Refrigerant

[CroweJeffery]

I am trying to better understand refrigerant. I know there are systems in an air conditioner that cycle the refrigerant around the different chambers and coils. Does refrigerant work in a single sealed coil? Does it stay cold, that is? Or is it just when it expands that it becomes cold?

[2sac]

Refrigerant doesn't expand it changes state. Sometimes a liquid, sometimes a gas. It changes state because of different components in the refrigeration circuit As basic as it gets, there is a compressor, a condenser, a metering device, an evaporator, and refrigerant. Each component serves a purpose to remove the heat from a space.

[amd]

Here's a diagram of the refrigeration cycle:



1. The refrigerant is the heat transfer medium
2. Temperature is the intensity of heat, not the amount of heat in a substance; compressing a gas increases its temperature (conversely, expanding a gas reduces its temperature)
3. The boiling point of any substance is proportional to the pressure (as the pressure goes up, the boiling point increases)
4. An enormous amount of energy required to boil a substance relative to raising the temperature of that said substance (it takes 970 times the amount of energy to boil water as it does to increase the temp by one degree Fahrenheit!)

The refrigerant starts out as a cool gas; the compressor in the outdoor unit raises the boiling point above the outdoor temperature by increasing the pressure.

The now hot refrigerant enters the outdoor coil and condenses into a warm liquid- in the process, the heat previously extracted from the cooled space is given off.

Liquid refrigerant travels to the indoor coil.

As the refrigerant enters the coil, it passes through the expansion valve (kind of works like a fine mist nozzle on a hose) which reduces the pressure and [B]allows it to boil off below room temperature. (lower pressure = lower boiling point)

The refrigerant picks up heat from the indoor air and boils off. It exits as a cool gas and returns to the compressor.

The whole idea is to get the refrigerant to boil off below room temperature and condense above outdoor temperature.

[amd]

Does it stay cold, that is? Or is it just when it expands that it becomes cold?

Gets cold and absorbs heat from the cooled space.

Gets hot (due to compression) and rejects heat into the outdoor air.

[Moonrunner]

Came across these 3 videos that are a decent primer on the reefer cycle: