Surface Condensers – Part 2





Welcome back and we are discussing condensers, so we started with the basics and we are slowly developing the concepts. Condensation on a single tube we have seen now we will see on a tube bank how condensation takes place and then ultimately we will move to the design analysis of a surface condenser. That is a very big condenser which is almost I’m in which is similar to a silent heat exchanger but there are very large number of tubes on which country station takes place typical condenser which are used in PowerPoint show the topic with Winchester today is design of surface condenser so you will slowly go to surface condenser if you recall we have done we have done one problem where we have taken a single tube and over the tube there is condensation of refrigerator so here we are taking up another problem from the book of heat exchangers selection rating and thermal design by Charlie Crockett and co-workers that refrigerant r134a is condensing under quizsent condition that is almost stationery paper on the sell side of a bundle of 41 the body can be configured in a square in line and it which is stone in the left and all in a triangular staggered element which is known to be right as shown in the figure find the average cell cycle coefficient for each of the configuration show here all the tubes we take part in contention but the condensate from The tube above will fall on the tube below and that will that will take in the condensate feeling of the QPR and which will diminish the rate of heat transfer and this demonizing of this effect of diminishing the rate of heat transfer is a progressive because as we go to video below and below there will be more detrimental effect of film storage this we have to take into consideration average heat transfer coefficient is there has to be estimated taking care of all the heat transfer coefficient on the different types of it so initially we have determine the heat transfer coefficient of a single tube and let’s say let’s sayhappy do you heat transfer coefficient which is this one this week holiday calculator now this is the suppose there is a rule of the fight there is a column of tubes so this is the first you this is the second time this is the 3rd to 4th and so on so on the first unit is not affected by the condensate from the top so we will have it transfer coefficient issue on which we have calculated are here so this will give the heat transfer coefficient age one which we calculated already we have calculated in the previous problem now on we will have lesser amount of heat transfer between the alignment alignment to be approximately 27 club 60 this is approximate because you see if the sale is of circular cross-section show on all the column the same number of this will not be there so we make an approximate approximate for the small problem it looks that it is little bit but when we consider every large condenser should be this approximation of considering average number of tubes on in a particular column is not unjustified she is kind of surface surface condenser are used in Portland and already I have shown some diagram where very large number of cubes are there in a column and then we are using three relationships these relationships have been described earlier so from our relationship we gave what is the average heat transfer coefficient where is the transfer coefficient of the first US 1620 and the average transfer coefficient is 1202 then we use muscletech relationship lasting relationships gives around thousand and then there is some sort of a correlation predicted from experiment show that also we use and we get something around 1407 so we can see the car or cars relationship is in between the other two so it is all the amenities many many times it is recommended that we should use correlation and we will use the litter problem also the corporation and relationship relationship what we can see that the average transfer coefficient is given by the transfer coefficient of the topmost you then the number of tubes come into place is b6 is the number of tube in a particular column so with this week the average transfer coefficient this is for alignment fall straight and not sideways because you see these staggering meant is something like this this is this so what we assume that this is from the talk to you on the tube so it does not fall from here to here so this is not I mean this this does not fall from The tube on the side so rather it falls directly directly from the top to the bottom of this is the way it falls through if we assume that there there are seven columns of 3 and two columns 13 columns of hit you with a is equal to that there are 7 columns and approximately 13 columns and approximately 3 tubes in each column so so let me go back to the previous figure then again let me go back to the previous thing that it will be here I would like you to do this calculation of your own so we can see this is the struggle this is this tiger direct me so just see what we have told that there are 13 colonies at approximately this many tubes are there so that you can get from the figure out from this particular diagram 102 this is what I like you to do this exercise then there is mathematical calculation very simple mathematical calculation and just like before what we will get the the national coalition will be the most conservative value of averages transfer coefficient that is the lowest value calculation the current relationship will be in between and the experimental Lee drive during relationship which has been shown last year that we give the maximum transfer quit is it will show you the nextcoefficient of heat transfer in kissing in school if there are no other people we prefer that design on a small designer small volume number of tubes that is first thing it is higher rate of heat transfer that is another thing and what we can find that it gives Lisa inundation of the contest this message to let us move to the next slide staggered of tubes is higher average transfer coefficient compared to in lineinundation gun videos this is what we can see the average transfer coefficient on surface condensation is getting reduced because of inundation of the contest between of course is to have staggered I meant to reduce the effect some extent but we can do what we can go for laying out in a slightly inclined plane that way it will help because gravity so it will at the same time the effect of all the detrimental effect of condensate inundationthis problem then they do only what we have seen how to calculate film condensation on his inner tube and how to calculate the film condensation if there is a tube bank and there are tubes in a column lock number of cubeswe find that the people of it is really very small but it had some effect on the field and obviously it will it will modify it will change sometimesTurkey season taken from the book of heat exchanger book called heat exchangers selection rating and thermal designed by Sadiq kakkar and his supporters and the problem reads like the this a sealant tube type condenser is to be designed for a coal-fired power station of 200 MW turbine at 5 mega Pascal and 400 Celsius III is denoted as I is denoted for order is used as a symbol for entirely sure I want the NFL has been in which can be really picked up from a steam table and the condenser pressure is 10 kilopascals 0.11 steam enters the turbine and comes out at PT 1 by the thermodynamic efficiency of the turbine is pointing this is actually calculated that we actually off and then design withoutis that steam is condensed on outside the tube and saw that you recirculate pulling water fool and his what are they had told and again I am repeating because people should have a good idea regarding at least the basic heat exchangers very important heat exchangers for a very interesting water is available at 20 degree celsius and can exit the condenser at 13 there will not be any change in temperature because is not considered that change from the outletmy dog passed latest calculate the mass from mass flow rate of the paper side-by-side or steal the condensing city to how do we find out we know the total amount of work that has to be extracted from the that can be extracted from the turbine and we know it is a 200 megawatt power plant show 200mg what will be the work done and from there and healthy we know in helping of these teams entering the turbine Intel is healthy of him leaving little by little and from there we can get this team flow rate that is 215.68 KG per second to this list included we are getting so basically this one flow rate of steam so this is what we have and this is a very important very basic information regardingit is 30 degree celsius in temperature will be 25-30 sand city probably we have mentioned it and we will mention it exchanged their is attending temperature in property calculation what we dospecific we have got the viscosity we have got the thermal conductivity and then we have got the density of liquid water and I’ll give it you got it from the number of the liquid were similarly saturated liquid properties of the contents to water on the safe side we have got the latent heat of vaporization the latent heat of vaporization sorry I had to go back to the previousliquid thermal conductivity and we have got Wendy liquidity conditions what would be the envy of the things we have got outside and inside you now these two things one can think of calculating but particularly but sometimes it is silly in a practical transfer transfer equipment design or heat exchanger design of the things are to be selected a priority when you start the design sometimes the selected quantities we do not change sometimes the selected quantities we change depending on Yvonne our inside and outside diameter of the tube sometimes it happens like this that these attitudes which are generally manufactured for this kind of pics so we have got limited selection and sometimes people use all the designers use his intuition and experience for selecting Attenborough keeping everything floating designing of a heat exchanger it becomes almost impossible if not a herculean task or take and that this thing working so now let us go back to the next line next line the cooling water velocity has been selected as to metre per second this is a problem she is depending on if we will have probably get set media210 he has got good knowledge or he has got access to handbook basic rules and standards so from their policy can be pickedthink that amount of temperature difference floor heating off the tube is there on one side of the other side there will be due to on both sides inside and outsidedesign it is tubular steel manufacturers association we have picked up and then from the data etc which have been supplied to you so we get what is the total amount of the transfer and we gave what is the coolant flow rate should these two are in very important information which we get from this go back totuba tuba tuba liquid velocity we have got liquid flooring we have got the number of deals we have to find out and the length of the tube that is also very selective that you will find out so when we get the number of tubes and link up with you then gradually we are moving towards the entire size of the heat exchanger like the size of the selectivity the most important dimension the other cultures which also need to be specified to this thing we will see what are the other features we need to specify for heat exchanger for a complete design at this point I like to mention that obviously mechanical design we are not in mechanical design of it explain in details like what should be the Celtic etc why we have calculated astuteness astuteness from mechanical design point of view or not but the mechanical design is not within the purview of the project or so we will concentrate basically to thermo hydraulic design more precisely the methods of analysis to arrive at a hurry and we are proceeding slowly towards that number of tubes once we have got the coolant fluid so the this equation will give us the number of calculator for calculating average number of rows on a particle is needed and we have gotcolumns columns in a column how many nukes will be there that is very important because the heat transfer coefficient between an addition of condensate depends on how many cubes are there on a corner this weekend explain in every in a month in a great day we had explained shown some consideration we are considering that there will be 72 you like this so like this there will be 72 so this is 17 this is what you show on a particular column there will be 72 this were considered and the coolant transfer coefficient can be estimated from the calculation outside the transformation. Lets go to the next slide,  I think  we have come to an end of this lecture and next lecture we carry on from this point. Thank you.