Winter has officially arrived, and it has snowed in many places, so it is necessary to drive with warm air; However, many vehicles will smell bad smell when using warm air. Where do these smells come from and how to solve them?
It is very normal that the air conditioning system of a car has an odor. As long as the air conditioner is used for one year, the smell will inevitably appear when using warm air. The reason is actually very simple. The first thing you need to know is the knowledge of "air conditioning water". Careful drivers will always find such problems. When the cold air conditioner is used at idle speed, a large amount of water will flow out in front of the chassis, which is the condensed water of the air conditioner.
basic knowledge
The principle of automobile air conditioning refrigeration seems complicated, but it is actually very simple. In short, it is two "heat conduction".
The refrigerant absorbs the heat energy of the evaporation box to cool the evaporation box.
The evaporation box absorbs the heat energy of hot air to cool it down.
After these two steps are completed, cold air will be produced. The so-called cold air is actually the air absorbed by the evaporation box. Condensed water also comes from air, because the higher the air temperature, the stronger the ability to carry water molecules, or the higher the humidity-water vapor will condense into liquid water when it is cold, and the evaporation box will reach the ideal standard for condensing water vapor after being cooled by refrigerant, so a large amount of condensed water will appear.
Figure 1: Refrigerant circulation process: the condenser cools the refrigerant, and after passing through the collision valve, the gaseous tetrafluoroethane (refrigerant) will become liquid; The boiling point of this refrigerant is below MINUS 28℃, and it will instantly boil and absorb heat in an evaporation box above zero.
Figure 2: Dynamic demonstration
Figure 3: Evaporation box structure (pay attention to drainage)
Note: the air humidity in the evaporation box will be very high, even if there are drainage holes; Therefore, low-temperature air will be sent into the car in a "high humidity" state, and at least a humid environment will be formed in the air conditioning duct.
Humid environment is the best environment for advanced mold, and the result can certainly be imagined, but it will also exceed the imagination of ordinary car users; Because in the evaporation box and inside the pipeline, the number of mold spores can reach more than 0/000 per square centimeter/kloc-,that is, there are many molds in a position the size of a small fingernail.
The key point is that these molds will also "metabolize", and mold decay will produce odor; Generally, there is fishy smell, earthy smell or sour taste, and there are different "smells" in different degrees.
But at this time, some people wondered why the smell was not obvious at the wettest stage of the pipeline in summer. In fact, the answer is very simple, because after turning on the cold air conditioning system, the temperature drops continuously.
The movement speed and intensity of molecules will be affected by temperature. For example, the tire pressure of long-distance driving will increase, because the high temperature generated by friction will enhance the movement intensity of air molecules. On the contrary, low temperature will reduce tire pressure. Similarly, low temperature will also reduce the movement intensity of odorous molecules, which is why they are not very sensitive to odor. At the same time, the air pressure will increase after the temperature drops. If the "air pressure difference" between lung pressure and atmospheric pressure is reasonable, you will feel naturally breathing. High temperature air will increase the pressure difference, and breathing will enhance the intensity and sensitivity.
High temperature smell, solution
There is no need to go into details about the causes of odor and the more serious reasons. In short, the high temperature strengthens the molecular movement, and the smell will obviously enter the car. However, have you noticed another phenomenon, that is, with the extension of car use time, the odor intensity of warm air will gradually decrease.
Many people think that this is difficult to detect after getting used to it, but in fact it is a wrong understanding; The main reason is that the continuous use of warm air conditioning and the internal temperature of the pipeline heated by the high-temperature water tank make the mold die. At the same time, the dry environment is not conducive to the growth of mold. The warm air conditioning system will not produce condensed water because the humidity of the external low-temperature air is very low. After passing through the high-temperature warm air tank, even some water vapor will be dried, so there will be less and less mold.
Low-cost solution: use the heating system itself for purification! The warm air of the car is a "water heating system", and the heat energy comes from the antifreeze coolant of the engine.
The temperature of antifreeze can reach above 90℃ in the hot car state, which is only the standard of idle speed; If driving continuously, the water temperature can be as high as 1 10℃. The temperature of the water tank will naturally be comparable to that of the antifreeze, otherwise the cold air cannot be "heated" in a short time (in fact, the low-temperature air absorbs the heat energy of the high-temperature water tank and heats up).
Then the air temperature in the pipeline will naturally be very high, and the air conditioning temperature will be adjusted to the highest and the air volume will be adjusted to the maximum in the hot car state; The standard of warm air is close to the level of killing mold. At this time, open the door and skylight, idle for about half an hour, and then clean the interior and seat; When you use the warm air conditioner again, you will always find that the odor is completely (or basically) gone.
This is a way to clean up the odor of air conditioners, which is better than using cleaning agents and the cost is much lower. The key is that it can be cleaned in this way every year when the heat and cold alternate, and the cleaning agent can only be used for one winter. Summer use is nothing more than the smell of detergent to cover up the odor.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.