.
The moving parts of the engine must be cooled to prevent deterioration. For this, the engineers of each car manufacturer develop and install a cooling system.
The cooling radiator is a metal heat exchanger filled with antifreeze (or antifreeze) inside. Rubber pipes are connected to it, which are attached to the corresponding motor necks.
Motor cooling works according to the following principle. The started internal combustion engine rotates the impeller of the water pump. Thanks to this, antifreeze begins to circulate in the system (in a small circle). When the temperature of the liquid reaches 80-90 degrees, the thermostat is triggered and a large circulation circle opens. This allows the engine to warm up faster to the desired temperature.
The following 3D animation clearly demonstrates how the system works:
What is it for in the car
The car engine works by burning fuel in the cylinders. As a result, all parts become very hot. When the temperature of the metallic elements rises, they expand. If they are not cooled, this will lead to various problems in the power unit, for example, cracks in the cylinder head, in the cooling jacket, cylinder head deformation, excessive thermal expansion of the pistons, and so on. Ignoring such problems will lead to expensive ICE repairs.
To stabilize the temperature, everyone internal combustion engines in their design they have a cooling jacket through which liquid circulates with the help of a pump. The heated antifreeze is fed through the highway to the car's radiator. In it, the liquid is cooled, and then flows back to the engine. This process allows you to maintain operating temperature of the internal combustion engine.
If there was no radiator in the design of the cooling system, the liquid in it would quickly boil. In the car, this part is installed in the front of the engine compartment. This is necessary so that more cold air enters its plane.
The efficiency of heat exchangers depends on the following factors:
- the number of tubes - the more there are, the better the antifreeze will cool;
- cross-section of tubes - oval shape increases the area of contact with air, which increases heat transfer;
- forced airflow - especially useful in urban driving mode;
- cleanliness - the more debris there is between the fins of the heat exchanger, the more difficult it will be for fresh air to get onto the hot pipes.
The material from which car radiators are made is metal (aluminum or copper). The walls of the heat exchanger are very thin, due to which the antifreeze quickly gives off its temperature and cools.
The design of the radiator consists of thin tubes welded together in the shape of a rectangle. This element is mounted on two tanks (one at the inlet, the other at the outlet). Additionally, plates are strung on the tubes, which increases the heat transfer area. Air flows between the ribs and quickly cools the surface of the part.
All heat exchangers have two openings: inlet and outlet. The system pipes are connected to them. To drain the liquid from the cavity, the heat exchanger is equipped with a plug installed at the bottom of the structure.
If the car is driving on a highway, there is enough air flow to cool the antifreeze naturally (blowing the ribs). In the case of city traffic, the air flow is less intense. For this, a large fan is installed in the cooling system behind the radiator. In older car models, it was directly driven by a motor. Modern cars are equipped with an antifreeze temperature control system and, if necessary, includes forced airflow.
How radiators are made - see the following video:
There are several types of heat exchangers. Each of them is designed for its own purpose, but they work according to the same principle - a liquid circulates inside them to ensure the exchange of heat. Heat exchangers are used in the following vehicle systems:
There are two categories of radiators most commonly used in the automotive industry.
- Tubular lamellar. This is the most common modification found on older cars. The heat exchanger in them consists of horizontally located tubes (circular section), on which thin plates are threaded. Most often they are made from an aluminum alloy. These modifications were installed on older vehicles. The main disadvantage is poor heat transfer due to the small area of contact with the air flow.
- Tubular tape. They use long tubes (oval section), folded in the form of a coil. The material that is used for their manufacture is either an alloy of copper and brass, or aluminum. Such modifications are installed in many modern cars. Copper models have excellent thermal conductivity, but are very expensive. Therefore, the cooling system is often equipped with aluminum counterparts.
Among the first category, there are two more types of radiators. These are single-pass and multi-pass models. They differ from each other in the principle of circulation.
- One-way. Coolant enters the heat exchanger cavity from one side and is evenly distributed over all tubes. They have a significant drawback: the antifreeze in the cavity is distributed unevenly, due to which the efficiency of heat exchange is lost.
- Multi-pass. The cooling elements are divided into several sections. This design increases the overall length of the line, which improves the heat transfer process.
Damage to radiators: causes, prevention
Like any part, the radiator in the car can also fail. Here are five main reasons.
- Mechanical damage. Since this part is installed in front of the vehicle, foreign objects often fall on it. For example, it can be stones from a car in front. Even a minor collision from a car can damage the radiator, compromising the tightness of the cooling system.
- Metal oxidation. Although all elements of the heat exchanger are made of stainless materials, the radiators are not protected against scale build-up inside their cavities. Due to the use of low-quality coolant, metal parts of the motor can oxidize, which clogs the line and prevents the free circulation of antifreeze.
- Natural wear and tear. Constant heating and cooling leads to "fatigue" of the metal, which reduces its strength. Vibrations in the engine compartment destroy the connecting seams, which can lead to leakage.
- Excessive line pressure. If a poor-quality plug is installed on the expansion tank, over time, the pressure relief valve stops functioning. Due to the heating of the antifreeze to a temperature above 100 degrees, the volume in the system increases. Most often, seams on plastic elements diverge. But the walls of the old heat exchanger become thinner over time, which leads to depressurization and leaks.
- Coolant freezing. This can happen in the case of using the wrong antifreeze or plain water. In the cold, water crystallizes and expands. From this, cracks appear on the walls of the tubes.
Most of these problems can be prevented by applying preventive methods. To prolong the service of the radiator, the owner of the car can take the following measures.
- Do not fill the system with normal water. In an emergency, you can use distilled, but in the near future you need to change it to antifreeze. This liquid boils at temperatures above 115 degrees. In addition, it contains lubricant, which has a beneficial effect on the pump impeller and other metal parts of the system.
- Change the antifreeze in a timely manner, and when the level decreases, top up it. Replacement must be done at least 50-70 km. mileage (for antifreeze, this interval is from 000 thousand). But if the coolant has changed its color and turned black, this is a clear signal for system maintenance.
- Install a radiator made for the given car model.
- Perform routine maintenance on the entire cooling system.
- Keep the fins of the heat exchanger clean.
- During the replacement of the antifreeze, periodically flush the inner walls of the coil.
Which is better: repair or change
All motorists can be roughly divided into two categories. The first believe that a failed part needs to be replaced with a new one. The latter are sure that everything can be repaired. And fixing radiators is a frequent topic of controversy.
The Internet is replete with all kinds of advice on how to fix the leak yourself. Some use special compounds. Others fill the system with crack bridging agents. Sometimes some methods help to prolong the life of the part for a while. But in most cases, these techniques only clog the cooling system.
It makes sense to repair copper models, because they are easy enough to solder. In the case of aluminum analogs, the situation is different. They can be soldered, but this will involve expensive welding. Therefore, the cost of repairing a leaking radiator will be almost identical to the price of a new part. It makes sense to agree to this procedure only in the case of an expensive heat exchanger model.
In most cases, repairs are only a temporary measure, because high pressure constantly builds up in the cooling system, which will lead to repeated depressurization of the line. If you carry out timely maintenance and cleaning of the system, you will often not need to change the radiator. Therefore, when a part breaks down and precious coolant poured onto the ground, it is better to replace this unit than to constantly throw away money to purchase another canister.
How to properly operate?
One of the most important conditions for the correct operation of the radiator is to keep it clean and to prevent excessive pressure in the system. The second factor depends on the expansion tank cap.
The first procedure can extend the life of this component. However, it must be done correctly.
- The manufacturer categorically prohibits the reuse of used coolant. Even if you clean it, it has already lost its properties, and therefore it will already be useless.
- If the antifreeze is very dirty, before pouring a new one into the system, it must be rinsed with distilled water (in no case use ordinary water). It does not contain salts and impurities that can build up inside the coil and reduce the cooling efficiency.
- When cleaning the outside, it is important to take into account that the fins of the heat exchanger are very thin and therefore even slight forces can bend them. Subsequently, this will prevent the natural airflow of the radiator pipes. If the procedure is performed using a mini-washer, you need to set up a small head. The jet should be directed perpendicular to the fins to prevent accumulated dirt from moving into the heat exchanger. Then it cannot be purified in any way.
Which radiator is better?
In most cases, the answer to this question depends on the material capabilities of the motorist. Copper-brass models lend themselves to inexpensive repairs. Compared with aluminum analogs, they have better heat exchange properties (the heat transfer coefficient of copper is 401 W / (m * K), and of aluminum - 202-236). However, the cost of a new part is very high due to the price of copper. And one more drawback is its large weight (about 15 kilograms).
Aluminum radiators are cheaper, they are lighter in comparison with copper versions (in the region of 5 kg.), And their service life is longer. But they cannot be properly repaired.
There is another option - buy a Chinese model. They are much cheaper than the original part for a particular car. Only the main problem with most of them is their short service life. If an aluminum radiator copes with its functions for 10-12 years, the Chinese analogue is three times less (4-5 years).
For details on breakdowns and maintenance of radiators, see the following video: