Antifreeze also has the following advantages:
The first is anti-corrosion. The engine and its cooling system are made of metal, copper, iron, aluminum, steel and solder. These metals come into contact with water at high temperatures and can corrode and rust over time. Antifreeze not only does not cause corrosion to the engine cooling system, but also has anti-corrosion and derusting functions.
The second is the high boiling point of the antifreeze. The boiling point of water is 100 ° C, and the boiling point of high-quality antifreeze coolant is usually 110 ° C above zero, so that in summer, antifreeze coolant is more difficult to open than water.
The third is that antifreeze can prevent scale. Water is the coolant. The most headache for the driver is the scale problem. The scale adheres to the metal surface of the water tank and the water jacket, which makes the heat dissipation effect worse and worse, and it is difficult to remove. The high-quality antifreeze is made of distilled water and is added with anti-scaling additives. It not only has no scale but also has descaling function. Of course, if your tank is very thick, it is best to wash it thoroughly with a tank cleaner before adding antifreeze.
A low freezing point cooling liquid formulated with an antifreeze is added to the cooling water of the water-cooled engine. When the temperature is lower than 0 °C, the use of antifreeze can prevent the cooling system failure and the parts from cracking caused by the freezing of the cooling water, and it can also save the water after the car is discharged and the water is added before the vehicle is discharged.
The requirements for antifreeze performance are: high boiling point and flash point; large specific heat and conductivity; low viscosity at low temperature, low vapor pressure, not easy to foam; no corrosion of metal parts in cooling system and rubber hoses and gaskets Deterioration.
Antifreeze is generally divided into three types: ethanol-water type, glycerin-water type and ethylene glycol-water type. Ethanol has a freezing point of -114 ° C and a boiling point of 78.3 ° C. Ethanol is easy to catch fire and easy to evaporate. Its content should not exceed 40% when it is formulated. It should not be used in diesel engine cooling system with high working temperature. Glycerol (glycerol) has a freezing point of -17 ° C, a boiling point of 290 ° C, and a freezing point of -46.5 ° C after mixing with water. When the content of glycerin in the water is relatively large, the low freezing point antifreeze can be obtained, which is uneconomical to use. The freezing point of ethylene glycol is -11.5 ° C, the boiling point is 197.4 ° C, and the freezing point after mixing with water can be as low as -68 ° C. Ethylene glycol is easy to corrode metals. When antifreeze is formulated, anti-corrosion agent should be added. Generally, 2.5-3.5 g of disodium hydrogen phosphate and 1 g of dextrin are added per liter of antifreeze. The glycol is highly hygroscopic and the storage container should be sealed. Ethylene glycol is not volatile, and it is used in a small amount, so it is widely used. Various antifreezes have a large thermal expansion and can only be added to 95% of the total capacity of the cooling system when filling. When formulating antifreeze, the freezing point should be 5 °C lower than the lowest temperature in the area of use.