ANSYS Fluent Tutorial: Analysis of Melting and Solidification of Phase Change Material (PCM)
ฝัง
- เผยแพร่เมื่อ 2 มี.ค. 2018
- From this tutorial, the viewer would be able to learn how to model a PCM and analyse its solidification and melting using ANSYS Fluent. Transient modelling along with solidification and melting model has been utilized in this tutorial.
Material properties can be downloaded from: drive.google.com/open?id=1KiF...
Like our facebook page: / ansystutor7 - วิทยาศาสตร์และเทคโนโลยี
![[FULL EP.69] #เอิร์นจิรวรรณ เปิดบ้านหมื่นล้านทุกมุม ครั้งแรก! l เคหสถานบานปลาย l One Playground](http://i.ytimg.com/vi/_J4_nw8c64o/mqdefault.jpg)
Thanks a lot for this... I'm searching this since 1 month... It will definitely help me... Thanks
Most Welcome:)
Thank you yaar. Appreciate your effort in making this channel :)
most welcome.
Thank you, for making this channel
most welcome
Hi, followed all the steps in similar way, but your nos. of element were about 16k and 20k for mine. Proceeding to setup, I did exactly same as you have shown in video, but the graph is similar in just starting and after 20 iterations it took a sudden jump. Why did this happen? Is there any parameter change done off screen or what settings I have overlooked?
Superb effort dude. Thanks a lot
Most welcome :))
Very helpful! Thank you.
You're welcome!
Hello, could you please clarify why you used shell conduction even though you meshed the steel pipe thickness?is it for for modelling the air gap ?
Hello Sir. As PCM melts/solidify the volume expands/compresses. To account for that expansion/compression how we can use air in the domain and whether it'll be two phase or single phase? It would be great if you can share any tutorial on that.
Sir Did you used parrafix wax as pcm material in this video?
Does it make sense to set piece wise linear density for PCM? The volume of PCM changes during melting, but the volume of container kept constant. Or have you assume the PCM to be compressible?
there is only phase change occurs, no change in volume.
i want to simulate model which consists of double glazed unit filled with phase change material which exposed to convection and solar radiation can you help please ?
hi, thanks for your tutorial , i have error with solution this problem , and the error message is (Error at Node 2: Dot product of flow direction and area normal is zero.
Check the specified flow direction on Mass Flow Inlet boundary
conditions for thread 16. ) , do you know how i can fix it
you might have not assigned the cell zone material properly, please check, also check if boundary conditions for inlet and outlet sections had been assigned or not.
Thank you for the video.It is very good for the beginner. I have a question about the boundary condition. I use fluent 14.0. When I select pcm_face_inlet, in the thermal conditons, I couldn't find the option of via system coupling. Do you know how could I do in this version? Thanks a lot.
There might be any other option try them like coupled or any
Yes , the PCM side walls are closed , so only to transfer heat, you can also assign as adiabatic wall by making heat flux to zero ,there would be no difference due to negligible thickness.
Thanks a lot. I have solved it
Sir I'm getting divergence error in amg solver for the pressure correction ( I'm using 3 walls the outer one is a hollow cylindrical heat sink)
Decrease the time step size and increase the no of time steps.
I appreciate for this video but there was an error happened when I computed the average volume of liquid fraction. It keep showing net value of 1 instead of 0.6~. Do you think this problem is occurred by the mistype of boundary conditions?
Check the cell zones , you might have defined wrong materials in different zones.
facing same problem
Thank you for awesome tutorial, i want to know that how to determine temperature dependent thermal conductivity for other material?
you need to search over the internet in books journals for the material property.
Thank you, sir.
Hello...I would like to model a high MP PCM in a rectangular thin enclosure with constant heat flux BC at one edge to look at the transient melting behaviour using VOF in fluent as the container has also air in it. But as I start to run the model shows floating error and shows diverging...can you please suggest any modification? Thanks
check for any void space in the geometry ,the model should be continuous.
There is no void space. It's showing divergence detected in AMG solver: pressure correction,VOF. Floating point exception
Hello, your simulation is good. Right now, I'm working on simulation of thermal conductivity so, if I need to fill the value of anisotropic thermal conductivity of material in matrix 3x3, how to find the value for each components to fill it ?
for that you need to take the help of user defined functions(UDF)
Hello Ansys-Tutor,
ANSYS Fluent provides two heat transfer models: the default ntu-model and the simple-effectiveness-model. I want to ask generally if there is possible to draw the curve of the local effectiveness according to the liquid fraction in this case. I would really appreciate your answer!
Are you talking about the heat exchanger models?
Yes, if we would have more tubes one next to the other to simulate, this situation will be given a behaviour of a heat exchanger with heat transfer fluid (water-liquid) and a stable fluid (PCM). I am asking if there is possible somehow to export the local effectiveness according to liquid fraction. More specifically, if there is a model in CFD to simulate this situation or if there is a choice creating an expession of the effecteviness (ε=exp(1-NTU)) to manage to draw this curve.
Sorry I dont hv much expertise on this .
no worries thanks!
could you make a solidification tutorial of a spherical PCM? thanks a lot for this tutorial!
did you see how to do this anywhere ?
Is it possible to have one phase flow in a fluid domain, and a multiphase flow, like vof model in another fluid domain? For example, PCM and air in the annular space using VOF model, with hot water flowing inside the inner pipe. Once I initiate VOF, fluent regard every fluid as mixture of the different phases. I have trouble with this. Could you please give me some suggestion?
in that case, you have to make a patching of the fluid regions as volume fraction for the PCM as "1", and for the domain where you want multiphase flow, you should proceed as usual.
Ansys-Tutor Thanks for your reply, but the problem is that once I initiate the VOF button, it will regard every fluid domain as the mixture of different phase, even the hot water part. I tried to set the water as the third phase, but it doesn’t work, I might have made some mistakes. Can I send you my cas file?
sir, is there any tutorial to find optimum insulation thickness in pipe for cryogenic flow in term pressure drop and heat transfer?
You have to take various thickness and find out the optimum one. You can watch our tutorial on critical thickness of insulation. Take the help of parametric analysis to get result with less time.
@@AnsysTutor Thank you sir ! I've found the video
Hi can I ask if I can use boussinesq approximation to achieve the same results?
yes ,try it.
I would like to know if utilizing the boussinesq approximation worked?
Hello! Is it necessary to define PCM as a peace wise linear? Can't we make it constant value?
If you make it a constant value, you would not be able to get the melting effect.
how you have choose piecewise linear properties of pcm? will this solution work in box (two box outer plastic inside steel)geometry where PCM panels were kept inside for temeraure control because operation range of temperer is 25-40 degree c. please respond thanks
For each phase change material simulation, you need to use temperature dependent material properties. For that reason, I have used piecewise linear properties.
25:58 There is not coupled option in ansys 2020 academic, how can I apply this option? why shell conduction thickness is .001m? when the wall thickness is 2 mm i.e .002m?
Use adaptive sizing option in the newer versions.
Thanks a lot for the video. For the post-processing, I want to plot the liquid fraction with time. However, when I chose the data of liquid fraction in fluent, it doesn't list in the CFD-Post. Do you know how to draw the curve of liquid fraction and time? Thank you very much.
go to fluent-> monitors-> volume monitors-> create -> report type:volume integral , Field variables :liquid fraction, cell zone :PCM,
In option tick the "plot" select window 2 , in x-axis :- time step and then click on "OK"
now change the graphics window layout to 2 window. , now calculate the solution, after the completion of iteration , switch to window 2
then click on the camera icon and save the graph
Thank you a lot!!! I see that the magnitude of liquid fraction calculated from volume integral and volume average is totally different. When we draw the contour of liquid fraction in Fluent, I think the value of liquid fraction is displayed according to the volume average, right? Can we draw the contour of liquid fraction depending on the volume integral? Thank you again!
Go for what you think relevant for your work. I have just written the steps as sample.
Sorry, maybe I am not expressed clearly. I mean when we draw the contours of liquid fraction by Result->Graphics and Animations->Graphics->Contours, the results are displayed depending on the volume average. How can we change the set that makes it show the results depending on the volume integral? Anyway, thank you very much for your reply.
Can anyone provide some journals name, links/ Ref where I can find the temperature dependent properties of phase change material. Thanks in advanced.
Hello Sir.. In this model in place of constant temperature to outer pipe,if I am giving constant heat flux boundary condition..I am not getting any liquid fraction after 1000sec.. Can you please suggest what to do?
try with adding pipe wall thickness in Shell condution option.
Actually I am doing a research work on Mr dampers. Which software would be suitable where I can change both magnetic field and viscosity of fluid?
Thanx in advance
I think you have to interlink the fluid and magnetic interface both. I mean to say you have to analyze the fluid in fluent and the results of temperature /pressure obtained from fluent to be linked to magnetic analysis interface. Search for the term "ansys multiphysics" over internet to get what i want to say,
Hi! Thank you so much for this valuable tutorial. When I search online I can't understand why you use "via system coupling" thanks!
thank you bro, this is very good tutorial but if you would make a 2d planner tutorial on same analysis of transient modeling with melting and solidification, this would be a great favor for us, plz make a 2d tutorial as it is not available on TH-cam. Thanks
Will try to make a tutorial.
can you execute Economizer in ansys fluent ?
I have its igs file
can you help me with design of heat pipe or vapour chamber please?
Please how is the under relaxation factor chosen for the pcm melting phase.
This is very useful, thank you! Do you think you can tell me from where did you find those temperature dependent properties of the PCM? It would be very helpful if you could tell me the source, because I want to melt several others PCM-s in ANSYS and I need their temperature dependent properties.
I had received the data of PCM from a subscriber. I have also attached the link to the description. Hope that might be helpful.
Ansys-Tutor do you think I can still have accurate results with only 2 points specified (in the piecewise linear section of the material's properties) for the density, specific heat and thermal conductivity?
No, you need to do some linear interpolations to get some intermediate points data. with only 2 point you might get divergence error or inaccurate results.
For which pcm material have you done this simulation and how did you calculate the points when you defined density as varying piecewise linear .
Its molten NaNO3, details material properties given in the description.
@@AnsysTutor OMG! Thank you so much Sir ❤️ for your immediate response. I am doing a small project on melting and solidification of pcm using paraffin wax. I am facing difficulty in defining the way you have defined for NaNO3 in the video using piecewise linear. Can I contact you through your email. I need to submit my project assignment by tomorrow Sir. Can you pl help me ?
Yes , you can mail it ansystutor7@gmail.com
@@satyanarayanavenkat3140 hello! i do have the same project as you.. may I know how to decide on the values to use when using the piecewise linear function for density? for my current simulations ive been using constant value which is from a datasheet.
Hi, if i want to simulate the solidification of a block of phase change material with a cold fluid circuoating on serpentines and i don't want to draw the thickness of the serpentines. Which boundary conditions i can put at this interface ? Is just coupled wall boudary enough or i put also shell conduction or wall conduction ? Thank you for helping
I have another questions :
when you put all the solids in one part? how does ansys recognize the interface because it seems that you don't have 'mesh interfaces' in the setup? did you apply share topology for that or you define them manually? and if is it possible for my case to make 2 parts (serpentine and PCM block) and apply the same methodology without considering the thickness of serpentines as i mentionned before?
If you have not created the pipe body, you can put the shell conduction or wall thickness.
In the cellzone ,you can define the material for that part.
Hello Sir. How to ensure that the orientation of heat exchanger is horizontal or vertical? As the sketch is drawn in xy plane and g acts in -ve z direction. So this is vertical or horizontal orientation?
It depends on you on which direction you want to keep the gravity.
@@AnsysTutor Thank you. So it is vertical orientation . How to model the volume expansion and compression during melting/solidification of PCM?Could you please share a tutorial on this type of problem.
I have some questions to ask regarding melting enhancement for PCMs using fins and foams.
Can you please ans me.
Yes , please ask .
I noticed you have not included gravity. Can Boussinesq Approximation be used for a bouyancy driven case? Also, it'd be great could you upload the melting animation video
I have not tried boussnesq , you please try once and check whether results are getting matched or not.for simplicity and to avoid divergence in the solution we have not considered the buoyancy. You can take gravity with a small time step to avoid divergence and analyze natural convection
@@AnsysTutor 2D cases work well with boussinesq, however, I am facing convergence issues for 3D. Fluent displays an error for temperature limits. Might have to rework the mesh
Thank you sir, ı want to know that how determine temperature dependent thermal conductuvity for RT35HC pcm material? Are there any formula? Please help me🙏
You need to search it in book or any research publications.
Hello.Thanks for the video. Can you please supply complete detail regarding the governing equations and BCs applied during the analysis?
its not possible to provide all the detail , you can search over some standard research papers or ansys fluent manual for the desired equations.
@@AnsysTutor ok..Thanks for your reply..I've to simulate another PCM (metal eutectic) having high fusion temperature. I don't find the relation between temperature and properties in any literature.Any suggestion how to handle ?
@@alokray9136 hello sir, currently i am working in the same field can you provide me some journal ref where i can find the pcm temperature dependent datas. thanks in advanced
Hi sir. I have been studying for six months. i have a problem during to define material properties of PCM . How can i define the spesific heat ( Cp ) as a function of temperature ? For example: At 400 K Cp is 1900 kJ/(kg*K) , at between 400-420 K Cp is 157190 kJ/(kg*K) , at 420 K Cp is 1900 again. I don't know how to define Cp as a function of Temperature. Because it is not piecewise - lineer or piecewise - polynomial or polynomial. Please , Help me about that.
you can input the user defined function (UDF )for this problem , or try with the piecewise linear option with multiple temperature points, and solve, if the results are satisfactory then proceed with that.
Sir thanks a lot i am working on PV/T system. that would be great help if you refer any tutorial or any reference especially for refrigerant system
just learn some basic concepts of Ansys ,then model your geometry and do the analysis in ANSYS . If you face any problem in any stage then mail to: ansystutor7@gmail.com
Sir, I am having "Floating Point Exception" while running calculations. I am working on Ansys R18.2 and the probable reason is that I am unable to turn off the "adaptive size function" while meshing. Kindly help me out as soon as possible.
no that might not be the reason , such type of problem occurs if you have not saved the solution or there is a less memory availability.
thank you very mitch
most welcome.:)
From where did u get the pcm properties?
we have given the PCM material properties used as PDF in the video description.
sir, is there any tutorial on 2D simulation of doublet tube with phase change material ?
No, we dont have tutorial in 2D. Will try to make a tutorial on this.
Nice video, Which reference did you use in pdf? please provide the original paper/source link for reference.
It was a request from one of our subscribers. He had only sent the pdf file ,which link I had given in the description.
@@AnsysTutor thanks
how can i apply this in plate heat exchanger design ?
Great video but dont we need to switch on "multiphase" in models ?
We don't need multiphase, as we had selected solidification and melting option.
CAN YOU PLEASE SHOW IT FOR 3 TUBE HEAT EXCHANGER WITH PCM IN 2 ND PIPE
Will try to make a tutorial.
thank you very much, how can I trace the evolution of the temperature as a function of time?
You can create a save output parameter, also you can get the simultaneous result from monitors->volume monitors -> create, select volume average as report type and volume fraction in field variable, select the cell zone where you want to see the simultaneous result. Tick on "plot" box, select the window where you want to see. make it window 2, and click on OK, now in the toolbar change the display into a two-sided window and run the calculation.
Ansys-Tutor thank you very much, I am in research period, and I have to model the phase change for a pcm. I need help, is not there a way to communicate with you?
you can contact me through email: ansystutor7@gmail.com
The latent heat of fusion used here is 161000J/kg. Is this value for the PCM solar salt (60%NaNO3+40%KNO3)?
Yes, reference table given in the description.
Sir,
First of all thanks for the video that you uploaded on youtube about PCM. the property values of PCM that you choose are from pdf, right? but the melting temperature was not there. what is that value.? and what is the PCM material? say I need to find the performance of paraffin wax instead of your PCM material, then what is the temperature limits that I have to give for corresponding properties values. please make a reply sir.
I have given the link of properties table in the description ,its the NaNO3 and KNO3 eutectic mixture. For paraffin wax you need to find the Thermo-physical properties and put these properties as shown in the tutorial.
@@AnsysTutor sir,I understood that, but melting point of paraffin in 62degree but what is the period of temperature (lower and upper limit of temperature and correspoding property values)..u choose 500to 900k
@@dyuthisreedeth are you doing research?
@@dyuthisreedeth hey my undergraduate dissertation is also based on PCM ith the addition of porous metal if you are still interested maybe e can help each other 😅
Thank you so much for the video ..may I know that how can we find the temp in between the pipe or at any point
You need to create a location line in between , then draw the tempr vs length. To get the temperature data in between the wall.
Thanku you so much for that sir . Actually I'm doing a project on latent heat storage unit parrafin wax so can you help me with that .
in my ansys fluent solver, iam unable to get via system coupling boundary condition for pcm inlet , pcm outlet, inner pipe wall and wall outer pipe solid. The options are only conduction convection, radiation and mixing. how to setup the boundary conditions for these four boundaries. i tried giving symmetry but it didnot not giving the same results as shown in the tutorial. can u pls. help me with this
Check the cell zone conditions, whether you have defined it solid or liquid.
in cell zone conditions, both pcm and fluid domain are given as fluid and inner and outerpipe solid are given as solids. exactly followed the modelling shown in tutorial
1. does anyone know of a research paper related to it
2, source of properties used in creating pcm
3. can't find liquid fraction and mass fraction in ansys 2019 R2 version
thanks in advance
This tutorial was requested by one of our subscribers, he had given me only the thermophysical material properties. You can find that pdf link in the description.
sir, will u make video on flowing of cryogenic fluid through pipe
If you have any research paper or this then pls send it, will try to make a tutorial if possible.
sir will u give your email id
Sir can you make video for solidification and melting of flowing water inside subcooled channel
How the flowing water can be further melted. It's already in molten state. Are you want to say the ice to water melting?
hi, the 'via coupling system' is a boundary condition to express what in the model? I don't understand what is the meaning of it?
It acts similar to the coupled wall BC, it make the wall permeable to heat transfer.
@@AnsysTutor thanks. i just have 2 questions : 1 -you mean by the permeable to heat transfer that these two faces inlet and outlet of the PCM are not insulated.They are just closed by a thin metal PCM pipe (copper) without any heat generation .
2-If it is closed by a metal with good insulation there at pcm face outlet and inlet(as if they are closed and insulated ), would the BC be a 0 heat flux?
1. Yes.2. if you want the pcm end faces to be adiabatic wall then you can put the heat flux=0 boundary condition.
Sir, hows the solidification process on this same problem, i need to complete the solidification of pcm for the same
As you decrease the temperature the solidification process starts. You can check the volume fraction after certain time.
hello please can you give us a tutorial on thermal analysis of a PCM content wall.
THANK YOU
will try to make a tutorial.
@@AnsysTutor yes please
where can I find the properties of boron phase change material?
Please search in some research paper.
What is the name of the mesh you are creating in this video????
It is known as "Hybrid mesh " as it contains all the type of cells like tetra ,hexa ,pyramid etc.
What are the residuals for this problem for continuity, momentum, and energy?
in the convergence criteria section I have provided the residual value ,please check
You can keep it 1e-3 to as minimum as possible.
thanks. Can you tell if the heat transfer fluid in the inner pipe has higher temperature than the pcm in annulus, PCM melting will take place wrt time.So for that type of problem what should be suitable BCs?
Can you provide a simulation video for phase change material integrated with metal foam in a 3D recatangular cavity.. thank you
Sorry cant do it.
hey my undergraduate dissertation is also based on PCM with the addition of porous metal if you are still interested maybe e can help each other 😅
Hi, I keep getting the error message; surface zone #f doesn't exist. Any idea why?
Check if any contact regions are still present, then make all the domains as one part i geometry.
Sir I am doing pcm and hot air in a rectangular hollow enclosure there is a problem pcm melting,no change in pcm.
is the heat from air is sufficient to melt the PCM ? Have you calculated the amount of heat required for PCM melting and the "pure solvent melting heat" value given in the PCM material properties.
Check the heat gain and lost from the air and pcm domain.
It shows divergence error at temperature.
what is the time step in your analysis?, Have you enabled the gravity?
Can static magnetic analysis be done in ansys fluent?
No, fluent basically deals with fluid flow and heat transfer problems.
Hi, I want to simulate the solidification of water in a pipe(PCM is the water). I want to consider the variation of thermal conductivity and density of the water and the ice during the process. I am able to set the water properties, but I don't know how to set thermal conductivity of ice(2.26 W/mk) which is greater than water(0.6 W/mk). and similarly density of ice. Thanks
use piecewise linear to define the thermal conductivity properties.
Thanks, I still have error, can i send you the file.
Have you got the solidus and Liquidous temperature of water and what have you given viscosity and pure solvent heat, would be useful if you have got the values
Hello,
I thank you for your generosity.
I need help with my thesis project. I can not have results. Can someone enlighten me?
yes , please tell me about ur problem, if its possible for me, then definitely I would help.
Ansys-Tutor thank you for you answer it's so kind. I work on solid particles tracking simulation generated from a source.
I can't define correctly the source and the boundary zones.
Thank you very much.
have you defined the boundaries in meshing stages? as "create named selections"
thanks for your tutorial. please I am looking for modelisation of solidification of abinary metal alloys under effect of naturel convection if you can help me for that.
are you facing any difficulty in this?
@@AnsysTutor yes please
If you can make a video to describe the method.
Example Tin with 10%and 3% and 6.5%lead
I didn't find this alloys in ansys
I will be grateful for you help
@@abdellatifboumaza6775 you need to define material properties for these as custom material in Fluent.
@@AnsysTutor yes I know but how?
I have all equations and there properties but I don't know how write UDFs for my problem it's difficult for me
you don't need any UDF. you can create an excel sheet and using these equations to find material properties for different temperatures, then put these properties as design points as shown in the tutorial and solve. And then validate the result with any previous research article, if it works well then proceed in this way.
Sir, can you give reference for PCM material properties used as PDF book or journal, Thank you for the tutorial
I have got these material properties from one subscriber. The material properties pdf file has been included in the description.
Hi Sir, may I know which research paper you referred?
Its made randomly without any reference.
@@AnsysTutor Thank you.
Your initializing temperature is between your solidus and liquidus temperatures. Doesn't that mean that your PCM is already in the melting process? Please correct me if I'm wrong.
As we had selected "compute from all zones" so the solver had taken the average temperature as per our Boundary conditions, that does not mean it will continue with that initial value throughout the simulation, It will solve as per the boundary conditions. You can do hybrid initialization in which the solver will solve some initial equation and will take the initial values on its own.
@@AnsysTutor Thank you. This is a very helpful tutorial. :)
Please sir i need your help, i only have energy curve (continuity ,x y z velocity curves does not appear in my case) they converge to zero
Please check the cell zone condition ,you might have defined the zones as solid material.
@@AnsysTutor Thank you sir , I found where is the problem.Please i need help in my studies project, I have problems with the mesh and the configuration , i need some advices. I can send u my geometry file it's an emergency. Contact me please/ harissmanal@gmail.com
@@harissmanal740 hi, what is the meaning of the graph? Please reply. I need help understand the graph
@@AnsysTutor hi, what is the meaning of graph? Continuity, x y z and velocity? Please reply i need help
im sorry ,im new to ansys. what is the objective of this analysis? it is to determine boiling point ?
it is an analysis to find out the amount heat that can be stored in the phase change material , which can be used later on.
@@AnsysTutor hi thank you so much, your video is helpful. im at bit confuses , when exactly in this video that we get the amount of heat that can be stored? please help
@@AnsysTutor sir, i need help.please reply. it involve my final year project
@@AnsysTutor Sir, How do I know the amount of heat stored in the analysis you made?
Please I traing to activat a convection in PCM domaine i have a message error for divergence please how I can do this correctely
you need to decrease the time step, increase the meshing, and decrease the solution controls with gravity enabled.
decrease the time step size and corresponding "Number of time steps", as time step size x No. of time step= total time ,
Hello sir. When i compute volume weightage average it is showing 0. What can be the reason. Thanks in advance.
Which parameter are you checking.
@@AnsysTutor soli to liquid convesrion . Can i send you my geometry.i have hot water in shell and pcm in tubes. There are total 8 tubes.
And also sir.., i have a doubt, consider a surface, for this surface i need to give a gradual increase in temperature from 300 to 450 kelvin with in a time period of 9am - 4pm. How can i give that
For this you need to set the time step size and no of time steps in the transient solver calculations page.
@@AnsysTutor how exactly tht work?. consider the same problem..you have applied 511k and run the soln for 200seconds..so melting started ..so in order for solidification the the temp should be less than 511 , we can only assign a constant temperature at a time..so thn i wont even melt?.sir if possible can u give ur email id.
There might be some region into which its losing heat ,or any convection BC on that wall. For such case you should not apply constant wall BC rather apply patching method. Our mail id ansystutor7@gmail.com
showing below error while running calculations
# Divergence detected in AMG solver: x-momentum -> Increasing relaxation sweeps!
check the meash and the solution controls
Anysys is automatically using my Named selections *Inner pipe outer wall*, *inner pipe inner wall*, *outer pipe inner wall* as contact regions and using it as interface in solver. I cannot change it as shown. What to do in this case?
You might not have made the parts into a single part.
@@AnsysTutor okk, I m sure I did but will check it again. Thnx for replying.
@@AnsysTutor hey man sorry to disturb u again. I m getting divergence error : Temperature at 20-22s. I have reduced time step size and increased time steps. My mesh is already refined. But it is still not going. Can u tell me what other possible reasons might be for this error, plz.
Do you have gravity on?
@@AnsysTutor Nope.
Hello. whether Gravity should be enabled in this problem or not? In which direction we'should enable for this problem?
if you want to enable gravity you need to decrease the time step and increase the no of iterations in each time step. , otherwise it might cause divergence. ,you can enable gravity in any direction as per your requirement. for the current model you can take it in the negative y Direction.
Thank you. I would like to transfer heat from inner fluid to PCM and store it there. The outer wall of outer pipe is insulated and inlet temperature of inner fluid is more than melting point of PCM. But the PCM is not melting after a long time. Can you suggest anything? I am using the same geometry and materials only changing the heat transfer direction.
@@alokray9136 what is the simulation time you have simulated? is that time is sufficient to melt the PCM?
@@AnsysTutor Nearly 2 hour. I think by this time I should get melting fraction to certain extent. I'm referring" Numerical investigation of heat transfer mechanism in a vertical shell and tube latent storage system". This is a 2D simulation and paraffin is the PCM. But I'm trying 3D with different materials. Thank you in advance
Can we do a 2d analysis with PCM in attic space?
Can you tell a little more about the analysis.
@@AnsysTutor I am applying PCM along with the lift and right wall of the attic with the air in the inner cavity. I am trying to compute the efficiency curve of the PCM. How much heat it absorbs from the outer wall before it turns its state completely.
@@prabhsingh5068 iam trying same can u help please ?
I tried for another material, and I am getting Liquid fraction as one. Can you help me sir/madam?
If you would not put the variable material properties, you would not be able to see any changes to the PCM.
Did you consider the convection between the water and pcm material? It seems that you didn't...I'd suggest before starting your solution, you describe your boundary conditions and assumptions so a viewer has some idea what you are trying to model....
there is a pipewall between PCM domain and water so there would be only conduction HT in between them. Convection has not been considered in PCM domain only as in this tutorial the main objective was to present the solidification and melting of PCM, assigning PCM material properties in fluent, we got many email query regarding modeling the PCM in CFD so we have created a just basic tutorial,hope it would be helpful . in the future we will show the detailed heat transfer from PCM including conduction and convection, molecular dynamics and multiphase simulation etc.
Thank you for your suggestion we will try to do that.
Hello sir
Why is the phase change material considered a fluid and not a solid?
We cant assign viscosity , solidus or liquidus temperatures in solid material properties.
PLEASE I HAVE A PROBLEME OF DIVERGENCE WHENE I RAN THE STAEDY CASE
you might not get the desired result in the steady case. If you are getting such error then try to decrease the solution controls and increase no of iterations.
Divergence can be solved. BY refining the mesh
or if using explicit method by reducing the time step. Best would be to refine the mesh
hi man, you dont need to fill inside of body because this body is not imported body which means fluent makes it fluid domain
How fluent will create the geometry and do simulation without the geometry and meshing. Fill option is used to create the geometry it has no relationship with the solver.
I copied every step in your video (same geometry, mesh, boundary condition), still the result isn't same. It diverges drastically after 65th iteration. and it keeps showing PCM value as zero after calculation( from volume integral).
Decrease the time step and turn off the gravity & try .
@@AnsysTutor Hey ! thanks for the prompt reply. Need a bit more of help here.
1. I literally copied every detail of ur video. Still, your result converged with 1 time step, mine didn't. (gravity was off).
2. It didn't worked with 0.1 time step even with 10 iterations, diverged very fast.
3. It worked with 0.01 time steps, did 800 iterations with it:
a) liquid fraction decreases very slow:
time step: 0.01,
iteration: 100
liquid fraction: 0.9629
time step: 0.01
iteration: 400
liquid fraction: 0.9611
inlet temp: 300
outlet : 573 K
time step: 0.01
iteration:400
liquid fraction: 0.95623
inlet temp:300
outlet :373 K
I saw your video and ur liquid fraction decreased very fast. 0.64 to 0.50 . Can you please have a look, why is it so?
P.s. It is an amazing video, would have been so much great if only voice was included.
You had mentioned the time step size & iterations ,what about the no of time steps ?
@@AnsysTutor ohh, I have mistakenly mentioned iteration, they are actually, number of time steps.
Getting error while solving.
Divergence detected in AMG solver: x-momentum -> Increasing relaxation sweeps!
Please help
decrease the timestep size and increase no of time steps.
Ansys-Tutor still getting the same error.
try to increase the mesh.
Ansys-Tutor I increases the number of divisions from 40 to 60 even then it is not working. If you want I can send to u the project file
Please help me.
how to give input for solidification of binary alloys.
Similarly you need to give input as I hv given for melting. decrease the temperature and give the density according to that temperature.
.
Thank you very much for your reply. But I do not have that relationship between temperature and density. The thermophysical properties of the eutectic alloy which has solidus and liquidus temperature both at 821.The liquid density is 3240 and solid density is 3410. So my question is how to get the density-temperature relationship as shown in your case.
in my case as, in the description of that video you can find i hv attched a PDF file, the property relations are obtained from that . For your case I would suggest you please find the preperty relationship table or any correlation formula.
thank you but a have style a same problem
decrease the time step size and corresponding "Number of time steps", as time step size x No. of time step= total time ,
PCM has melting point and solidification point. Why you have taken 9 points?
These are the points to show the melting simulation. Otherwise, fluent would not be able to show melting process.
@@AnsysTutor how do we know pcm melt at this point. and temperature rise to this
You haven't considered gravity terms. How is buoyancy for natural Convection considered?
for simplicity and to avoid divergence in the solution we have not considered the buoyancy. You can take gravity with a small time step to avoid divergence and analyze natural convection.
Ansys-Tutor is it possible to insert different liquid and solid PCM properties? If not which properties must be inserted to study melting problem.
are you asking about a PCM mixture problem?
Ansys-Tutor - I've got different properties for solid and liquid phase for the same PCM. But only liquid properties can be inserted in fluent. How can I insert separate solid-liquid properties.
you have to see this tutorial video carefully, we have also inserted the PCM material properties which is solid initially and as it gains heat it changes to liquid. You have to model the solid PCM as dense fluid and with solidus and liquidus temperature given in the property.
Why this video is not playing as usual other do.??
please wait for some days , we are figuring this out with the help of youtube support. ther might be any issue from youtube they are trying to figure this out soon. Stay connected for further updates. Thanks for your report.
Pls check now the issue has been resolved.
it is better to give voice over for proper understanding
Thanks for your suggestion. I had given voice over in our latest uploads , please have a look into.
Hello sir
I'm a mechanical engineering student my final year project is pcm based heat exchanger
I wanted to do the same analysis but with fluid flow
Can you please make a video for the same
We would be very grateful sir
My project deadline is in 2 months
Please sir
It's also a fluid flow problem, can you tell a little more about your project so that I can get you.
Sir actually we have designed a heat storage device with the phase change material in which we are phasing some problems regarding CDF because the pipe contains fins which are provided on the inner tube wall surface so we have to asign a new material to that also ??
I have sent you a mail of the photo of that design.
@ Chandraprakash Singh hi I'm a Energetic engineering student my final year project is pcm based heat exchanger
i want Your email to exchange information please.
@@cfdengineeringmorocco9069 hey my undergraduate dissertation is also based on PCM ith the addition of porous metal if you are still interested maybe we can help each other 😅