What are the Internal and External Circulation in a Car?

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Internal circulation in a car refers to the process where the air inside the vehicle is heated or cooled and then recirculated back into the cabin. External circulation, on the other hand, involves drawing in outside air, heating or cooling it, and then introducing it into the cabin, facilitating gas exchange between the interior and exterior of the vehicle. Uses of internal and external circulation: 1. In cold weather, after starting the car and waiting for the engine temperature to reach normal levels, activating internal circulation can quickly raise the cabin temperature; 2. During high-speed driving, external circulation can be turned on as needed to maintain cabin temperature while ensuring fresh air supply. Advantages and disadvantages of internal and external circulation: The advantage of internal circulation is the rapid cooling or heating effect of the air conditioning system, while the drawback is that prolonged use may lead to poor air quality inside the cabin. The advantage of external circulation is maintaining clean air inside the cabin, but the downside is slightly less effective cooling or heating due to the influx of outside cold or hot air.