Plate Fin Heat Exchanger: Multi-stream Analysis
 
Welcome to this lecture where we have been talking about the plate fin heat exchangers and we were discussing about the analysis of plate fin heat exchangers where we have analysed the fin equation and we try to differentiate between the different type of flow again seems not presents another the temperature in temperature conditions that is possible in life and in that context we have seen that the flipping types it itself may be multiple to its rim and we have to analyse this kind of protection year that we were attempting are basically a type of word is called what is called the simulation problem we are trying to solve and here we have seen that we have the freight train going in at 18 and it is coming out that are out where is this is for the a great strength and this is the twi – 1 is the multiple assets and this is the twi this late is that temperature twin3 has displayed temperature at bwi -1 this configuration where we may have said this is the ice cream and we can decide – 1st class 1st Street and this what temperature is designated as y -1 and this while temperature is designated as he wy soin that context we have solved the best Excel equation connecting between the two walls maybe we can solve it as considering it to be team a and team b in the generalized form but here it is it is in the mods analyse form of t w y -1 and t w y circle II twist3d and TWA TWA – what is this correspondence is that if we are solving equations and we find out the transportation for this enjoy this two parallel plates or disability place and the sweet showing on top of it is easier to digest and it has already been should do we have not explicitly state that the fluidwhat the if the temperature and the places are like that we can have the tour will come back to this again that generalized configuration before that we just want to recapitalize what we have none in the earlier class when we have seen that this q&a the amount of heat getting transferred from the wall to the fluid when the brick temperature is tissue and the wall temperature is and this is basically QB it is not looking properly secured from the wall to the fluid and this is from the RTA to the fray by The fray and this is what temperature is it is itgive criteria likely to the power 2 x is equals to this correlation and here in this constant equal to 1 RT we buy theta equals to one we find that x becomes so that means when these two temperatures are the same we have been minimised the middle or at the centre of this place now if this is notif this is not because 21 or if it is having some other value and we were talking about the different possibilities in that context we have seen that sometimes it may be possible that the location of this extremum may go beyond the physical boundary physical boundaries mean that this is the frame this is us to separating plates and is any mummy orchid beyond the physical boundary of this one either on this site or on this size depending on the value of r and we tried to analyse the different situations so in that context we have seen that we have first of all we have evaluated this QA and QC and we have seen this is the expressions for QA and QB it is important and we will look into this again when we talk about the other the event configurations are possibilities are the types of the temperature of the plate and the freight know what is the other possibility that we have already talked about in the last class it was such that in case because to exactly one by cos hyperbolic email so in that situation we find that the extreme of is occurring at the base of the QB and now if we find that if this r equals to 1 by cos hyperbolic MLB was not only giving the external and the wheelbase of the other of the other is a plate we are also finding that this show will change its rotation so this is no longer I will only have seen that it was coming from the plate to the two it since that is expected because the plate temperature is higher than the freak temperature so this fluid is supposed to give this plate is supposed to give it to the parade but here we are finding that if it is thought that the situation is such that one by I’m in our vehicles when are becomes 1 by cos hyperbolic ml it may so happened that are is one by cos hyperbolic ml you will find that that x is not only but this fluid is this plate is no longer giving it to the fluid that you know this heat has already been in of which is having origin from this point it is coming to the fanbase be so this is nothing but what we have said that transfers conduction of heat and sometime we had two I mean face this situation depending on differentremember that QE has been opened in 05 in treating are calculating the heat transfers within this context and they sell – x and we have done the integration over this part and the spark separately we have calculated and that is cured is from here and QB was some here and according to this even if it is the articles to 1 by cos hyperbolic inverse we will find that for this length x we have the amount of it because to this much and he’ll – x over this length l – 63 will have this heat transfer QB what happensthis case also even find that this to equations are taking care of that even if there is actually conduction I’m in South transfer transit conduction of heat it is automatically being taken care of the situation that we are in the last class that there may be a situation where the temperature of the fridge is intermediate to the fair so this is displayed his attitude to this onewe have obtained the screen equation and it will require t20 we will have a correlation I’m in relation for the x and the lead at which it is coming theta is equals to zero is given by the relation is not exactly what we have obtained earlier the ideal expression if you remember it will be something like this it was it to the power 2 m x is equals to it with a power ml – r / 4 – y ^ -7 this was the expression when the minimum was lying in wait wait beyond the physical boundary of the friction the fluid so we have to calculate the square and cube and that is given by the relation so they are not exactly similar to the situation and it will be there in the way that is the same asand in fact we need to walk away and Cuba separately to estimate the black temple it is so it is important now it has become scarce dependent that if the Audi cars to lease then she’ll ore0 is intermediate to a&t we find that we have to keep it in mind that to take care of the transfers heat conduction from one place to the other plate there has to be some kind of additional parameters that is to be added or subtracted with the appropriate manner with the appropriate kiwi or cubed so this isn’t an additional task but has also been and we will findthat one and how is that I mean since we know the temperature profile of the space I mean 20% profiling already we have calculated that is the theta x we have solved so we’re all the temperature for fine so another way of calculating the qvr QB is ino from the Queen equation and we will look into that in the next last night so we find thattelling it as QA on me now we’re telling it as qfn base so that means are really bad trying to estimate the heat transfer and where we have I will try to locate where is the minimumautodesk us and 30 seconds to Mars kpbx please mind that this it is only we have not considered the other dimensions of the base length dimension of the field this is basically transfer New Zealand so this is Katie in 2D thita xdx at location x equals 20 and we can try to find out this queue be at the field base of b&b dignitaries as QPR in base that’s why every and that is similar to Katie ti-30x articles to work so this is x equals 12 exactly we will find that this expression isI mean is there any special significance that q where p and q are equal where it is expected that the train was a transfer and heat transfer taking place to this thing is supposed to be the same but we will find the difference and later on so here in this case as such when r is equals to 1 and x is half of 4 other relations well we know the face of extreme where is located within this region and it is slightly on this side or on this side this expression is remaining credit so now let us go look into the other situation well as we are saying that it is beyond the physical boundary of the fee responding to that the situation we have an equal is to 1 by cos hyperbolic levels and is also we have analysed earlier now in this situation we know that at x equals 2 l or responding to our equals to 1 by cos hyperbolic email that if the minimum at x equals 12 but if we find the heat transfer at the field base expressions like you know – 18 DDD hx620 that is at x equals to zero on this side and training base at the theatre XD excited call Stuart on this side or back will be this month and you see again here this q&a is because to sleep in beds and q b is equals to QB fingers so share also we don’t find any difference between the fingers heat transfers or the heat transferred from the chain length calculation but what's about the situationdisplay temperature and TV and initial value is less than she responding to the situation is an intermediate and giving a man related to this temperature this year unless you ask why this relationship is Freddie Mercury and queen best qbr they’re not similar to or they are not similar to The cure and the QB expressions that we have obtained a based on the length because it was different the ex that we have estimated for this q&a was taken from this eggs and that’s why our QB and QB expression was either having a blast – shy turn lights in this case since this is completely based on the film paisa transfertaking place from one place to the other Street so that means while analysing the flipping type because I’m in the room number of multiple number of multiple strains are multiple is Addington multiple layers what we need to look into a mini cannot separately keep locust away that you know there is a kind of transfers conduction or not because it’s not possible exam intermediate location what is happening between the plate and the free temperature so automatically the equation should be friend such a way that dude that that perfect is taken care so for that we find that if we are taking this cube a prism best expression then it is always taking care of that heat transferI’m in a common common multiply him yet so that will be taken care automatically buy this expression so please understand that this particular expression we will be using our for doing the multi-city play Queen heat exchanger analysis so about the expression says it looks this phone that you think you will finish and this is the expression what we get for the US are now based on this information we will again go back to ours thatI’m in number of plus one number of what temperature is in a generation we have this is the temperature and this is the outside temperature of questions surrounded by these two walls pwynt w y -1 in this context we will write that we have already told that if there are a number of questions we have been number 1 number of wolves and we have all together 2n + 1 number of equations and unknowns are there so we have to scream does 2n + 1 number of equations so first of all what we will like to do is that we will take him energy balance over this highest number of channel where this is enteringplay some amount of people we coming from hear some amount of it will be coming from this and the food will be receiving that amount of it and it will come out so this to get the combined height kiwiplus QV that becomes cutie and that we have seen as constant and we will take care of I will be safe if we take an energy balance will look into that in details so in the next life we will now go to this that when we are to the heat transfer and having energy balance and even this far the highest tablet stream we find that the heat is getting transferred from the primary surface as well as height is coming from the AP so both for this type of flea and worming for this final so either it is a and b and and separate email this primary service area so this is the primary heat transfer surface area contribution from the primary across the surface area and of the highest played this is HIV primary eye and this is the difference in temperature this is so if we consider it to be TiK season averaged between 3 in and day out and then it is t.i. – twi and then we have this is for the twra so this is this temperature difference between the state and the is this one the other party we - two8two we will bdwy – ti so that’s the heat capacitythis side is Swedish a minus one and this is why is bread so we have the heat transferred between this surfaces of indus primary service area on the a minus-one its side to transport surface area than it was before pressure temperature difference between the fluid and the walls and then the primary heat transferred in a contribution on the wall side so and then we have this contribution from the Sci-Fi and the heat transfer from the inverse of the Hyatt – I’m in a minus-one itself through it and then we have the transfer QB for the inside and the fan base as we have decided on the outsidehe transferred them as fleet soul intact we will have them 2n + 1 number of Pitt Street and and I’m sorry any number of tweets wings and n plus one number of walls so altogether 81 class in number of such equation so you’d be able to fit and thus becomes in a algebraic equations then we need to solve this equation to find out the White elephant sale as well as the predicted temperature and that’s exactly what we look we were looking for 2 simulator 15 typha changes. Once we know the exit temperatures of the fluid streams, then we will be able to calculate the heat duty of plate fin heat exchangers. So thank you for your attention.