Hey thanks for watching this quick video on the basic refrigerant circuit, basic refrigeration circuit. Whatever you want to call, this is like 101 stuff, every educator, every instructor, every book likes to start somewhere different, and I like to start a little more practical area, ideas that are more, maybe universal, that you can utilize in a lot of different types of systems. There are some things that you're going to want to memorize with the basic refrigerant circuit, and so the there's four components that you're going to want to kind of know in order and those components are the compressor, the condenser, the metering device and the evaporator. And I'm just going to give it to you right off the bat.

I want you to think of the compressor as the pressure increase or the condenser as the heat rejector, the metering device as the pressure drop ER and the evaporator as the heat absorber. So if we say without the without the component names, it would be the pressure increase, er, the heat rejecter, the pressure drop er and the heat absorber. So we're absorbing Heat, we're pressurizing, it increasing the pressure, we're removing the heat, we're dropping the pressure or absorbing Heat pressurizing round and round and round and round. Those are the four components, so one of the laws that is sort of the basis of the basic refrigerant circuit is the ideal gas law and you don't have to know fancy laws and things to be a good air conditioning technician.

But what the ideal gas law says and we'll put it up here for you: it's PV equals NRT and really what that means. If you kind of separate it out, it's pressure and volume equal mass and temperature, so you have mass and temperature on one side along with a gas constant. You have pressure and volume on the other side of the equation, but what that equation tells you is, if you change any one of those you change all the others. So if you change the volume, you change the pressure.

If you change the pressure, you change the volume, if you have some that remain constant mass, tends to remain more constant of those, but we're always changing temperature volume and pressure significantly. When we think of what we're moving through the circuit, we tend to use things called refrigerants. You may have heard the term freon before or pure on, and those are just brand names for types of refrigerants or categories of refrigerants that have been around a long time. But early on, some of the first refrigerants that were used were air and water, and then they moved on to co2 and other types of and poisonous gases that were used for a while until today, where we have relatively safe gases generally used.

Although we are going back to some explosive and poisonous gases again like propane or ammonia, but what a refrigerant really is, is it's just something that we're continuously pressurising and depressurising, so we're increasing the pressure and we're decreasing the pressure in order to manipulate the temperature in Order to get heat into the refrigerant and then back out of the refrigerant, I'm gon na say that again, our goal is to get heat into the refrigerant and then get it back out of the refrigerant, but that refrigerant doesn't have to be anything fancy. John Gorrie was a doctor who's, often credited with building the first functional, fully functional refrigeration device, and it used essentially air and water in different iterations, and all he was doing was just pressurising and depressurising pressurizing in order to increase temperature, so that heat can be rejected. From the refrigerant and then depressurizing to decrease temperature so that we can absorb heat into the refrigerant, so some of these things might be coming at you. A little fast we're moving heat around is what we're doing, but heat and temperature aren't exactly the same thing, and so temperature is to be technical average molecular velocity and all that means is it's the average speed that the molecules are moving within a substance, and so We can manipulate the average molecular velocity by changing the volume of the refrigerant, the space that it can occupy, and so that's what we're doing when we compress something we're causing it to occupy a smaller space which increases the pressure when we decrease the pressure, we're allowing It to occupy a larger space which then can decrease the temperature.

So when we increase the pressure, we increase the temperature when we decrease the pressure, we decrease the temperature. So that's what we learn from the from the gas laws, this relationship between volume, pressure and temperature. There's really important concepts and so we're gon na start with the compressor. So what is the compressor? Do the compressor has a line connected to it called the suction line, and it's quite obvious: it's a line that sucks the vapor refrigerant back.

In now, compressor only pumps vapor, but it draws vapor into the suction line, which is actually quite cool to touch. Generally speaking in a air-conditioning type environment, it increases that pressure significantly by causing the refrigerant to occupy a smaller volume. Now there's different types of compressors: there's scroll, compressors, there's rotary compressors, there's reciprocating compressors. They all do generally the same thing.

The outcome is the same: we're taking in refrigerant that's at a lower temperature and a higher volume we're causing it to occupy smaller space. In other words pressurizing it, and then it comes out of the compressor at a higher pressure. So that's what we call the compressor, the pressure increase or that's the way. I want you to think about that early on when you think of yourself.

I have no idea what a compressor is. Its job is to increase the pressure now in the process of doing so. It also decreases the pressure on the suction line. It moves and circulates the refrigerant fluid through the system, and so it's important to know those things as well, but start with, knowing that it is a pressure increase or so then that discharge gas travels down the discharge line and enters the condenser coil when it condensers Transferring its heat to a liquid, we generally will call that a heat exchanger and there's many different types of heat, exchangers, tube and tube and plate heat exchangers.

We see these in many commercial applications, water source, heat pumps, geothermal units, that's what we're gon na see us transferring heat to water as the medium, but no matter what the condenser is. The HEA trajector its job is to take that high temperature that we revealed by pressurizing that refrigerant in the compressor change the state of this refrigerant to a liquid. Now, like I mentioned John Gorrie in his original designs, he wasn't actually really changing the state. He was just pressurising and depressurising.

You can create a refrigerant circuit that does not change the state at all. We focus a lot on state change when we're teaching air conditioning, but it isn't necessary. It just greatly increases the amount of heat you can move. So this whole change from liquid to vapor boiling condensing.

All of that, regardless a condenser is going to reject heat. Is it condenser? Is the heat rejected on the process of rejecting heat either to air or water? That's where we're going to eventually change it to a liquid, but then you also have air-cooled condensers, which is the typical type like we have right here in my little video here you can see this is an air-cooled condenser air is drawn over that over those fins Over those aluminum fins and then it rejects that heat out as the air passes through. So it's rejecting heat from that condenser oil in this case to the air around it. It's a heat rejecter.

So once that condenser rejects the heat now, the liquid refrigerant. That has fully condensed moves towards the metering device and the metering device can be several different types. So three of the most common types that you're generally going to see are going to be the thermostatic expansion valve or TXV, as well as the capillary tube, which you would see in smaller appliances like window units package terminal air conditioners. Maybe your frigerator at your house and then there's another type of metering device called the piston device and a piston is commonly used in older air conditioning systems or low efficiency systems that have been installed for many years.

It's essentially just a piece of brass with a hole in it. There's also a new modern type of metering device called the electronic expansion valve the EEV or some call it an exv which essentially is just like the TXV, but it uses electronics in order to modulate it regardless. The purpose of the metering device is to act as the pressure drop er, so we have the pressure increase or at the compressor we had the heat rejector in the condenser, and now we have the metering device, which is the pressure drop or pressure decrease, or if You, if you prefer more a formal language there, but what it does is by dropping that pressure on the liquid. Not only does it drop the pressure, and so when you drop the pressure, you drop the temperature, but it also begins to boil a term that we use is it's called flash gas.

It means that it's immediately starting to change its state from liquid to vapor and in that process it's able to absorb a lot of heat, we're leveraging. That's that phase change from liquid to vapor and vapor to liquid in order to move more heat, but, like I mentioned before, it's not necessary when you drop the pressure you are affecting that one half of the equation of that PV equals NRT that that ideal gas Equation and so what what happens? In any case when you drop the pressure on most substances, you're going to see a decrease in temperature drop the pressure you're going to decrease the temperature. So when we decrease the temperature of that evaporator coil and that air moves over it, that lower temperature of a protocol is going to absorb heat from the space. So that's what we're doing that inside portion of your air conditioner at your home.

If you have a split system when you're running it in air conditioning mode, what it's doing is absorbing heat from the air in your home. That's passing over that coil into that refrigerant, and now that refrigerant turns into a vapor as it boils it turns fully into a vapor and out travels back to the compressor down the suction line. So, by way of memorization, there are a few things that I strongly suggest that newer technicians people are interested in pursuing the trade just memorize. It's one of the first things I ever memorized and that's compressor, condenser metering, device and evaporator, and then you can memorize the three most important lines, which are the discharge line, the liquid line and the suction line.

You'll see in some of my diagrams, like my full refrigeration circuit diagram, that I show a line in between the metering device in the evaporator called the expansion line that isn't always there and there's a lot of different names that are used in the industry. That's just a name. I was taught early on you're gon na see those systems like ductless systems where the metering device is located outside, and so the expansion lines are often not going to be as common, but the main three that you really need to know and you need to know The difference between or your discharge line, which is the line between the compressor and the condenser, your liquid line, which is the line between the condenser and the metering device and your suction line, which is the line that goes back from the evaporator to the compressor. But remember, compressor is pressure, increase, ur condenser is heat, rejector metering device is pressure, dropper and the evaporator is the heat absorber.

So it's absorbing heat from the space. That's the one that I more than anything else than anything else. I want you to get that kind of picture in your head of it. It was absorbing heat from the inside of the space.

I hope that was helpful, we'll catch you next time.