00:00:00.000 [Music] 00:00:13.50000:00:13.510 welcome to this lecture tubular heat 00:00:17.14000:00:17.150 exchangers and today we will be talking 00:00:21.46000:00:21.470 about the sail and tube heat exchangers 00:00:23.50000:00:23.510 in details but before going to that in 00:00:26.20000:00:26.210 details we first of all like to solve 00:00:29.67900:00:29.689 that incomplete numerical problem that 00:00:34.56900:00:34.579 we have taken up in the last class so 00:00:37.20000:00:37.210 we'll go first to that and if you 00:00:43.03000:00:43.040 remember we have calculated the internal 00:00:47.08000:00:47.090 heat transfer coefficient and we have 00:00:50.38000:00:50.390 also calculated the external heat 00:00:53.02000:00:53.030 transfer coefficient using the 00:00:55.00000:00:55.010 appropriate correlations and we have 00:00:58.51000:00:58.520 obtained H I and H 0 so we have gotten H 00:01:03.91000:01:03.920 I as 4 9 1 1 what per meter square 00:01:14.62000:01:14.630 Kelvin and we have obtained 1 3 4 5 watt 00:01:27.39900:01:27.409 per meter square as the heat transfer 00:01:32.98000:01:32.990 coefficient of the annular space so 00:01:35.88900:01:35.899 based on this data we would be able to 00:01:38.83000:01:38.840 calculate the overall heat transfer 00:01:42.52000:01:42.530 coefficient that is equals to 1 by U is 00:01:49.92900:01:49.939 equals to 1 by this is in terms of the 00:01:57.74900:01:57.759 external diameter and this is D 0 by di 00:02:04.41900:02:04.429 by H I plus this is d0 and then L n D 0 00:02:15.88000:02:15.890 by D I so where we are taking care of 00:02:21.46000:02:21.470 the resistance of the 00:02:24.08900:02:24.099 and this is the thermal conductivity 00:02:26.61000:02:26.620 part of it and then we have one by H 00:02:31.44000:02:31.450 zero this is the heat transfer 00:02:34.00900:02:34.019 resistance offered by the external I 00:02:38.16000:02:38.170 mean the annular fluid this is the 00:02:41.00900:02:41.019 resistance offered by the fluid I mean 00:02:44.64000:02:44.650 the metallic part and this is the heat 00:02:48.36000:02:48.370 transfer offered by the internal fluid 00:02:53.28000:02:53.290 flowing through it so this is how do we 00:02:56.03900:02:56.04900:02:58.61000:02:58.620 surface I mean overall heat transfer 00:03:00.62900:03:00.639 coefficient and then this will come out 00:03:03.42000:03:03.430 to be 948 watt per meter square Kelvin 00:03:10.69900:03:10.709 so once we know this overall heat 00:03:14.64000:03:14.650 transfer coefficient then we would be 00:03:17.00900:03:17.019 able to calculate the heat transfer 00:03:21.17900:03:21.189 surface area n0 that will come out to be 00:03:28.28000:03:28.290 H 0 is the costume Q already we know and 00:03:36.49900:03:36.509 you zero and then we have the delta T 00:03:40.64900:03:40.659 log mean so Delta - Delta - log mean 00:03:46.25900:03:46.269 here in this case if you look at you 00:03:48.65900:03:48.669 will find that delta T 1 is equal to 00:03:52.28900:03:52.299 delta T 2 and that is equal to 15 degree 00:03:56.52000:03:56.530 centigrade and so we have both delta T 00:04:00.05900:04:00.069 log main is equals to delta t mean and 00:04:02.75900:04:02.769 it is coming out to be 15 degree we do 00:04:08.36900:04:08.379 not go for the log mean temperature 00:04:10.46900:04:10.479 difference we go for only the main 00:04:13.86000:04:13.870 temperature difference so here this 00:04:16.14000:04:16.150 comes out to be 15 degree and from there 00:04:20.33900:04:20.349 we would be able to find out the heat 00:04:22.49900:04:22.509 transfer area a to be 00:04:29.70000:04:29.710 q what is that Q we have obtained Q we 00:04:33.62900:04:33.639 obtained already MC dot CP C multiplied 00:04:41.70000:04:41.710 by delta T and that we have to put here 00:04:46.80000:04:46.810 then we have already obtained this 948 00:04:51.30000:04:51.310 and 15 and from there we will be able to 00:04:54.30000:04:54.310 calculate the a 0 so once we calculate 00:04:57.27000:04:57.280 the a 0 we will find out what is the 00:05:01.74000:05:01.750 heat transfer surface area per unit pin 00:05:04.83000:05:04.840 per pin so part pin the area of hair pin 00:05:11.34000:05:11.350 for each one is 2 PI D 0 into L so this 00:05:19.08000:05:19.090 is nothing but 2 into PI into point zero 00:05:24.92000:05:24.930 six zero three and we have the L given 00:05:30.36000:05:30.370 as three point five meter so this will 00:05:33.12000:05:33.130 be about one point three to five meter 00:05:36.65900:05:36.669 square so once we know the a zero and 00:05:41.65900:05:41.669 once already we know the hairpin so this 00:05:46.11000:05:46.120 will be able to calculate it that will 00:05:49.37900:05:49.389 give you the number of hair Queen so you 00:05:59.49000:05:59.500 can try calculating this a zero from 00:06:02.21900:06:02.229 that and we can then you know this is 00:06:05.61000:06:05.620 already given so that will give you the 00:06:08.15900:06:08.169 total number of a hair pins so now with 00:06:12.77900:06:12.789 that we will now sit to the next 00:06:17.31000:06:17.320 discussion but we are talking about the 00:06:21.54000:06:21.550 shell and tube heat exchangers and you 00:06:25.86000:06:25.870 have already learned about it in the 00:06:28.64900:06:28.659 earlier classes now we will try to go in 00:06:31.35000:06:31.360 details about this cell and tube heat 00:06:34.02000:06:34.030 exchangers so we know it is the one of 00:06:37.62000:06:37.630 the most versatile type of heat 00:06:40.08000:06:40.090 exchanger used in the process industries 00:06:42.42000:06:42.430 or even in the 00:06:43.53000:06:43.540 nuclear plants and they can be used as 00:06:47.72000:06:47.730 as pre heaters water heaters then you 00:06:53.10000:06:53.110 know condenser and it also it is used as 00:06:56.40000:06:56.410 the kettle boilers and they can also 00:06:59.73000:06:59.740 find applications where including in the 00:07:02.94000:07:02.950 geothermal or in the ocean or in the 00:07:08.24000:07:08.250 then many thermal applications 00:07:10.97000:07:10.980 particularly whenever we are using heat 00:07:16.20000:07:16.210 exchangers where it needs occasional 00:07:18.99000:07:19.000 cleaning so that gives us I mean these 00:07:23.58000:07:23.590 are the some of the heat exchangers 00:07:25.68000:07:25.690 where we typically use the shell and 00:07:31.32000:07:31.330 tube type heat exchangers as I told you 00:07:33.54000:07:33.550 that condenser stream generators and the 00:07:35.97000:07:35.980 feed water heaters and the advantage of 00:07:39.75000:07:39.760 this type of exchangers are that it 00:07:43.17000:07:43.180 gives very good design flexibility we 00:07:47.10000:07:47.110 have a different type of heat exchangers 00:07:50.61000:07:50.620 geometry possible we will discuss about 00:07:53.25000:07:53.260 that part and the advantage lies not 00:07:57.75000:07:57.760 only with the design flexibility it also 00:08:01.23000:08:01.240 gives us a pretty good opportunity to 00:08:04.37000:08:04.380 use some of the fluid streams where the 00:08:08.10000:08:08.110 pressure are very high and as I told you 00:08:12.06000:08:12.070 that the cleaning option is again 00:08:15.24000:08:15.250 another big advantage of this particular 00:08:18.06000:08:18.070 type of heat exchangers whenever we need 00:08:21.59000:08:21.600 whenever we are using some dirty fluids 00:08:24.63000:08:24.640 and which often generates scales on the 00:08:31.14000:08:31.150 heat transfer surfaces and thereby it 00:08:34.83000:08:34.840 gives some kind of fouling resistances 00:08:37.20000:08:37.210 to the heat transfer we have to often 00:08:41.70000:08:41.710 clean the exchangers and that it's not 00:08:46.38000:08:46.390 possible for many it's not possible with 00:08:49.32000:08:49.330 many exchanges to regularly clean it 00:08:51.51000:08:51.520 particularly when the hydraulic diameter 00:08:53.28000:08:53.290 of the heat exchanger is very small but 00:08:56.76900:08:56.779 in case of shell and tube heat 00:08:58.15000:08:58.160 exchangers it's it gives that 00:09:01.62900:09:01.639 opportunity to clean it at regular basis 00:09:05.31900:09:05.329 but again it is so versatile that any 00:09:10.03000:09:10.040 kind of heat exchanger design I mean we 00:09:13.99000:09:14.000 have a guideline given by the tubular 00:09:17.65000:09:17.660 exchanger manufacturer Association that 00:09:20.76900:09:20.779 is in short form we call it Kenna and 00:09:23.47000:09:23.480 they tell you exactly what are the 00:09:26.07900:09:26.089 standards that are to be followed for 00:09:28.44900:09:28.459 design of the heat exchanger so we have 00:09:32.01900:09:32.029 taken up the heat transfer coefficient 00:09:35.94900:09:35.959 for the shell side at in in some of our 00:09:39.36900:09:39.379 earlier classes or in earlier lectures 00:09:43.42000:09:43.430 and there we might have told you how to 00:09:47.01900:09:47.029 evaluate the heat transfer coefficient 00:09:48.84000:09:48.850 but as you can understand from the 00:09:52.36000:09:52.370 lectures in details of this classes that 00:09:55.21000:09:55.220 that is the nova simplification of the 00:09:57.51900:09:57.529 actual process but in reality we will 00:10:00.28000:10:00.290 find that the processes are much more 00:10:03.00900:10:03.019 complicated so we will look into the 00:10:07.03000:10:07.040 first of all the design of the heat 00:10:09.91000:10:09.920 exchangers how it looks like for example 00:10:13.61900:10:13.629 there are different type of shell and 00:10:17.31900:10:17.329 tube heat exchangers as we have told and 00:10:20.54900:10:20.559 there are we will only show some of them 00:10:24.40000:10:24.410 in this in the in this lecture here you 00:10:30.04000:10:30.050 can see this is the sell-side 00:10:34.88900:10:34.899 fluid so the fluid will come like this 00:10:39.28000:10:39.290 then it will be flowing on top of the 00:10:42.49000:10:42.500 fluid of the tubes and then again it 00:10:47.98000:10:47.990 will come like this it will come like 00:10:50.86000:10:50.870 this and then finally it will have a 00:10:54.09000:10:54.100 exit from this end so here we have the 00:10:58.32900:10:58.339 battles 00:10:59.25900:10:59.269 so this baffles will allow or rather not 00:11:03.54900:11:03.559 allow the continuous flow of the fluid 00:11:06.44900:11:06.459 along the tube length so it will make 00:11:10.33000:11:10.340 the flow alike following this particular 00:11:14.64000:11:14.650 zigzag path or like this and it will 00:11:17.89000:11:17.900 finally come out on the other hand we 00:11:20.68000:11:20.690 have the sell-side fluid or the tube 00:11:23.98000:11:23.990 side fluid which may enter from here and 00:11:28.69000:11:28.700 then then what will happen this will 00:11:32.29000:11:32.300 this will enter over here this will 00:11:37.81000:11:37.820 enter through this space and then you 00:11:40.48000:11:40.490 see we have a divided at this place so 00:11:43.63000:11:43.640 it is not able to come from here to this 00:11:45.76000:11:45.770 point so it has to go through the tube 00:11:48.91000:11:48.920 side it will flow like this then it will 00:11:51.94000:11:51.950 take a diversion and the same thing this 00:11:56.56000:11:56.570 is getting distributed coming over here 00:11:58.63000:11:58.640 at this point they will get diverted and 00:12:02.20000:12:02.210 they will follow this path and finally 00:12:04.93000:12:04.940 come out of it and then it will follow 00:12:07.63000:12:07.640 this path so it is like one and then to 00:12:14.38000:12:14.390 pass to pass for the tube so two tube 00:12:19.45000:12:19.460 passes that is why we call it two tube 00:12:22.36000:12:22.370 pass but this is a single cell pass so 00:12:27.22000:12:27.230 this is single cell to tube pass heat 00:12:30.88000:12:30.890 exchanger and here the another 00:12:33.67000:12:33.680 speciality is that of this particular 00:12:36.07000:12:36.080 type of exchanger is that the this is 00:12:40.39000:12:40.400 the tube sheet this is where we have the 00:12:43.51000:12:43.520 tube sheet and this tube sheet is 00:12:45.40000:12:45.410 drilled with the holes to create in all 00:12:48.82000:12:48.830 the tubes and here finally we get them 00:12:52.99000:12:53.000 welded at those corners so this will be 00:12:57.19000:12:57.200 finally welded and all these points will 00:13:00.10000:13:00.110 be finally welded and like that we have 00:13:04.54000:13:04.550 this parts are getting welded so that 00:13:08.68000:13:08.690 means these tubes are fixed rigidly with 00:13:13.54000:13:13.550 the puget so this is the tube shape this 00:13:20.19900:13:20.209 tube sheet and 00:13:22.25000:13:22.260 the tubes are rigidly connected and 00:13:26.41000:13:26.420 that's why this is fixed t of 00:13:30.07000:13:30.080 exchanger with two t passes so it has 00:13:34.34000:13:34.350 obviously gives an advantage in the 00:13:38.60000:13:38.610 sense that whenever we remove this part 00:13:41.48000:13:41.490 this two ends if we remove if we unbolt 00:13:46.25000:13:46.260 this part and if we unbolt this part you 00:13:50.24000:13:50.250 can understand that this is these tubes 00:13:53.06000:13:53.070 are now exposed and if we have any kind 00:13:56.99000:13:57.000 of scaling formed inside this tube we 00:13:59.69000:13:59.700 would be able to physically clean them 00:14:01.52000:14:01.530 so that gives the advantage of using 00:14:05.81000:14:05.820 this kind of shell and tube type 00:14:08.33000:14:08.340 exchangers so here we will go to the 00:14:11.48000:14:11.490 next particular type of exchanger where 00:14:16.22000:14:16.230 we find that this is a floating head now 00:14:21.77000:14:21.780 you see this is this has become a 00:14:24.29000:14:24.300 floating head bundle removable bundle 00:14:27.50000:14:27.510 heat exchanger so here in this case what 00:14:32.15000:14:32.160 we find is that this is again the shell 00:14:36.37000:14:36.380 side to fluid there is no problem it 00:14:39.98000:14:39.990 will enter and depending on the number 00:14:42.50000:14:42.510 of depending on the number of this 00:14:46.51000:14:46.520 battle's or the type of battleship will 00:14:49.85000:14:49.860 be diverted and finally come out of it 00:14:52.34000:14:52.350 but what's about the tube sight fluid 00:15:00.59000:15:00.600 this is coming over here 00:15:03.11000:15:03.120 they will get and come out of it from 00:15:07.19000:15:07.200 here this is the double pass so that's 00:15:10.07000:15:10.080 up to that part but why this complicacy 00:15:12.89000:15:12.900 we have in the design of this exchanger 00:15:15.95000:15:15.960 so now you can understand that there may 00:15:19.04000:15:19.050 be situation where the tube site and the 00:15:23.65000:15:23.660 shell site fluids are of pretty 00:15:27.14000:15:27.150 different temperature and that may 00:15:29.48000:15:29.490 result some kind of thermal stress 00:15:32.03000:15:32.040 generation so thermal stress will be 00:15:35.12000:15:35.130 generated 00:15:36.22900:15:36.239 the sale and the tube if they're getting 00:15:39.67900:15:39.689 elongated at a different rate then it 00:15:43.54900:15:43.559 will generate some kind of thermal 00:15:45.22900:15:45.239 stress so that means we have to allow 00:15:48.07900:15:48.089 the tubes to expand 00:15:50.38900:15:50.399 I mean if such situations occur then the 00:15:54.37900:15:54.389 tubes will be able to expand as contract 00:15:58.15900:15:58.169 in contrast to our the shell side so 00:16:02.38900:16:02.399 this allows this particular type of 00:16:04.75900:16:04.769 exchanger design allows expansion of the 00:16:08.32900:16:08.339 tubes in contrast to the cells so they 00:16:13.33900:16:13.349 are not rigidly fixed up with the tube 00:16:16.15900:16:16.169 side and this is how we how it looks 00:16:21.31900:16:21.329 like then we have another common type 00:16:26.89900:16:26.909 but this is this is what we call as the 00:16:30.22900:16:30.239 you tube removable bundle this is one of 00:16:33.71000:16:33.720 the simplest geometry that is possible 00:16:36.28900:16:36.299 safe here the cells I fluid as usual you 00:16:40.27900:16:40.289 can see that depending on that depending 00:16:45.37900:16:45.389 on the baffles this fluid will be 00:16:48.37900:16:48.389 entering here and it will come out from 00:16:51.43900:16:51.449 this end now about the about the tube 00:17:00.67900:17:00.689 side fluid it's simple it will enter 00:17:03.91900:17:03.929 over here and this is just like that 00:17:08.26900:17:08.279 they will come out and move out of this 00:17:12.04900:17:12.059 space the advantage of this one is that 00:17:15.98000:17:15.990 the expansion or differential expansion 00:17:19.42900:17:19.439 of the tube it is automatically taken 00:17:22.97000:17:22.980 into account it's already u-bend and 00:17:25.49000:17:25.500 that if it is differentially expanding 00:17:28.18900:17:28.199 it has the possibility to expand it on 00:17:30.64900:17:30.659 this side then only one tube seat is 00:17:39.00900:17:39.019 good enough to accommodate all the tubes 00:17:43.34000:17:43.350 and if you look into the other fluid 00:17:48.08000:17:48.090 stream you will find that 00:17:49.79000:17:49.800 is coming over there and then you know 00:17:52.73000:17:52.740 it is coming over there and finally it 00:17:55.91000:17:55.920 is moving out like this but that 00:17:59.24000:17:59.250 disadvantage of this particular type of 00:18:01.51000:18:01.520 heat exchanger is that if there is any 00:18:07.70000:18:07.710 kind of fouling occurring inside the 00:18:10.67000:18:10.680 tube we are not in a position to clean 00:18:13.37000:18:13.380 it so that's the disadvantage with this 00:18:16.97000:18:16.980 particular type of heat exchanger so now 00:18:20.54000:18:20.550 if we go to the other type you will find 00:18:26.63000:18:26.640 that this the standard shell and type of 00:18:32.93000:18:32.940 the front and head types and the is 00:18:36.74000:18:36.750 already specified as I have told that 00:18:39.80000:18:39.810 the tubular exchanger manufacturers 00:18:43.10000:18:43.110 association or dema has given so many 00:18:47.09000:18:47.100 standards and that according to that 00:18:50.81000:18:50.820 standard we have a different type of 00:18:54.46000:18:54.470 front stationary heads and then we have 00:18:59.18000:18:59.190 the eared stationary heads and the shell 00:19:02.63000:19:02.640 type so as you have seen in the previous 00:19:07.01000:19:07.020 I mean previous slides that we have one 00:19:13.78000:19:13.790 entry side one exit side or the deer 00:19:17.90000:19:17.910 side and then we have the different type 00:19:20.63000:19:20.640 of cell sides so these are different it 00:19:26.15000:19:26.160 is as per the specification or the 00:19:28.97000:19:28.980 standards we cannot just like that and 00:19:31.43000:19:31.440 design any type of sale or choose any 00:19:36.14000:19:36.150 type of cell and they're numbered 00:19:40.45000:19:40.460 alphabetically so this is an e type of 00:19:43.58000:19:43.590 cell for example so if you look at this 00:19:47.81000:19:47.820 is e and this is one parcel that means 00:19:51.23000:19:51.240 this will come here and move out like 00:19:53.99000:19:54.000 this this is a two pass so it will come 00:19:58.76000:19:58.770 like this and it will be coming like 00:20:01.31000:20:01.320 this here this is 00:20:03.27000:20:03.280 speed split flow and that is coming 00:20:06.63000:20:06.640 inside getting distributed and then 00:20:09.09000:20:09.100 rejoining and coming out like that so 00:20:12.89000:20:12.900 similarly you have double speed do we 00:20:16.05000:20:16.060 have the divided flow we have the kettle 00:20:18.24000:20:18.250 type and we have the cross flow so 00:20:21.56000:20:21.570 instead of naming them by individually 00:20:25.47000:20:25.480 double spread flow or divided flow we 00:20:29.13000:20:29.140 use these numbers h j k like that X 00:20:34.41000:20:34.420 these are the type of the shells which 00:20:37.68000:20:37.690 are in use similarly as we have seen 00:20:41.55000:20:41.560 that we have the channel and recoverable 00:20:47.19000:20:47.200 cover the removable cover so this is for 00:20:51.81000:20:51.820 the entry and you see this is named as a 00:20:55.43000:20:55.440 similarly we have other configurations 00:20:59.91000:20:59.920 like ABC in B and on the side L M and P 00:21:05.52000:21:05.530 like that we have different type of 00:21:07.83000:21:07.840 configuration specified by the Tina so 00:21:12.21000:21:12.220 while designing the heat exchangers or 00:21:14.88000:21:14.890 using a particular type of while solving 00:21:17.91000:21:17.920 a particular type of exchangers we have 00:21:19.92000:21:19.930 to look for this 00:21:22.14000:21:22.150 defined type of nomenclature that has 00:21:25.53000:21:25.540 been given by them suggested by the Tim 00:21:29.48000:21:29.490 so now if we look into the different 00:21:36.00000:21:36.010 type of battles we have several type of 00:21:38.91000:21:38.920 baffles that is possible so the baffles 00:21:42.96000:21:42.970 are basically providing are giving two 00:21:47.19000:21:47.200 type of advantages one is first 00:21:50.49000:21:50.500 apologies it gives the mechanical 00:21:53.31000:21:53.320 stability to the tubes that means that 00:21:58.11000:21:58.120 if a long tube is there I'm sorry if a 00:22:03.66000:22:03.670 long tube is there and there is no 00:22:07.26000:22:07.270 support for that one there is the 00:22:09.06000:22:09.070 possibility that you will be having 00:22:11.13000:22:11.140 sagging at the middle or at the at 00:22:14.58000:22:14.590 different points so 00:22:16.84000:22:16.850 that gives a some kind of mechanical 00:22:19.99000:22:20.000 support to this and not only that the it 00:22:24.55000:22:24.560 also allows a longer diverts the fluid 00:22:29.56000:22:29.570 from on to the other end and thereby 00:22:33.27000:22:33.280 enhances the heat transfer coefficient 00:22:36.73000:22:36.740 but at the cost of of course the 00:22:39.07000:22:39.080 pressure drop so as I was telling that 00:22:42.61000:22:42.620 there are different type of baffles are 00:22:44.77000:22:44.780 possible we have the single segment 00:22:47.32000:22:47.330 baffle so it is only one segment then we 00:22:52.78000:22:52.790 have the other segment and if it is you 00:22:57.10000:22:57.110 know it if this is the one corresponding 00:23:00.64000:23:00.650 to this the other one corresponds to 00:23:03.10000:23:03.110 that so we have about 30 to 35 percent 00:23:09.10000:23:09.110 or percentage up it is cut and that cut 00:23:13.72000:23:13.730 portion is if it is on this side the 00:23:16.81000:23:16.820 other one in the next immediate 00:23:18.76000:23:18.770 successive one will be on the opposite 00:23:21.82000:23:21.830 end of it so that's how this is the 00:23:25.06000:23:25.070 single segmented battle is used whereas 00:23:29.02000:23:29.030 in case of double segment as you can 00:23:32.35000:23:32.360 understand that we have this part for 00:23:37.45000:23:37.460 one end and the other part is at the 00:23:40.84000:23:40.850 middle which is like this so this is the 00:23:43.66000:23:43.670 one which corresponds to this one but 00:23:46.53000:23:46.540 corresponding to this part this part and 00:23:51.51000:23:51.520 this part we have this end and this end 00:23:56.17000:23:56.180 so like that they are arranged in the 00:23:58.93000:23:58.940 double segmented battle similarly we 00:24:04.15000:24:04.160 have here the triple segment battle so 00:24:07.30000:24:07.310 that means this one this 2 and this 2 00:24:12.21000:24:12.220 this 3 constitute a single unit for the 00:24:16.84000:24:16.850 baffle so first of all this is one part 00:24:20.44000:24:20.450 then we have this part and then we have 00:24:24.16000:24:24.170 this part at this end this will come 00:24:27.70000:24:27.710 here this will come here 00:24:29.92000:24:29.930 so like that they're arranged in 00:24:31.87000:24:31.880 sequence and then we have other type of 00:24:36.91000:24:36.920 battles also where this particular is 00:24:42.72000:24:42.730 baffle is no tube in the window segment 00:24:45.79000:24:45.800 so that means we have baffles here here 00:24:49.81000:24:49.820 and finally on this part you see there 00:24:52.99000:24:53.000 is no baffle in this particular segment 00:24:55.53000:24:55.540 so this is back end so like this 00:24:58.69000:24:58.700 this is flowing and we have on this part 00:25:03.01000:25:03.020 again we have no baffle or I mean no 00:25:06.37000:25:06.380 tube in the window segment this is 00:25:09.46000:25:09.470 another type of baffle then we have the 00:25:14.11000:25:14.120 disc and the doughnut set so this is the 00:25:17.89000:25:17.900 disc and do not say this is the disc 00:25:21.04000:25:21.050 part and this is the doughnut and if you 00:25:26.50000:25:26.510 look at the doughnut part is placed over 00:25:30.70000:25:30.710 here and the disc part is placed at the 00:25:34.54000:25:34.550 center of the cube so this is another 00:25:42.25000:25:42.260 type of the baffle this is called the 00:25:45.61000:25:45.620 orifice baffle where we will find that 00:25:48.22000:25:48.230 the I mean tubes are fitted like this 00:25:52.93000:25:52.940 this is a tube and we are connecting or 00:25:56.91000:25:56.920 we have the baffle like we put it the 00:26:03.67000:26:03.680 baffle like this so if the baffle is 00:26:07.69000:26:07.700 like this what will happen the fluid 00:26:14.95000:26:14.960 will be flowing like it is coming over 00:26:18.37000:26:18.380 here and it is passing through this it 00:26:22.75000:26:22.760 is passing through this ain't we have so 00:26:28.27000:26:28.280 this is on the sell side fluid one fluid 00:26:30.91000:26:30.920 is obviously going through this as usual 00:26:34.27000:26:34.280 I'm sorry this is a this fluid is 00:26:37.30000:26:37.310 passing this is the tube side fluid this 00:26:39.94000:26:39.950 is the sell side fluid and we have this 00:26:42.76000:26:42.770 is 00:26:43.11000:26:43.120 baffle this is the baffle and baffle 00:26:46.65000:26:46.660 between the baffle and the tube we have 00:26:49.44000:26:49.450 a small gap through which we allow the 00:26:52.13000:26:52.140 shell side fluid to pass through so that 00:26:55.11000:26:55.120 is what is you see here this is the it 00:26:57.51000:26:57.520 is forming a kind of orifice at between 00:27:01.02000:27:01.030 the baffle and the tube and that's why 00:27:03.42000:27:03.430 you know the fluid will be passing 00:27:05.40000:27:05.410 through obviously you can understand 00:27:07.38000:27:07.390 that it will give you a very large I 00:27:09.95000:27:09.960 mean kind of heat transfer I'm sorry 00:27:14.28000:27:14.290 heat transferred but at the same time 00:27:16.44000:27:16.450 there would be large amount of pressure 00:27:18.41900:27:18.429 drop also so now we go to the basic 00:27:24.12000:27:24.130 design approach quickly and we will you 00:27:29.01000:27:29.020 have already learned about it to some 00:27:31.62000:27:31.630 extent but as you can understand from 00:27:35.28000:27:35.290 the geometry of this particular heat 00:27:37.41000:27:37.420 exchanger that that you know any kind of 00:27:42.15000:27:42.160 thermal design will be I mean quite 00:27:44.66900:27:44.679 complicated if we have to really look 00:27:47.25000:27:47.260 into its geometry so now here what we do 00:27:51.09000:27:51.100 first is the we we know the heat 00:27:54.96000:27:54.970 exchanger geometry and in a in a basic 00:27:59.43000:27:59.440 design approach what we firstly do is we 00:28:02.66900:28:02.679 try to calculate or we try to first 00:28:06.33000:28:06.340 estimate a kind of design or the heat 00:28:11.79000:28:11.800 exchanger and then we go for the rating 00:28:14.52000:28:14.530 that means we know first of all we have 00:28:18.24000:28:18.250 been given the inlet condition of the 00:28:21.84000:28:21.850 fluid and we know the both the fluid 00:28:26.19000:28:26.200 streams both the fluid streams inlet 00:28:28.59000:28:28.600 fluid exit temperatures are known what 00:28:31.71000:28:31.720 it is not known is the overall length of 00:28:34.56000:28:34.570 the exchanger and other details how many 00:28:37.95000:28:37.960 tubes how many number of tubes how what 00:28:40.91900:28:40.929 is the diameter what is the cell 00:28:42.45000:28:42.460 diameter de cetera etcetera so what we 00:28:46.14000:28:46.150 first try to do we we make a rough 00:28:49.08000:28:49.090 estimate of the overall length and the 00:28:52.62000:28:52.630 heat transfer area then we make 00:28:56.74000:28:56.750 and estimate off this heat transfer 00:28:59.95000:28:59.960 surface area and then we try to figure 00:29:03.28000:29:03.290 out the actual number of the tubes NT we 00:29:08.29000:29:08.300 will the number of tubes we will be 00:29:11.41000:29:11.420 trying to find out and from there when 00:29:14.56000:29:14.570 we have some kind of geometry known to 00:29:17.95000:29:17.960 us then we go for the rating problem as 00:29:21.04000:29:21.050 if we have finalized the heat exchanger 00:29:24.55000:29:24.560 and we had the inlet temperature known 00:29:27.91000:29:27.920 to us and then we try to calculate the 00:29:30.97000:29:30.980 exit temperature so basically it is a 00:29:33.58000:29:33.590 kind of trial and error method but 00:29:36.37000:29:36.380 slightly better than the trial and error 00:29:38.95000:29:38.960 so if we have the heat transfer known 00:29:43.06000:29:43.070 what is the heat duty that is known we 00:29:46.57000:29:46.580 have the delta T LM known because we 00:29:51.01000:29:51.020 know in a design problem all the exit 00:29:54.01000:29:54.020 temperatures this factor generally we 00:29:57.85000:29:57.860 assume it to be 0.9 or around because in 00:30:03.40000:30:03.410 a counter-current exchanger it is 1 but 00:30:06.88000:30:06.890 it's not really a counter-current 00:30:09.13000:30:09.140 exchanger and actual value of the F 00:30:12.09000:30:12.100 finally when we go for the rating 00:30:14.32000:30:14.330 problem we have to get that value and 00:30:17.31000:30:17.320 this u 0 now we have to make an estimate 00:30:20.98000:30:20.990 so we have a certain known value it is 00:30:26.14000:30:26.150 already also given in this particular 00:30:28.27000:30:28.280 book one can refer to this book while 00:30:31.39000:30:31.400 designing such kind of exchanger and 00:30:33.91000:30:33.920 from there we get the value of U and 00:30:37.98000:30:37.990 from there we can try to estimate the a 00:30:41.89000:30:41.900 0 once we know the a 0 we try to find 00:30:45.40000:30:45.410 out the number of tubes in terms of the 00:30:50.68000:30:50.690 PI D 0 and the length is already known 00:30:54.18000:30:54.190 and then for one pass tube we have this 00:31:00.34000:31:00.350 is the kind of n key I mean number of 00:31:04.36000:31:04.370 tubes and we have this constants we will 00:31:07.78000:31:07.790 talk about this particular 00:31:09.85000:31:09.860 type of constant why it is coming like 00:31:12.22000:31:12.230 this and finally we have this relations 00:31:16.27000:31:16.280 by which we can try to estimate the 00:31:19.12000:31:19.130 number of tubes for different number of 00:31:21.34000:31:21.350 passes and we have this CL equals to one 00:31:27.85000:31:27.860 for ninety degree and this is for 45 00:31:31.84000:31:31.850 degree that is the cube arrangement this 00:31:35.41000:31:35.420 depends on the type of tube Arrangements 00:31:38.41000:31:38.420 we are following if it is like this way 00:31:42.40000:31:42.410 I mean they're 40 I mean they are at 90 00:31:46.15000:31:46.160 degree or in line configuration then it 00:31:49.21000:31:49.220 becomes 1 or if it is 45 degree then 00:31:56.04900:31:56.059 this is also this is also 45 degree 00:32:00.58000:32:00.590 corresponding to that CL equals to the 00:32:02.59000:32:02.600 if it is 45 then it is 1 whereas for 30 00:32:06.31000:32:06.320 and 60 degree angle if it is 30 degree 00:32:09.70000:32:09.710 it is 0.87 and if it is 60 degree also 00:32:13.90000:32:13.910 it is CL comes out to be 0.87 and that 00:32:19.53000:32:19.540 0.9 and point 93 and 0.85 all this tube 00:32:25.12000:32:25.130 constant calculation comes to count 00:32:27.76000:32:27.770 constant calculation constants that we 00:32:30.43000:32:30.440 have I mean used in the earlier I mean 00:32:36.34000:32:36.350 relation in the previous in the previous 00:32:39.76000:32:39.770 slide if you look at we have used that 00:32:43.56000:32:43.570 relation and based on that we would be 00:32:47.23000:32:47.240 able to calculate the diameter of the 00:32:51.78900:32:51.799 shell side so we will try to look this 00:32:55.99000:32:56.000 one in details in a later on and finally 00:33:00.22000:33:00.230 you will get once we have this known to 00:33:06.52000:33:06.530 us then we can go for either of these 00:33:09.19000:33:09.200 two types either we use the current 00:33:12.19000:33:12.200 method or we use the well deliver method 00:33:16.27000:33:16.280 to calculate the actual 00:33:19.26000:33:19.270 actual heat transfers so that's all 00:33:27.02900:33:27.039 thank you
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