Question: Does
car antifreeze coolant need to be replaced in winter, and does it need to be adjusted for cross-regional self-driving? The winter of 2020 may be colder than in previous years, and the antifreeze of automobiles has become an important topic; the coolant used in internal combustion engines also has antifreeze functions, so they are collectively referred to as "antifreeze coolant" (hereinafter referred to as antifreeze). The antifreeze used in
family cars is mostly EG-glycol water-based, and the main components are ethylene glycol and water; the reason is that the manufacturing cost of this chemical raw material is the lowest, and the fluidity is compared with propylene glycol and glycerol (glycerin) Be ideal. At the same time, mixing with water in a ratio of 6:4, the lowest freezing point that can be achieved is ﹣48.3℃, which basically ensures that the antifreeze in the area where you can drive will not freeze, but the antifreeze standards used in different areas are different Oh.
Inspection method
antifreeze mainly uses distilled water or deionized water, but no matter which kind of water, the cost is much lower than EG; and the winter minimum temperature in different regions has a big difference, such as the experience in Fujian, Yueqiong It's less than freezing point, but it can be as low as minus 20 or 30 degrees in Heijiliao.
Therefore, the proportion of EG in the antifreeze coolant used in the southern region will be very low, and the freezing point of the mixed solution can reach -10/20℃. It is enough; while the antifreeze used in the northern region will have a higher EG If the self-driving span is too large, it is necessary to adjust according to the minimum temperature of the target area. For example, some vehicles have been used in the south for a long time, but they will drive to the north during the return trip in winter. If they are not adjusted, it will inevitably freeze.
Key point: If the antifreeze is replenished with distilled water for a long time, it is best to mix the same type of antifreeze once in winter; the internal combustion engine will cause the normal evaporation of the antifreeze, and the main component of evaporation loss is water molecules, but EG has poor volatility but also Not that it will not decrease. Therefore, it is generally recommended to fill up with distilled water three times, and then add another antifreeze according to the consumption; otherwise, the decrease in the ratio will cause the freezing point temperature to rise.
On the contrary, if the cooling is added at a high frequency instead of distilled water, it is also important to add water again; because the main loss is water, adding antifreeze will reduce the proportion of distilled water. But as long as the proportion of EG exceeds 60%, the freezing point temperature will also increase.
Question: Is car antifreeze really afraid of freezing? The answer is obviously yes, because when the engine is started after freezing, the antifreeze fluid cannot flow in the cylinder head normally, that is, it cannot cool the cylinder head; the work temperature is over 1,000 degrees, and the antifreeze is not used regularly. Circulation, the body material will inevitably be damaged.
At the same time, if the antifreeze fluid freezes, the heat dissipation tank and pipe storing the antifreeze fluid are likely to be broken-because the water will expand when it freezes!
Interesting knowledge
water conforms to the law of "thermal expansion and contraction" in an environment above 4°C, but when it falls below this standard and freezes, the volume will not shrink, but will expand and become larger. The principle of
thermal expansion is well understood. Heat energy will increase the intensity and frequency of molecular motion; that is, water molecules will vibrate and collide with high frequency, and the distance of water molecules will increase after the collision degree is increased. It is understandable For each water molecule, more space is needed to "irregularly swing". Therefore, the volume of the heated water vapor will be very large, and the water conforms to the principle of "thermal expansion" in a high temperature environment.
The cold shrinkage above four degrees is also easy to understand. After the heat energy is reduced, the frequency and degree of air movement decrease, and the water molecules are not so "mutually repulsive"; instead, the water molecules are held together in a more "dense" state with gaps. Of course, the shrinkage will reduce the volume of water.
Problem: Water molecules include two hydrogen atoms and one oxygen atom. Hydrogen atoms are positively charged, while oxygen atoms are negatively charged, so H20 can form water molecules firmly. But these water molecules will not be completely separated separately, because the hydrogen atom of the water molecule will "attract" with the oxygen atom of another water molecule, and will become a hydrogen bond-associated water molecule after being attracted.
When the water is still in a liquid state, the water molecules will be connected like a spider web, but the structure is still irregular. After all, the state of water molecules is not stable enough, but it will change after freezing. The temperature drop of
will make the water molecules become more "lazy", that is, enter a very stable state; at this time, there are a large number of hydrogen bond groupsThe resulting associated water molecules will also tend to reach a stable structure, that is, the hexagonal crystal lattice. This arrangement expands the gap between the molecules. Specifically, when water turns into ice, it is an increase in volume; so if the antifreeze in the car's water tank freezes, the expansion of the main component of water may break the water tank. This is It is recommended to check the cause of the antifreeze.
(the picture below shows the frozen antifreeze)
This article comes from the author of the car home and does not represent the viewpoint of the car home.
