# Concentric Tube heat-exchanger: Final year Project Help

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 March 13, 2011, 18:03 Concentric Tube heat-exchanger: Final year Project Help #1 New Member   sushil goswami Join Date: Feb 2011 Posts: 4 Rep Power: 15 Hi all I am trying to simulate a concentric tube heat-exchanger in 2D. The heat-exchanger data is as given below: inlet tube internal diameter = 54mm pipe thickness = 3mm (aluminium) Outer tube diameter = 159mm Heat-exchanger height = 1000mm i have meshed the whole geometry using mapped meshing in gambit with quad mesh. I have modelled two mesh models. one with 5 zones: water-aluminium-gas-aluminium-water. Second with 3 zones: water-gas-water with walls separating the zones from each other instead of solid zones (aluminium). inlet velocity for gas = 0.5m/s with 723 K. I%= 5% & hydraulic diameter = 0.054m inlet velocity for water on left zone = 0.2 m/s with 323 K. I%=5% and hydraulic diameter = 0.052m the outer tube walls are defined as adiabatic Boundary condition. I am unable to decide the 'Boundary condition' for the walls separating water from aluminium and aluminium from gas to allow heat transfer from gas to aluminium and from aluminium to water. In 2nd geometry with 3 zones only, how should i define the 'Boundary condition' for the walls separating water from gas to allow heat-trasnfer between gas and water. in this geometry, i am defining wall thickness as 3 mm to account for aluminium. I can email the .cas & .msh files to anyone who could help. I would highly appreciate your help. Thanks in advance. Sushil

March 13, 2011, 18:06
#2
New Member

sushil goswami
Join Date: Feb 2011
Posts: 4
Rep Power: 15
Quote:
 Originally Posted by fufilnikku Hi all I am trying to simulate a concentric tube heat-exchanger in 2D. The heat-exchanger data is as given below: inlet tube internal diameter = 54mm pipe thickness = 3mm (aluminium) Outer tube diameter = 159mm Heat-exchanger height = 1000mm i have meshed the whole geometry using mapped meshing in gambit with quad mesh. I have modelled two mesh models. one with 5 zones: water-aluminium-gas-aluminium-water. Second with 3 zones: water-gas-water with walls separating the zones from each other instead of solid zones (aluminium). inlet velocity for gas = 0.5m/s with 723 K. I%= 5% & hydraulic diameter = 0.054m inlet velocity for water on left zone = 0.2 m/s with 323 K. I%=5% and hydraulic diameter = 0.052m the outer tube walls are defined as adiabatic Boundary condition. I am unable to decide the 'Boundary condition' for the walls separating water from aluminium and aluminium from gas to allow heat transfer from gas to aluminium and from aluminium to water. In 2nd geometry with 3 zones only, how should i define the 'Boundary condition' for the walls separating water from gas to allow heat-trasnfer between gas and water. in this geometry, i am defining wall thickness as 3 mm to account for aluminium. I can email the .cas & .msh files to anyone who could help. I would highly appreciate your help. Thanks in advance. Sushil
When i use air in all the fluid zones, i get heat transfer across the zones. However, it fails to show any heat transfer when water is used the surrounding fluid around Gas zone. the flow in the tubes is parallel.

 March 16, 2011, 11:01 #3 New Member   cfd.freelancer Join Date: Mar 2011 Posts: 1 Rep Power: 0 Mail me the files. May be I can help you..!

 May 16, 2011, 16:51 hello #4 New Member   Join Date: May 2011 Posts: 3 Rep Power: 15 hello there, i have almost the same problem but using STARCD not fluent : ( if any one can help it will be nice !