How does freon keep your car cold?
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It’s something called a “refrigerant”, which means that you can alternate compressing it and evaporating it to move heat from inside the car to outside the car. It’s the same as an air conditioner, a heat pump heater, and refrigerators.
It works because compressing it into a liquid makes one side heat up, while letting it evaporate back into a gas cools it down.
Acts like a sponge. Sucking up heat inside the cars air system and your cars AC unit (compressor) squeezes it to get the heat outside so it dissipates into the environment
Its properties of thermal capacity and boiling point at certain pressures make it useful to do it.
Though other gasses still work (if the system is set up to do it. DO NOT USE gases not meant for your car!!)
Liquid is passed through an evaporator. As the liquid transitions to gas it absorbs energy (heat). The gas is then compressed and passes through a condenser that changes it back into a liquid to go around again. That releases energy (heat) but it’s outside the passenger compartment so that’s fine. Freon was used because it worked well and was nontoxic and non-flammable (it was used in fridges). But nothing is perfect; it escapes and is bad for the ozone so there are alternatives now.
You ever empty a gas cylinder really quick and have it get really cold? Or walked past a compressor and it was warm? Any time you compress a gas, you get heat. And any time you release that pressure, you get cold.
Freon is any gas that’s good at conducting heat. We use a low pressure and high pressure side. We compress the gas and run it thru a condenser, and that’s kinda like a pre cooler that’s just outside air blowing over it. It then passes over a valve called the orifice tube or expansion valve. The orifice tube separates the high side from the low side of the system and this is where the fun stuff happens. It’s like when you have a garden hose and your nozzle is spraying a fine mist. It then goes through a dryer that removes any moisture that may have entered the system during service and then the evaporator core that is a mini radiator that a fan can push air through to transfer the cold from the metal to the air in the car and then back to the compressor to start all over again.
You can do this with any gas, but it works better with some gases than others. Not all oils are comparable with all gases. We try to use gases that are environmentally friendly and safe under all conditions. Some swear on propane as an alternative, but I don’t think it’s a good idea if you’re a smoker, or even with relays clicking. The ideal air to fuel ratio would be pretty easy to hit in a sealed car.
The simplest explanation is that the system manipulates the pressure of the refrigerant so that it is cold enough when it is in the indoor portion to absorb heat and hot enough when it’s in the outdoor portion to reject heat.
Raising the pressure raises the temperature and lowering pressure lowers temperature. The compressor and metering device are what makes the pressure manipulation possible.
Change of state from liquid/vapor and vice versa enhances how much heat can be absorbed/rejected.
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