Tubular Heat Exchanger: Shell and Tube Design
Welcome to this lecture, in this lecture we are trying to explain to you the the shell and tube design approach in detail. You may remember in the last class, in the last lecture we have talked about the shell and tube heat exchanger design approach and here with an example will try to elaborate the sun now just to recap each unit what we have talked in the last class please stop all we need to define the problem like what is the problem definition one of the constraints what is the desired output and based on that if we have this all these informations with us we have to first select the type of exchange rate that we’re planning to design so he died designers like what will be the expected heat transfer coefficient for a typical kid just like chill and do a different kind of fruits so once we have that knowledge will be able to find out using the hair salon and you are the other exactly have known earlier classes so basically we will be able to find out some of the parameters or design parameters so by saying that we went to say that we come to know about the length maybe we come to know about the diameter of the tube we will be able to tell about the shell diameter etc so once we know all those parameters then we do is that now we go for anything probably till now trying to sell up to this part we are trying to solve a finding problems that mean when all the inlet and flow conditions and the extra conditions temperature for rotisserie unknown and we try to estimate the height and length of the Indy 500 qualifying problem as we have learnt in the earlier this monththe exchange in English and to strengthen know and when we know the condition of both the fruits and their attacks in the configuration is no we can find out what’s happening to the exit fruits trees or the other we try to find out the performance of the heat exchanger if we find that the heat exchanger performance is acceptable like what is the pressure what is the heat load etc that we have defined the earlier in the firstif we find that the engine performance is the acceptable like what is the precious what is the height load etc that we had defined area in the first problem definition it is compatible with or it is acceptable to our problem to the definition or not then accordingly we will go for the mechanical design if we find that it is not in accordance to our designs output or what we intend to do when we have to make a change in the estimation so basically you can understand that this is the kind of Friday so we are starting with initial rock designs and we’ll try to rectify that one according to our date so let us try to sell this one willwe have this is the baffles and one trick is entering the condensed water is entering on this side and it will be flowing like I’m sorry this is supposed to but this is not a good design so it is supposed to come Thursday signed and it should come like this and it is it is supposed to come another couple should be there so it should come out from here so now on the other side that our water is coming and it is flowing like this and finally it will flow like this from this house so here all the public definition that is 7 this is entering at 70 degree centigrade and it’s CP is also given it is for 1845 kzl and it is at 60 70 result 67 degree centigrade and .2 now it has 50000 kg per hour no the temperature of the water below the inner temperature of the condensed water what is the expected that we had to design a Shell and tube heat exchanger weather exit temperature for today supposed tooverspeed not be anytime less than positive recent recordspindle steel bars not necessarily also single and coolant velocity is maximum 1.5 metre per second that is the maximum allowable velocity there is some kind of form resistance or that means there is a possibility that over the time it will accumulate some kind of skill and that resistance that found resistance will be the pole resistance is equals to point triple zero than 176 if you need to be metre square kill me but like just involves all what we get for the heat transfer coefficient distance of this because of the tube material this cube materials are made of carbon steel so that we know the thermal conductivity so it becomes k equals to 61 per metre Kelvin now the tube diameter also has been specified to the tube diameter is also specified and it is basically it is lying to them and the it that is equals to it will be in line flow and this is how they are going to be arranged this is supposed to look at the floor is taking place like this and this is the minimum area we have already learnt about I didn't even touch and the pitch ratio that is beach shipyard that is 50 by 200 is the outside diameter and this is it so that pity by The Zero is equals to 1.25 so this has already been certified and there is also the battle spacing the battle spacing is .6 are the same time it is 25% to 25% so I can't leave behind this is that project we have shown so we will stand with this is the problem definition has already been told now we have to all leaders also selected know you will try to make a long destination of the design palomitas life will try to find out what will be the number of tubes on the shield side what will be the diameter of the shelf and once you know that so all this time so that we’ll be able to find out the amount of heat transfer so this is nothing but if you trying to calculate this is 30000 I'm good and yourepeat the question will be used to find out the exact temperature without the fourth grade and it will come out already we know they're all a lift and if the temperature of the heatinghow do I do thank you know to do that we have to depend on saddle realistic values of the internal and external kitne pratishat this is the overall heat transfer to find the Walgreens just installing the outside then we have the overall distance of the external ones and this is the overall heat transfer coefficient of the we have one by 80 then we have our schedule buy ris is defined in terms of the external the heat transferred by the walls of thegiven this election is so they had given a child of theirs is typically which can be considered for different kind of fluids and different kind of detection configuration so based on the value if we now estimate we will find that already we know each other if we can substitute our schedule already have talked about all she do is already known to us this is and this is all she do is say if we define it in terms of this can also be below by the eye surgery is basically the zero is equals to 19 ml and Di is 16 m m h I is already given on a file is already known that is because 2.30 176 you just tell people what and we have 20 or 30 and you have to put the value of k and where does the pole into the distance the sounds of bird we also try to find outyou can see that this part is not there so when this part is not that corresponding value is not happening here and in this case all the other parameters being known we can try to find out you see and this will come out to be 19 silhouette .09 watt per metre square killed me so you can understand that this is in contrast to our in contrast to our earlier valuable we were considering the following resistance and that was appearing 14 28.4 what per metre square building so this resistance or I’m sorry not this this is the following resistance the following distance contribute I mean weird considering various answering the following resistance we are finding that the future will be substantially small as compared to the clean already have the knowledge the knowledge about the transfer so long winter pressure difference in the future islands DNA counter-current exchange is configurationdefine toss the coin is entering from 17 days ago and it is coming out at 40° ok so now we can find out the 31st and we will find that difference and the difference will be appearing in these expressions to install a delta tlm of will be able to find out the truth will come out if you put all this while you will find that this is something else 31.4 degree centigrade is bellator class so in reality crucial factor of .9 still this we have already learnt that college what time or if I mean when you have a single fast and the furious single-celled what will be the first founding correction factor but we have just assuming it and this moment just as long she has to be laid alongsideyou would be able to calculating to the overall transportation was considering and here this is where we have not considered the founding and this is basically clean so I think we will be able to find out area and obviously as you can understand that this will be higher than this one findPeter’s Square to the qt maintain their identity Ellen every month them and only thing is changing is Europe and uses that is giving rise to different kind of overall area no once we know this is for surface areacannot be expected after certain time so now you look into the area of this is why I see so what is the king surface area and this is anticipating some kind of falling what is this ratio this comes out to be 1.34 look at that it had been told that the only thing should be less than 35% so as we can understand that this is less than 1.25 so this design over sizing is within the limit, thank you
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