00:00:00.030 ok ladies and gentlemen let's start with 00:00:02.24000:00:02.250 chapter 11 chapter 11 I think is 00:00:05.53000:00:05.540 actually a very practical and the most 00:00:09.56000:00:09.570 enjoyable of all the chapters that is 00:00:11.99000:00:12.000 where everything comes together and that 00:00:13.99900:00:14.009 is the chapter on heat exchangers okay 00:00:17.30000:00:17.310 so let's start with the top of a 00:00:19.25000:00:19.260 definition for heat exchangers 00:00:22.59900:00:22.609 okay heat exchangers in literature in 00:00:26.77900:00:26.789 many cases we would refer to an H X heat 00:00:31.00900:00:31.019 exchangers and what is a neat exchanger 00:00:34.22000:00:34.230 sort of by definition the definition of 00:00:38.29900:00:38.309 a heat exchanger is firstly it 00:00:41.04900:00:41.059 facilitates the exchange of heat 00:00:43.36900:00:43.379 transfer it facilitates the chain of the 00:00:47.90000:00:47.910 change of heat transfer that's the first 00:00:50.15000:00:50.160 requirement then secondly there will be 00:00:52.45900:00:52.469 two streams a string one and a stream 00:00:56.99000:00:57.000 two and these two streams would be at 00:01:00.86000:01:00.870 temperatures t1 and t2 where these two 00:01:04.75900:01:04.769 temperatures are not equal to each other 00:01:07.10000:01:07.110 of course otherwise it wouldn't make 00:01:09.23000:01:09.240 sense otherwise it wouldn't be possible 00:01:11.45000:01:11.460 that there can be a heat transfer and 00:01:14.05000:01:14.060 then the third requirement of a heat 00:01:18.41000:01:18.420 exchanger is that there is no mixing no 00:01:23.08000:01:23.090 mixing between the two streams we keep 00:01:25.99900:01:26.009 them separate let's start by looking at 00:01:31.13000:01:31.140 the types of heat exchangers the 00:01:36.71000:01:36.720 different types of heat exchangers 00:01:43.95900:01:43.969 lots of heat exchangers and let's start 00:01:46.14900:01:46.159 with the simplest type simplest types of 00:01:55.63000:01:55.640 heat exchanges okay now the simplest 00:01:58.51000:01:58.520 type it I would recommend that you 00:02:01.33000:02:01.340 divide your page into two columns left 00:02:04.63000:02:04.640 column and a right column and then we're 00:02:07.66000:02:07.670 going to look at the two different types 00:02:09.13000:02:09.140 next to each other the simplest type is 00:02:13.42000:02:13.430 two concentric tubes the one inside the 00:02:16.69000:02:16.700 other an inner tube and an outer tube 00:02:24.69000:02:24.700 and in the inner tube 00:02:27.99000:02:28.000 let's choose there the hot stream and 00:02:34.90000:02:34.910 the cold stream dot stream in the inner 00:02:40.72000:02:40.730 tube and the cold stream in the annulus 00:02:42.78900:02:42.799 can be other way it can be the other way 00:02:45.16000:02:45.170 around also doesn't have to be like that 00:02:47.68000:02:47.690 okay so there's the hot fluid and 00:02:50.30900:02:50.319 there's the cold fluid for if that is 00:02:57.40000:02:57.410 the hot fluid we can put in the cold 00:03:00.40000:03:00.410 fluid in the opposite direction so that 00:03:03.75900:03:03.769 direction would be that way and in the 00:03:06.58000:03:06.590 annulus the opposite direction if we 00:03:11.97900:03:11.989 look at the temperature as a function of 00:03:15.15900:03:15.169 H the temperature as a function of X 00:03:21.11900:03:21.129 like that temperature as a function of X 00:03:32.19900:03:32.209 what would the difference be the 00:03:34.78000:03:34.790 difference typically would be that for 00:03:37.08900:03:37.099 the hot fluid for this type of heat 00:03:40.36000:03:40.370 exchanger the characteristics would look 00:03:44.11000:03:44.120 something like that while the cold fluid 00:03:47.05000:03:47.060 would do something like that so in the 00:03:51.25000:03:51.260 beginning 00:03:59.58900:03:59.599 so in the beginning we will have a very 00:04:02.08900:04:02.099 high temperature difference and the 00:04:03.80000:04:03.810 temperature difference would decrease 00:04:06.19000:04:06.200 downstream of the heat exchanger okay 00:04:09.08000:04:09.090 I think Richard difference at the 00:04:10.64000:04:10.650 beginning and they need to decrease to 00:04:13.48900:04:13.499 the end with this type of heat exchanger 00:04:16.77900:04:16.789 the hot fluid temperature distribution 00:04:19.27900:04:19.289 would look something like that and the 00:04:23.60000:04:23.610 cold fluid one something like that 00:04:28.45000:04:28.460 okay so that is hot that was cold hot 00:04:34.07000:04:34.080 and cold this type of heat exchanger is 00:04:38.60000:04:38.610 called a lateral heat exchanger and this 00:04:43.24900:04:43.259 type of heat exchanger is called a 00:04:45.20000:04:45.210 counter flow heat exchanger they are 00:04:49.76000:04:49.770 very easy to build very very simple and 00:04:52.45000:04:52.460 I've built or built many of them 00:04:55.12900:04:55.139 typically up to about 100 kilowatts but 00:04:59.12000:04:59.130 you can also do is you put the one tube 00:05:01.18900:05:01.199 inside the other and you use soft drawn 00:05:04.33900:05:04.349 tubing and then you can call away 00:05:06.49900:05:06.509 otherwise the links are just too long 00:05:08.64900:05:08.659 and you can make them typically very 00:05:12.14000:05:12.150 compact 80 or 100 kilowatt heat 00:05:15.95000:05:15.960 exchanger typically the size of I can 00:05:20.48000:05:20.490 put it in here not much larger than an 00:05:23.02900:05:23.039 overhead projector in size okay but up 00:05:26.60000:05:26.610 to about 80 200 kilowatts 00:05:29.95000:05:29.960 okay the next type of heat exchanger is 00:05:32.62900:05:32.639 a compact eat exchanger 00:05:37.46000:05:37.470 compact exchanger now the compact heat 00:05:40.83000:05:40.840 exchanger has a definition that you can 00:05:44.19000:05:44.200 take a melt off but you're not going to 00:05:46.71000:05:46.720 really use it the contact heat exchanger 00:05:50.22000:05:50.230 is described by a bita which is called 00:05:53.73000:05:53.740 the area density the area density and it 00:06:02.76000:06:02.770 is defined as the surface area of the 00:06:10.26000:06:10.270 heat exchanger to which the heat 00:06:15.09000:06:15.100 transfer occurs divided by the volume of 00:06:18.80000:06:18.810 the heat exchanger detalls the surface 00:06:23.43000:06:23.440 divided by the volume and typically this 00:06:27.42000:06:27.430 beta is larger than 700 then it would be 00:06:34.10000:06:34.110 considered as a compact heat exchanger 00:06:36.90000:06:36.910 very compact okay a car radiator it's 00:06:44.43000:06:44.440 approximately a thousand 00:06:50.31000:06:50.320 correlator 00:06:56.62900:06:56.639 okay no move you can think of a very 00:07:00.75000:07:00.760 compact heat exchanger a fridge there 00:07:06.42000:07:06.430 what else there's some fins and I'm 00:07:11.10000:07:11.110 going to say something about that just 00:07:12.65900:07:12.669 now 00:07:23.34000:07:23.350 ladies and gentlemen any any 00:07:28.20000:07:28.210 contributions nothing a condition is 00:07:33.15000:07:33.160 sure okay there are a few values of beta 00:07:37.80000:07:37.810 a gloss comic type of heat exchanges 00:07:41.88000:07:41.890 which are found in gas turbines 00:07:46.61000:07:46.620 typically for the Stirling engine the 00:07:49.26000:07:49.270 regenerator about 15,000 that the most 00:07:52.44000:07:52.450 effective and the most compact heat 00:07:54.45000:07:54.460 exchanger is the human lung the human 00:07:57.51000:07:57.520 lung the lungs there's a value of about 00:08:00.32000:08:00.330 20,000 square meters per cubic meter 00:08:03.60000:08:03.610 that is the most effective and most 00:08:06.60000:08:06.610 compact heat exchanger the human lung 00:08:09.59000:08:09.600 okay 00:08:11.46900:08:11.479 right now as a rule of thumb take note 00:08:21.71900:08:21.729 as a rule of thumb okay we in the moment 00:08:26.61900:08:26.629 we have a gas site and with gas we 00:08:30.54900:08:30.559 obviously include air the moment we've 00:08:33.04000:08:33.050 got a gas site we normally have funds 00:08:35.81900:08:35.829 how does things work obviously we will 00:08:39.90900:08:39.919 have some tubes and the spicing of those 00:08:46.12000:08:46.130 tubes is already an important thing let 00:08:52.32900:08:52.339 me just draw three of these tubes and 00:08:56.06900:08:56.079 then on the inside we will typically 00:09:00.79000:09:00.800 have a liquid flowing through the inside 00:09:06.40000:09:06.410 and the liquid can be a single phase 00:09:09.10000:09:09.110 fluid or it might be a fluid which is 00:09:12.57900:09:12.589 being condensed or evaporated or which 00:09:16.21000:09:16.220 is being boiled so it is B it is it 00:09:19.05900:09:19.069 might be changing its face if we've got 00:09:23.68000:09:23.690 heat transferred to a gas or from a gas 00:09:26.05000:09:26.060 to this liquid then normally as a rule 00:09:29.23000:09:29.240 of thumb we will have some funds 00:09:34.49000:09:34.50000:09:41.49000:09:41.500 and the fun's the function of the funds 00:09:45.49000:09:45.500 is to increase the surface area isn't 00:09:47.98000:09:47.990 that the funds increases the surface 00:09:50.71000:09:50.720 area and you've done the funds in 00:09:55.72000:09:55.730 Chapter three of the textbook of single 00:09:58.06000:09:58.070 and you might remember that you've 00:10:02.08000:10:02.090 worked with funds which were called and 00:10:05.56000:10:05.570 one of the boundary conditions was an 00:10:08.02000:10:08.030 adiabatic depth what does an adiabatic 00:10:10.69000:10:10.700 tap means it means that there's no heat 00:10:13.87000:10:13.880 transfer there okay so if this 00:10:16.75000:10:16.760 temperature and that temperature is the 00:10:18.49000:10:18.500 same then there if you would measure the 00:10:21.94000:10:21.950 temperature gradient the temperature 00:10:25.63000:10:25.640 gradient like that DT DX would be equal 00:10:29.05000:10:29.060 to zero okay and that would then there 00:10:31.93000:10:31.940 will be an adiabatic fun so those 00:10:35.35000:10:35.360 conditions for those funds in Chapter 00:10:37.36000:10:37.370 three can then be applied to these 00:10:40.66000:10:40.670 conditions and usually if you've got 00:10:43.63000:10:43.640 funds like this you'll have the gas side 00:10:46.62000:10:46.630 moving over the funds in the same 00:10:49.69000:10:49.700 direction as the funds so that you can 00:10:53.11000:10:53.120 have a very good heat transfer so the 00:10:58.54000:10:58.550 funds so the rule of thumb is to use 00:11:04.45000:11:04.460 funds on the gas side 00:11:10.80900:11:10.819 since on the gas side increases the 00:11:15.73900:11:15.749 surface area that would be the function 00:11:19.24900:11:19.259 of the funds now terms of nomenclature 00:11:24.67900:11:24.689 and definitions we are also going to 00:11:28.48900:11:28.499 refer to a cross flow heat exchanger 00:11:34.78000:11:34.790 cross flow 00:11:37.16000:11:37.170 and cross-flow by definition means that 00:11:41.09000:11:41.100 if that is the fluid stream direction of 00:11:44.99000:11:45.000 fluid 1 and that is the direction of 00:11:51.62000:11:51.630 fluid 3 - and that angle is 90 degrees 00:11:56.12000:11:56.130 then it is called a cross flow heat 00:11:58.67000:11:58.680 exchanger so this heat exchanger would 00:12:01.25000:12:01.260 also be a cross flow heat exchanger the 00:12:04.63900:12:04.649 two flow directions is perpendicular to 00:12:06.86000:12:06.870 each other okay now there are two 00:12:11.72000:12:11.730 different types of cross flow heat 00:12:13.88000:12:13.890 exchangers two different types the first 00:12:17.75000:12:17.760 type is called unmixed and the second 00:12:23.00000:12:23.010 type is called a mixed one an unmixed 00:12:27.31900:12:27.329 cross flow heat exchanger and a mixed 00:12:29.96000:12:29.970 cross flow heat exchanger the unmixed 00:12:34.10000:12:34.110 one looks like this 00:12:41.48000:12:41.490 and show it schematically this would be 00:12:47.56000:12:47.570 the one stream moving through these 00:12:50.84000:12:50.850 tubes typically like that and year we 00:12:57.82900:12:57.839 will have the plates which are the fins 00:13:05.00000:13:05.010 and because it's a cross flow heat 00:13:09.06000:13:09.070 exchanger the to flow directions must be 00:13:12.90000:13:12.910 perpendicular to each other and this 00:13:21.27000:13:21.280 flow stream cannot move in the 00:13:23.88000:13:23.890 transverse direction okay 00:13:31.23000:13:31.240 Conte moving the transverse direction 00:13:41.37000:13:41.380 now this is specifically very important 00:13:44.47000:13:44.480 if on the tube side they are not in 00:13:46.87000:13:46.880 picture differences these plates are 00:13:49.51000:13:49.520 actually forcing the flow that it can't 00:13:54.19000:13:54.200 go into the transverse direction the 00:13:57.37000:13:57.380 mixed one on the other side would be 00:13:59.35000:13:59.360 these tubes I can show all five of them 00:14:08.53000:14:08.540 like that 00:14:14.76000:14:14.770 and again there is our fruit stream won 00:14:17.37000:14:17.380 and now our fruit stream to causes the 00:14:21.72000:14:21.730 flow to be a cross flow heat exchanger 00:14:23.57000:14:23.580 but now they might be movement in the 00:14:27.54000:14:27.550 diet in the transverse direction in 00:14:30.75000:14:30.760 terms of the temperature gradient okay 00:14:36.30000:14:36.310 if you don't like my sketches there's 00:14:38.51900:14:38.529 two better sketches in the textbook to 00:14:41.85000:14:41.860 make it more clear okay the unmixed and 00:14:45.15000:14:45.160 the mixed type of cross flow heat 00:14:47.61000:14:47.620 exchanger any questions situation I beg 00:14:56.46000:14:56.470 your pardon indeed a situation that 00:14:58.17000:14:58.180 flows actually mixing with each other in 00:15:01.38000:15:01.390 either one now it love we all know let's 00:15:06.26900:15:06.279 let's look at this one 00:15:10.95000:15:10.960 and let's look at it from above okay in 00:15:13.98000:15:13.990 both cases so what you're going to have 00:15:19.71000:15:19.720 here is that this temperature gradient 00:15:26.36000:15:26.370 of of that fluid is going to do 00:15:30.48000:15:30.490 something like that maybe 00:15:33.79000:15:33.800 and with that one it might be something 00:15:36.24900:15:36.259 like that in this case if you look at 00:15:41.37900:15:41.389 the fluid particle there then because of 00:15:45.24900:15:45.259 the temperature difference that this 00:15:47.49900:15:47.509 particle might have some convection 00:15:50.18900:15:50.199 characteristics and you might get that 00:15:52.21000:15:52.220 the two particles does that in terms of 00:15:54.30900:15:54.319 the temperature distribution that is 00:15:56.67900:15:56.689 what we mean with mixed these two plates 00:16:03.28000:16:03.290 who will sure that I can't mix well in 00:16:07.62900:16:07.639 this case the temperature gradients in 00:16:10.35900:16:10.369 this direction remember the temperature 00:16:12.78900:16:12.799 there there and there or not the same 00:16:16.50900:16:16.519 might decreases and that might cause the 00:16:19.68900:16:19.699 same picture streams on the outside to 00:16:22.62900:16:22.639 be mixed okay I haven't seen many 00:16:28.32900:16:28.339 applications in industry of this many 00:16:30.91000:16:30.920 thanks 00:16:33.26000:16:33.270 okay now the most important type of heat 00:16:36.98000:16:36.990 exchanger is the shoaling shoot the 00:16:50.48000:16:50.490 shouted tube heat exchanger that is the 00:16:54.23000:16:54.240 one you're going to find most in 00:16:55.94000:16:55.950 industry for heat transfer applications 00:17:04.04000:17:04.050 of a few hundred and megawatts so the 00:17:07.01000:17:07.020 moment you talking of hundreds of 00:17:08.60000:17:08.610 kilowatts or megawatts then you're going 00:17:12.77000:17:12.780 to go into the shell and tube 00:17:14.09000:17:14.100 application usually there are too needy 00:17:17.68900:17:17.699 to be used in in transport in course and 00:17:22.80900:17:22.819 or aerospace too heavy but in terms of 00:17:30.04000:17:30.050 workhorses and good value for money 00:17:34.10000:17:34.110 that is really the base type of heat 00:17:36.02000:17:36.030 exchanger and the most common type of 00:17:38.27000:17:38.280 heat exchanger you're going to find an 00:17:40.37000:17:40.380 industry now let's start with it very 00:17:42.65000:17:42.660 simple and then we're going to make it 00:17:44.84000:17:44.850 more complicated okay make it start 00:17:49.10000:17:49.110 simple by starting with a shell 00:17:55.87000:17:55.880 okay there is the show and the show we 00:18:01.82000:18:01.830 must have an inlet and an outlet right 00:18:11.53000:18:11.540 in the bay and the outlet there okay and 00:18:18.20000:18:18.210 you can see that if a flow stream is 00:18:21.77000:18:21.780 coming in there then obviously it is 00:18:24.17000:18:24.180 going to go out there okay that is the 00:18:26.45000:18:26.460 shell side now what we do is we put in 00:18:34.46000:18:34.470 the header header like that and we put 00:18:42.89000:18:42.900 in tubes through them 00:18:50.08000:18:50.090 that is the first tube just to keep 00:18:53.41900:18:53.429 things simple I'm going to put in three 00:18:55.22000:18:55.230 tubes here's the city tube like that and 00:19:01.64000:19:01.650 yes the third tube 00:19:11.39000:19:11.400 typically like that 00:19:24.82000:19:24.830 and now I can put the fluid through the 00:19:29.42000:19:29.430 inner tubes through the three inner 00:19:31.13000:19:31.140 tubes and for reasons that's but going 00:19:35.93000:19:35.940 to become clearer to you later let's put 00:19:39.05000:19:39.060 it in a counter flow type of direction 00:19:41.30000:19:41.310 which means that we put the fluid 00:19:44.24000:19:44.250 through in there coming out there and 00:19:47.54000:19:47.550 let me just use another color to make it 00:19:50.60000:19:50.610 clearer so the tube side go in there it 00:19:56.15000:19:56.160 would go out there and through the tube 00:19:59.00000:19:59.010 side the flow would be then going 00:20:01.70000:20:01.710 through Vale like that okay and you can 00:20:06.98000:20:06.990 see now that in the shell side the flow 00:20:09.95000:20:09.960 is going to do primarily that degree 00:20:17.65000:20:17.660 now this is called the front in tether 00:20:26.28000:20:26.290 the front in headed 00:20:28.74000:20:28.750 why is this the front because it's the 00:20:31.66000:20:31.670 site with the flow comes into the tubes 00:20:34.35000:20:34.360 okay that is why we call that the front 00:20:36.67000:20:36.680 side the side through which the flow 00:20:40.45000:20:40.460 comes into the tubes and that would now 00:20:42.97000:20:42.980 be the inside the rear inside now this 00:20:55.12000:20:55.130 type of heat exchanger is called the one 00:21:00.13000:21:00.140 shell pause and a one to pause a one 00:21:10.60000:21:10.610 shell side and a one to force 00:21:42.44000:21:42.450 okay now it wasn't long after people 00:21:46.71000:21:46.720 started building these one shelters and 00:21:49.20000:21:49.210 one to pause it exchanges when people 00:21:53.04000:21:53.050 start looking at it and and think well 00:21:55.14000:21:55.150 maybe I should modify it a little bit 00:21:57.29000:21:57.300 okay and what type of modifications can 00:22:00.75000:22:00.760 we make well the one type of 00:22:03.27000:22:03.280 modification that we can make is we can 00:22:05.37000:22:05.380 say well let's change things a little 00:22:09.39000:22:09.400 bit in the shell what we do is we put in 00:22:15.66000:22:15.670 a baffle like that so what is going to 00:22:21.93000:22:21.940 happen now with a flow coming in through 00:22:24.03000:22:24.040 the shell side it's going to do that 00:22:26.55000:22:26.560 but at the in it it is being forced to 00:22:30.32000:22:30.330 actually flow like that so it means we 00:22:33.57000:22:33.580 have to put the outlet there now okay 00:22:37.02000:22:37.030 the baffle in 00:22:39.43000:22:39.440 the other function of the baffle is that 00:22:41.95000:22:41.960 these tubes are very long they start 00:22:43.84000:22:43.850 sagging so if we put the baffle in we 00:22:46.90000:22:46.910 actually support the tubes better but at 00:22:51.04000:22:51.050 the same time we are actually changing 00:22:52.75000:22:52.760 the heat exchanger from a counterflow 00:22:55.87000:22:55.880 type of heat exchanger to a cross-flow 00:22:58.75000:22:58.760 type of heat exchanger and in the graphs 00:23:01.48000:23:01.490 that we are going to do later on you're 00:23:02.98000:23:02.990 going to see that the effectiveness of 00:23:04.63000:23:04.640 these types of heat exchanges or better 00:23:07.56000:23:07.570 okay so that is the first type of 00:23:10.18000:23:10.190 modification that can be made the second 00:23:13.33000:23:13.340 type is to say well these tubes 00:23:20.10000:23:20.110 why don't we modify things a little bit 00:23:25.23000:23:25.240 so that we do the following the tube the 00:23:31.15000:23:31.160 flow through there let's not let it go 00:23:34.84000:23:34.850 out there 00:23:35.38000:23:35.390 what we do is we actually connect the 00:23:39.31000:23:39.320 tube like that okay so that the flow 00:23:42.34000:23:42.350 through this tube would go in this 00:23:43.75000:23:43.760 direction and then it would go back in 00:23:46.00000:23:46.010 that erection okay and then here again 00:23:49.09000:23:49.100 we can connect it like that so that this 00:23:53.23000:23:53.240 flow direction is now in that direction 00:23:55.11000:23:55.120 and then it goes out like that that is 00:23:59.32000:23:59.330 called a three to pause it exchange are 00:24:03.01000:24:03.020 now three tube pause because the tube is 00:24:07.30000:24:07.310 through three times so let's make things 00:24:11.23000:24:11.240 a little bit more simple and schematic 00:24:14.71000:24:14.720 so without blowing all the detail 00:24:17.88000:24:17.890 without looking at all the detail if 00:24:21.28000:24:21.290 that is the shell okay that is the shell 00:24:25.00000:24:25.010 and the tube goes in and out like that 00:24:30.15000:24:30.160 if we look at the shell 00:24:32.26000:24:32.270 how many flows are they through the 00:24:34.51000:24:34.520 shallow one so it is a one shell pass 00:24:40.60000:24:40.610 and the to to boss heat exchanger one 00:24:50.21000:24:50.220 shell pause and the two coupe pours it 00:24:53.42000:24:53.430 exchanger okay the next one would be 00:24:57.46000:24:57.470 again 00:24:58.73000:24:58.740 let's get that let's suppose that is the 00:25:01.76000:25:01.770 shell and now we say one two three four 00:25:08.65000:25:08.660 okay so immediately it's a full force 00:25:16.75000:25:16.760 for to pause heat exchanger and let's 00:25:21.85000:25:21.860 make the shell like that 00:25:29.72000:25:29.730 and the shell flow through the show let 00:25:34.58000:25:34.590 me just use another color does this 00:25:40.27000:25:40.280 because of that battle there the flow is 00:25:42.76000:25:42.770 being forced to flow like that and out 00:25:46.29900:25:46.309 there so this is the in course call a to 00:25:50.56000:25:50.570 shell us to shell us and a four to 00:25:58.84000:25:58.850 fourth heat exchanger later on you're 00:26:04.24000:26:04.250 going to see some sketches like that in 00:26:05.95000:26:05.960 your text look so you don't have to 00:26:07.24000:26:07.250 remember it just look at the schematics 00:26:09.01000:26:09.020 to lead you in terms of the nomenclature 00:26:11.38000:26:11.390 it is obviously important because in the 00:26:13.99000:26:14.000 taste going in exam I might say the heat 00:26:17.02000:26:17.030 exchanger is a a four shell pause and a 00:26:21.13000:26:21.140 twelve tube or heat exchanger and then 00:26:24.27900:26:24.289 you need to understand what the flow 00:26:26.44000:26:26.450 configuration is on the inside okay any 00:26:30.61000:26:30.620 questions on the shell and tube heat 00:26:31.89900:26:31.909 exchanger okay this a little bit of a 00:26:36.78900:26:36.799 better sketch if you don't like mine 00:26:39.18000:26:39.190 terms of there you can see the function 00:26:42.94000:26:42.950 of all the battles on the inside I'm 00:26:45.90900:26:45.919 going to come back to that heat exchange 00:26:47.40900:26:47.419 changes just now but that is typically 00:26:50.95000:26:50.960 how it is how it looks during 00:26:52.93000:26:52.940 construction okay 00:26:55.09000:26:55.100 it is huge okay few hundred tubes going 00:26:58.51000:26:58.520 through it you can see the battles on 00:27:03.34000:27:03.350 the inside which are also being used to 00:27:06.52000:27:06.530 support all the tubes with typically a 00:27:09.58000:27:09.590 header there you can see some of the 00:27:12.19000:27:12.200 tubes on the inside and you can start 00:27:14.98000:27:14.990 making things more interesting these 00:27:17.28900:27:17.299 baffles do not have to do not have to be 00:27:20.74000:27:20.750 like that you can go and put in inert 00:27:22.72000:27:22.730 angles okay 00:27:24.22000:27:24.230 which means that the flow is being 00:27:26.08000:27:26.090 forced to do that a longer pause or flow 00:27:29.89000:27:29.900 through the heat exchanger okay 00:27:35.36000:27:35.370 okay before we go on to the next type of 00:27:37.67000:27:37.680 heat exchanger any questions on the 00:27:39.50000:27:39.510 shelling tube heat exchanger nothing 00:27:42.29000:27:42.300 okay let's look at the plate and flame 00:27:45.95000:27:45.960 heat exchanger that is what they call it 00:27:48.77000:27:48.780 in the textbook we normally call it call 00:27:50.84000:27:50.850 it a plate heat exchanger might eat 00:27:57.08000:27:57.090 exchanger okay a plate heat exchanger is 00:28:01.13000:28:01.140 very very simple 00:28:12.45000:28:12.460 this is just schematically let's suppose 00:28:16.81000:28:16.820 this your first plate and then and plate 00:28:24.49000:28:24.500 next to it 00:28:27.51000:28:27.520 third one and a fourth one and there 00:28:36.61000:28:36.620 will be many more I'm just not going to 00:28:39.16000:28:39.170 draw all of them in 00:28:50.13000:28:50.140 so what you can imagine now is that 00:28:52.81000:28:52.820 between these two plates I can let my 00:28:58.24000:28:58.250 fluid 1 flow through it 00:29:00.77900:29:00.789 and then here on this side I will have 00:29:06.31000:29:06.320 my second fluid between these two plates 00:29:12.27000:29:12.280 through two two and then here I can have 00:29:17.79900:29:17.809 something that redirects the flow in 00:29:20.89000:29:20.900 between those two plates again the 00:29:25.69000:29:25.700 result would be 00:29:35.33000:29:35.340 something like that okay so between 00:29:39.54000:29:39.550 every plate we will be hot side and a 00:29:42.24000:29:42.250 cold side okay as you can imagine these 00:29:48.90000:29:48.910 types of heat exchanges can be quite 00:29:50.76000:29:50.770 compact very compact type of heat 00:29:53.70000:29:53.710 exchanges they are very flexible in the 00:29:56.43000:29:56.440 sense that many of them you can actually 00:29:58.17000:29:58.180 buy for a certain number of kilowatts 00:30:01.26000:30:01.270 and maybe things changes in your 00:30:03.96000:30:03.970 production and you need to increase the 00:30:06.69000:30:06.700 heat transfer right and then you can do 00:30:08.79000:30:08.800 it by just adding on a few more plates 00:30:11.30000:30:11.310 so which is very nice however they 00:30:15.39000:30:15.400 cannot take large pressure differences 00:30:17.93000:30:17.940 so is the pressures or about the same 00:30:20.82000:30:20.830 order of magnitude typically liquids 00:30:24.26000:30:24.270 liquids works very well in the milk 00:30:28.50000:30:28.510 industry we want to eat a cool milk for 00:30:33.06000:30:33.070 example process in the street is being 00:30:35.55000:30:35.560 used a lot but it is not being used a 00:30:38.97000:30:38.980 lot as condensers or evaporators in 00:30:42.33000:30:42.340 heating and ventilation industry the 00:30:44.76000:30:44.770 reason why because then the refrigerant 00:30:48.60000:30:48.610 side the pressures on the orders of mega 00:30:51.66000:30:51.670 Pascal's and the liquids are in the 00:30:55.62000:30:55.630 orders of kilo Pascal's okay and the 00:30:59.22000:30:59.230 result is that the pressure difference 00:31:00.96000:31:00.970 over the plates are so large that the 00:31:03.45000:31:03.460 plates would Bend and you will have 00:31:06.03000:31:06.040 problems with the seals so that is 00:31:08.43000:31:08.440 normally the problems that we have with 00:31:10.80000:31:10.810 plate heat exchangers that are very well 00:31:13.77000:31:13.780 suited for liquid to liquid type of 00:31:16.95000:31:16.960 applications 00:31:22.04000:31:22.050 the good to liquid type of heat 00:31:25.08000:31:25.090 exchanges 00:31:30.50000:31:30.510 here's some examples of these type of 00:31:35.41900:31:35.429 heat exchanges and yet what you will see 00:31:37.46000:31:37.470 is that people originally started with 00:31:41.03000:31:41.040 flat plates and then they decided now 00:31:43.54900:31:43.559 wait a minute we can make it much more 00:31:45.11000:31:45.120 interesting if this is the flat plate we 00:31:48.02000:31:48.030 can actually change the geometry like 00:31:50.51000:31:50.520 that to purposes it makes it 00:31:54.03900:31:54.049 structurally stronger so that it doesn't 00:31:56.69000:31:56.700 bend that easily but at the same time it 00:31:59.93000:31:59.940 increases the turbulence and if I look 00:32:02.24000:32:02.250 at the plate from this side I can 00:32:04.37000:32:04.380 actually also start putting in very 00:32:06.76000:32:06.770 interesting fourth ways for the liquids 00:32:09.88000:32:09.890 which means that the flow doesn't only 00:32:12.98000:32:12.990 go in this direction but maybe you know 00:32:16.49000:32:16.500 something like that 00:32:17.29900:32:17.309 much more complicated and there you can 00:32:19.78900:32:19.799 see some of the the plates which are 00:32:23.33000:32:23.340 being bent like that there are some 00:32:28.52000:32:28.530 examples 00:32:34.83000:32:34.840 okay any questions on the plate heat 00:32:37.33000:32:37.340 exchangers okay another type of heat 00:32:40.87000:32:40.880 exchanger is called the regenerative 00:32:44.13000:32:44.140 heat exchanger 00:32:53.44000:32:53.450 regenerative type and in that clause 00:32:58.28000:32:58.290 there are two different types the first 00:33:00.65000:33:00.660 one is the static top the static done 00:33:07.63000:33:07.640 and usually in these types of heat 00:33:10.40000:33:10.410 exchangers we've got a porous material 00:33:14.86000:33:14.870 so this is the porous material it can be 00:33:21.73000:33:21.740 steel wool for example is a very good 00:33:25.52000:33:25.530 one we want a material that can absorb a 00:33:29.21000:33:29.220 lot of heat and if I look at this porous 00:33:37.37000:33:37.380 material what has then being done is 00:33:40.76000:33:40.770 that I've got a flute one flowing 00:33:47.33000:33:47.340 through it and increases the heat until 00:33:50.57000:33:50.580 it is being heated where this 00:33:53.36000:33:53.370 temperature and that temperature is 00:33:54.92000:33:54.930 approximately the same okay and once it 00:33:58.40000:33:58.410 has been heated and let's call that T 00:34:02.12000:34:02.130 equal t1 to t2 we do that and then after 00:34:09.08000:34:09.090 that you're going to use fluid two and 00:34:12.53000:34:12.540 it's put through to through then this 00:34:16.12900:34:16.139 will - and that would be for time equal 00:34:19.31000:34:19.320 T 3 - 2 for T 4 so it has been heated 00:34:23.74000:34:23.750 okay and now you use the other stream 00:34:26.68000:34:26.690 flow to flow through it and then you 00:34:29.24000:34:29.250 transfer the heat from the one stream to 00:34:31.36900:34:31.379 the other stream but usually never flow 00:34:36.02000:34:36.030 with both streams active at the same 00:34:39.16900:34:39.179 time okay first the one and then the 00:34:42.26000:34:42.270 other another very interesting 00:34:44.21000:34:44.220 application of this is that we install 00:34:48.05000:34:48.060 abortion University are being funded as 00:34:52.82000:34:52.830 a so-called concentrated solar up and we 00:34:56.93000:34:56.940 are looking at the problem of generating 00:34:59.99000:35:00.000 electricity the Sun as you know during 00:35:03.23000:35:03.240 the night time there is no Sun then you 00:35:05.60000:35:05.610 can't generate 00:35:06.36000:35:06.370 electricity and that is one of the big 00:35:07.89000:35:07.900 disadvantages of concentrated solar 00:35:10.38000:35:10.390 power but if during the day you can 00:35:13.08000:35:13.090 store the heat then you can actually 00:35:16.71000:35:16.720 generate electricity during the night 00:35:18.42000:35:18.430 and one other method of using a 00:35:21.21000:35:21.220 regenerative type of heat exchanger is 00:35:23.97000:35:23.980 to use Rock okay if you use Rock in big 00:35:28.98000:35:28.990 open spaces falling up with rock and 00:35:31.50000:35:31.510 then during the day you've got the hot 00:35:33.81000:35:33.820 stream you in increases the temperature 00:35:37.17000:35:37.180 of the rock you store the energy there 00:35:39.18000:35:39.190 then during night you can actually do 00:35:42.93000:35:42.940 the heat transfer and get all the heat 00:35:44.67000:35:44.680 back okay so that is an example of a 00:35:48.15000:35:48.160 static type of regenerative type of heat 00:35:50.55000:35:50.560 exchanger okay what can also be done is 00:35:54.57000:35:54.580 it can be bought as a dynamic type and 00:35:58.88000:35:58.890 as a dynamic type 00:36:03.12000:36:03.130 very simple example would be a wheel 00:36:06.51000:36:06.520 like this a porous wheel porous wheel 00:36:13.43000:36:13.440 which rotates usually very slowly and 00:36:20.75000:36:20.760 then on this side we will have fluid one 00:36:27.11000:36:27.120 you will be a baffle and they will be 00:36:30.84000:36:30.850 fluid too now let's suppose this is the 00:36:37.29000:36:37.300 heating fluid it will increases the 00:36:39.87000:36:39.880 temperature of the material the porous 00:36:42.54000:36:42.550 material it would move through the 00:36:44.91000:36:44.920 baffle and then it will be exposed to 00:36:47.07000:36:47.080 the cold fluid and the heat transfer 00:36:48.72000:36:48.730 will be from that fluid to the cold 00:36:50.79000:36:50.800 fluid equations right other types of 00:36:59.85000:36:59.860 heat exchanges means that sort of riff 00:37:04.52000:37:04.530 or typically names that reflect the 00:37:07.53000:37:07.540 application and the first type is a 00:37:10.32000:37:10.330 condenser 00:37:15.04000:37:15.050 condenser now a condenser is a heat 00:37:21.62000:37:21.630 exchanger where if we look at the TS 00:37:27.47000:37:27.480 diagram that is a constant pressure line 00:37:32.62000:37:32.630 the fluid is being cooled from a gas to 00:37:38.63000:37:38.640 a liquid fluid is called from the gas to 00:37:50.27000:37:50.280 a liquid okay so it will enter as a gas 00:37:56.56000:37:56.570 to being contains until everything as a 00:37:59.72000:37:59.730 liquid and during that process the heat 00:38:02.75000:38:02.760 rolls for right would be equal to the 00:38:05.69000:38:05.700 mass flow rate multiplied by H okay 00:38:11.75000:38:11.760 let's rather use F 00:38:16.44000:38:16.450 if they're and if they're indicate the 00:38:20.26000:38:20.270 fluid heat transfer rate would be equal 00:38:22.99000:38:23.000 to the mass flow rate multiplied by the 00:38:24.79000:38:24.800 change in enthalpy between those two 00:38:27.07000:38:27.080 values that is a condenser a boiler is 00:38:37.09000:38:37.100 for example where we generate power 00:38:40.02000:38:40.030 we've got water which is being pumped to 00:38:43.42000:38:43.430 a high pressure and here we've got the 00:38:46.75000:38:46.760 fluid and there's the gas okay and now 00:38:50.98000:38:50.990 the fluid is vaporized from the fluid to 00:39:02.53000:39:02.540 the gas 00:39:08.65000:39:08.660 the kinds of a condenser it has been 00:39:11.52000:39:11.530 rejected with a boiler we need to put in 00:39:17.41000:39:17.420 the heat to vaporize it and again the 00:39:22.54000:39:22.550 heat transfer rate would be equal to the 00:39:25.87000:39:25.880 mass flow rate multiplied by H FG 00:39:46.22000:39:46.230 okay the third type is the evaporate 00:39:49.11000:39:49.120 that 00:39:56.64000:39:56.650 evaporator the evaporator métiers 00:40:01.84000:40:01.850 diagram we typically be in a vapour 00:40:06.94000:40:06.950 compression cycle but what is important 00:40:11.53000:40:11.540 is is that the heat transfer right is 00:40:20.11000:40:20.120 now from this point here okay from a 00:40:23.98000:40:23.990 mixing point in so the process again is 00:40:31.39000:40:31.400 the Viper is the fluid vaporize and now 00:40:37.84000:40:37.850 it is from m2g evaporator remember 00:40:43.87000:40:43.880 usually we do not get everything as a 00:40:46.83000:40:46.840 saturated fluid it goes through the 00:40:52.39000:40:52.400 expansion valve and then the heat 00:40:55.81000:40:55.820 transfer rate is equal to the mass flow 00:40:57.94000:40:57.950 rate multiplied by a by H it's called in 00:41:02.53000:41:02.540 G 00:41:06.87000:41:06.880 and to make that possible again we need 00:41:12.52000:41:12.530 some heat some temperature at a higher 00:41:15.73000:41:15.740 temperature 00:41:21.14000:41:21.150 okay there are two more types of heat 00:41:23.50900:41:23.519 exchanges okay and it's going to take me 00:41:26.87000:41:26.880 one minute to explain them both are 00:41:29.23900:41:29.249 called the radiators but with different 00:41:31.54900:41:31.559 meanings radiators okay the first one is 00:41:39.31900:41:39.329 the type that you get into your car okay 00:41:43.48900:41:43.499 lots of tubes with fins and usually a 00:41:48.76900:41:48.779 fan here in the back through some ear if 00:41:53.21000:41:53.220 you drive that cools the water which is 00:41:57.73900:41:57.749 on the inside at a high pressure and so 00:42:01.57900:42:01.589 that is called a radiator core radiator 00:42:03.84900:42:03.859 then the other type of radiator is also 00:42:07.88000:42:07.890 an heat exchanger but now it transfers 00:42:14.26900:42:14.279 heat by radiation 00:42:23.28900:42:23.299 my radiation transfers eat by radiation 00:42:32.04900:42:32.059 so if that is the ambient temperature 00:42:34.88000:42:34.890 and that is the surface temperature then 00:42:38.59900:42:38.609 they don't have a good toilet on in the 00:42:40.19000:42:40.200 textbook but my feeling would be if that 00:42:43.37000:42:43.380 temperature difference is in the order 00:42:47.87000:42:47.880 of about a hundred degrees Celsius maybe 00:42:50.27000:42:50.280 even already at 50 or 80 degree Celsius 00:42:53.52900:42:53.539 then there would be a significant amount 00:42:55.91000:42:55.920 of heat transfer by radiation on me okay 00:43:03.07900:43:03.089 ladies and gentlemen that is the basic 00:43:04.73000:43:04.740 types of heat exchanges we didn't do any 00:43:06.92000:43:06.930 theory today we'll start doing that with 00:43:09.44000:43:09.450 the next lecture and they will also look 00:43:11.45000:43:11.460 at some problem solving thank you very 00:43:14.00000:43:14.010 much
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