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How to apply temperature continuity condition between the wall of a reactor and the Heat Transfer Fluid?

Posted 2019年5月6日 GMT-4 03:34 Heat Transfer & Phase Change, Heat Transfer, Chemical Reaction Engineering Version 5.4 4 Replies

Long Chen
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Hi ,does anyone can help me? I want to konw how to apply temperature continuity condition between the wall of a reactor and the Heat Transfer Fluid? I am currently try to simulate a reactor , heat transfer fluid flow move heat through the heat exchanger wall ,asume the temperatures of inner side (the reator side) and the outer side( HTF side) are the same. How to apply this in COMSOL? The heat transfer fluid modules I use are heat transfer in fluids and laminar flow. The reactor is heat transfer in porous media.

4 Replies Last Post 2019年5月13日 GMT-4 08:06
Lasse Murtomäki
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Posted: 5 years ago 2019年5月7日 GMT-4 06:20

Without seeing your model I suggest the following:

I guess you have two physics modules, heat transfer in solids and heat transfer in fluids. If the former has the temperature variable T1 and the latter T2, set in the former module temperature to T2 on the boundary, and in the latter T1.

Wish this helps Lasse

Without seeing your model I suggest the following: I guess you have two physics modules, heat transfer in solids and heat transfer in fluids. If the former has the temperature variable T1 and the latter T2, set in the former module temperature to T2 on the boundary, and in the latter T1. Wish this helps Lasse
Long Chen
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Posted: 5 years ago 2019年5月12日 GMT-4 05:13

Hi ! I am currently doing a two dimensional simulation of a reactor. Chemical reaction take place in this reactor. The reactor is a cylinder reactor. I set up a two-dimensional axial symmetry model to simulate this process. In the core of the cylinder a cooling pipe run through the cylinder and water flow through the cooling pipe taking the heat away. I use heat transfer in porous media to simulate the process in the reactor, and laminar flow, heat transfer in fluid to simulate the heat transfer in the cooling water. Finally I use heat transfer in solid to simulate the heat transfer in the cooling pipe wall. However, I dont konw how to apply boundary conditions between the cooling pipe wall ,the reactor and the cooling water.I dont konw how to apply boundary conditions between the reactor and the cooling pipe wall, and boundary conditions between the cooling pipe wall and cooling water in order to make the heat transfer from the reactor to the cooling water. The model figure is attached. Could anyone tell me how to solve this problem? Thanks in advance!!

Hi ! I am currently doing a two dimensional simulation of a reactor. Chemical reaction take place in this reactor. The reactor is a cylinder reactor. I set up a two-dimensional axial symmetry model to simulate this process. In the core of the cylinder a cooling pipe run through the cylinder and water flow through the cooling pipe taking the heat away. I use heat transfer in porous media to simulate the process in the reactor, and laminar flow, heat transfer in fluid to simulate the heat transfer in the cooling water. Finally I use heat transfer in solid to simulate the heat transfer in the cooling pipe wall. However, I dont konw how to apply boundary conditions between the cooling pipe wall ,the reactor and the cooling water.I dont konw how to apply boundary conditions between the reactor and the cooling pipe wall, and boundary conditions between the cooling pipe wall and cooling water in order to make the heat transfer from the reactor to the cooling water. The model figure is attached. Could anyone tell me how to solve this problem? Thanks in advance!!
Lasse Murtomäki
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Posted: 5 years ago 2019年5月13日 GMT-4 03:44

During my chem. eng. studies (decades ago) I learnt to use the heat flux boundary condition: Assume that the fluid temperature is T1 and in the pipe wall T2. Then the heat flux (Q) follows the cooling law

Q = ±k·(T1 - T2)

where k is the heat transfer coefficient. Its value can vary a lot depending on the convection and the materials involved. Typically they are in the range of 100...1000 W/m²K. You must choose plus or minus depending on the side of the boundary, i.e. in the fluid and the solid the signs are opposite.

Lasse

During my chem. eng. studies (decades ago) I learnt to use the heat flux boundary condition: Assume that the fluid temperature is T1 and in the pipe wall T2. Then the heat flux (Q) follows the cooling law Q = ±k·(T1 - T2) where k is the heat transfer coefficient. Its value can vary a lot depending on the convection and the materials involved. Typically they are in the range of 100...1000 W/m²K. You must choose plus or minus depending on the side of the boundary, i.e. in the fluid and the solid the signs are opposite. Lasse
Long Chen
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Posted: 5 years ago 2019年5月13日 GMT-4 08:06

Thank you very much!!

Thank you very much!!

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