Plate Heat Exchanger Fundamentals (HVAC & Engineering) | SaVRee 3D | Skillshare

Plate Heat Exchanger Fundamentals (HVAC & Engineering)

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10 Lessons (1h)
    • 1. Course Overview

      1:16
    • 2. Welcome

      1:08
    • 3. Components

      6:28
    • 4. How PHEs Work

      9:51
    • 5. Plates

      8:11
    • 6. Gaskets

      9:01
    • 7. Varying Cooling Capacity

      3:58
    • 8. Flow Types

      5:44
    • 9. Assembly Disassembly and Maintenance

      13:21
    • 10. Final Thoughts

      1:27

About This Class

Learn about the plate heat exchanger! Components, design, how it works, maintenance and more!

Many machines, and almost all industrial processes, require some form of heat transfer. Designing machinery to transfer heat in an efficient and safe manner is not a 'nice to have', its a necessity. Despite the numerous processes that require heat transfer, only two heat exchangers are commonly used today, the shell and tube type, and the plate type. This course covers the plate heat exchanger in great detail.

You will learn:

  • All of a plate heat exchanger's components.

  • How plate heat exchangers work.

  • Different plate heat exchanger designs.

  • How to vary the cooling capacity of a plate heat exchanger.

  • Tips and tricks when assembling and disassembling a plate heat exchanger.

  • Maintenance tasks associated with a plate heat exchanger.

  • Advantages and Disadvantages associated with a plate heat exchanger.

This course gives you all the information you need to know about the plate heat exchanger and can also be used later as a refresher course. Irrespective of your engineering background (oil and gas, chemical engineering, HVAC, mechanical engineering, automotive engineering etc.), this course will enrich your engineering career because heat exchangers are so common!

Interactive 3D models are used extensively to show you all of a plate heat exchanger's components and how it works. 

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: in this course, we're going to look at one of the most common items of machinery you're likely to encounter during your engineering career, and that is the plate heat exchanger. Well, look at all of the place. Eat Exchange's main components. We'll look at how places exchanges work. Then we'll have a look at some of the design features off the plate heat exchanger, as well as how we can vary the cooling capacity of the heat exchanger. How to identify the flow type that the heat exchanger uses. And finally, we'll look at the advantages and disadvantages. Associate ID with play T Teach dangers. I'm going to use interactive three D models to show you every single component off the plate heat exchanger. We'll use three D animations to discover how it works on. We use custom images so that we can look all of the plate. Each exchanges design features in great detail. This course could be used as an introduction to place heat exchanges, and it can also be used as a refresher course. Check out some of the free preview videos, received the contents on your level, and if you like the teaching style and if you do and I hope to see you on the course 2. Welcome: higher and welcome to the course. My name's John Russell. I'm an engineer of several dot com On in this course, I'm gonna be teach you about the place heat exchanger play Teach. Exchanges are a common machinery item that you're likely to see in many industrial plants. In this course, you're gonna learn about the plate, eat exchanges, components, some of its design features and how it works. We're also going to discuss many other interesting topics, such as how you can assemble and disassemble the place heat exchanger, as well as how you can vary the cooling capacity off the heat exchanger. I am very much looking forward to teaching you about place heat exchangers. There's some of the most interesting machinery items that you're likely to encounter. They do look quite simple, but I can guarantee you there are many interesting things happening within a plate heat exchanger on that you're going to learn a lot from this course that you can also apply to different areas of the engineering world. So let's now get on with the course. We can have a look at a plate. He teach danger in three D on we'll go for all of its main components, 3. Components: welcome to this lesson about plate. He teach danger. Components can see. I've loaded up on interactive three D model. We're gonna use this to have a look at all of the components associated with the plate each danger. We've also got some labels, so that should help. Also, as we move around and have a look at each of the different items, this particular play heat exchanger has been exploded into its various parts on. We've also got some flow indicators as well as some temperature indicators which are actually indicated by using different colors red for hearts, on blue for cold. We're not going to use the temperature indicators so much in this video because we're not here to discuss that works where here is simply to have a look at the components involved. It started this end. We can see it's been manufactured by severally. So we know this particular heat exchanger is going to last forever, and it requires no maintenance. Okay, that was just a joke. Let's have a look. We've got an inlet on the left on. We've got a discharge on the right. We go down here, can see that we've also got on inlet on the right, on a discharge on the left so the cold fluid is flowing in here and that is coming out of the top. The hot fluid is flowing in here, and it is being discharged from the bottom. So there are two inlets and two discharges on. This allows to fluids to flow into on out off the heat exchanger. We've got a fixed plate, that is, this blue plate here concedes, quite thick. Sometimes people refer to this plate also as the fixed cover. We've got some tie bars. That's these long screw threaded items here and at the top. We've got a guide bar. The guide bar is there so that when we push these plates along, for example, if we pushed them all to left, they will stay in the correct alignment because off the guide by shape, let's have a look here can see that we have this very you need shape on each of the plates on. They will slow onto this guide bar, and that ensures that the place are correctly aligned with each other. So that is that guide bar the plates themselves. They're three different types off plates we have a start plate that is the first plate directly after the fix cover. That's this one here that I'm indicating. Then we have, ah, middle plates on the middle plates extend all the way back until the last plate. This is actually called the end plate. So if I zoom out, can see we have a start place here on then we haven't in place on the opposite side. If we zoom out slightly, we can actually see a bar on the lower side on this bar is also used to ensure that the plates are aligned correctly and to carry some of their weight. Let's just go down to the opposite end. You can look at the final piece off the plate heat exchanger. We have here another plate. This is a movable plate, sometimes called a movable cover. The reason we call it a movable color is because when we assemble the place heat exchanger , all of these thing plates are going to be pressed together on. They're going to be sandwiched into a very small area. The move will cover, then comes along on, is pressed onto the plates on we end up with what we refer to as a plate stack. So when the plates are separated out individually, there simply plates on. When we push them together and we press them together will say that they form a plate stack . We also have this item here, which helps us to roll along the guide bar as we pushed the movable plate towards the fix plate. Now the nuts themselves are not going to be fixed onto the movable plate, like shown here, because she should always be tightening the nuts onto the bolt rather than the bolt onto the nuts. However, you can see that if we were to press all of this together, the nuts on the right hand side of screen would then be able to be screwed onto the Fred here and will be have to use those nuts to gradually clamp all of the place together. And then we're gonna end up with quite a compact plate heat exchanger. We're going to look at the plates in more detail later in the course, but I wanted to show you one area that is off particular interest, and that is the gaskets, these black items here that are stuck to the side off. The plates are gaskets, and they are very, very important in order to ensure that the heat exchanger is operating correctly. We'll talk about gaskets bit later on the course, but notice for now how each gasket is slightly different from the corresponding plate that it's next to. So, for example, here we have a gasket that comes around here and then goes back down. But on the other side, we have quite a complicated looking gasket. The one after that we have. Ah, simple gasket again comes around here and down on the one after that. We have a complicated looking gasket. Again, the gaskets are actually reversed on every second plate. So if resume out slightly, you can see maybe the pattern. Complicated. Simple, complicated, simple. But notice that the design itself is simply reversed have a complicated one here on on the next plate. It's on the opposite side on next, plates on the opposite side again. And if we go to look at the fourth plate, you'll see it's on the opposite side again. So this alternating pattern is very important, and I'm gonna explain to you why that is in the next lesson where we're going to discuss how plated exchanges work. So that's kind of look at that now, 4. How PHEs Work: welcome to the lesson on this lesson. We're gonna look at how play TV changes work as mentioned in the previous lesson. We have to in Let's onto discharges on their installed on the fix plates notice the hot fluid goes in the top left side and comes out the bottom left side. The cold fluid goes in the bottom rights and comes out the top right. You just spin it around so we can see the arrows so hot goes in at the top and out of the bottom, and cold goes in the bottom and out of the top. The reason we feed the fluids into the heat exchanger like that is actually quite simple. As the cold fluid goes into the bottom here, it's going to pass through the heat exchanger and become warmer, and as it does so, it becomes less dense on. Then it's gonna come out of the top three, This hole here, when it becomes less dense, it's gonna have a tendency to try and rise above any of the fluid that is more dense. So that means it's going to try and brize upwards out of the heat exchanger. So if we're pumping fluid around the heat exchanger, it makes more sense to pump it into the bottom, and then that way, as it gets warm, it's going to pass up anyway. And then out of the heat exchanger. If we did it the other way round would be pumping the fluid in cold through here. It will get warmer, and it would want to actually rise back up as its density decreases on would have to put more effort into pumping it down and out through this hole. So is the general. If we put in a cold fluid into a heat exchanger and it's going to be heated up slightly, then he's going to go into the bottom and add on top reverse Lee. If we take a hot fluid and we put it into the heat exchanger life seen you on the upper left side, then we're gonna put the fluid in at the top on out of the bottom because as the fluid cause its density increases on, then we can take it out off the bottom. So there's no point trying to fight the laws of physics, because if we do that, then we're just gonna waste energy, and that's something that we definitely don't want because energy usually costs money in order to learn how the lately exchanger works. Let's just imagine for a moment on the hot fluid side, we've got the flu going in at 50 degrees. I'm not going to say Celsius or Fahrenheit because you can work with whatever units you're comfortable with, but it goes in at 50 and comes out at 40 correspondingly. If we've got a 10 degree temperature drop, we're going to have roughly a 10 degree temperature gain on the cold fluid side. So if we go in at 50 and come out 40 on the hot side, it's just imagined on the cold side. We go in it 30 on. We come out at 40 now. These are rough approximations, but will stick with them for now. So 10 degrees lost on the hot fluid side equals 10 degrees gained on the cold fluid side. If we're looking at thermodynamics, the example we're using is not strictly correct, but for us, it's a good enough approximation. Let's have a look at what happens to the fluids when they go into the heat exchanger. We can see that on the first plate, this plate here, non off the fluid flows between the area off the plate, that is to say, the start plate on the fixed frame. The reason we don't have any flow in this area is because the frame itself is a very poor heat exchanger. We don't really want to heat up the frame and try and get rid of that heat to the air. As you can see, the frame is quite thick, and so it's not going to transfer the heat very well. So the start plates has gaskets that surround both off the inlets on discharge holes, and see here is completely surrounded on the next one as well. If you got here, can also see that the gasket is completely around here and also around there. And that means that when we press the plate against the fix cover, so pressing to start playing against you fix cover. No flow is going to be able to pass through the gaskets on onto the side of this plate here , so keep that in mind. The gaskets are sealing certain areas off each plate for the start plate. We're sealing this entire section off the plate so that no flow is allowed between the fix plate on the start plates, at least on this side. However, on the next side, you can see that are Gasquet has changed slightly, and it is the gasket that is controlling the flow to every single place. So now imagine this plate is pressed up tight against the one on the left. When the mouse is now, we're going to allow the fluid to come in and it's gonna flow downwards. It's gonna flow the way down here. Down here, down down, down this place quite long, Andi. If we get down to the bottom and zoom out slightly, you can actually see. The flow is gonna come down and it's gonna pass to the bottom section where analyses. Now, when we get to this section, the flow is going to flow to the left and it's gonna be carried out off the heat exchanger . So let's go up to the top again. Can see it comes in over here trying to line this A little bit better comes in here. Flows downwards soon mount slightly in their flows downwards, downwards, downwards, downwards! A main goes out on this side here, and that is all that is occurring for the whole fluid. If we have a look at some other plates, we can see the same thing happening again. The analyst correctly, you might actually see exactly how the flow goes through the heat exchanger. Hot, cold, hot, cold, heart, cold parts, every hot plate or every hot side of the plates has the same gasket. See here this is a hot plate. Look at the gasket in this area. Go across same again, same again. So we know that we're taking flow in at the top. It's coming down flowing downwards, and it's coming out at the bottom left. Once we get all the way to the end, you can actually see that we've got a hot plate on this side. Well, this is the hot side off the plate on the opposite side because it's an N plate. We actually have a gasket, which was the same as what we used at the start. On this prevents any flow going between the plates on removable cover or the movable frame . Now we do this for the same reason as before. The movable frame itself is not a good heat exchanger, so we don't use. It is part of the heat exchanging process. But let's now have a look at what happens to the cold fluid We've seen that the hot fluid goes in the top left and comes out the bottom left and it passes through each of these plates. The cold fluid comes in the bottom rights and it goes out off the top rights. Let's pull out one of the cold plates. Start with this one here. The cold fluid comes in here. It flows upwards, upwards on, then reaches the top. Right section of the plates on is pushed outwards by the flow from all the other plates on from the pump. So the cold fluid is entering the bottom right on. Flown out of the top right on. The hot fluid is entering the top. Left Onda flowing out off the bottom left. Andi were circulating the two fluids within the heat exchanger because we always have this hot, cold, hot, cold, hot, cold pattern for outrage. Danger on because the plates themselves quite thin. We're going to exchange heat from one side of the heat exchanger. So here, where It's blue and cold compared to the other side, which is red hot. So they're coming not into direct contact with each other, but they are coming into thermal contact. The hot fluid is going to be cooled down by the cold fluid on the cold. Fluid is going to be heated up by the hot fluid, and that is essentially how a plate heat exchanger works. The plate heat exchanger allows us to bring to fluids into close contact with each other, not direct there, actually in direct contact and allows us to exchange heat so they're in thermal contact with each other. And that allows us to exchange heat between the two flow mediums without them coming into direct contact with each other. The process is incredibly efficient. The reason it's so efficient is because of the design off the plates. So let's not go and have a look at these plates in a lot more detail 5. Plates: welcome to the lesson on plate heat exchanger plaints. I'm quite excited to do this lesson because I find the plates of a plate heat exchanger very interesting. And hopefully, by the end of lesson, you also feel the same. You see, we got three plates we've got in a play on the left Be played in the middle, Andan in plate on the right. This could also be a start plate because the design is the same. So let's imagine for a moment the A plate is our hot plates or is for I helped fluid. The beep ladies, for our cold fluid on this one on the end would be both our start on N plate. The end plate usually has a gasket on the front side on the back. On this one, it doesn't, but it should also have one here. Whereas the other two plates, the A play and deeply is hot and cold fluid plates. They will have a gasket only on one side. That's because the gasket on the back of each plate is going to press up into this area on into these channels around here. So there's always one plate that presses onto the back of another. That does ceiling. We spin around here. We can see we've got alternating gasket pattern again on this allows us to control the direction off the fluid through the heat exchanger. So why are the plates so interesting? Let's analyze them first. Visually, all heat exchanges have a large cross sectional area in order that the two fluids can have a large thermal contact area. So you're never going to get a heat exchanger that has a small thermal contact area, because that doesn't make sense. We want to maximize the thermal contact area between whatever is flowing through the heat exchanger. This ensures we get good heat transfer between the fluids. So each of our plates has a large cross sectional area on because of this large cross sectional area, because we have a hot fluid on one side, for example, here on a cold food on the backside, for example, here we're going to get very good, he transfer. In addition to that, you'll notice that each off the plates is very thin, and this also ensures that we keep the fluids separated only by as much as needed, because the plate itself forms a barrier between the two fluids and hinders heat transfer between them. So we want to make the plate as thin as possible so that we can get as much heat transfer as possible. In order to build a very thing plate, we're gonna have to use corrugated Tin's Nick orig ations are these weeds squiggly lines that are on each of the plates and see them in this section here? This is what we refer to is a herringbone pattern. You'll often see herringbone patterns on gears. Now this herringbone pattern that forms a core a Gatien. He's used to stiffen the thin plates. It allows us to produce a thinner plate than if we were using simply a flat rolled plate. The stiffness is needed to give mechanical strength to the plates, but the Coreg ations also serve other purposes. Have a look. You can see that we have this weird, squiggly pattern, and that's going to interrupt the flow off the fluid as it passes over each of the plains. This creates a very turbulent flow. The turbulent flow increases the heat transfer rate. Not only that, but the turbulent flow prevents deposits building up on the plate surfaces, so the turbulent flow helps to keep the plates clean. If the place get dirty them right, you're going to form a barrier between the plates on the fluids. Let's imagine for a moment that we have some deposits in our hot water circuit. Let's imagine that these deposits buildup is a thin layer spread all across this herringbone pattern. So all across congregations and they're gonna form a insulate er. Now the insulator is not going to allow heat to transfer through it very well. And this means we're gonna get a corresponding drop in the heat transfer rate off our plates. Heat exchanger. If we get a drop in the heat transfer rate, this is going to express itself when we look at the temperature in and out off the heat exchanger. We call this sometimes it delta T. So normally, perhaps we get a temperature difference between the India and the outlet off, say, 10 degrees. But once we have these deposits forming on the plates, maybe we only get a drop in temperature or a delta t off about eight degrees. And as this problem gets worse, the Delta T is going to reduce and reduce and reduce until we're getting almost no heat exchange between the fluids. It all so the Keurig ations helped to prevent this occurring. Notice that each of the plates is manufactured from some sort of metal or alloy. The material selected is going to be a material chosen for its thermal conductivity, not just based upon its mechanical strength. We want to allow heat to transfer through the plates almost unhindered, because this will give us the maximum he transfer rate, so material selection off the place is very important. Another interesting design consideration, though, is how are we gonna use these plates for what system do they need to be corrosive resistant ? Did they need to be erosion resistance? What system are there going to be used in? I used to work with play, teach exchanges that were used for sea water systems, and it was not unusual to have titanium plates because they were very, very good. Foresee water systems. They would resist corrosion. Anyone who's ever worked with seawater and metal or alloy is before will know that sea water eats away at metal quite readily, and you'll often choose copper based alloys such as brass or bronze in order that the metal can resist the corrosive effects off the seawater. Titanium itself is an alloy, quite an expensive one, but because it naturally builds up in oxide layer on the alloy surface, it's almost impervious to corrosion from sea water. So it's an ideal material for a heat exchanger that's gonna be exposed to seawater. So although the plates look simple, they've actually got a ton of engineering design features. Three. Cat. They've got a large cross sectional area to promote. He transfer. They're very thin again. This promoted transfer the material selected. He's gonna have high thermal conductivity, which further increases the heat transfer rate. The Keurig ations allow us to manufacture a thinner plate whilst also promoting turbulent flow on preventing deposits forming on the plate surfaces. Because the plates are so thin, we can pack a lot of them together to form a plate stack, and we're going to get a very large cooling capacity despite the fact that the plate eat exchanger itself is gonna be very compact and small compared to other types of heat exchanger the plate. Each danger has a very high transfer rate compared to its size. So now we've learned a little bit about plates. Let's have a look at the gaskets, which are also not quite as simple as they appear. 6. Gaskets: Let's have a chat now about the gaskets on the plates. Now the gaskets alternate as discussed earlier from one plate to the other. We also have our starting in place, which is quite unique gaskets on the road. The interesting thing about gaskets is they have to be able to expand and contract, irrespective of the changing temperature and pressure within the system. The plates themselves, they're going to expand and contract as they heat up and cool down. And it's important the gaskets are able to expand and contract with them. If they don't expand and contract at the same rate as the plates, then the gaskets are no longer going to fit into these ridges there on each of the plates, and we're not gonna get a good seal. If we don't get a good seal, then we risk having leakage on leakage may go from one plate out into the surrounding environment, off the who teach danger, or we may get a leak from the cold fluid side to the hot, fluid side. If we get a leak from one of the fluid systems to the surrounding area around the heat exchanger, it might not be such a big deal. Let's imagine for a moment we have a fresh water system. We get a whole or perhaps a gasket is pinched out of its group. And then we're gonna get a leak out here. And maybe a bit of fresh water is greatly gonna leak out, and we can make a note to change that particular plate. Because the league is external, it's quite easy to identify on. It's easy to find the plate on, replace a gasket or replace the plates in its entirety. He gets more difficult, though, when we have a leak from one gasket when I cold fluid side, for example. And it leaks into the other system, for example, are hot, fluid side. If you cannot see the leak externally, it's very difficult to locate it within the place. Heat exchanger now water mixing rewards. There might not be such a big deal, but let's imagine for a moment that we had oil and water. We don't necessarily want water mixing with oil on. We don't necessarily want oil mixing with water. If you've got water mixing with oil and the always used for lubrication, then we risk damaging the machine that is being lubricated. If you've got oil leaking into the water system, it may be that this water goes back to a lake or a pond or river on. We risk pumping oil into these water sources. If that happens, then we're going to be polluting the environment. And in many countries there are very large fines that discourage you to do this So we don't want war going on oil, and we don't want all going in the water when we have a plate stacked pressed together. Though finding the leak wherever it may be is going to be very difficult. So will there. The gaskets do expand and contract along with system pressure and temperature. If we have a system to system leak, call fluid too hot fluid, it may be quite difficult to identify in order to get around this problem, though we use what's referred to as tell tales. The most likely place for a leak between the fluids is through the gasket here, specifically from this point here, around to this area here. If we were to get a hole in this section and perhaps a hole in the other section here, then the fluid will be able to leak out across year on. It will contaminate the other system fluid. So if we have a hot fluid coming through, this pipe here absolutely leaks a little bit through here a little bit through here, and then it reaches the opposing system. Then we're going to get contamination. So it's get around this problem. We say, OK, the leaking area is likely to be here because there's nowhere else that the hot fluid is gonna be able to contaminate the cold fluid. We take a little bit away from the gasket here and perhaps a little bit here. And if there's any leak from this section here, then the leak is going to just pass through and come out off the tell tale that's going to allow us to know where the leak is occurring. So we'll be able to identify the plate that's going to allow us to schedule maintenance so that we can either change the gasket, replace the plate in its entirety or remove the pair of plates. For example, this cold plate onda corresponding hot plate. If we remove a pair of plates that were reduced, the cooling capacity of each danger, but we can then reassemble the plates stacked and everything will work as before. The gaskets themselves are often manufactured from nitro rubber because this has very good sealing capabilities on will expand and contract with plate. You may need to remove the gaskets from the place when you're performing maintenance. Where if the gasket is damaged. In the past, this used to be quite difficult to do. Sometimes you actually have to send the until I play away on the gasket would be reinstalled in the factory. It would actually use liquid nitrogen, and they would freeze the gaskets off the plates and then install new ones. More modern plated exchangers allow you to exchange the gaskets on site rather than sending the entire plate away. So this is a much better solution. Keep in mind that Noel Plate heat exchangers use gaskets, the type of plates that we're looking at now. I used for gas kitted plates, heat exchanges. If you're handling something that's quite corrosive or erosive, and you don't arrest any of that fluid leaks out into the area surrounding the heat exchanger, then you can purchase a braised heat exchanger or a welded heat exchanger. So rather than using gaskets, you will braise the plates together or weld them together, I have to say, though this is usually only used where you have concerns about what happens if the fluids leak out off the heat exchanger. If you're pumping a very corrosive fluid through the heat exchanger, the last thing you want is a gasket leaks, and somebody gets sprayed with corrosive fluid on. For this safety reason, you're perhaps choose to purchase a braised heat exchanger rather than a gas kitted heat exchanger. Sometimes you'll see that the gaskets of 50 with markings. These will be small bits of rubber or plastic that have been stuck onto the side of the gasket or formed part of the gasket itself. The reason we use these indicators or markings is because when we assemble the plates stack , we want to ensure that all of the plates have been assembled in the correct order. So in order to do that, we use markings, and then we can cross check the markings to ensure that we have, ah, hot, cold, hot, cold, hot, cold pattern throughout the whole plate stack. If we don't have markings or indicators on the gaskets themselves. The best thing to do is to take a can of spray paint and spray a diagonal line across the assemble plates. Stack. When you disassemble the plates, stack and clean all the plates. You should be able to see that when you reassemble the bait stack, the line is still there. The diagonal line should still be in alignment. If it's not, then you re assembled a plate stack in the wrong order. That's a very cheap and effective way to ensure that your plate stack is assembled in the correct order. Personally, I found that if you used a thinner line on multiple markings, it was a lot easier to cross. Check for everything was assembled correctly. If using spray paint, it's not exactly very precise, and sometimes it's difficult to know if you've assembled the plates that correctly or no. So perhaps a thin paintbrush would be a bit more appropriate. And try to remember that putting one marking on the plate stack is good. But having two or three doesn't hurt, and it really does allow you to cross check and make sure everything's working correctly. The last thing you want to do is reassemble the plates, stack, put into service and then find out that you've accidentally exchanged when you're hot plates for a cold plate. I should also mention at this point that you shouldn't restrict this practice of putting markings on machinery or components when you take them apart. Have you ever taken motor apart or an engine? You'd always punch holes or paint lines on into the components in order that you can reassemble everything correctly now? I mentioned a moment ago that if we remove one plate, we have to remove the opposing plate in order that we can put the heat each danger back into service. So let's go have a look now how we can regulate the cooling capacity off the plate heat exchanger. 7. Varying Cooling Capacity: in this lesson will talk about varying the cooling capacity off a plate heat exchanger, the first and most obvious way off regulating the cooling capacity of the heat exchanger used to regulate the flow through the heat exchanger. You can do this by throttling, which is another word for regulating the outlet valves off the heat exchanger. I noticed, Sara said. Outlet valves. I didn't say inlet valves. The reason you throttle the outlet valves and not the inlet valves is because we don't want to starve the heat exchanger off fluid. If we do that, then we might get localized overheating, and we may damage the heat exchanger plates or gaskets. So frontal the heat exchanger, using the outlet valves or discharge valves only. And in this way you can regulate the cooling capacity of the heat exchanger. One of the big advances use we've played the changes is that if you have a problem with one of the plates, you can remove that plate on the plate behind it, and you'll then be able to put the heat exchanger back in service. The plates stacked will be smaller, so we have a smaller cooling capacity. But at least we can keep the heat each danger in service, so this is very useful when we only have one heat exchanger, and there's no redundancy in the system. Obviously, you can only do this procedure so many times because the more plates you remove, the more cooling capacity you remove on. This might not be acceptable for the system as a whole. Let's imagine for a moment we needed to maintain a delta T, but it's a temperature difference of 10 degrees across the heat exchanger in order that the machine associated with that system did not overheat. Well, if we start removing plates and we only have a delta t of eight degrees, then the machine associated with the heat exchanger may overheat because it's not being called as much as it should be. A good example would be perhaps a large engine who used a heat exchanger to call the lubrication or but the engine uses the lubrication. Oil itself is required to take away from the engine in order that the engine does not seize because if it comes to home, so if we're not cooling down the oil using the plate heat exchanger, then the engine is also not being cooled down, either, so that's what we don't want. However, for most systems, remove in a couple of plates from the place that is not gonna make a huge difference to the system as a whole. The final way off, varying the cooling capacity of a heat exchanger, is to use a single pass or multi pass design. Single passage exchangers allow the flowing mediums to float past each other only once. Multi pass heat exchangers allow the flow mediums to flow past each other several times. Most played exchanges that I've seen used a single past design, although it is possible to have to pass or free pass plate heat exchangers. So keep that in mind. When you're looking at different types of plate heat exchanger, they may be single or multi pass, so those are the three main ways or very in the cooling capacity off a plate heat exchanger . You can regulate the flow using the outlet valves. You can increase or decrease the number of plates in the plate stack, or you can use a single or multi pass design. The simplest option, by far to regulate the cooling capacity is simply to regulate the outlet valves. The next option would be to regulate number of plates in the plate stack, and the final option is more a design consideration for the system as a whole because you're me to purchase a different play, each danger. If you're upgrading, for example, from a single pass to a multi pass design, let's now have a look at some different flow types that you're likely to see when looking at heat exchanges. 8. Flow Types: If we're taking a look at heat exchanges in general, then you'll see that there are three main types of flow through he exchanges. These are parallel counter and cross flow. You'll also see these flow patterns used in other machinery. Items such as cooling towers are many other types of machine. Let's first take a look at the most basic type of flow, which is parallel flow. Parallel flow essentially means that the two fluids are flowing in the same direction. That means they enter at the same point on they are discharged at the same point. So if you remember when we first looked a plate eat exchanger on the top of the huge danger , we had an inlet on the discharge because the two fluids were flowing in opposing directions . One was going in on one was going out. Now, if we had a parallel flow plate eat exchanger, then what we would have actually seen is that there are two in Let's on the top of the heat exchanger onto outlets on the bottom of the heat exchanger. Because the two foods are flowing in at the same place. That is to say, at the top of the heat exchanger on out of the same place, that is to say, at the bottom of the heat exchanger, so that is parallel flow. What's interesting about parallel flow is, and we can see this on the graph is that as the fluids passed through the heat exchanger, they converge upon a certain temperature at this point will no longer exchange any heat. So on a graph, we can see that one fluid enters the heat exchanger 70 degrees, the other 90 degrees on the ninth degree. Fluid drops in temperature by eight degrees has a delta T of eight on the 70 degree fluid, increasing temperature by eight degrees, so that also has a delta T off eight degrees. If the heat exchanger was extended, then the temperatures from both fluids would converge upon 80 degrees, at which point will no longer get any heat exchange between the fluids, so that is parallel flow. We're now looking at a counter flow. Example. Notice that the two fluids flow in opposing directions. Counter flow is quite interesting. No. T c. We've got one fluid entering at 90 degrees on dropping down to 82 degrees on another fluid entering at 70 degrees on increasing to 78 degrees at the outlet. Notice, though, that the difference in temperature between the two fluids is maintained a 12 degrees. This is because the outlet for one fluid is the inlet for the other, so the cooler fluid will approach the inlet temperature off the warm of fluid. Because of this counter flow, sometimes called contra flow, he's the most efficient off the three flow types. That's the reason why most heat exchanges use a counter flow design. There is a final flow design, and that is the cross flow design. This is where the two fluids flow at 90 degree angles apart. So, for example, one fluid will flow downwards on a novel. Fluid will flow from left of right, so the two fluids are flowing at 90 degrees apart across flow. Heat exchanger is normally used where we are changing the state off one of the fluids. For example, we are changing the state off steam to water or a gasol vapor to a liquid. They're not normally used where we do not have a change off state. We can actually see on a graph that one of the fluids changes temperature from 70 to 78 degrees, and this is in a linear direction that is to say, a straight line. But the other fluid, which is changing states we can see that it enters at 90 degrees on drops down to 82. But because of the change of state on because the thermodynamics sensible and latent heat, we get a non linear change in temperature. I can't remember ever seeing a cross flow plate type heat exchanger, although I have not seen every type of heat each danger out there. So perhaps they exist. I should also mention that the counter flow single past plate heat exchanger is the one that I found to be the most common. But keep it in mind. Three different flow types may be single past maybe multi pass. That may be unique requirements in the system that require a special type off flow. Keep in mind there are always exceptions to the rule. I've seen one system that was quite peculiar, and it was peculiar because the entire system was designed, so the fluid being circulated was not agitated. In other words, they tried to reduce the turbulent flow through the system as much as possible. So things like corrugated tin's on heat exchangers would not be desired because they create turbulent flow. But just keep your mind open that there are always exceptions to the rule, and there may be reasons why people opt for a less efficient heat exchanger on that. Maybe something to do with the product may be something to do. The fluid you just won't never know unless you're in charge of the entire system. And you know the system very well. Let's now go have a look at some advantages and disadvantages. Associate ID. We've played type heat exchangers. 9. Assembly Disassembly and Maintenance: in this lesson will talk about assembling and disassembling a plate heat exchanger on. We'll also talk about some of the common maintenance tasks that you're likely to do when you disassemble the heat exchanger. When you think about it, the reason you disassemble of heat exchanger in the first place is usually because maintenance is required. You can see on this three D model that it's been exploded into its parts. We can see each of the individual plates. Then we've got a plate stack on the frames, etcetera. If we played animation, you can see it'll being assembled. See the upper and lower guide bar going down to see the plates sliding along like stat comes along, and then the movable frame comes on top of that to press. It'll together and the bars go on the side, and we're going to use the nuts to tighten up the tie bars. So that is how a plate heat exchanger is assembled. Let's imagine for a moment we want to take it apart before we even think about taking it apart. We need to ensure that when we put it back together, it's gonna be the same as it was before. There are two rules that every young engineer needs to know about. One of them concerns maintenance, in which case you leave it like you found it on the other one concerns when you try to perform maintenance, you break something. And in that situation, you say it was like that when I found it. Gates like joke there. We should actually be putting the machine back or the component back as we found it. That is the correct way to perform maintenance. So what are we gonna look at when we look at our latest exchanger to ensure that we put it back the way we found it? Well, the first thing we can look at is the plates stack the plates stack. If we measure it from the movable frame to the fixed frame, he's going to be a certain length now, with the measure that length, and we also compare it to the value in the manual. We can ensure that when we reassemble the plates stack, the length remains the same. This ensures that we haven't over tightened the plates stack or under tight in the plate stack. The place stack itself will have a honey comb structure, and if you look at that, it's not very apparent on one here. But if you look at it normally, you'll be able to see a pattern that carries on a way through the plates. Stack on this honey comb pattern will help you identify if the plates air in order or no, you're also sometimes have tags on the side of each plate. If I go back a little bit here, see, one plate might have a blue tag the next one red, blue, red, blue, red. And we can check these tags to ensure that the plates are in the correct order. When we reassemble the plates stack. If we actually just open up the plates stacked for a moment, we'll go along here. He was sometimes see an indication round about here, and it will say a on the model number of the plate. The next plate will say Be on the model number of the plate again so you can also check a B A B when you're assembling. But you may also be able to check the tags on the side, and you will be able to check the honeycomb structure on the side of the plate. Stackers will. Apart from measuring the distance from the movable frame to the fix frame. We can also put a line across the plate stack. It should be ideally away. Down the plates stack, although usually is just here, you can do another one. Stretches down here on that will also ensure that you've put the plates back in the correct order. So these are all things that you should be thinking about before you even take the plates. Stack part. The other things you need to ensure are the basics. Is the system drained down correctly? Are both systems? Let's imagine for a moment we've got a hot water circuit on an oil circuit. Are the two systems isolated? All the pressures relieved? If we've got hot water circuit, what sort of temperature is the hot water at? Do we need to wait and allow the hot water's cool down before we can work on it? So we need to ensure that both systems are isolated. The pressures are relieved. The temperatures are acceptable for people who are working on the plate heat exchanger. The fluids are a corrosive if they are, do people need protective clothing. Do we need event the area when we open up a plate heat exchanger, etcetera. So there's a lot of things to do before we even take the place heat exchanger apart. In addition to allow that we can have a look at the tie bars. Specifically, you want to look along this area here after each of the nuts. The reason you want to look along the Thai bar is because you're gonna have to undo that, not all the way to the end of the Thai bar. And you have to do that on a lot of the tie bars. Sometimes if the place heat exchanger is in an area that's not very clean, and you want to get a wire brush onto each of these dive bars and clean them off after you clean them off, you want to grease them up as well. Need to make sure there's no obstruction on your guide bar here. Maybe you need to clean up and apply a layer of grease onto the upper on the lower guide bar as well. So consider all of these factors when planning to perform maintenance on the plate heat exchanger. Even if you've done the job 10 times before, always print out the checklist or get the manual and just read through it before you open up the heat exchanger itself. Because once you open up, it's out of service until you can put it back together again. If you've only got one plate et changer in the system, then most likely needs to be returned to services quickly as possible, which definitely adds to the stress level of all the people involved if you need to put it back together quickly. But it just doesn't seem to want to fit together. Let's assume for a moment we've done all the preparation. Onda. We know that we can open the place et changer in the stack and put it back together again, and it shouldn't be an issue, So we'll open up the heat exchanger. No, if I go over here, concede to the plates now that we've opened up each off the place, what we actually want to do is spread them out normally of these one at a time as they come off the plate, stack Factiva, spin around this side a little bit easier, but you want to spread them out, and you want to clean each of the plate surfaces. Usually you will do this with a brush on a cleaning agent on. Then you'll rinse them with water. As soon as the clean agent has been applied on may be done its work for a minute or so. The reason that you don't leave the cleaning agent on the plates very long is because Clean agent can damage to gaskets on. It can also sometimes caused the glue that holds the gaskets in place. To become less adhesive on. The gaskets would literally just peel off. So if you're using a cleaning agent, make sure you apply it on. Let it do its thing for a little bit and then wash it off. If using brush, then use a soft brush can use a soft brush. Maybe you can even use the brass brush, but don't go in there with pneumatic tools and a wire brush and try to scratch all off the plate completely clean. Sometimes you have stainless steel plates. Sometimes you have titanium plates, sometimes made of different materials, but generally you want to treat the plates with care. Remember, they're quite thin. There's no need to be attacking these plates with a stainless steel wire brush on, especially not with pneumatic tools, which may actually considerably damage each other plates. So you just treat them with care on. Try to pay attention that you don't damage the overall surfaces of each of the plates. Once you've cleaned all the plates, then the place that could be reassembled, and you can then check the diagonal lines. People on the plate stack. You can measure the distance from the movable plate to the fix plate, and then you can check that there's a honey comb structure or that the pattern is consistent throughout the entire place. Stack a common very mode for plate eat exchanges. He simply that the titles are over tightened. Typically, you may find a talk rating that you can use in the manual. But even if you don't have that, you should also be able to measure the distance between the movie foreplay and fix plate. And this is a good way to double check that you've assembled the plates that correctly. The problem with over tightening is first that people reassemble the heat exchanger incorrectly. Andi. Secondly, they just over tighten each one of these and pinch out a gasket, crushed the congregations or perform some other damage to the eat exchanger. There will be in the manual a correct tightening procedure for the heat exchanger. Typically, if there are eight Tybalt here we have six. It's imagine there was another 21 here and one here. What would actually do is we were tight in the centre ones first a little bit on, then we work on the outer ones. Next on, then the middle ones again on then the outer ones again. But what would actually do? We would cross tighten the titles. So we go here one to three four and then we would tighten up here 12 three on four, back at the top and repeat. But it really depends on what the manufacturer tells you to do Here. We've got six tables, so we have to think off how we could tighten these up correctly without pinching out the gaskets. To my mind, I'd probably start here. 12 3456 on you do it incrementally. That means that perhaps one full turn here, One full turn here one full turn here on Repeat, You can actually do more turns at the start. Perhaps 222222 But as the plates stacked becomes thinner. As you start to push Always plays together, then you're not going to be doing to turns at a time. What you're actually going to do is do one turn at a time and in half a turn at a time until the distance between the move will play in the fix plate is the same as it was before you started maintenance. So that's how we assemble and disassemble the place et changer on also how we clean the plates. There is no other option, though, that a lot easier than taking the whole thing apart and now is simply to clean it when the plates stack is assembled. So what we would do here is disconnect each off the two systems here, and then we would pump or circulate cleaning fluid through the place heat exchanger. That means that we connect to pump between this pipe here on this pipe here. Sometimes people call these portholes, by the way, and then we connect to pump between this pipe here on this one here. We would then turn on the pump on. We would circulate cleaning fluid through the heat exchanger on. It would clean each off the plates. A common cleaning agent is sulfuric acid or south acid. This tends to remove any organic material that has built up on the plate surface, but it will not damage inorganic material, so the seals, for example, the gaskets will remain unaffected on the plate will remain unaffected. But if you have any organic material that's accumulated within this fine space between each of the plates, for example, seaweed and a seawater system, then the acid will attack the seaweed or the organic material on the plates will be effectively cleaned. If there's calcium or calpers also built up on the plate heat exchange of services. Then you'll be able to dose it with a chemical in order to break down that talc. So they're a different chemicals you can buy not just from the manufacturer balls on the open market, and usually they'll be acid or alkaline based, and you can use these chemicals to clean the plates without actually opening up the plates stack. Let's now go to the final lesson where we can do a short summary covering all of the topics that we have talked about, and we can reflect a little bit on what we've learned. 10. Final Thoughts: in this course, we've looked at all of the components, associating with a place heat exchanger. We've looked at how the plate heat exchanger works. We've looked at different designs, like a single pass and multi pass design. Different flow types such as parallel cross encounter. We've also looked at some of the interesting design features off plate, each exchange of plates as well as gaskets. And we've talked about the advantages and disadvantages Associate ID. We've played heat exchangers. I hope that the previous lesson explaining how to assemble and disassemble a place heat exchanger will be useful to you. And I hope that generally, in this course you've learned not just a lot about place heat exchanges, but also some good engineering practices on fundamentals that you'll be able to take with you for at your engineering career. Be sure to check out a resource section of this course, that piece of links there to interactive three D models and maps and other things where you can cement what you've learned as a personal note. I really do hope you enjoyed the course. I hope you got a lot from it. Have you enjoyed it? And it was informative. If you got any questions or comments, and please do shoot them over to me either through your training manager for your course provider or directly through several dot com. Thank you very much taking the time to complete this course, and I hope so. You another course soon. Bye for now.