How does the ideal gas law relates to air conditioners?

Answer 1

PV=nRT- you can ignore n and R because they do not change. Then rearrange to P = T/V. Inside the air conditioner is a little tube, think coffee straw tiny. One end is attached to the compressor unit storage and the other end dumps into a container with a very large volume relative to the connecting tiny tube. As a fluid is pressed through the tube it is under some specific pressure. Remember that pressure is force/ area and the area in the straws end is very small. The pressure on the compressor side is very high and on the dump side, it is very low. Also, the volume inside the tiny tube is very small. After the fluid passes through the tiny tube, it jumps out into the relatively huge new volume container and the pressure simultaneously drops very low. From the original equation, and because both sides must be equal, when the P drops to a very small number, the T/V must respond exactly proportional and since the V is getting huge relative to the little tube, the T must drop even faster. The temperature drop is then transferred to metal fins near the dump container by means of thermal conductivity in the metal and air is blown over those fins, which cools the air. To see this in action, buy a can of compressed air for cleaning computers. They usually cost a couple bucks and are available at most office supply stores or Walmart. Remember to attach the included straw and let it fly. Notice that with this practical test the volume changes from size of the can to the area inside the room you are in. The difference between the two volumes (can vs. entire room) should help your perspective in understanding the relative size between the tiny tube and the dump container in an air conditioner. One other thing to note is that different gases have different evaporation rates. That means that some chemicals jump out of the tiny tube faster than others, all else being equal. Hope this helps.