Speaker A
Hey there, YouTube, it's Paul here from TheEngineeringMindset.com. In this video, we're gonna be looking at the basic operation of a chiller, and this is gonna follow a series of videos on the subject of chillers.
Learn the basics of how chillers work, including their components, circuits, and operation in building air-conditioning systems.
Ask about this video. Answers come from its transcript only — with the timestamp, so you can check them.
Generated from the transcript and can be wrong — check the timestamp.
Key Takeaways
- Chillers are essential for producing chilled water used in building air-conditioning systems.
- The refrigeration circuit transfers heat from the chilled water loop to the condenser circuit.
- Four main components—evaporator, condenser, compressor, and expansion valve—are critical for chiller operation.
- Chilled water and refrigerant circuits are isolated to prevent mixing while transferring heat.
- Chillers vary in size and capacity depending on the building's cooling load and may include redundancy for critical environments.
What the video covers
- Introduction to the basic operation of chillers and their role in generating chilled water for air-conditioning.
- Explanation of how chilled water circulates through the building, absorbing heat and returning to the chiller.
- Description of the heat transfer process via refrigerant between the evaporator and condenser circuits.
- Overview of the cooling tower's role in rejecting heat from the building.
- Discussion on the factors affecting chiller size and thermal rating based on building heat load.
- Introduction to the four main components of a chiller: evaporator, condenser, compressor, and expansion valve.
- Explanation of the three main circuits in a chiller: refrigeration circuit, chilled water loop, and condenser circuit.
- Detailed description of how refrigerant and water flow through the chiller components without mixing.
- Presentation of a real centrifugal chiller example with a 3D model to identify components.
- Encouragement to learn and understand the essential parts and circuits for effective chiller operation.
Chapters
- 00:00Introduction to Chillers
- 00:51Chilled Water Production and Heat Rejection
- 01:50Heat Transfer Cycle Explanation
- 02:37Cooling Tower and Heat Dissipation
- 03:22Sources of Unwanted Heat in Buildings
- 04:13Chiller Redundancy and System Design
- 04:48Main Components of a Chiller
- 05:32Essential Components for Operation
- 06:28The Three Main Circuits
- 07:05Detailed Component Functioning
Full Transcript — Download SRT & Markdown
Speaker A
So please remember, check out our other videos and also our website. So firstly, let's look at what a chiller is and what a chiller does.
Speaker A
So a chiller is a noisy, large piece of machinery which is used to generate cool water, and that's used to provide air-conditioning in buildings.
Speaker A
You can see on the animation here the chiller down in the basement. You can also get chillers up on the roof here as well in a slightly different design, but let's not get too involved in that right now.
Speaker A
In this video, we're gonna be looking at what's happening inside this plant item and how it produces the chilled water for the air-conditioning and also how it rejects the heat, as well.
Speaker A
So in the chiller, the chilled water, which is produced in the evaporator, when it leaves, it's leaving, you can see here, it's leaving at about six degrees Celsius.
Speaker A
And this centrifugal pump here is then pushing that water around the building where it enters into these AHUs that collect up all the unwanted heat within the building, and this heat is then returned back to the chiller.
Speaker A
And it's returning here about six degrees, 12 degrees, sorry. By the time it leaves the chiller again, it will have given up six degrees worth of Celsius of heat, so it's leaving at six again.
Speaker A
So it leaves at six, comes back at 12, and this cycle repeats and repeats and repeats.
Speaker A
Now, the heat that leaves this circuit here is transferred via a refrigerant over to the condenser.
Speaker A
Now, these two systems are completely isolated from each other. There was just the refrigerant, which transfers the heat between these two circuits.
Speaker A
So the heat that is picked up in the condenser is then pushed in another circuit up to this pump here, the centrifugal pump, and that is pushed then up into the cooling tower where the air is forced by a fan inside,
Speaker A
and that dissipates and rejects the heat from the building. So this water then returns at a cooler temperature.
Speaker A
See, it's being sent up at 32 degrees Celsius, and it's coming back at 27 degrees Celsius.
Speaker A
So this water returns back to the condenser ready to pick up more heat from the chilled water system and reject the heat from the building.
Speaker A
Now chillers come in all shapes and sizes and thermal ratings, and that really depends on how much heat the building is producing, how much unwanted heat the building is producing.
Speaker A
And this unwanted heat comes from sunlight, people, the equipment within the building. Even the chiller itself will generate quite a fair bit of heat as it produces this chilled water.
Speaker A
So the system will all be designed to cope with this and to reject that heat and produce enough cooling as it was designed to do.
Speaker A
And the chilled water system in this example here, it's a central system, so it's got to a point where having small air-conditioning units on each floor is not going to be sufficient to provide the cooling that you need.
Speaker A
So it becomes economical to install this large central plant system to produce that chilled water.
Speaker A
And you may have more than one chiller. You usually have N plus one, so the amount of chillers you need plus one more.
Speaker A
If you're in a critical environment, you may even have plus two or plus three, depends on what that building needs.
Speaker A
But we won't go too much into the detail of that. Let's look at what's happening inside this device here.
Speaker A
Okay, let's have a look at an illustration of a chiller to help us understand what's happening inside this plant item and all of its components.
Speaker A
So I advise you to grab a piece of paper and a pen and write this down because you need to know this.
Speaker A
There are many designs for a chiller, but these are the four main components which will appear in every single one of them.
Speaker A
So firstly, let's have a look, we've got the evaporator, then we have the condenser, then we have the compressor up on the top there, and down below it we have the expansion valve.
Speaker A
Now every component of these four components is essential to the operation of a chiller.
Speaker A
A chiller cannot work without just one of these, any of them. All of them must be present in the chiller for it to work.
Speaker A
Now there are three main circuits in a chiller which you also need to know about, so write this down, as well.
Speaker A
We've got the refrigeration circuit, the refrigeration loop, and this is the refrigerant which passes around each of the four components and transfers that heat from the evaporator over to the condenser and back again, a constant loop getting the heat out of the building
Speaker A
and over to the condenser where it can be sent to the cooling towers. The secondary circuit you need to know about is the chilled water loop, and this is the heat from the building that's being collected, sent to the chiller,
Speaker A
and then back to the building. The third and final circuit that you need to know about is the condenser circuit.
Speaker A
This is the heat which is being sent to the cooling towers and coming back to pick up more heat.
Speaker A
So these are the four components. These are the three circuits. You might be wondering about what's happening inside here.
Speaker A
So the evaporator of the chilled water circuit is the water, if you remember, that's being sent up to the AHUs to collect the unwanted heat from the building.
Speaker A
And that's returning at about 12 degrees, and it's coming back into the chiller, passes through the loop, and by the time it leaves again, it needs to be around six degrees.
Speaker A
Obviously, the temperatures can vary a bit. It depends on the setup and design of your chiller.
Speaker A
But this is for explanation purposes. So the water that's coming in is within the, held within these tubes, and that keeps the water completely isolated from the refrigerant.
Speaker A
The two never mix. The water comes in, passes through the tubes, and then leaves again.
Speaker A
It does not leave these tubes. The refrigerant passes through, picks up the heat, and it just transfers that heat through the tube walls there, and refrigerant picks that up and then transfers that round to the compressor.
Speaker A
The compressor is located up from the top here usually always above the chiller, and that is the driving force of the refrigerant.
Speaker A
That is pushing, that's creating static pressure here, and it's pushing that refrigerant around the circuit.
Speaker A
That refrigerant enters into the condenser. That picks up, well, sorry. That dumps the heat into the third circuit there, the condenser circuit, and that is the water which is being returned from the cooling tower up on the roof.
Speaker A
It's entering into the chiller again through these tubes where it's held within the water in there.
Speaker A
It does not leave. It enters, passes around these tubes, and then leaves again. The refrigerant comes in and condenses along the tube wall.
Speaker A
It does not enter into the water. The water does not leave. It just condenses on there and continues flowing through there pushed by the static pressure until it hits the expansion valve.
Speaker A
The expansion valve is just expanding that refrigerant giving it a greater ability to pick up heat when it gets into the evaporator there.
Speaker A
So these are the four main components and the three main circuits you need to know about that will appear in every chiller, all types of sizes and shapes.
Speaker A
Alright, so let's apply that knowledge we've just acquired to a real scenario. So this is a chiller.
Speaker A
This is a centrifugal chiller. This is a McQuay chiller, actually. And we can have a look around it to name the components, and then we're gonna come back to this picture here and maybe a couple of pictures to test yourselves
Speaker A
on what each thing is. Going around a chiller is a little bit difficult, so what I've done is created this 3D model here, and this will allow us to just go around the chiller a bit e
Speaker A
So as you can see, we've got the compressor up on the top here, and mounted to the back is a large electrical motor.
Speaker A
Now that's the driving force for the compressor. And obviously, we're gonna look at each of these components in much greater detail in further videos.
Speaker A
But for now let's just apply each of the four components and try and work our way around the chiller to see where each of these are actually located and transfer that knowledge from the illustrations to the actual model.
Speaker A
So you should be able to, by the end of the video, tell me, or tell yourselves, where each of the four components of the chiller are.
Speaker A
So as I was saying, there's the compressor up on the top there with the electrical motor mounted on the back there.
Speaker A
Now down here we've got the condenser. That's this large tube or cylinder here with the inlet and outlet.
Speaker A
That's where the water comes in and leaves again. And if we turn the chiller around a bit and we'll see here we've got the expansion valve, the expansion valve just there located on the bottom there, and that's so the refrigerant can leave the condenser
Speaker A
and then enter into the evaporator. The evaporator, again, is another large, large cylinder, very similar design to the condenser.
Speaker A
The pipe arranged with a tube arrangement inside there may be slightly different, but again, we'll look at that in greater detail in further videos.
Speaker A
And again, you can see the the inlets and outlets of where the water will enter and leave, and you can see some of the tubes inside there.
Speaker A
And refrigerant inside this then leaves through this tube and enters back into the compressor located up on the top here.
Speaker A
Let's just spin it around so you can get another view of it. So that's the condenser.
Speaker A
The expansion valve where the refrigerant passes through this into the evaporator. And that then leaves there and then passes back into the compressor.
Speaker A
Remember, the condenser water enters and leaves in the condenser, and the chilled water enters and leaves through the evaporator there.
Speaker A
So you should have written down the four main components and the three main circuits within every chiller.
Speaker A
So I'd like you now to test yourselves. If we bring up this photo here of a real life chiller, and just apply your knowledge here.
Speaker A
So take few moments. Can you tell me what is this cylinder here? Now remember, it's got a tube.
Speaker A
It's being fed refrigerant off of the compressor, and it's coming down and entering the condenser.
Speaker A
And if we look at the back of this chiller, it has the condenser again there, and you'll see this tube, this pipe coming along from there and entering into this black box.
Speaker A
It's covered in the insulation. This is all insulation, by the way, because that chilled water costs quite a lot of money to produce.
Speaker A
So you want to retain as much coolth into that water as possible. So that is entering into the expansion valve which expands the refrigerant and allows the refrigerant when it enters here into the evaporator, and that allows you to pick up a bit more heat,
Speaker A
where it passes through this tube at the back there, passes through here, enters into the compressor.
Speaker A
Remember, this on the back again, is a large in electrical motor which is forcing the compressor to spin and push that refrigerant all the way around the system.
Speaker A
And meanwhile, the chilled water is entering and leaving here. It's entering at about 12 degrees, and it's coming back out about six degrees Celsius.
Speaker A
You may have noticed on this system here on this design, the pipe or the chilled water is entering and leaving.
Speaker A
It's entering through one end and leaving through the other end, whereas, our design has the pipes coming in and out.
Speaker A
That is fine, that it's just a different type of design. We'll go into much more detail about that on another tutorial video.
Speaker A
And as you can see here, the pipes actually are entering and leaving on the condenser just on one side there.
Speaker A
So this is a two-part system, but again, don't worry about that. For this video you should just be able to, we should be worrying about what these four components are.
Speaker A
Actually, you shouldn't be worrying, you should know now what these four components are and the three systems within them.
Speaker A
If you don't know them completely off by heart yet, that's fine. I'd recommend going back through the video just to learn it again and kind of get that fixed into your brain because these are essential knowledge, if you want to get into the industry for this.
Speaker A
Alright, that's it for this video. Thank you very much for watching. Please remember to hit the subscribe button below, and there's a couple of links there for some videos you might also be interested in.
Speaker A
We're also on Facebook, Twitter, Google+, YouTube, and obviously our website. Please check it out, thank you.
Topics:chiller basicshow chillers workchiller componentsrefrigeration circuitchilled water systemcooling towerHVACbuilding air conditioningcompressorexpansion valve
