Introduction to Heat Exchangers (Mechanical Engineering) | SaVRee 3D | Skillshare

Introduction to Heat Exchangers (Mechanical Engineering)

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18 Lessons (1h 24m)
    • 1. Course Overview

      1:42
    • 2. Introduction

      4:18
    • 3. Types of Heat Exchanger

      1:02
    • 4. Shell and Tube

      11:27
    • 5. Plate

      16:52
    • 6. Flow Types

      8:08
    • 7. Comparisons of Types of Heat Exchanger

      1:25
    • 8. Single and Multi Pass

      1:10
    • 9. Single Pass

      1:23
    • 10. Two Pass

      2:03
    • 11. U-Tube

      0:26
    • 12. Regenerative and non regenerative

      6:42
    • 13. Heat Exchanger Type Summary

      2:24
    • 14. Car Radiator Example

      5:46
    • 15. Two Stroke Engine Example

      1:22
    • 16. Refrigerator Example

      4:38
    • 17. Solar Furnace Example

      3:07
    • 18. Refresher Lesson How Plate Heat Exchangers Work

      10:22

About This Class

Learn about heat exchanger designs, construction and how they work. Ideal for HVAC and Mechanical Engineering!

Almost all industrial processes require some form of heat exchange. Oil refineries, power stations, chemical plants and HVAC installations, all must exchange heat. But how you do this in a controlled and efficient manner? What equipment is involved and how does this equipment work? This course will answer all of these questions and many more!

In this course, you will learn about heat exchangers. You will learn about shell and tube heat exchangers and plate heat exchangers. By the end of the course you will be able to:

  • Identify different types of heat exchanger.

  • Know advantages and disadvantages associated with each heat exchanger type.

  • Identify single and multi-pass heat exchangers.

  • Identify regenerative and non-regenerative heat exchanger systems.

  • Identify cross, parallel and counter flow designs.

  • Know terminology for the shell and tube heat exchanger, and plate heat exchanger.

  • Know common reasons for heat exchanger failure and fouling.

The course is designed to take you from zero to hero concerning heat exchanger knowledge. Even if you already have some background engineering knowledge, this course will serve as an efficient refresher. Whatever your level of understanding, or engineering background (mechanical engineering, HVAC, chemical engineering, oil & gas industry, power engineering etc.), we can guarantee you will have never taken an engineering course like this one (unless you have taken one of our other courses...).

Interactive 3D models are used extensively to show you each individual heat exchanger and all of their main components. 

The course is packed with 2D images, 2D animations and 3D animations.

Written content has been read aloud so that you can 'learn on the go' without needing to watch the screen constantly.

Hope to see you on the course!

Transcripts

1. Course Overview: Almost all industrial processes require some form of heat exchange. Oil refineries, power stations, chemical plans on hate back installations almost exchange heat. How do you do this in a controlled and efficient manner? What equipment is involved and how does this equipment work? This course will answer all of these questions, and many more in this course will be learning about heat exchangers. You will learn about the shelling to type heat exchanger on the plate type heat exchanger. By the end, of course, you'll be able to identify the different types of heat exchanger. You'll be able to identify all of their main components. You'll learn the advantages and disadvantages associated with each type of heat exchanger, and you'll know exactly how they work. This course is ideal if you're working or training in any mechanical engineering industry or industrial engineering industry. Because he exchanges really are involved in almost all industrial processes. We use interactive freedom models throughout the entire course to show you exactly what's happening. Inside each of these heat exchanges, we'll use a unique cross section feature so that we can take each heat exchanger apart. In addition to that will be using two D images and two D animations so that you can actually see each heat exchanger working on all of the courses. Written content has been read aloud, so you don't need to watch the screen constantly, but you can also learn on the go. So if you want to learn about heat exchanges, or maybe you just want to refresh your memory after a long time in the workplace, and this course is definitely for you, Hope See you on the course. 2. Introduction: So let's get started. An introduction to heat exchanges in many industrial processes. Heat must be transferred from one place to another or from one medium liquid or gas to another. Heated exchanges. They used to transfer heat from one medium to another in a controlled and efficient manner . This course discusses the common types of heat exchanger, their application, design advantages and disadvantages. Let's load up the first lesson. A heated danger is a component that allows the transfer of he from one medium liquid or gas to another. Reasons for heat transfer include the following to he a cooler fluid by means of a heart of fluid. To reduce the temperature of a hot fluid by means of a cooler fluid the boiling liquid by means of the hearts of fluid. To condense a gaseous fluid by means of a cooler fluid. The boiler liquid were condensing Ah, hotter gaseous fluid. Regardless of the function, the heat exchanger for fills. In order to transfer heat, the medium's involved must be at different temperatures, and they must come into thermal contact. He can flow only from the hottest of the cooler fluid when they come into thermal contact in the heat exchanger. There is no direct contact between the two fluids. The heat is transferred from the hot fluid to the barrier, isolating the two fluids on, then to the cooler fluid. Okay, so let's just do a short recap. I'm going to read the lessons through allowed, so you can listen to the text and reading on the screen on. Then I'm gonna elaborate a little bit more on the lesson on, hopefully increase your level of understanding so we can see the numbers 1 to 5. They're they're talking about different uses off a heat exchanger. Let's just have a look at that in a different way with a couple of examples. Let's imagine that we want to condense steam to liquid, and we do this in power stations with a steam turbine. In order to do that, we'll use a heat exchanger on. What we're actually doing is cooling the steam down in order that we can turn into a liquid . So we're changing the state from vapor, which is steam to liquid or what they refer to his condom. Say so we are changing the state, thereby cooling the steam down. Another example where we're not changing. The state would be in a engine in an automobile engine. We need to cool down. The cooling water on the cooler water helps us control the temperature off the engine. Now, we don't need to change its state. The cooling water is water within the system, but we do need to cool it. So what we're gonna do is cool it down. Using ambient air, we're going to get rid of that waste heat to the ambient air on. We're going to cool the cooling liquid. So we're not changing the state. We just want the temperature of the cooling water to reduce. So two different examples there were with a change of state and one without an important concept with heat exchanges is that the two flowing mediums should not come into direct contact with each other. There will always be a barrier between them. Our goal is that we can put them as close together as possible so that they can transfer for more energy between each other or from hot to cold. But what we don't want is the two mediums to mix In order to stop the mixing, we will use something called a barrier which we can think off, is simply being a metal plate or some long, porous material that the two mediums cannot flow through. The thinner the barrier is, the higher the heat transfer rate will be between the two mediums. The contact surface area between the two mediums should always be a xlat as possible. If it is, then we would increase the heat transfer rate between the two mediums so I heat transfer capacity for the heat exchanger will be greater. Let's not get bogged down the details just yet. It's the first lesson. Let's go now to the next lesson. 3. Types of Heat Exchanger: types of heat exchanger construction. Although heat exchanges come in every shape and size imaginable, the construction of most heat exchanges falls into one of two categories. Shell and tube or plate. As with most equipment, each type has its own advantages on disadvantages. Okay, so to my mind and in my experience over the past 16 or 17 years, I would say that I've seen four different types of heat exchanger. However, two of them, such as the shell and tube in the plate, I've seen many, many, many times on the other two I've seen only once once was on a Merchant Navy shipping vessel on the second time was in a biodiesel plant in Germany. So I only two instances where I've seen heat exchanges that are not shelling tube or plate types. So for this course, we are only going to focus on shell and tube and plate type heat exchanges 4. Shell and Tube: shelling tube. Most basic and the most common type of heat exchanger construction is the shell and tube. This type of heat exchanger consists of a set of tubes in a container called the Shell. The fluid flowing inside the tubes is called the tubes. I've fluid on the fluid. Flowing on the outside of the tubes is the shell side fluid. At the end of the tubes, the tubes side fluid is separate from the shell side fluid by the tube sheets. He choose a rolled and press fitted or welded into the tube sheet to provide a leak tight seal. So the shell and tube type edict changer is essentially a Siri's off pipes that will pass through a heat exchanger on. We'll have one medium flowing through the pipes on one medium flowing on the outside of the pipes were going to have a look at an example in a moment. In systems where the two foods are vastly different pressures, the higher pressure fluid is typically directed through the tubes on the lower person. Fluid is circulated on the shell side. This is due to economy because the heat exchanger tubes could be made to withstand higher pressures than the shell of the heat exchanger for a much lower cost. The support plates shown below actors baffles to direct the flow of fluid within the shell back and forth across the tubes. So what we mean here is when we are pumping a fluid or a medium through a heat exchanger, the medium, our higher pressure is going to go through the tubes. Sometimes. If you have two mediums, such as oil and water, where the water is cooling down the oil, it may be very important that the oil does not leak out into the water. This is especially true for using something like river water or lake water to cool down the oil. We don't want oil leaking out through the tubes, Andi going back into the river or the lake, or even the ocean. So what we'll do? We'll have what they call a double walled tube on. We will have a tube that has two walls on def oil was to leak out of the inner wall of the tube. It will go into the middle between the outer and inner wall. On. It will set off a leak along so that way. We know that one of the tubes is leaking and we haven't along, but it doesn't leak out directly into the shell and into the water. It's just load up a model here so I can show you more detail. How the heat exchange of works. Okay, so you we have a standard shell and tube heat exchanger. Just do a little spin. We can see these two pipes on the top on two pipes on the bottom. We gotta stand on. That is for installing the heat exchanger. It's been around this side. We can see the nuts and bolts on the end Here. We will undo those to open up the end cover and get inside the heat exchanger or doing inspection or maintenance to take a cross section. Okay, so we've got a cross section now. The heat exchanger we can see here. Tube side fluid out. Stoop side fluid in. When we say tube side, we mean the medium that is flowing through the tubes. The opposite of tube side is shell side will have shell side fluid in Andi. Shell side fluid out. That is this lower section here than lower pipe. Let's get to an overview so we can follow the flow through the heat exchanger. Okay, so we have got a cold fluid flowing in from the bottom is then flowing along through the heat exchanger through these tubes. It is doing a u turn. This is actually called a U turn challenge to type heat exchanger. You turn here and then it is flowing back that way, and it is coming out off the top. Let me just been around this side. We can see the entrance points on. We can see there are the tubes and the tubes going off into the distance so the fluid is gonna be flowing directly into these tubes. We can also see a plate which is used for separating the fluid as it flows in from the bottom and then out off the top. So if we were to move this plate or take it out, we would actually just have a fluid that flows in from the bottom and directly at the top is gonna choose the path off least resistance. But because the place there, it's coming in on flowing through the bottom tubes. Onda, we just follow along along these tubes and we can see here. This is where it suddenly turns around its coming while traveling to the right on the lower section around the jujubes around this u turn on back the other way, and it's gonna keep going all the way until it comes out off the top again, or the top section off the heat exchanger. What actually happened is it's gone in the bottom out of the top on Did it has absorbed some off that heat. Andi is then going to take away that heat and distribute it somewhere else, perhaps to ambient air. Or perhaps it would just go back to a reservoir. Sometimes they're leaving. Use some of the warmer fluid for a later stage in the process. It's a good way to recycle the heat rather than just waste it essentially, when you're removing the heat, that is a efficiency or an energy loss. So if you can use it earlier or late in the process again, you're recovering some of that energy on your increasing the process efficiency. Have a look at the fluid comes in at the top shell, so I fluid in in at the top. Now it does know, unlike the tubular flow, which flows relatively direct, the fluid that is flowing in on the shell side is going to flow around. A Siri's off baffle plates is gonna come around here and before to turn is going to turn again. It's going to turn again on it's going to keep doing that all the way along on. Then he's going to exit at the bottom off the heat exchanger. I have to say it would be slightly better if this discharge port from the heat exchanger was more to the right in order that it could throw through the heat exchanger in down on the right hand side rather than here. But that is how the heat exchanger has been built in Freedy here. The reason for this crisscrossing pattern this is actually called cross flow is because we want to maximize the heat transfer between the two flowing fluids on. We do this by having a cross flow pattern. There's no point, the fluid entering in the top flowing director here and then dropping out of the bottom because if we do like that, we've had very little turbulent flow on. There's not gonna be as much heat transfer between the two mediums, compared to when we do this cross flow pattern. And although you can't actually see it inside these tubes, there is normally a thin piece of copper or plastic on. It will slide into each and every one of these. Choose now this thin piece of copper or perhaps plastic or other form of metal. It depends on the system that you actually using it for is similar to a very thin strip, a flat bar, a thin, flat bar of copper, for example. And the idea is, as the fluid is flowing through the troops, it does not get to flow in a straight lamb in a direction. It is going to come into contact with this thin, perforated copper bar, and then it is going to be forced to float over and under the copper bar. In other words, it's gonna have a very, very turbulent path through the tubes on this is what we want. We want turbulent flow because this is going to increase our heat transfer. The other benefit with turbulent flow is simply that if we have suspended bodies within the fluid, that may stick to the sides of the tubes, they won't be able to stick to the size off the choose as easily. If they do stick to the side of the tubes that is going to reduce our transfer rate where heat transfer capacity. So by having his turbulent flow were preventing them or reducing the risk that they're gonna be able to stick to the side of the tubes on this will maintain Hey, transfer capacity. Now, if you don't know what I'm talking about, when I talk about things sticking to the sides of surfaces of a heat exchanger, go and have a look at your kettle. Now, if you boil your kettle of 1000 times using standard tap water, it's very likely you'll notice a thin, white powdery substance building up within the kettle. Now this is actually reducing your heat transfer. His white powdery substance comes from the water itself, the minerals and suspended bodies within the water, and over time it will stick to the inside metal surfaces of your kettle, and it will reduce the transfer rate, and that's exactly what can also happen in a heat exchanger. Another example is a boiler with boilers. They go to great lengths to ensure that the water quality is as clean as possible. And the reason again is that any suspended bodies that stick to the surface off the boiler tubes will reduce the transfer rate on in severe conditions. It can actually cause the piping to melt, so it's very important that you keep the contact surface areas within your heat exchanger as clean as possible. So that is a you type shell and tube heat exchanger. For its click, you could actually have a look at some of the more specific pieces. Example. Let's just have a look at the tubes. We can see tubes for I do a full version again. You can see all of our tubes there in the way they are installed, but also highlight the baffles on the baffles now have shown, and we'll see how flow comes in and around the baffles like So So the baffles I just highlighted for you are those pieces here, and they'll be designed to be installed in this pattern so that we get this cross float. If that was all a bit quick, don't worry, we are going to go through this in more detail later in the course with some different examples. I just think that was a nice introduction to what a shell and tube type heat exchanger is. Now let's go on to the next lesson. 5. Plate: So we looked at the shell into type heat exchanger, and now we are going to take a look at the plate type heat exchanger. A plate type heat exchanger, which is shown below, consists of plates instead of tubes to separate the hot and cold mediums. The home cold mediums alternate between each of the plates baffles direct the flow of fluid between plates. Because each of the plates has a very large surface area, the plates provide each of the fluid proven, extremely large. He transfer area, therefore a plate type heat exchanger, as compared to a similarly sized tube and shell heat exchanger is capable of transferring much more heat. This is due to larger contact surface area. The plates provide over tubes, so this is a plate, I plead exchanger. We can see the example here and we'll see that there is a hot fluid flowing in a top, and it is coming out at the bottom. We'll see the same on the other side. The cold fluid is going in the bottom and coming out at the top. Well, actually, notice is the place are arranged so that there is always a red, blue, red blue, red, blue, red, blue all the way along throughout the entire plated exchange a construction. Now the reasoning is very simple. Between each of the plates were gonna have different mediums that are flowing. So here we've got a hot medium, followed by cold. Hey, who followed by cold, hot, cold, hot, cold. And we've made these plates as thin as possible in order that we can transfer as much heat as possible. We've also made the plates relatively large. They have a very large contact surface area, and that will also increase our heat transfer. Hurry. If you compare a plane type heat exchanger to a shell and tube type food exchanger, you'll find that plate type heat exchanger has a much higher transfer rate than Michelle and to type heat exchanger off the same size. So wait, I've hit. Exchanges are very good when space is limited. However, there are also more expensive. Generally in shelling. Toots, I plead exchanges. A typical example for a plate I peed exchanger would be when you need to install one in a relatively small room, and there is no other option to build in another room or to expand the working area. For example, on a ship on a merchant navy vessel, you only have a certain amount off space. You can't build on additional room onto the side of the ship on. If they are using a plate, I peed exchanger. They will need to replace it with a plate type heat exchanger. It simply won't be enough space to install a shell into type each danger. However, if you're working in a factory and space is not so important, perhaps you've got an empty room. It may be more cost effective to install a shell into type heat exchanger, the rubber advantages and disadvantages between the two types. One of them is simply that on a shell and to type heat exchanger, it's a lot easier to find a leak. A leak on a plate type heat exchanger is relatively difficult to find the leak of becoming from any one of these plates, and there are many plates normally within what they call a plate stack. With the shell and tube type, you could literally just pressurize each of the tubes, and you would quickly find the leak that is not true with the plate type. It's continuing down due to the high heat. Transfer efficiency off the plates plate type he'd Exchanges are usually very small when compared to a shell and to type heat exchanger with the same heat transfer capacity. Play type heat exchangers is still widely used despite having the inability to reliably seal the large gaskets between each of the plates. Because of this ceiling problem, played type heat exchangers are primarily used for low pressure systems. However, new improvements in gasket design and overall heat exchanger design have allowed for some higher pressure applications of the plate type heat exchanger. What we're referring to him we talk about gaskets is the ceiling arrangement that is placed on each of these plates. I don't go into detail about it now because what will do We will load the Freedy model, and then we can have a look exactly at the gaskets and how they function. Okay, so here's a plate type heat exchanger. Let me just explode it. We can see it's construction we have here and plate. We have the plates stack. That is what it's referred to when you pressel the plates. Together we have the individual plates, and then we have a gasket, which we're talking about a moment ago, that is, this slightly weird shaped black hides him here on each gassed. It will replace between each off the plates for sealing, and we'll talk about how that works in a moment. We've also got some bars or tie bars on the side, which were used to plant all of those plates together. Very important, we don't over time the clamps, because if we do, we'll squeeze the gasket out. The gaskets might be night troll rubber or some flexible soft material that is good for sealing but will be squeezed out when you over tighten that plates. If the gas that you squeezed out, then we're actually gonna have leaking between the plates or leaking from the place directly into the surrounding area. Once you've squeezed the gasket, our unfortunately is not very easy to replace. It's better just to remove a couple of plates and you'll make the entire plate stack slightly smaller. You will notice also that if we were to remove a couple of plates, let's imagine we had one or two that were leaking. We can still operate the heat exchanger, so this is very useful. We can take out a few plates. The heat transfer capacity off the heat exchanger will reduce slightly, but the heat exchanger could be returned to operation with a slightly reduced the transfer capacity. Other than that, we can only see that some nuts and bolts. It's a relatively simple construction. Or push the play button so that we can see it being assembled. See the bars coming in the top and the bottom. The gasket gets pressed onto the end plate. The place get pushed together. He played. Stack is put together. The bar's gonna side on. Then it is simply a case of tightening up the nuts onto the studs. Sorry, I mentioned Bolt earlier with reasonable Cesaire, actually, metal studs. We spin it around. We can now see how it looks when it is assembled. So there we have it as I played huge danger. Normally, how we would see in assembled condition. We can see that these bars one of the top and one on the bottom. These are actually just locating bars on were used them to pull the entire plate stack or all of the plates out. The idea is we have a role on the top. The roller will roll along the bar on will push it all the way back to this position here where the mouse is. Once you're back there, we can separate with the plates out. In fact, let me just back up. Maybe we can do that. Then we go. So here we are. You see the plates that just moved back along that bar on this will allow us to either remove the plates completely or perhaps cleaning to the plates. We can separate them out individually clean, eat the plates, check the seals and gaskets and then weaken Sandwich it all back together again. I want to elaborate a little bit more on these gaskets now, because the gaskets are perhaps the most important piece off the plate type heat exchanger . You just see if we can explode out for a moment. What you'll see here is a slightly unusual shape in the corner so we can angle it so that you have a white background. Okay, so this is a piece off its imagine not raw rubber on. He's coming down here across there on this circle is going to be sandwiched or the entire gassed. It is going to be sandwiched between two plates. What's interesting here is that when we have a circle like this, the fluid is gonna pass straight fruit, one of plates because it will flow into this circle area. Andi, it cannot pass over the gasket because the gasket is sandwiched between two plates, so it's gonna be forced to just continue flowing. So what that means is it would flow fruit here, and then it's gonna flow through next play. Now the next plate. Now we look around, there is no gasket. So the flu is gonna just flow outwards or it can flow in any which direction it likes. Now, there would normally be a gasket here. It should actually be a gasket between each of the plates. And if we look on the backside here, we can see it. However, you should notice a slight difference. We're now doing the reverse so we can see on where we had a the gasket shape. Here we have a circular black shape. We come through here to the next plate. It is the opposite. The circular shape is now on this side. Now, the reasoning behind that is quite simple. The fluid is going to flow in, and it is going to then spread out in all the directions that it can. Now the directions that he can flow are simply up to here, where the black line ease up to their anywhere up until the point where it impacts upon the black gasket. Ultimately, the fluid is going to flow downwards because the black gasket covers the entire plate. We can see on the left side and on the right. So the fluid is gonna be forced to flow downwards because you can't flow out and it's gonna get down to the bottom here. Now the bottom. It can't flow over the black gasket again because this is gonna be pressed against the other plate. So it's gonna be forced to flow out through this hole, the one in the bottom. So what were effectively done? There is. We have entered the plate type heat exchangers or the fluid is entered at the top has been forced to flow down and leave at the bottom on Gizenga. New go back to the pump. All the storage tank. It is essentially done. Its job well. Imagine for a moment. That was the cooling water. So it's taken away some of the heat on the other side. We can see that the gasket is more or less. It's just in reversed this time. So if we were on this side now, we would have a hot fluid on the hot fluid would not be able to flow on this side of the plate. We can see here that the Black seal is around this area so the hot fluid is gonna come through here and it is gonna get through. And now that it's on the opposite side, we can see the gasket shape is actually gonna be able to flow down. And then it will flow out of the bottom right hand corner and can't fly at the bottom left . So before supply at the bottom, right, So we've always got this oscillating or changing gasket type. Roy's gonna have a gasket like this on. Then we're gonna have one of the opposite one like the one we're looking at now, Onda again opposite again. So you can see the black seal in the background black gasket again, you see? Was under left side then he sealed on the right side and then he sealed on the left side and then it's sealed on the right side. So what were effectively doing is saying the hot fluid can flow in through this hole here on, then must flow down the plates on the next one. It's gonna be forced to flow through, so it's not gonna be able to flow down this plate. Where On Willimon house. Now, on the next one, you can flow down the plate on the next one. It cannot flow down the plate because the Black seal is there. And that's how we control the flow in the plane type heat exchangers. So the gaskets are very, very important. Unfortunately, there are also very easily damaged. So if we damage one these gaskets, we're gonna have a leak. And that means the two mediums are gonna mix, which is exactly what we don't want. That is, unfortunately, one of the disadvantages off this type of heat exchanger. The other limiting factor is that you need to use this type of heat exchanger on lower pressure systems. The gaskets simply cannot withstand very high pressures. They get blown out by the pressure and obviously we will then have a leak. The tolerances between each of these plates when they're pressed together are very low. We can see the plates stack here on the center of the screen, on the plates. When they're pressed up together, you almost can't see the individual plates. So there is a huge contact surface area when you put all of these plates together. So we have a very good heat transfer rate. But because the tolerances between the place is so small, they also get easily fouled. And that means that foreign bodies or perhaps minerals in the water they may stick to the surface is off the plates and there will reduce the heat transfer re. And that is why we want to open the plates up, separate them out individually on we're gonna clean each of the plates. So it's another slight disadvantage. We can see again that we are promoting turbulent flow in the same way we did with shell into typing exchanger by using the's Keurig ations and see the weird shapes, the weird squiggles. These squiggly lines are actually used to promote turbulent float. So instead of entering from the top or from the bottom and flowing down, up we're actually having is the fluid is gonna enter, and then it's gonna be forced to flow in a very turbulent manner. This again is gonna increase that transfer rate on and reduce the likelihood off fouling because a lot more difficult for minerals and foreign bodies to stick to the plates off the heat exchanger. If the flow is very totaling, it's almost like a self cleaning arrangement. The place themselves are incredibly thin. They're very flexible, these plates. Normally, if you were to press down the top, you will actually be able to make a curved shape on. The gaskets are adhered onto the plates. You won't be able to just replace the gaskets. Normally, you have to send the plate away, and the gasket will be reattached in the factory to the plates. So, unfortunately, if the plane is damaged or the gasket is damage, it is more or less beyond your control to remove it on repair it. That's not so with the shell and to type heat exchanger you can normally well there or braise it or somehow patch up so that it works the shell and to type it exchanger is also relatively easy to repair because she can block off the leaking, too, on the reduction in the heat. Transfer capacity off the heat exchanger is relatively low because you're only blocking off the 12 So that's what we're gonna talk about for now, for the plate type heat exchanger. We'll just assemble it so you can have in your mind how it would normally look in assemble condition. 99% of the time. The plate I beat exchanger will be in assemble condition because it will be in service and it's gone to my next lesson. 6. Flow Types: Welcome back. Well done for making it this far, we've already looked at the basic types off heat exchanger such as the plate and shelling tube type. Now we're gonna look at the different types of flow through a heat exchanger. On the next few lessons, we're gonna build our knowledge base on, look more into the design features of each type off heat exchanger. So let's get writing because he'd exchanges come in many shapes, sizes, makes and models. They are categorized according to common characteristics. One common characteristic that could be used to categorize them is the direction off flow the two fluids have relative to each other. The free categories off parallel flow, counter flow and cross flow parallel flow. Parallel flow exists when both the tubes I fluid and the shell side fluid flow in the same direction. In this case, the two fluids into the heat exchanger from the same end, with a large temperature difference. As the fluids transfer, heat water to cool up the temperatures off the two fluids. Approach each other. Note that the hottest cold fluid temperature is always less than the coldest hot fluid temperature. So let's have a look at parallel flow type heat exchanger conceived that the hot fluid is entering in the top. It is flowing along through the heat exchanger on down the bottom, so enters at 90 degrees, found light and leaves at 82 F. On the other side, we have the cold fluid inlet, which is 70 degrees finally, and it is flowing towards the right hand side of the screen, where it reaches 78 F. So one fluid, the colder food is increasing in temperature by 8 F on the hotter fluid is reducing with decreasing in temperature by 8 F. We can actually see that on the right hand side of the graph. Fear that as the inlet from the cold fluid increases, the inlet from the hot fluid decreases. So there's a relationship between the two if he is given away from one to the other. In other words, if one is becoming cooler, then that means the other fluid is becoming warmer on the temperature. Change between the two is roughly equal. So in other words, if the hot fluid drops by 10 degrees, then the cold fluid will increase in temperature by 10 degrees so that he transferred between them. His equal is no, actually 100% equal. That's not totally correct. But for our purposes, we can just say that he transfer is equal This type of flow. The parallel flow is not the most efficient type. Simply because we've got to fluids flowing in the same direction as each other. They're not passing over each other. Multiple times is not a very turbulent type of flow, so it's not gonna be the most efficient means of transferring heat. However, when you have a fluid that you don't really want to agitate, maybe it will foam up or there will be some sort of negative reaction. When you agitate, it will create a turbulent flow. Then this parallel flow is ideal because the flow path is relatively direct with little turbulence. I'm looking out the next type of flow, which is a counter float. Counter flow exists when the two fluids flow in opposite directions. Each of the fluids enters the heat exchanger opposite ends because the cooler fluid exits the counter flow heat exchanger at the end, where the hot fluid enters the heat exchanger, the cooler food will approach the inlet temperature off the hot fluid counter flow. Heat exchanges are the most efficient off the free flow types, in contrast to the parallel flow heat exchanger, a counter flow heat exchanger can have the hottest cold fluid temperature greater than the coldest, hot fluid temperature. So although there is a bit of ah mouthful, let's actually just see that in operation. We've got the hot fluid entering in the bottom, which is 90 F. We've got it leaving at the top 82 F. We got the cold coming into the left at 70 on leaving at 78. The difference, though, is that, whereas before we had the fluids flowing in the same direction, such as from the left hand side of screen to the right. This time we've got one flowing in at the bottom and flowing to the left and out, and we've got one flowing in from the left and going to the right. This actually changes the way the heat is transferred between the two fluids, and we can see that on the right hand side of the screen with this simple graph. So we got the cold fluid on the bottom whose temperature is being heated up to 78 ungodly hot fluid on the top whose temperature is being reduced. So rather than converging to a specific temperature between the two mediums or the average temperature between them, the lines on the graph are actually moving in opposite directions. But maintaining the distance between the two lines, it's possible with the top type the parallel flow, that if we have a longer helix danger, the temperature will actually average out to about 80 degrees on. Then it will remain stable. There will be no more. He transfer between the two different fluids. This is not true for the counter flow. If we have a longer heat exchanger, this lower arrow is actually gonna continue to increase on the up. Arrow is also going to continue to decrease, so are actually going to get more heat transfer between the two fluids. It also means that potentially the lower arrow could come all the way up to 90 degrees, whereas that would not be possible. With the parallel flow type, you can see they're converging onto a single point, which is gonna be approximately 80 F. So I do different types there. The counter flow is very, very, very common simply because it is the most efficient type of float. Have a look now at our final type of flow, which is the cross flow. Cross flow exists when one fluid flows perpendicular to the second fluid that is, one fluid flows through tubes on the second fluid passes around the tubes at 90 degree angles, cross flow heat exchanges are usually found applications where one of the fluids changes state to phase float. An example is esteem systems condenser, in which the steam exiting the turbine enters a condenser shell side on the cool water flowing in the tubes absorbs the heat from the steam, condensing it into water. Large forms of vapor may be condensed using this type of heat, exchange of flow and we can see our graph on the right hand. Side is also representing this type of flow, but this time for a condenser. So those are the three main types off flow on over. Next few lessons we're gonna have a look at some examples that use these types off float. Each of these flows has been idealized here, but in reality you're not likely to see each of these types of flow on their own. You normally likely to see a mixture off 23 For example, a counter flow heat exchanger combined with a close flow heat exchanger is pretty standard on def. You remember back to the first challenge tube type each danger. We looked, UH, which was a YouTube type. We were using exactly that. We were using both counter flow on and cross flow. Later on, we'll look at a few more examples, such a single pass to pass and also the YouTube type on. We can explore the flow types more in depth. 7. Comparisons of Types of Heat Exchanger: comparison off the types off heat exchanges. Each of the three types of heat exchangers has advantages and disadvantages, but of the three, the counter flow heat exchanger design is the most efficient when comparing heat transfer rate per unit surface area, the efficiency of a counter flow heat exchanger is due to the fact that the average delta T the difference in temperature between the two fluids over limp for the heat exchanger is maximized. It has been proven that, given the same operating conditions, operating the same heat exchanger in a counter flow manner will result in a greater heat transfer rate than operating in a parallel flow. In actuality, most likely of exchanges are not purely parallel flow, counter flow or cross flow there usually a combination of the two or all three types of heat exchanger designs. This is due to the fact that actual heat exchanges and more complex than their simple idealize counterparts the reason for the combination the various types is to maximize the efficiency of the heat exchanger within the restrictions placed on the design that is size , cost weight, required efficiency, types of fluid, operating pressures and temperatures, or help determine the complexity of a specific heat exchanger. 8. Single and Multi Pass: single and multi pass. One method that combines the characteristics of two or more his exchangers and improves the performance of a heat exchanger is toe have to fluids past each other several times within a single heat exchanger. When the heat exchanges, fluids pass each other more than once, a heat exchanger is called a multi pass heat exchanger. We could see that in a diagram. Here we have a multi pass heat exchanger. The fluid is flowing into the top, passing around the baffles Andi going out off the bottom. On the other, fluid is coming in the right hand side, flowing through the tubes on exiting on the left hand side that is a multi pass heat exchanger. If the fluids pass each other only once. The heat exchanger is called a single pass heat exchanger, so let's have a look. The fluid is flying in the top, flowing along the heat exchanger on out of the bottom. On the other, fluid is flowing in the right hand side, through the tubes on about off the left hand side. Let's load off a couple of freedom models now where we can demonstrate this 9. Single Pass: Okay, so here we have a heat exchanger again. You can see the end covers and no on. We have tubes. Onda tubes on this side right there is. I will take a cross section quickly. We could see the fluid is flowing in the top, going around the baffle plates out of the bottom. The fluid on the tube side is going in for these holes and see the arrows on is then going along the tubes and coming out on the left hand side. Zoom out, can get an overview. What we can see. We've got a counter flow arrangement because one fluid is entering on the left and leaving on the right and the tubes. I fluid is entering on the right. On leaving on the left. You can also see We got a multi pass arrangement on cross flow because one fluid is being forced across the tubes several times. So this is not an idealized flow heat exchanger. This is how they would look in the real world, a counter flow and cross flow and multi pass. Those are very, very common designs. Let's see if now we can load up a single pass shell into type heat exchanger 10. Two Pass: Okay, so we don't actually have a single pass heat exchanger in our database. I had a chick or apologize about that. But what we'll do, we'll try and use our imagination a little bit. Let's imagine for a moment the fluid is coming in on the left and it is coming out on the right where my mouse is now. And we're just imagine that this metal plate stretches along the way through the heat exchanger after my angle it a little bit like this. Here we go. So the fluid is gonna come in, It's gonna flow along the Jews on, drop out on. We'll call that a single pass got. Imagine that the fluid here is also coming in on dropping out here as well. That would be a single pass. What we've actually got, though, is a two past type heat exchanger. It is coming in the bottom, going through the tubes. It is in turning around and flowing back and out the top. We've also got Michelle side. The fluid coming in from the top is doing turns as we can see here on flowing out off the bottom. Before we had a counter flow and cross flow design. This design is slightly different On the lower side of the heat exchanger. We have a parallel flow cross flow design because both fluids enter on the left on both fluids exit on the right. The exit point on talking about the lower side is this area here, so that would be parallel cross flow. However, when the tube on the right hand side turns around, we have a cross flow counter flow design that we conceded of many different variations and the idealized flow versions that we looked at earlier on. Not always true, I can say from experience. This design is also relatively standard. We have another design which I'll show you in a moment called the YouTube design, and it's very similar, except that the tubes are extended into the right hand side rather than talk about it. Let's just have a quick look 11. U-Tube: So here we are again, roughly the same design. Except now, on the right hand side, the tubes have been extended on. The flow is controlled on git is going around the right hand side and looping back. That is a YouTube design on. It would be more common to have this pipe here on the right hand side in order that we could maximize the flow through the heat exchanger. 12. Regenerative and non regenerative: regenerative Andi know regenerative. Commonly, the multi passage exchange of reverses the flow in the tubes by use of one or more sets of you bangs in the tubes. You Ben's, allow the fluid to flow back and forth across the length of the heat exchanger. The second method to achieve multiple passes is to insert battles on the shell side of the heat exchanger. These directors shell side fluid back and forth prostitutes to achieve the multi pass effect, and we saw these battles earlier, so we're not gonna elaborate on that much more. But that is the easy way and the cheap way of achieving the multi pass effect he'd. Exchange's rules are classified by their function in a particular system. One common classifications is regenerative or norma regenerative. A regenerative heat exchanger is one in which the same Florida's both the cooling fluid on the cool fluid has illustrated below. So in the diagram here on the left hand side, we've got a hot fluid coming from the left. It's coming from the process, passes through a heat exchanger a day mineral Isar pump, and then comes back through the heat exchanger and returns to the main process. The idea here with a regenerative type heat exchanger, is to recover some off that heat that is being removed from the process. If we can recover the heat, then we will actually increase the efficiency. We also reduce the risk off thermal shock. Imagine for a moment that the fluid passed through the heat exchanger went after a reservoir sat in the reservoir for a few days, cooled down, then came back through the heat exchanger and to the process. Now, if we didn't have the heat exchanger there, we would be stuck in straight from the reservoir. It's imagine it's cooling water on, then would be pumping it straight back to, let's say, for an example to an engine. This is not ideal. The cooler water is very cold, and the engine is perhaps very hot on What we're gonna have is thermal shocking when the cooling water enters the engine. In order to avoid, this will heat up the incoming cooler water in the heat exchanger by recovering some of that heat from the cooling water system, and this will reduce our chance of firm shock as well as increasing overall efficiency off the engine has perhaps a bad example because I've never seen an engine. It's soft water from a reservoir, but hopefully you'll understand my point. It's elaborate still further. That is the hot fluid. Leaving a system gives up its heat to regenerate or heat up the fluid returning to the system. Regenerative heat exchanges are usually found in high temperature systems where a portion of the systems fluid is removed from the main process on, then returned because the fluid removed from the main process contains energy, which is heat the heat from the fluid leaving the main system is used to reheat the return in fluid instead of being rejected to an external cooling medium to improve efficiency. It's important to remember that the turn, regenerative and non regenerative only refers to how a heat exchanger functions in a system on does not indicate any single type of heat exchanger characteristic Juman shell plate, parallel flow, counter flow, etcetera In a normally generated heat exchanger, the hot fluid is called by fluid from a separate system on the energy or heat removed is not returned to the system. A non regenerative heat exchanger diagram is shown on the screen. Now we can see that the fluid enters on the left from the main process. This is the hot fluid passes through a heat exchanger through a D mineral Isar through a pump on exits. Let's imagine the de mineralized isn't there because this just complicates the system unnecessarily. So what we have is the fluid passing through the heat exchanger going through the pump on returning to the process. A good example here would be a combustion engine. If we have cooling water coming in from the left hand side, passing through the heat exchanger on returning to the engine, the cooling water is going to give up its heat. It's going to transfer that heat to air, so we're going to blow air across the heat exchanger. It's gonna remove the heat from the cooling water on. We're going to cool down cooling water on. This is gonna help us control the temperature off the engine norm. Regenerative types of heat exchanger are very common. Any time when you distribute heat to atmosphere or to ambient air, this would be classified as a non regenerative type of heat exchanger. Because we're passing all of that, he directly to the surrounding air that he energy is then gone. We didn't recover it on. This will give us a corresponding drop in process efficiency whenever possible. It always makes sense to recover the heat because any heat that is recovered will give us a increase in efficiency. On this normally relates also to across saving. If we go back up. Teoh regenerative heat exchanger type. One example that springs to mind here for every generative type of heat exchanger, although strictly speaking is not a closed system would be for a coal fired power station or a large industrial boiler. The air coming into the boiler is usually heated up by the exhaust gas. This reduces the probability of thermal shocking of the boiler so the air will pass through the heat exchanger. It will be heated up. You will then go to the boiler where combustion will take place on then the exhaust gas or the what is exhaust gas now from the air will be passed through the heat exchanger to heat up the incoming air. You can see here how we can recover some of the energy from the process rather than just waste it. And this is becoming more and more commonplace because energy costs money. If we look at large air compresses and industrial plants, you will notice the air compressors generate a lot of heat. In the past, this heat was just expelled atmosphere using Axel fans nowadays that he is no expelled toe atmosphere. It'll actually taken through ducks on. We were used that heat for heating up a warehouse or heating up the building, so this represents actually a cost saving. 13. Heat Exchanger Type Summary: important information from this course so far is summarised below. There are two common heat exchanger designs. These are the plate type on the shell and tube type. Parallel flow, the warmer medium and the cooler medium flow in the same direction. Counter flow, the warmer medium and the cooler medium flow in opposite directions. Remember, counter flow is the most efficient type of float. Cross flow. The warmer medium and the cooler medium flow at 90 degree angles perpendicular to each other, so those are three different types of flow. And just remember, those are idealized types of float. Normally, a heat exchangers and mixture off the two or the free single passage. Exchanges have mediums that pass each other only once. Multi passage exchanges have mediums that pass each other more than once for the use of YouTube's on door baffles. Regenerative heat exchanges used the same medium for heating and cooling. Normally generated heat exchanges. You separate mediums for heating and cooling, so we can use all of their information to help us classify or categorize heat exchangers. We can look at the flow types we can look at the number of passes on, then we can further classify as I have a regenerative or non regenerative. And obviously the most simple classification is simply it's designed, such as plain or shell and tube we're actually gonna do in the next lessons is look at some applications off heat exchangers, so we're going to look at some systems, and then we're going to see how the heat exchanges work. What type of heat exchanger is employed on the reasoning behind it? The idea is, I wanna look at two free examples, and I want to show them to you and explain them to you so that in the future when you see certain designs or characteristics, you'll be outside of our recognize that because it's this and this. I recognize this because of that and that fundamentally, exchanges always have a large contact surface area. So if you ever see fins or metal plates sticking off machinery or transformers or inverters or anything like that, that is normally a type off heat exchanger. 14. Car Radiator Example: So welcome back. Let's have a look at our first example. We're now gonna have a look at a radiator Now. Could read the text here, but one can do instead is just load up the three d model on. Then we can have a look at the engine on how it works on how we can use a heat exchanger to control the temperature off the engine. Very important to control the temperature, the engine. Because if we didn't call the engine down continuously, what we'd actually have is a situation where the engine overheats on when it overheats. The parts within the engine will expand on. The tight clearances within the engine will no longer be there. And that means the parts are going to press together. And we could have a situation where the entire engine seizes. But let me just explain that a little bit further. We can see here on the side, just pause it to get really arrows. The pistons on the left hand side of the screen are incredibly closed to the cylinder, Lina, which is this black line coming down screen here. So if the engine becomes hot, the pistons and the cylinder Lina will expand on. Day will come into contact with each other. The tight clearances will no longer be there. And we'll get a seized engine. So controlling the temperature engine Very, very, very important. And we control that temperature with a cooling water system. Let me just press play again. We can see the arrows going around now. The arrows indicate that the cooling water system, which is running for all these pipes here, is cold. Not just pause it, excluding more system is coming from a pump passing through a firmer stats. And he's coming along the pipe along this point here and then going to the engine. Now the cooling water is at the moment being heated up continuously because it is just doing a loop is coming here along there on back to the engine. The reason that we're eating the cooler water up in this manner is because when we start the engine, we don't want to cool the cooler liquid down. We want the cooler water to heat up at the same pace as the engine until we reach a desired temperature. And this maybe around 80 degrees Celsius when the engine is warm when it's been operating for a couple of minutes or five minutes. We then need to get rid of the heat because the engine is going to continue to get hot. So now we have to switch our method of cooling instead of having a situation before where we circulate the cooler water. We have a situation where we need to cool the cooling water. Let's just push play and we can see that as it's gonna happen. So it's still passing through the engine. The engine's 60 degrees Celsius, 70 degrees Celsius at some point is gonna go 80. Now it's 90 now. It's too hot. The engine is too hot. So the firmest that he's directing the liquid this way and it's not allowing liquid to go the other way. So what we're doing is sending the liquid down. This so we're actually doing within the liquid up through the top pipe on were blocking off the bottom pipe so the radiator is no longer bypassed. The radiator is a heat exchanger. That's what we're using to get rid of the heat. It's just push play so you can see it's coming in the top of the radiator. It's flowing down the radiator on. Then it's cool because it's been cooled down by the air. This fan on the end here may also be turning and blowing air across the heat exchanger as we can see the white arrows and we are cooling that truly water down. So we're cool it back down. Once we've called it down, it's gonna go back to the engine, and it's gonna absorb some heat again on. Then it's gonna get rid of that heat on. It's just going to continue this process in order that we can maintain the engine temperature within design limits the heat exchanger. Although it's not exactly like the ones we looked at earlier, it has some very interesting characteristics on. These characteristics are common with the heat exchanges that we saw earlier, so let's have a look. The water is coming in at the top. It's flowing through the heat exchanger through channels. These are normally be tubes, and then he's passing out through the bottom of the heat exchanger. The word radiator is simply another word for heat exchanger. If you go high up again, we can see that these crisscross metal plates here they are used for transferring heat. Normally be solid metal pieces, and these solid metal pieces will absorb that he as it flows through the pipes on its way down to the bottom off the radiator. This heat, once it's been absorbed, is then gonna be delivered, were expelled to the air, which is being blown across the heat exchanger. So this is one example off a heat exchanger in action. It's not, strictly speaking, a shell and tube life or a plate type, but you can see how we use the heat. Exchanging principle on this example for an engine is extremely common, especially for four stroke engines to strike. Engines have a slightly different set up. I'm gonna show you the example next. 15. Two Stroke Engine Example: on the screen. Now we can see a small two stroke engine. The model is animated to show you how it works, but the bit that interests us if we zoom in is thes bits on the side. Here is thin metal bits sticking out the side off the cylinder Lina, which is pauses for a moment, slightly distracting. We can see that they go all around the top of the cylinder liner on. This is another form off heat exchanger. You'll actually see this design where the metal plates stick out of the main metal body on a lot of different machinery types. Small domestic transformers. Also, inverters will have this design. The metal plates are there to dispel this heat to the surrounding ambient air. Small two stroke engines also have this arrangement. If you look on a motorbike, you'll also see these thing metal plates sticking out beside off the engine, and they're all there for cooling purposes. It's a very basic type of heat exchanger, but it is still a heat exchanger. The next example that I want to show you is a heat exchange. We reduced for a refrigeration system, so let's get right to it. 16. Refrigerator Example: air conditioner evaporator on condenser. All air conditioning systems contain at least two heat exchangers, usually called the evaporator on the condenser. In either case, evaporate or condenser, the refrigerant flows into the heat exchanger and transfers heat by the gain Ingle releasing heat to the cooling medium. Commonly, the cooling medium is air or water. Refrigerant. Cooling systems used for air conditioning are also used for refrigerators and freezers. The process is the same. In the case of the condenser, the hot, high pressure refrigerant gas must be condensed to a sub cooled liquid. The condenser accomplishes this by cooling the gas, transferring it eat either air or water. The cool gas then condenses into a liquid in the evaporator. The sub, called refrigerant, flows into the heat exchanger, but the heat flow is reversed, with the relatively cool, refrigerant absorbing heat from the hotter air flowing on the outside of the tubes. This Causey air on boils the refrigerant that is essentially how a fridge system works doesn't matter if you're using it for air conditioning or domestic refrigeration or large scale industrial refrigeration, the process is pretty much the same. Its load up the three D model now on dykan talk you through exactly how it works very quickly and show you the heat exchanges that used. Okay, so here we have a standard domestic refrigerator. Well, I'm gonna dio I'm gonna explode out some of the parts, and we're going to see if we can figure out how it works. So here we've got a slightly exploded view. We've got a compressor. That is this black, right? Um, in the bottom of your refrigerator. That's the thing that makes the humming noise in the background. When you having dinner? Andi, resume out. We conceded the compressor, compresses the refrigerant gas and sends it along this pipe here on into a condenser. The condenser isn't going to cool down the gas on it is going to then send it to a valve. This'll yellow item here on from the valve. The pressure isn't gonna be reduced on. We're going to get that liquid turning to vapor on. The vapor then is going to be sent through these other tubes on the inside of the refrigerator. Andi is going to cool down the inside of your refrigerator. So that's how it works. But we're interested in the heat exchanges so we can see on the back. We have a tubular arrangement on. We can see the gas is coming through here and he's passing through the condenser and he's going up, down, up, down, up, down. It's gonna be cooled down by the air as it passes up and down through these pipes. But we also have you these thin metal bars going across the tubes. They're going to absorb some of the heat from the refrigerant and they're gonna expel it air. When they do this, they're gonna call the refrigerant down on. They're gonna condense it into a liquid. Remember these bars? We actually saw them earlier. The same design was used on a car radiator. So we're doing the same again. We're just applying the same techniques in order to get the same results. The result we want here is to increase the contact surface area off the heat exchanger. We could do this by either having more tubes on the back, or we could do this by adding a lot off thin metal bars. In this example, it's obviously cheaper and easier to do the thing metal bars, and that's what we've done. So we increase, I heat transfer using this method. So that's essentially how a refrigerator works, and you can see that it's heavily dependent on heat exchanges. Even the one within the refrigerator is a relatively simple design, but the pipes are thin enough that they can transfer enough called energy to the inside off the fridge and cool the refrigerator down in the next example will have a look. A power station type of operation on what have a look at heat exchanger, which has been used for steam generation. 17. Solar Furnace Example: Okay, This is the final example I'm gonna show you on this time. We're gonna use age, shell and tube type heat exchanger. I don't go into the details of exactly our solar furnace works. Actually, video for this on YouTube, so feel free to check it out. But in summary, we can see the sunlight is coming down. It's bouncing off these items called Helio stats. It's going to the solar furnace. It's gonna bounce off these mirrors on into this furnace area. So we're concentrating although that light onto a furnace on the reason we're doing that because we want to get away the heat from the sun's rays. So later on down in the process, I'm going to show you a heat exchanger or what we can refer to as well as a steam generator . Having summary we actually have all of that heat from the sun. It's been pumped along here. We actually use the heat to heat up molten salt. It's gonna be pumped along here, and it is going to a heat exchanger is gonna pass in through the plight grimmer analyses. Now it's going to loop around the heat exchanger. So it's the YouTube design on. It's gonna pass back out again almost where it came in on. We've essentially then taking the heat from the molten soul on we're gonna use it to heat up water on. We're gonna heat the water up and we're going to generate steam on the steam. Then we're gonna use to drive a steam turbine, which you can see off towards the back of the screen now. So that's another example of how we can use a heat exchanger on. This is by no means the only example. If you wanted to, we could also take off the solar furnace section here and we could put some other form of linear concentrator there, which is another way of generating heat. Once we've generated the heat, we still need a heat exchanger. In order to generate steam from personal experience from working on large container ships, you also need heat exchangers for cooling down the jacket water system often engine, which is the cooling water system. When I visited large power stations all over Central Europe, we reduce heat exchangers for cooling down steam in order to turn it into condoms. Say the condensate would then be pumped back to the boiler where it returned to steam again . So there are huge array off operations and systems and processes for which you will need a heat exchanger. It doesn't matter if you're expelling, he recovering, he controlling the process temperature. You will still need a heat exchanger. So they're fundamentally one of the most common pts of machinery you're likely to encounter in any industrial or engineering process. I'm gonna do a short wrap up in next video before I start my blogging about her. Great exchanges are I hope you've enjoyed the courts so far. I'll see you in the next video for a short summary. 18. Refresher Lesson How Plate Heat Exchangers Work: in this video, we're going to look at the plate heat exchanger. By the end of the video, you will know all of the play. He exchanges main components how it works on some of the events, shoes and disadvantages associated with this type of heat exchanger compared to other types of heat exchanger, such as the shell and tube type play. Teach. Exchanges consist of relatively few parts because plate heat exchanges air used for transferring heat that require inlets and outlets where the flowing mediums or fluids can enter and leave the heat exchanger a fluid, maybe a liquid or a guess as fluids are often assumed to be liquid only. We were used to turn flowing medium to avoid confusion, gaskets and plates who used to separate the flow mediums and prevent the mixing. The gaskets are adhered to one side of each plate. Only the plates hang upon a carry bar on a pressed together, using clamping bolts. When the plate to compressed together, they form a plate stack. A guide bar ensures the plates are aligned correctly when the plates stack is open and closed. The final components of interest are two covers at opposite ends of the plates stack. One cover is movable, whilst the other is fixed. The movable cover and fixed cover are also sometimes referred to as the frame plate and pressure plate. Note that the inlets and outlets amounted to the fix cover only. Now we know about the place. Heat exchanges, main components. Let's have a look at how it works, and some of its design features the demonstration purposes. We will assume that we have to flowing mediums on that. One is cold and the other is hot. The hot medium needs to be cool by the cold medium on. This will occur in the plate heat exchanger. The hot medium enters a heat exchanger through the hot medium. Inlet gaskets direct the hot medium as it flows through the heat exchanger. Each plate has an alternating gasket pattern. The hot medium flows into the space between a pair of plates but does not flow into the space between the next pair of plates. Because the gaskets prevent this, the process continues so that each second set of plates is filled with the hot flowing medium. At the same time, the cold medium enters the heat exchanger through the cold medium inlet, but this time the gaskets of position to allow the cold medium to flow into the space. When no hot medium is present, we now have a heat exchanger that is feel route both hot and cold flowing mediums. Each medium flows out of its associated outlet. On the process is continuous notice that the to flow mediums are always adjacent to each other throughout the heat exchanger. The floor mediums thus have a hot, cold, hot cold flow pattern as they flow through the heat exchanger, they are completely separated from each other by the gaskets and plates, and they do not mix due to the close proximity of the flow mediums. Eat is exchanged between them. The hot medium heat up the plate on the plate passes some of this heat to the cold flow medium. Thus, the hot medium temperature decreases whilst the cold medium temperature increases. But what makes play tease exchanges? So if fishing compared to other types of heat exchanger such as the shelling tube type, let's look into some of the play he exchanges. Design features plates themselves are the main reason plate heat exchanges air so efficient this plate may appear simple, but it is actually full of interesting engineering design features. For example, when the plates of compressed to give its former plates stack, the gap between each of the plates is very small, which ensures good thermal contact between the two flowing mediums. The gap between the plates is also known as clearance plates a thin, and have a large contact surface area, which gives each plate ah, high heat Transfer rate plates are manufactured from a material with high thermal conductivity, which further increases the heat transfer rate. Coreg ations on the plate surfaces prevent Landon have flowed and promote turbulent flow, which increases the heat transfer rate whilst also reducing the likelihood of deposits accumulating upon the place surfaces. The Keurig ations also serve to stiffen the plates structure, which allows a thinner plate to be used compared to a plate that has no Coreg ations. Note that plate Keurig ations are sometimes referred to is having a herringbone pattern. So although the plates look simple, a lot of engineering was applied to their design. But the plates are not the only part of a plate heat exchanger with extensive design features. Take the gaskets. For example, the gaskets are able to maintain a seal between the plates even when the system pressure and temperature varies. Holes in each gasket known as tell tales, are used to identify leaking gaskets. This feature allows operators to change the effective plate before the leaking medium leaks through the next gasket and contaminates the overflowing medium. Because the gaskets guide flow through the heat exchanger, it is essential that they be installed in the correct order. For this reason, gaskets are often 50 route markings so that operators can check. Each plate is installed in the correct order throughout the entire plate stack. Another way to check the order of the plates is to spray paint a diagonal line from the top , left to bottom right of the entire plate stack. Although we have only shown to gasket designs so far in this video, they were actually free gaskets alternate for out the heat exchanger, except for the first and last plates within the plates. Stack, which press against the fixed removable covers. Plates that press against the fixed removable covers. A known a start on end plates. Because of their position within the plate, stack the purpose of the starting in plates is to prevent flow into the space between the fix, cover and start plate and to prevent flow into the space between the move book cover on end plate. In this way, the covers and actively used to exchange heat. This makes sense because each of the covers is quite thick. There are no Keurig ations and their poorly designed to exchange heat. There are several ways to vary the cooling capacity of a heat exchanger. One way is to regulate the outlet valves so that the flow is increased or decreased. This method is useful because no dismantling of the heat exchanger occurs. Another way is to increase or decrease the number of plates in the plates. Stack increase in the number of plate in the plate stack gives a corresponding increase in cooling capacity. Decrease in the number of plates in the plate. Stack gives a corresponding decrease in cooling capacity. In short, more plates equals more cooling and less plates equals less cooling. The final method of varying a plate eat exchanges cooling capacity is to use a single pass or multi pass design. Single path. Heat exchangers allow the to flow mediums to flow past each other only once. Multi pass. Each exchanges allow the flow mediums to flow past each other several times. Most plated exchanges use a single pass design flow through plate heat exchanger, maybe parallel cross or counter place. Heat exchanges usually use counter flow, as this is the most efficient type of flow for heat transfer. Counter flow is also sometimes known. Is Contra flow. Because play teach exchanges air used for wide ranging applications, they must be designed to withstand the process conditions in which they operate. This may include corrosive and erosive environments. It's possible to construct plated exchanges from various materials, including metals, alloys and plastics. Different materials made the place heat exchanger more suitable for different applications . For example, if a particular flowing medium reacts aggressively when coming into contact with certain metals, polymer based materials such as Teflon may be used. Instead. There are numerous advantages associated with play heat exchangers play. He exchanges way less require less space on a more efficient compared to other heat exchanger designs of the same size. Replacing and cleaning of the plates is a simple task because the plates that can be opened easily. And unlike shell and tube heat, exchangers play each. Dangers do not require additional space for dismantling, but there are also some disadvantages. Plate heat exchanges tend to be more expensive than other heat exchanger designs. If there is a leaking gasket, causing one flow medium to mix with the other, the leaking play it is often difficult to locate. Replacement of plate gaskets in situ can be difficult or impossible. Some plate gaskets must be returned to the manufacturer for replacement, which costs both time and money when played to compress together to form a place stack. The clearances between the place is small. This increases the likelihood of fouling with a corresponding reduction in the heat transfer rate. When reassembling the place stack over, tightening, the clamping bolts can lead to crushing of the plates, which would damage the plate, Keurig ations and squeeze out the gaskets. If the gaskets have squeezed out, the plates will no longer seal correctly plated exchanges and not suitable for high pressure applications. Because the gaskets would be expelled by the system pressure, the situation is referred to his gasket blowout. However, it is possible to get around this problem by using a gasket list design. These designs usually use braised or welded plates raised on well do plate heat exchangers more suitable for higher temperature and higher pressure applications. You now know all of the plate. Eat Exchange's main components. You know how it works. Some of its design features on the advantages and disadvantages associated with this type of heat exchanger.