Should I mesh the solid domain ? or should I use wall thickness? or Shell conduction? for Heat Transfer between two fluids of a Heat Exchanger.
what is recommended?
You need to determine boundary conditions for each material involved. Then use multiphysics like Heat Transfer in Solids and Liquids. But still it depends what is the primary focus of your study. Hope it helps
Mahad Shaikh hi , brother you didnt get my question, basically this is a conjugate heat transfer simulation. so there are two fluids one hot and other is cold between them is a solid wall. the heat will be transferred from hot fluid to solid wall via convection than that heat will flow accross thickness of solid wall via conduction and there will be again convection between solid wall and cold fluid. in this way heat exchange is taking place. now as far as my knowledge is concerned there are different ways of dealing solid domain. From the forums i have seen, some says it is recommended not to include solid domain in your analysis and only use fluids. some says use shell conduction and assign thickness of wall over there to avoid more element counts and some says use wall thickness and assign thickness over there inside fluent. i know BC and all the stuff. I am just tryna know should i include solid domain in my model while meshing or should i not and then assign the solid thickness later inside fluent? also then in fluent we have two options for assigning thickness of solid domain one is shell conduction and other one is wall thickness. so im tryna now which one is recommended? which has which sort of a use?
Hi Muhammad Shariq Khan
You are totally right about the Conjugate heat transfer as the governing physics in the heat exchangers. So, as it is inferred from the term, there is mutual heat transfer between the solid and fluid domains. If you don't consider the influence of liquid on solid, you can still solve the problem, however, you are neglecting one side of this mutual relationship. Is it going to be a problem? Indeed, this is the simplest approach for the heat exchangers found in heat transfer textbooks and the analysis is really valid. However, when the characteristic length of the fluid domain is comparable with that of the solid domain, it is a good to consider the domain (mesh it in fluent and solve it). This is usually the case for meso or micro scale heat exchangers. Indeed, for certain cases, neglecting the conjugate heat phenomena leads to large errors. For example, the axial wall conduction in the counter-flow and direct-flow heat exchangers play a critical role in the overall performance of it:
Article Experimental analysis of the influence of wall axial conduct...
Or in our article (Simulations are performed in ANSYS-Fluent), conduction in the solid is a way for controlling the temperature of the fluid:
Article Experimental analysis of the influence of wall axial conduct...
Regarding the shell conduction model, I think it depends on the relative thickness of the solid walls with respect to the channel hydraulic diameter.
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