The working principle of heating and air conditioning system, the correct circulation and other matters needing attention when the car is used in windshield mode in winter
How to correctly use the air conditioning system for automobile heating and how to quickly increase the warm air temperature? If you are interested in these two questions, let's take a look at the heating principle of fuel vehicles first.
The so-called warm air is actually "heated air", or it is understood that the air absorbs heat energy and heats up; If you want to warm up, you need to provide heat energy for the air blown by the blower, which comes from the operation of the internal combustion engine. There is no doubt that doing work will produce light energy and heat energy, which can be explained by striking matches. Only about 30% of this heat energy will be converted into power, and most of the rest will be converted into other forms, including heating antifreeze coolant.
Knowledge point 1: When gasoline burns, the flame temperature can reach 1200℃, and diesel oil exceeds 600℃. This shows how high the temperature is in the combustion chamber of the engine. Without temperature control and heat dissipation, the steel in the engine block is easy to melt.
The correct cooling methods are water cooling and air cooling. Air cooling is mainly used to cool radiator water tank, and electric fan is used to cool car body from outside to inside. However, the core is the antifreeze coolant flowing in the cylinder head and engine block. When this solution flows to the cylinder head, it will quickly absorb heat energy. After heating, it flows to the radiator water tank, and is absorbed by heat energy to cool down, so that the engine keeps a constant temperature and at the same time makes warm air.
2. The warm air of the car comes from the heated antifreeze coolant. Just adjust the knob of the empty panel or press the button, set the temperature to the high temperature standard, and then turn on the air volume adjustment switch; At this time, the valve in the pipeline will open, and the high-temperature antifreeze will flow into the "Xiao Nuan Water Tank".
Will the water tank reach the same temperature as the coolant after absorbing heat energy? The answer is yes, but don't worry about high temperature. Because the blower will constantly blow low-temperature air outside the water tank, and the air will absorb the heat energy of the water tank. So far, warm air has been generated by two exchanges, and the temperature of the system has been controlled, so it is easy to understand how to get warm air quickly.
Operate the engine correctly and drive normally after starting!
When the car is cold started in a low temperature environment, the body and antifreeze coolant will drop to the same low temperature standard as the ambient temperature. At this time, even if the warm air is turned on, it is useless, because the antifreeze does not have enough heat energy to be absorbed by the water tank, and the air from the blower flows through the water tank and has no heat energy to be absorbed, so the air actually blown into the car is still cold air.
Therefore, in order to quickly raise the temperature, it is necessary to accelerate the temperature rise of antifreeze, and the basis of heating antifreeze is the combustion work of internal combustion engine; Even if the idle speed of the car is around 1200rpm (cold start standard), the actual work is only 600 times per minute, because the crankshaft of a four-stroke engine only does work once every two revolutions. It is difficult to heat antifreeze quickly at this working frequency, but the average speed of about 2000 rpm during normal driving can improve the efficiency, which is why if you want to get warm air quickly, you need to start driving immediately.
No matter what consideration, there is no need for cold start, and the hot car is in place.
Key points: it will be difficult to drive in low temperature environment, especially when the leather seat is still cold; At this time, the seat needs to be equipped with "electric heating", and the anti-freezing heating efficiency is relatively slow, but the wire with high temperature generated by electronic collision of high-resistance conductors heats up quickly.
Generally, it will feel very warm after two or three minutes of driving, while the power consumption on the stage is generally only 50/70 watts. In other words, the battery will not lose power after a few minutes of use, and the power consumption after constant temperature is only twenty or thirty watts. Therefore, the correct way to use cars in winter should be electric heating seats. When the vehicle is not so cold, start the engine and drive normally. Vehicles without this configuration can consider installing electric heating seat covers, with basically the same power consumption and relatively low cost.
Note: You don't need to turn on the [A/C] switch when using the heating and air conditioning system!
The heat energy of automobile heating and air conditioning system comes from antifreeze, and there is no need for compressor in the whole process. The air conditioner switch is used to turn on or off the compressor, which is used to drive the "refrigerant" to circulate in the pipeline.
At present, tetrafluoroethane is generally chosen as the refrigerant in the industry, which will boil below 28℃. Then, gaseous tetrafluoroethane flows in the pipeline after being pressurized by the compressor, and will become a liquid with lower temperature after being adjusted by the condenser and expansion valve.
And finally flows to the evaporation box in the form of liquid. If the temperature of the box exceeds zero, it is equivalent to far exceeding the boiling point of the substance. Instantaneous boiling will absorb the temperature of the box to cool it down, blow out the outside hot air through the low-temperature evaporation box, and realize the cooling (refrigeration) of the air by absorbing the heat energy of the evaporation box. This is the role of the compressor-heating is completely unnecessary.
Therefore, there is no need to turn on the compressor when driving in winter, unless it wastes fuel, which has no other significance; This is the basic usage of heating and air conditioning system. Next, we need to know the choice of circulation mode and air outlet.
Adjust the mode of internal and external circulation, switch the air outlet, use external circulation when driving long-distance buses, and use internal circulation when driving short distances; Because the internal circulation only draws empty air from the car through the blower, and sends it into the car after heating or cooling. The air quality will decrease linearly with the driving time, because the CO2 concentration in the inhaled air is only ≤0.03%, but the exhaled air can be increased by hundreds of times.
The increase of CO2 concentration will reduce the oxygen concentration in the inhaled air, so with the increase of this molecular ratio, cars driving long distances will be sleepy due to lack of oxygen.
Warm air is easy to make people sleepy, because after the temperature rises, the skin and capillaries are in a "soothing" non-tense state, the demand for blood on the body surface increases, the blood supply to the brain will also decrease accordingly, and the excitement and stimulation signals of the central nervous system will also weaken. This is the truth that "spring is sleepy and autumn is sleepy, and winter is short of summer air". Then, if the car artificially creates a warm environment, coupled with the reduction of oxygen concentration, and the car is not allowed to exchange with the outside air (using external circulation), the driving safety factor will be reduced.
(After arriving at the hot car, the external circulation can also effectively control the temperature inside the car. )
Important: Suggested options for outlet air.
Long-distance driving-long-distance wind with feet-short-distance feet and front gear-feet and upper body
The density of warm air inside the car is lower than that of empty air inside the car, because the humidity of empty air inside the car is high. Breathing, for example, exhales water vapor. The humidity of the cold air outside is very low, and it will dry after passing through the high-temperature water tank, so the air entering the car will be quite dry; Pushing your face for a long time will make your nose uncomfortable.
Therefore, the correct way should be to blow out the air under your feet, and the low-density warm air will automatically rise to a high place; Therefore, the air outlet at this position can effectively heat the whole vehicle without feeling dry.
Fogging on the front bumper is the biggest headache when driving in winter, because the moving car will quickly cool the front bumper because of the cold air outside, and the humidity of the air inside the car will increase with breathing, and the airflow inside the car will condense into fog when it hits the front bumper.
At this time, if you turn on the air conditioner and use cold air to remove fog, the effect will be very good, but it will fog soon after it is turned off. Driving in winter can't always turn on the air conditioner, and it won't waste oil and affect the experience. So when preparing for long-distance driving, turn on the warm air first, and then turn it on when the water temperature is not high enough. At this time, the warm air is not warm, but it is not cold at all-adjusting the windshield to the foot and the front bumper, and slowly raising the temperature of the front bumper can effectively prevent fogging, and at the same time, the warm air can also play a role in dispersing the contact between high humidity air in the car and the front bumper.
Summary: The above is all the precautions about using warm air conditioning. The adjustment of the air outlet can be felt by yourself. The so-called "cold comes and summer goes", generally, when your feet are warm, you will feel warm all over.
There are not many other precautions, mainly to check that there is not too little antifreeze coolant, even if it is lower than the MIN line of the kettle; At the same time, we should pay attention to whether extreme low temperature will exceed the freezing point limit of antifreeze. This winter may be colder than usual.
Million car purchase subsidy