kc_flatTube |
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 flat tubes and several fin geometries.
There are basically three differences:
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_L_p * Pr^(1/3) * lambda / L_p (Louver fin)
or
kc = j * Re_D_h * Pr^(1/3) * lambda / D_h (Rectangular offset strip fin)
with
D_h | as hydraulic diameter [m], |
kc | as mean convective heat transfer coefficient [W/(m2K)], |
lambda | as heat conductivity of fluid [W/(mK)], |
L_p | as louver pitch [m], |
Nu_D_h = kc*D_h/lambda | as mean Nusselt number based on hydraulic diameter [-], |
Nu_L_p = kc*L_p/lambda | as mean Nusselt number based on louver pitch [-], |
Pr = eta*cp/lambda | as Prandtl number [-], |
Re_D_h = rho*v*D_h/eta | as Reynolds number based on hydraulic diameter [-], |
Re_L_p = rho*v*L_p/eta | as Reynolds number based on louver pitch [-], |
The mean Nusselt number Nu representing the mean convective heat transfer coefficient kc is shown below for different fin geometries at similar dimensions.