Surface Condensers – Part 4
Hello everyone, so if you recall we were solving the problem of surface condenser which is a shell and tube type surface condenser and we are, this is a very comprehensive problem because many aspects of condenser design we want to discuss. And we are continuing with the problem for we are continuing with the problem the last lecture. So if you see if you recall we have done the calculations and subtle design quantities of day we have got the mass flow rate of steam we have got the master rate of coolant we have got the total amount of heat transfer we have got the number of cubes and linked up with you this90254 like to remind you for the capitulation I like to mention that in this water as coolant is flowing through the tubes tied and steam is condensing overdue and this is a very large condenser and it is for a pot plant of high-capacity now we are we should estimate the cell diameter and check the fuel pressure drop we should also have a closer look to different transfer register so now if we go to this class we can see that there are five resistances of side to side street there is a registered that means the water flowing through the youth side there will be some connectivity since that is 25% of the total resistance tube side housing that is 36% of the total resistance tube wall that is only 2% say it is it transferred through metallic surface by conduction and generally it is small in many heat exchanger calculation at the first round people may neglect this one because this is generally small then sell side fouling that is 16% and sell-side resistance that is 35% of all these thing 36% is the cute cycling and that is quite large inside the transfer coefficient that is condensation heat transfer coefficient that should be low but what happens due to the effect of inundation etc the average transfer coefficient falls unless we make some method to take care of this so the average transfer position that falls but what is to be noted that tube cycling is quite high 36% sure there should be even sell-side fouling is also not negligible so there should be some method in heat exchanger to take care of the filing that means time to time the heat exchanger positive side and the sell side needs to be clean and particularly keep cycling is very hard to keep cycling over the maximum resistance and they’re two different scheme septic cleaning one scheme of cleaning could be chemical cleaning and another scheme which is also very widely used that people use people circulate metallic balls of suitable size to having the following layer and then it has to be clean this is one aspect of it now so far we have not got the Celtic sailing to have got some idea that you playing this around 15 I believe that is what we have calculated show up that order the same length should also be up that order the expression of cell diameter is a function of the transfer area and tube length in cube layout parameters ptpr and obviously the outside diameter of the tube that is so true there is some sort of a formula which is actually basically empirical formula with that a or sales in diameter can be so if we look into the how it is done so it is like this late like this like thiswhich show that will also come to Legacy what are the things here this is kind of a formula which is bit empirical with this we can calculate the centimetre where is the team player constant series 14 90 degree and 45 degree to 1945 1945 suppose this is the fuse layout that means they are late or early in square area of this included angle is 90 degree this is your 90 degree and take this we will get some sort of a 45-degree kind of arrangement if they are standard then one can get this 30 or 60 days depending on how the tubes are rotated so depending on these kind of things something has been discussed in in case of earlier also I have discussed this thing and in case of facility with exchanges these things discussed so I will not spend much time on this what we like to say that this year can be taken depending on the tube layout and cl is equal to 1 4 90 degree and 45 degree let us take that and CPT accounts for the incomplete coverage of the cell diameter by deuce what is happening in that actually we cannot bring it you very close to the sale so that's why sometimes sometimes go half a tube will come so we avoid to have any clue there so how can I explain it it is like this late save one of you with something like there's another row of 2 is so probably here want you we do not give us the age we do not keep should what’s the age generally it happens so this secretly comes for me in complete coverage of the cell diameter by The cube and the CBD is equal to .9341 cube + more number of pupils is the value of CPT will be lower and CBD is equal tostupid a stupid why did you know so that we can calculate she has been given as in can't remember the inner tube and diameter and outer tube diameter ware supplied in this problems so she will allow this I have told how to select the or what could be the guidelines for selecting inner diameter and outer diameterobviously that is not very good and if you make it more spots that use if you make more spots then what will happen your cell diameter increase the heat exchanger 501 us to make a compromise from experience from the eye again from a handbook excetra one can take some sort of things and then cancel it be so all these things have been calculated next slide if we move then from there we can calculate the sale diameter is 0.1 this is this is thiswhile doing the mechanical in this course we are giving we are focusing on only design and design we will be satisfied with thiscalculation calculation is not on the safe side because he said for sale sign your Steam is flowing and the motive power for this team or the capability for steam movement that comes from the dark by itself so turbine is religion the steam at a certain velocity and pressure and so this will give this team ability to move to all The cubes of the cube xtube side pressure drop again there are certain things let us try to understand what it is if the tubes late like this this is acting this is the second and third floors but sometimes what happens is like this and this side this week 40 hillside Street this could be the inlet and this could be out to this kind of configurations are possible and it's kind oftube inside the tube and delta PR4 return the pressure drop through the tubes can be calculated from this this is very easy you can understand there is a friction factor and the length of the tube then there is some sort of a mass flow rate through the tube so simple pressure drop formula one can use and this this kind of correlation has been suggested so with this one can calculate what is the what is the pressure drop so you see a patient actor we are getting and from friction factor this is your Reynolds number so this this this gives the friction fact that if is the friction factor now if we go to the next live show increase the number of buses here it is only 12 number of process is important because that is the total total if there is if the length of the tube is to see if the length of the tube is Gail and if there is a number of passes then the total length of the tube which liquid has to pass through me to tell so in this case it is 12 diameter we have got and she is the related to the mass flow rates historically have got and therefore we have got what is the pressure dropped to the cube cube and then what is pressure drop due to return is given by the situation and here there is only one pass through this kind of inflation so basically these pressure drop to The cube and pressure drop to the return that can be combined to eat at to get the total pressure drop total pressure drop we got and they’re from the total pressure drop the pumping power can be determined that aim into delta ptotal / rope and efficiency of the pom pom poms so one can take as and the ipcmc to be high like 85% or so and with that we have got that the power will be 829 almost a 38-33 can understand the septic pump this is basically the feed water form of the pipeline that it should be quite large for such a capacity of the movement and we are getting 8:29 or 8:30 till around 8:30 p.m.now you see there will be there will be other requirements so only for the Dubai distance of the condenser which one should not take that this is the bottle pumping for what 40% now let us go to the next line next line pattern analysis has been so you see what we have done at the beginning of the calculation do you say velocity will assume that this to me so now let's say this this velocity which we have got the calculation for one is 1.5 m per second what is 2 metre per second for the calculation and another is calculated asincreasing the transfer as you can see that this number is increasing so we will have an increase in the transferthis is because that they have told that it is the average transfer petition and there is like a pickup in additionit should be small for us 100 velocity of water and it will be large for higher velocity of water and similarly be pumping power that will also increase because of the change in depressionit is a good opportunity that you can repeat this problem which is a very comprehensive problem for different water will answer key to the coolant and check whether you are getting these figures are not this will give you a good practice keeping that in mind I have selected this problem so that you can go for this now what generally is left for the latest this is but let us discuss what we design we have design features we have got and then what is left quite a few things in your design is not complete why did you think the tubes are quite large recycling by our calculation we have got around 13 and if we go on increasing the water velocity and you can get 1513 cannot be raced onto seats at the end of the show we should have arrangement for supporting the tube this is one thing one has to end this support comes in the form of and we’ll sit there so they will also help to have the glass floor of the same size 3 in this which is yourlet me call or other features of the foetus has to be taken care of so fasting is your things which one has to take care of which is very obvious because the very long then second thing that condensate to collect at the bottom of the condenser surface condenser and then from there it has to be taken out of the condenser so there is something called hot wheel in surface condenser so there is something called hot wheel city hot wheel design is also to be done when we are designing then cement this also needs to be design then of course the Raiders of the sale he does QC yes expansion device if required if required ok all these things there are many other things all this thing has not taken care of and obviously needs to be looked into all these things I think I can go back to thank you for joining and we are continuing because because of its comprehensiveness and I think we are at the end so you can recapitulate it and you can also do the problem by changing some parameter, one parameter change I shown that is the velocity of coolant or liquid water to the tubes, so you can check the design principle. Thank you
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