Design and Simulation of Regenerators
You are welcome to this lecture, today we are going to talk about the design and simulation of regenerators. You may remember that we have talked about different types of regenerators and it is fixed bed type, the rotary type and out of that we have specifically looked into the fixed bed type regenerators, you may remember that we have solved some of governing equation for those regenerators fixed bed types counter current regenerators. And to add to that just there are regenerated of counter-current and parallel current similar to the idea but it’s not possible to have a cross-flow type generator so generally have counter-current and parallel current and here we are going to talk about the fix bit error rate so noin one cycle the hot spring is flowing another cycle the Coldstream is flowing from the opposite direction so that’s how it is performing a counterflow regenerated and while analysing it we have seen that visit the governing equations and in that governing equations which ma’am also talked about the boundary conditions but we have said that will not submit it is beyond the scope of this and if anyone is interested specifically he or she can look into the articles on this particular reference or he can also also can also look into the elements book for the solution of these situations and then we will try to relate around implies that the solutions of these equations and while solving is equations they will find that there are different kinddid you hear this is call Larry display pedometer and this is that you’d use the time parramatta and if you can I’m in coordinated with the NQ but basically this is called the Lambda and 545 Lily is known as what is called the land of five method and the other method is proposed by London and London and this is pretty similar to the heat exchanger analysis that we are family and this is called the issue of solving the counter currency generator fixed so we have chosen in this analysis in this class to look into particular restaurant youontvtonight thank you so looking to the details of this definition of the Epsilon and q&a since we have with family at this time in larger and we'll try to stop one of the fruit called on the heart ratescapacity to it and it may be also possible that both of them is the saint of seeming rcmax are equal in that Kristen will have her because to buy soap otherwise if you look into this definition of the NTU it comprises of the hot side he transferred area the hot side a transfer coefficient and this is the cold side heat transfer coefficient and the cool side heated and open you will find for the fix battery generator that this is c&h are mostly equal in case of expertise and a generator but which is not the case in case of fajita not going to the other definition the definition of the highlands to buy cubot Max so the maximum transfer that is possible and she is in this case this will be minimum x the maximum difference in temperature so this can be correlated like this in the regenerator whentfsph too dependent on the time in the later part of the cycle you will find that the cord fluid is coming at the temperature of PCI and it is coming out at PC2 and it is dependent on time as time passes this is changing as time passes this password will be changing so what is fixed sth1 and respect as 5141 anticipate the maximum difference in temperature x the minimum capacity through it and listen to darte is the amount of eggs that are actually that is getting transferred in the teacher is so that’s how you know we define the generator effectiveness and it is pretty similar to the definition of the effectiveness48 * the school's sports page inlet and outlet outlet but this is the average temperature of the hot cool food restaurant and take a picture of the so-calledpowder into the details of this temperature profile but we will be using the final andmaster heat capacity ratio ratio you can understand that msps basically that msps is a product of the mass of division record matrix x the specific heat of the resident of metrics and you have the scene in the minimum capacity fruit x 300 is the total time periods each comprising of both the hot and cold feet I feel you so this is the pH + sin theta is equals to page number of different type of dimension and dimensional if we look into the solution it has been proposed by The corporation and solution number of heat transfer units per team he find that you and Max capacity ratiogive the different Epsilon and corresponding to different a new and different metrics capacity ratio and if we know the answers we will be able to find out the cost of generatoryou know that if the market cap of cos3 and the ntas somewhere at 15 then we will have something like white 975 as the generator effectiveness so this corresponds to this one and this corresponds to the styling so this is what is the effectiveness of the original effectiveness 25975 corresponding to value a painting because 250 and cm equals 230 this particular solution has been off tint for vehicles 21 when the original introducing balanced condition or c mean by see much is equals to 1/4 we'll try to understand how best we can utilise this chart for designing and simulating the regenerated so in the next like we are going to be the one to talk about the regenerate assimilation he will find that we have what are the parameters no NQ is no you may remember that when we talk about the simulation that means the rigid matrix I mean all the internal things unknown it’s geometry is known and it’s only temperature is known in the temperature of the hot plate is known in the temperature of the cold fluid is also no 31th one is alone geometry and all other details like in heat transfer service area below the heat transfer coefficient can also be obtained because we know the hot tray to freeze chlorate and perchlorate so from then you'd be able to calculate thereminder to you’re looking for is trying to find out the app silence of the simulation problem for a balanced condition when is equals to what we know the mass of the metrics that is present and she is the specific heat because we know what is the temperature of tentatively what is the exact temperature of the 48th and tc1 being known we know that to estimate is so we would be able to find out what is the operating temperature of this year’s average and cement is already known 30 is the same. The duration of the hot and cold so that way if not and the time is also known as what we are trying to find out is the effectiveness of that particular itemwe have to look a row in the chart what is the corresponding value corresponding to this ain’t you say in imagine as we have said earlier that this comes out to be 50 and this comes out to be free and all it may be in intermediate from intermediate value also in that case we have to interpret from discharge so if that is so we will find that directly we get the value as .975 corresponding to this one and this onethis is how we can select the effectiveness of simulate the performance of the regenerated when we know it’s geometry and we know some of the parameters of fluid flow parameters and this is pretty similar to our heat exchanger design for the inlet conditions and the heat exchanger geometry and we try to find out what is the exact temperature so this is how we know the performance of the overall performance of the regenerated in this contextis generated only need a high IQ value we also need to have a high value of the max capacity weight ratio so thatwe need a high value of the same and also needs its high-value of this until you can understand the metrics we should also have a lot of the CSC mean is basically in the process dependent we don't have much control on that and is again but I'm feeling it comprises of the hot and cold feet time. Should ideally be okay ifand that is temperature-dependent so when it is temperature-dependent particularly hard-to-crack application application you will find that the specific heat of the matter is changing very fast with the temperature in the temperature is less than 30 by 12 you will find that the CV of the specific heat at constant volume always constant volume and concentration equivalent of an attitude I mean as it is as the temperature is falling even find that certificate is falling rapidly and it depends also on the Divine temperature today and some of the common material for the p30 common material used for the generatorthat is what it follows and the inner it’s also quite rapidly so that means the specific heat of the material is very small and in that case nscs becomes a roller-coaster also whatever you know whether you put the large muscle knot it becomes a mini pizza it’s a very small amount you’re multiplying with a small value of the CS and we’re losing or decreasing that particular so we have to be very careful particularly when we are designing the regenerated in this rain here this late is the appropriate material in the range 10 to 30 k because it is having a low body temperature and lonely by temperature will ensure a higher value of the CPR the city and specific heat of the material but when it is designed for high temperature so the stainless steel or brunch materials suitable particularly when it isnot appropriate and in that range will look for a special property of magnetic materials like IBM nicol3 nickel so deserve that kind of material which is suitable for very low temperature and look into NQ part if we have to make the NQ high it is obvious that we should have a high heat transfer coefficient for the cold side and the hot side and then you know obviously have to put more amount of surface area associated both cold and hot wings with this one will move to the design part once again it is not always expected that we will have our we will encounter with the situation that cl equals to always win this year’s audience talked about this that we have this matrix capacity ratio and they sent you this chart in chart is 9/4 c equals to what but we may encounter situation because 20 equals 21 in that case how to make an effective use of this chart that has been given or suggested by arkasia and in this particular difference in Cabot and this is also I mean just to remind you that whether it is a pile and a method or it is a qualitative method has also shownin that case we have to make use of this particular chart then you have to define some new paramedics are one is the effective NTU and effective cm er that is the metrics in our capacity weight ratio you have to redefine and additional content that this has been suggested by official that cm equivalent become a CMP and it comprises of c m x c / 1 + 2 and 1/5 into is a modified by distillation so now you have the effective and q and effective see Amy and that is metrics capacity weight ratio so now we can use this chart and we get the car looked like a point at 6-5 0.85 so these are the values and this values are the asylum one will get the kind operational effectiveness but we know that that’s the project is not appropriate for us because this charge is mint for CR equals 21 now we’re trying to use it for 10 equals 21 and we have defined the nqf active and then to ACL effective with best value what is lcm the effectiveness we are getting that is known as a cylon month so based on that a salon one we need to find out another kilometre eggs and that experiment finally put in the situation we get the actual regenerative effectiveness so this is how we can make use of this chart suggested by open London and suggested term in a modified subsequently by Usher to find out the effectiveness of the generatorunderstand that situation on be slightly different in this case we have to follow the game but what is known is the effectiveness because in this case we are trying to design the regenerator maybe you know we know the diameter of it or you know we have to find out the length of it or sometime it may be such that you know we had to find out both length diameter and etc and even the what are the particular type of matter general metrics that may also be in that may also be decided we have to decide about that one and there are different options so one by one we have to finalize and there’ll be different type of constants so as we understand that the design becomes always multi-objectiveand the call Floyd and what is the expected temperature that is also known as both hot and cold feet and not so in that case we have since it’s all on his own we can find out just as we have defined if you remember that are layered expression so from there we can find out the x10 buy eggs we can find out the Epsilon this is the reduced if I do but we don’t have any idea about this early because see Amy contents in it and that cm contains mscs by indot cp30 so this NCS we do not have any idea about the amount of mass that is going to be there inside the Witcher writer so sure at this point to have to make an assumption of this regenerator a matrix p.m. effectiveness based on thathome Depot calculate the actual into by this process and actually you can also find out evaluate a long-wheelbase number of international law this is a perforated plate and alternative search engines and sparesproblems petrol station and the pressure drop in original it is packed with the headshot and this is diameter of the snapshot is 1.6 ml and their effect inside a bit of diameter it is given as 154 mm and the length of this originated is 915mm the policy is also given as .38 and the mass flow rate is basically in doctor is .080 KG per second and the gas is nitrogen gas flowing at a pressure of 2 atmosphere and active average temperature of 200 Kelvin this information we need to find out what is the address for efficient and what is the pressure so you know that by this time that the cnfr the value of which we can calculate the value from which we can you calculate the heat transfer on individual transfer coefficient and this will be linked to the pressure drop associated with this flow of gas through this flat bed. We will try to solve this example in the next class and thank you for your attention.
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