Why does the car exhaust pipe drip with the warm air?

The dripping of the exhaust pipe has nothing to do with turning on the warm air. \x0d\ Turn on the air conditioner while turning on the warm air, and there will be water droplets. If the air conditioner is not turned on at the same time, it is suspected that the heating water tank is leaking. Whether it belongs to air conditioning water or the water in the warm air tank (the water in the warm air tank comes from the engine circulation channel and is antifreeze), just observe the dripping water. Generally, antifreeze is added with color additives, or red, blue or green, which will of course fade after a long time; If it is air-conditioned water, it must only be white. This is an intuitive difference. If the antifreeze fades and is difficult to identify, you can dip it with your fingers and distinguish the taste with your tongue. If it is bitter, it is antifreeze, and tasteless is air conditioning water. \x0d\ If the engine burns completely, hydrocarbons in gasoline will produce water (in the form of steam); Then after the exhaust pipe expands, water vapor will condense on the exhaust pipe wall at the end because of the temperature drop of the exhaust gas, and finally water will be taken away by the exhaust gas flow in the exhaust pipe belly. Because the temperature in the front section of the exhaust pipe is relatively high, it is impossible to form the necessary conditions for water vapor condensation, so even if the front section of the exhaust pipe leaks, it will not drip. \x0d\ In addition, to be more precise, water dripping from the windshield should also be excluded.