/ News & Press / Video / Plate Heat Exchanger, How it works - working principle hvac industrial engineering phx heat transfer
Plate Heat Exchanger, How it works - working principle hvac industrial engineering phx heat transfer
WEBVTT Kind: captions Language: en
00:00:05.250 --> 00:00:06.431 Hey there guys, Paul here from 00:00:06.431 --> 00:00:07.731 theengineeringmindset.com. 00:00:08.610 --> 00:00:10.530 In this video we're gonna be looking at the 00:00:10.530 --> 00:00:13.580 plate heat exchangers and they're often referred to as 00:00:13.580 --> 00:00:18.133 PHE's, PHX's, or sometimes just HX or HEX. 00:00:19.110 --> 00:00:21.200 Now, plate heat exchangers are very common, 00:00:21.200 --> 00:00:22.770 they are used extensively in 00:00:22.770 --> 00:00:24.880 building services and manufacturing. 00:00:24.880 --> 00:00:26.380 The reason they are popular is because 00:00:26.380 --> 00:00:28.890 they are very compact, they're very efficient, 00:00:28.890 --> 00:00:30.440 they're easy to service, 00:00:30.440 --> 00:00:32.943 they need very low maintenance as well. 00:00:34.450 --> 00:00:37.000 Their purpose is to transfer thermal energy 00:00:37.000 --> 00:00:39.755 from one fluid in one system to another 00:00:39.755 --> 00:00:42.700 without the two fluids mixing together. 00:00:42.700 --> 00:00:45.410 For example, in building services you might want 00:00:45.410 --> 00:00:48.890 to transfer heat from a primary loop connected to a boiler 00:00:48.890 --> 00:00:51.120 over to a separate secondary loop 00:00:51.120 --> 00:00:53.210 or maybe in a district heating network. 00:00:53.210 --> 00:00:56.890 Or in manufacturing you may want to cool down some 00:00:56.890 --> 00:00:59.980 oil and use water to cool that down but obviously 00:00:59.980 --> 00:01:02.630 you don't want to mix the oil and the water together. 00:01:03.470 --> 00:01:06.170 Now, we have pulled one of the heat exchangers apart. 00:01:06.170 --> 00:01:09.423 We're gonna have a look at some of main components here. 00:01:11.800 --> 00:01:14.580 So we've got the end plates here or the front and back cover 00:01:14.580 --> 00:01:15.830 and these are made from usually 00:01:15.830 --> 00:01:18.480 a mild steel and they're very strong, 00:01:18.480 --> 00:01:20.580 they're there to hold everything together. 00:01:21.530 --> 00:01:24.190 Then we've got the nuts, these attach obviously and tighten 00:01:24.190 --> 00:01:27.090 up onto the tightening bolts. 00:01:27.090 --> 00:01:29.940 The tightening bolts, they fit in some grooves in 00:01:29.940 --> 00:01:33.240 there and they'll run the entire length of the 00:01:33.240 --> 00:01:38.120 heat exchanger and the bolts are tightened on these and that 00:01:38.120 --> 00:01:40.950 will compress all the plates together and squeeze the 00:01:40.950 --> 00:01:43.480 gaskets against the plates to make the 00:01:43.480 --> 00:01:46.683 heat exchanger completely waterproof or leak proof. 00:01:47.880 --> 00:01:50.520 And then wedged in between there we've got the plates 00:01:50.520 --> 00:01:52.590 where the heat transfer occurs and we've also 00:01:52.590 --> 00:01:55.450 got the gaskets which sit in between 00:01:55.450 --> 00:01:58.163 the plates and that's what gives it the seal. 00:01:59.180 --> 00:02:02.090 Larger heat exchangers will also have this supporting bar 00:02:02.090 --> 00:02:04.170 at the top and the bottom and you can see here 00:02:04.170 --> 00:02:07.170 that the case and the plates, they just slide along 00:02:07.170 --> 00:02:09.570 there and there's various ways that they can come off, 00:02:09.570 --> 00:02:11.500 either they twist these ones, they'd be too big to 00:02:11.500 --> 00:02:14.470 twist off but there's a section removed at the back 00:02:14.470 --> 00:02:16.850 where these would just drop out but the smaller ones, 00:02:16.850 --> 00:02:18.550 these would just slide in and out. 00:02:19.895 --> 00:02:21.270 And you can see a real plate heat 00:02:21.270 --> 00:02:23.440 exchanger plate there on the screen. 00:02:23.440 --> 00:02:25.250 Now, these are typically made from steel 00:02:25.250 --> 00:02:27.200 or titanium and you can see they've got this 00:02:27.200 --> 00:02:30.113 pattern grooved into them or stamped into them. 00:02:31.020 --> 00:02:33.390 These patterns are gonna strengthen the plates, 00:02:33.390 --> 00:02:36.090 obviously they're incredibly thin and they're also 00:02:36.090 --> 00:02:39.210 gonna increase the heat transfer surface area 00:02:39.210 --> 00:02:42.070 as well as creating a very turbulent flow inside them 00:02:42.070 --> 00:02:45.610 so it's not smooth, all the water has to row across 00:02:45.610 --> 00:02:48.560 these and come out very rough and turbulent. 00:02:48.560 --> 00:02:51.800 Now between the plates we've got the gaskets here, 00:02:51.800 --> 00:02:54.970 just this rubber gasket and that is attached 00:02:54.970 --> 00:02:58.450 to the face of the plate and the purpose of the 00:02:58.450 --> 00:03:03.090 gasket is to ensure a tight fit and to prevent leaks. 00:03:03.090 --> 00:03:05.330 The gasket also allows or prevents 00:03:05.330 --> 00:03:07.283 the flow of fluid into the sheet. 00:03:08.140 --> 00:03:11.240 You can see here, so this section here we've got the 00:03:11.240 --> 00:03:13.980 rubber seal coming across and double seal on this one 00:03:13.980 --> 00:03:18.180 so that no fluid in this can leak out or flow in, 00:03:18.180 --> 00:03:22.210 as well as this side, whereas here there is no gasket there 00:03:22.210 --> 00:03:24.850 so the fluid if it entered here could flow down and come 00:03:24.850 --> 00:03:26.800 down and enter into this one here 00:03:26.800 --> 00:03:28.480 because there isn't anything there. 00:03:28.480 --> 00:03:31.430 Same as this one, the fluid can only come out of here and 00:03:31.430 --> 00:03:34.693 travel up and then into this section here, into that hole. 00:03:35.660 --> 00:03:38.810 Now, you'll probably notice that the tightening bolts 00:03:38.810 --> 00:03:42.580 they're actually, they extend far past the heat exchanger. 00:03:42.580 --> 00:03:46.059 That's for a few reasons, one is obviously to be able 00:03:46.059 --> 00:03:47.850 to fit all these plates and et cetera on during 00:03:47.850 --> 00:03:51.900 the installation or during maintenance but also 00:03:51.900 --> 00:03:54.200 this gives you the ability to extend the 00:03:54.200 --> 00:03:56.770 plate heat exchanger in future so this one here 00:03:56.770 --> 00:03:59.820 is actually from a district heating network and at the 00:03:59.820 --> 00:04:01.590 moment the building's only half complete and they're 00:04:01.590 --> 00:04:03.850 expecting to double the building size. 00:04:03.850 --> 00:04:08.470 So they've allowed extra bolt lengths to be added and that 00:04:08.470 --> 00:04:10.730 means that the plates can be added and this 00:04:10.730 --> 00:04:12.963 heat exchanger can grow with the demand. 00:04:14.400 --> 00:04:15.580 Now, there's a couple of ways that the 00:04:15.580 --> 00:04:18.080 plate heat exchanger can be piped up. 00:04:18.080 --> 00:04:20.000 This is the most common version and the version 00:04:20.000 --> 00:04:21.650 that we're gonna be looking at today. 00:04:21.650 --> 00:04:23.858 That is where the inlets and outlets are all 00:04:23.858 --> 00:04:27.473 on the front plate so the fluids will enter, 00:04:28.450 --> 00:04:30.190 flow through their channels and then make their 00:04:30.190 --> 00:04:31.653 way back to the front plate. 00:04:32.750 --> 00:04:35.770 The other version is where the fluids, 00:04:35.770 --> 00:04:38.730 one of the fluids enters through the front plate and it 00:04:38.730 --> 00:04:41.380 passes through there and then makes it way and it will 00:04:41.380 --> 00:04:44.010 then exit through the back plate as well as 00:04:44.010 --> 00:04:46.640 one of the fluids will enter there as well. 00:04:46.640 --> 00:04:49.160 Now, this version here, the first version is the most 00:04:49.160 --> 00:04:52.480 common version and that is because you don't need 00:04:52.480 --> 00:04:54.690 to alter the pipework if you need to extend the 00:04:54.690 --> 00:04:56.930 plate heat exchanger in the future, 00:04:56.930 --> 00:05:00.610 whereas, with the second version here all the pipework 00:05:00.610 --> 00:05:02.900 that's connected would have to be removed and remade 00:05:02.900 --> 00:05:07.570 to fit depending on how far you extend your heat exchanger. 00:05:07.570 --> 00:05:09.410 So it's not really so practical, 00:05:09.410 --> 00:05:11.793 that is why this one is far more common. 00:05:12.660 --> 00:05:14.850 And you can just see in all these examples here 00:05:14.850 --> 00:05:16.150 that is exactly what's happening. 00:05:16.150 --> 00:05:20.053 So the flow return are happening on the front plate there. 00:05:21.760 --> 00:05:22.593 So how does it work? 00:05:22.593 --> 00:05:24.630 Well, we've already seen that if you remove some 00:05:24.630 --> 00:05:28.410 of the seal then the fluid can flow through there. 00:05:28.410 --> 00:05:30.660 So if we stack a number of plates together 00:05:30.660 --> 00:05:33.270 then you'll see it forms this channel, 00:05:33.270 --> 00:05:37.143 this pipe like feature flowing through all the plates. 00:05:38.040 --> 00:05:40.210 And then we can add the front and back plates onto 00:05:40.210 --> 00:05:41.630 there and we get these channels where 00:05:41.630 --> 00:05:44.950 the water or the fluid, whatever you've got can then flow 00:05:44.950 --> 00:05:47.030 through certain plates and it can't 00:05:47.030 --> 00:05:49.090 flow through other plates. 00:05:49.090 --> 00:05:51.000 And let's just see an example of 00:05:51.000 --> 00:05:52.820 how this would work practically. 00:05:52.820 --> 00:05:55.020 So if we opened up the heat exchanger again, 00:05:56.470 --> 00:05:59.750 now you can see here that the gaskets are oriented 00:06:00.700 --> 00:06:05.420 differently on the alternating 00:06:05.420 --> 00:06:07.450 plates there for the heat exchange. 00:06:07.450 --> 00:06:11.250 So this one here you can see fluid in this pipe 00:06:11.250 --> 00:06:13.390 would not be able to pass through or this one and this 00:06:13.390 --> 00:06:15.780 one it would so it just alternates, 00:06:15.780 --> 00:06:17.393 vice versa all the way through. 00:06:18.655 --> 00:06:20.580 And so if we pass one fluid through there 00:06:20.580 --> 00:06:23.210 you can see it entering through this top port, 00:06:23.210 --> 00:06:25.553 passing all the way through, it can't pass through this one, 00:06:25.553 --> 00:06:28.340 there's a seal there, it gets to the next plate, 00:06:28.340 --> 00:06:30.261 oh there's no seal there so we can pass through there, 00:06:30.261 --> 00:06:32.300 can't go into this hole but you can 00:06:32.300 --> 00:06:34.370 into this one because there is no seal and 00:06:34.370 --> 00:06:35.840 so all these will pass through, 00:06:35.840 --> 00:06:37.923 collect up and make its way back out. 00:06:39.260 --> 00:06:40.700 Now, the same thing is gonna be happening 00:06:40.700 --> 00:06:42.790 with the other fluid we're passing through. 00:06:42.790 --> 00:06:44.890 So you can see here we're passing hot fluid through. 00:06:44.890 --> 00:06:47.570 So this one is entering through the bottom port, 00:06:47.570 --> 00:06:49.900 coming along, it's getting to the plates, 00:06:49.900 --> 00:06:51.860 some of them it can pass through so it will, 00:06:51.860 --> 00:06:54.450 others it cannot leave that pipe so it will not and then 00:06:54.450 --> 00:06:56.220 it will just pass through all the way 00:06:56.220 --> 00:06:58.563 until it creates that loop and exits. 00:06:59.630 --> 00:07:02.410 So if we mix these two fluids together what's gonna happen 00:07:02.410 --> 00:07:05.400 is the cold fluid is going to enter, 00:07:05.400 --> 00:07:07.640 pass through and then on the other side of the plate 00:07:07.640 --> 00:07:11.320 is the hot fluid so that is gonna take some 00:07:11.320 --> 00:07:13.500 of that heat away so the cold fluid will 00:07:13.500 --> 00:07:15.540 warm up and that will leave as a much 00:07:15.540 --> 00:07:18.350 warmer fluid and the hot fluid that comes 00:07:18.350 --> 00:07:20.120 in is going to cool down because it's going to 00:07:20.120 --> 00:07:23.560 give up some of its heat into the cold stream and then that 00:07:23.560 --> 00:07:26.823 will leave as a much more cooler fluid. 00:07:27.930 --> 00:07:30.170 So if we just look at a very basic example of 00:07:30.170 --> 00:07:32.820 how this is working, let's just say we've got 00:07:32.820 --> 00:07:35.150 a few plates here and we've got a cold channel, 00:07:35.150 --> 00:07:37.600 hot channel and another cold channel. 00:07:37.600 --> 00:07:40.360 Now, if we let the hot fluid enter into the 00:07:40.360 --> 00:07:44.670 channel there and as that happens heat is then going to 00:07:44.670 --> 00:07:48.020 conduct through into the plate because they are touching, 00:07:48.020 --> 00:07:51.343 so that heat will then pass through and warm up this plate. 00:07:52.490 --> 00:07:54.790 And if we then pass the cold fluid into the 00:07:54.790 --> 00:07:59.350 cold channels and some of the heat in those plates 00:07:59.350 --> 00:08:01.720 which have been heated up, it will start to cool down 00:08:01.720 --> 00:08:03.090 because some of the thermal energy 00:08:03.090 --> 00:08:06.203 is transferring over into the cold fluid. 00:08:07.430 --> 00:08:08.730 That's through conduction. 00:08:09.630 --> 00:08:13.370 And as that happens the cold fluid begins to warm up and 00:08:13.370 --> 00:08:17.183 obviously the hot fluid is going to start to cool down. 00:08:18.300 --> 00:08:21.320 So then the heat exchanger starts to equal up and equalize 00:08:21.320 --> 00:08:25.870 out and that means that the cold fluid is going to enter, 00:08:25.870 --> 00:08:29.633 is gonna exit warm and the hot fluid is going to exit cool. 00:08:30.730 --> 00:08:33.240 And that temperature grading is going to then 00:08:34.130 --> 00:08:37.010 vary through the heat exchanger, through the plates and also 00:08:37.010 --> 00:08:40.143 through the fluids which is conducting the heat. 00:08:41.010 --> 00:08:42.810 So when you combine all of this together 00:08:42.810 --> 00:08:44.270 that is how you get the heat 00:08:44.270 --> 00:08:47.230 transfer occur in the plate heat exchanger. 00:08:47.230 --> 00:08:49.880 You can also notice that these fluids are flowing 00:08:49.880 --> 00:08:54.030 in counter flow and that is the best configuration 00:08:54.030 --> 00:08:57.990 for the most effectiveness because the log mean 00:08:57.990 --> 00:09:01.920 temperature difference, the LMTD is at the greatest. 00:09:01.920 --> 00:09:05.480 We'll have a look at what that means in another video. 00:09:05.480 --> 00:09:07.270 This video is just for you to understand 00:09:07.270 --> 00:09:09.650 how it's working and why it works. 00:09:09.650 --> 00:09:11.690 I'll just give you a real world example of 00:09:11.690 --> 00:09:13.170 a heat exchanger here as well. 00:09:13.170 --> 00:09:16.260 So this is a German heat exchanger as you can see 00:09:16.260 --> 00:09:19.300 right down here but you can see this heat exchanger here 00:09:19.300 --> 00:09:24.300 provides 1500 kilowatts of thermal energy and has a 00:09:24.440 --> 00:09:28.060 transmission area of 29.3 meters squared with a 00:09:28.060 --> 00:09:33.060 flow rate of 42,000, or almost 43,000 liters per hour. 00:09:34.976 --> 00:09:37.080 It would also handle up to 100 00:09:37.080 --> 00:09:39.290 bar on each side of the plates. 00:09:39.290 --> 00:09:41.480 So you can see these things are very powerful and they're 00:09:41.480 --> 00:09:44.860 very efficient and they're very compact in how they work. 00:09:44.860 --> 00:09:46.610 Now, if you do have one of these in your buildings 00:09:46.610 --> 00:09:49.700 please also remember to insulate as it's much 00:09:49.700 --> 00:09:52.658 more energy efficient, keep the plastic threads, 00:09:52.658 --> 00:09:55.390 plastic sheets on the threads to protect 00:09:55.390 --> 00:09:56.760 them from damage otherwise you won't be 00:09:56.760 --> 00:09:59.540 able to get these nuts off very easily. 00:09:59.540 --> 00:10:00.830 Okay, that's it for this video, 00:10:00.830 --> 00:10:02.330 thank you very much for watching. 00:10:02.330 --> 00:10:04.530 I hope you enjoyed it and it helped you. 00:10:04.530 --> 00:10:05.440 Please don't forget to like, 00:10:05.440 --> 00:10:06.960 subscribe and share and if you have 00:10:06.960 --> 00:10:08.890 any comments leave them in the comments section below. 00:10:08.890 --> 00:10:11.330 I'll try to get back to you as soon as possible. 00:10:11.330 --> 00:10:13.553 Once again, thank you very much for watching.
Office location
Engineering company LOTUS®
Russia, Ekaterinburg, Lunacharskogo street, 240/12