How to calculate convective heat flux coefficient and reference temperature?

brenton_101
brenton_101 Altair Community Member
edited July 2021 in Community Q&A

Hi,

In numerous AcuSolve tutorials (ACU-T: 3100, ACU-T: 3110) there is a value for convective heat flux coefficient and reference temperature provided. The convective heat transfer coefficient is chosen to model the heat transfer between the steel pipe and the surrounding air.

Where did these values come from and how are they calculated? 

image

Tagged:

Best Answer

  • acupro
    acupro
    Altair Employee
    edited July 2021 Answer ✓
    brenton_101 said:

    Thanks Junta.

    Is the reference temperature dependant on the heat flux coefficient? Or can I specify any value for the reference temperature?

     

    This web-site also has a pretty good description and ranges of heat transfer coefficients for free and forced convection, along the with the standard convection equation.  You could also find other sites with similar information.

    https://www.engineeringtoolbox.com/convective-heat-transfer-d_430.html

    Q = h * A * ( T - T_ref )

    h is the convective heat flux coefficient, as Junta mentioned often in the range of 10 or so, but you can see how larger/smaller values affect your overall results.

    The reference temperature T_ref is typically the surrounding 'room' temperature or bulk fluid temperature (not meshed), to which the surfaces are convecting energy.  That would be specified by the user, and is independent of the specified heat flux coefficient.

    T is the temperature determined by the solver, to balance everything in the energy equation.

Answers

  • Junta_20361
    Junta_20361 New Altair Community Member
    edited July 2021

    Hi,

    These 2 values aimed to represent the convection heat transfer between the steel pipe outer surfaces and the surrounding ambient. We need to assign this because we didn't create the mesh for outer volume.

    These 2 values can be found in the convection heat transfer equation, which can be found on the internet.

    The HTC represent the rate of heat transfer through convection. Usually, when the ambient is static air, this value should be around 5 to 10. This value depends on the conditions of the ambient. In the tutorial, it was 100 >> awfully large.

    Meanwhile, the reference temperature is the ambient temperature which surround the object.

     

  • brenton_101
    brenton_101 Altair Community Member
    edited July 2021

    Thanks Junta.

    Is the reference temperature dependant on the heat flux coefficient? Or can I specify any value for the reference temperature?

     

  • acupro
    acupro
    Altair Employee
    edited July 2021 Answer ✓
    brenton_101 said:

    Thanks Junta.

    Is the reference temperature dependant on the heat flux coefficient? Or can I specify any value for the reference temperature?

     

    This web-site also has a pretty good description and ranges of heat transfer coefficients for free and forced convection, along the with the standard convection equation.  You could also find other sites with similar information.

    https://www.engineeringtoolbox.com/convective-heat-transfer-d_430.html

    Q = h * A * ( T - T_ref )

    h is the convective heat flux coefficient, as Junta mentioned often in the range of 10 or so, but you can see how larger/smaller values affect your overall results.

    The reference temperature T_ref is typically the surrounding 'room' temperature or bulk fluid temperature (not meshed), to which the surfaces are convecting energy.  That would be specified by the user, and is independent of the specified heat flux coefficient.

    T is the temperature determined by the solver, to balance everything in the energy equation.

Categories