Convective reference temperature

Unknown

Hi all, 

I have a question regarding the problem setup. I want to model conjugate heat transfer between the plate at mid and hot/cold fluid as shown in the figure below. I have specified the value convective heat transfer coefficient as 100 W/m2k at each interface surface. I think the solid and fluid should be thermally coupled at the interface. So, is it necessary to define h at the interface for CHT fproblem?

To correctly model the problem, do I also need to specify convective reference temperature (which I dont think I need to) or leave it as 0?

Thanks

acupro

The 'Heat Flux' entry is for a user-applied heat flux on that surface - in W/m2.  For example if you have a heat tape applied to the surface and you know what the output is.  Or if you know the output of some attached device, not being modeled, being applied to the surface.  The default for 'Heat Flux' is zero - meaning no additional applied heat flux.  If the surface is the boundary of the domain, no mesh on the other side, this indicates an insulated surface - zero heat flux.  If the surface is the boundary between two volumes, it would yield the natural heat flux across the boundary due to material properties and temperature difference - zero additional/applied heat flux.

The convective heat flux coefficient (or convective heat coefficient) along with the reference temperature (or convective heat reference temperature) allows for additional user-defined 'convection' heat flux, with h being the coefficient and T_inf being the reference temperature.  This would allow for any assumed convection heat flux from that surface, using those assumed parameters - coefficient and reference temperature.

As stated before - the convection coefficient and reference temperature would give heat flux in addition to the natural heat flux due to material and temperature differences - and generally not applied on a surface between volumes - or left as the defaults of 0.

Ravi Harti_21199

Hey Prabin,

Interface surface between fluid and solid are thermally coupled (adiabatic), no need of assigning heat transfer coefficient transfer and reference temperature.

Thanks,

Ravi

Unknown

Ravi Harti_21199 said:

Hey Prabin,

Interface surface between fluid and solid are thermally coupled (adiabatic), no need of assigning heat transfer coefficient transfer and reference temperature.

Thanks,

Ravi

Hi Ravi,

I just wanted to know if the interface is adiabatic (no heat is transferred), then how can a system be modelled for a Conjugate Heat Transfer?

Thanks!

Unknown

I am surprised why the temperature of the cold fluid is not increasing when i put convective heat transfer, h=0. Also, I tried leaving the interface as default walls (i didnt assign or touch it). I see temperature at top (cold section) as complete blue. 

When i changed h=100 W/m2K, then only the temperature at the top region (cold section) is increased.

Can someone explain why this is happening?

Thanks!

acupro

The 'Heat Flux' entry is for a user-applied heat flux on that surface - in W/m2.  For example if you have a heat tape applied to the surface and you know what the output is.  Or if you know the output of some attached device, not being modeled, being applied to the surface.  The default for 'Heat Flux' is zero - meaning no additional applied heat flux.  If the surface is the boundary of the domain, no mesh on the other side, this indicates an insulated surface - zero heat flux.  If the surface is the boundary between two volumes, it would yield the natural heat flux across the boundary due to material properties and temperature difference - zero additional/applied heat flux.

The convective heat flux coefficient (or convective heat coefficient) along with the reference temperature (or convective heat reference temperature) allows for additional user-defined 'convection' heat flux, with h being the coefficient and T_inf being the reference temperature.  This would allow for any assumed convection heat flux from that surface, using those assumed parameters - coefficient and reference temperature.

As stated before - the convection coefficient and reference temperature would give heat flux in addition to the natural heat flux due to material and temperature differences - and generally not applied on a surface between volumes - or left as the defaults of 0.