This information is part of the Modelica Standard Library maintained by the Modelica Association.

Calculation of the mean convective heat transfer coefficient kc for the air-side heat transfer of heat exchangers with round tubes and several fin geometries.

Functions kc_roundTube and kc_roundTube_KC

There are basically three differences:

• The function kc_roundTube is using kc_roundTube_KC but offers additional output variables like e.g. Reynolds number or Nusselt number and failure status (an output of 1 means that the function is not valid for the inputs).
• Generally the function kc_roundTube_KC is numerically best used for the calculation of the mean convective heat transfer coefficient kc at known mass flow rate.
• You can perform an inverse calculation from kc_roundTube_KC, where an unknown mass flow rate is calculated out of a given mean convective heat transfer coefficient kc

Restriction

• According to the kind of fin geometry the calculation is valid in a range of Re from 300 to 8000.
• medium = air

Geometry

Calculation

The mean convective heat transfer coefficient kc for heat exchanger is calculated through the corresponding Coulburn factor j :

    j = f(geometry, Re)

with the resulting mean convective heat transfer coefficient kc

    kc =  j * Re * Pr^(1/3) * lambda / D_c

with

D_c	as fin collar diameter [m],
kc	as mean convective heat transfer coefficient [W/(m2K)],
lambda	as heat conductivity of fluid [W/(mK)],
Nu = kc*D_c/lambda	as mean Nusselt number [-],
Pr = eta*cp/lambda	as Prandtl number [-],
Re = rho*v*D_c/eta	as Reynolds number [-],

Verification

The mean Nusselt number Nu representing the mean convective heat transfer coefficient kc is shown below for different fin geometries at similar dimensions.

References

C.-C. Wang, C.-T. Chang:

Heat and mass transfer for plate fin-and-tube heat exchangers, with and without hydrophilic coating. In International Journal of Heat and Mass Transfer, volume 41, pages 3109-3120, 1998.

C.-C. Wang, C.-J. Lee, C.-T. Chang, S.-P. Lina:

Heat transfer and friction correlation for compact louvered fin-and-tube heat exchangers. In International Journal of Heat and Mass Transfer, volume 42, pages 1945-1956, 1999.

C.-C. Wang, W.-H. Tao, C.-J. Chang:

An investigation of the airside performance of the slit fin-and-tube heat exchangers. In International Journal of Refrigeration, volume 22, pages 595-603, 1999.

C.-C. Wang, W.-L. Fu, C.-T. Chang:

Heat Transfer and Friction Characteristics of Typical Wavy Fin-and-Tube Heat Exchangers. In Experimental Thermal and Fluid Science, volume 14, pages 174-186, 1997.