Thermal Contact Resistance
Basic thermal contact resistance between two materials
Description
Equations Fundamental equation is:
References
Variables
Connections
Parameters
See Also
The Thermal Contact Resistance component models a heat transfer between two materials which have different thermal conductivities. The following image illustrates an example of apparent contact area of two materials.
Because of the surface roughness of both materials, the actual contact area of two materials becomes spots of contact. The other areas are regarded as the void space filled by fluid such as air. The following image illustrates the mechanism of jointed surface in more detail.
Then heat flow of the contact of two materials is regarded as the following image. This component is based on this.
Using each option, you can control the apparent area size, area ratio, and the thickness of void space by real input signals.That makes it possible for you to change contact resistance value during simulation. For example, change by deformation of actual contact area size caused by joint pressure change.
Qflow=1RC⋅A⋅dt=hc⋅A⋅dT
dT=T__a−T__b
The equation for the areas is shown below:
A=Ac +A__v
The equation for heat flow is as below:
Qflow=Q__solid+Q__fluid=dTL2`Material_a.k`Ac+L2`Material_b.k`⋅Ac+dTLkf⋅Av
[1] : J. P. Holman. "Heat Transfer Ninth Edition", McGraw-Hill Higher Education.
Symbol
Units
Modelica ID
Qflow
W
Heat flow rate from port a to port b
Q_flow
dT
K
Temperature difference between port a and port b
Rc
m2KW
Thermal contact resistance
hc
Wm2K
Coefficient of thermal contact conductance, which is the inverse of Rc
A
m2
Apparent contact area
Ac
Actual contact area
Av
Area of void space
L
m
Thickness of the void space
Name
Condition
port_a
Thermal port a
port_b
Thermal port b
A_input
if use Apparent contact area input is true.
Apparent contact area is defined by Real signal input.
Aratio_input
if use Area ratio input is true.
Area ratio A__cA is defined by Real signal input.
L_input
if use Void space thickness input is true.
Thickness of the void space is defined by Real signal input.
Default
Material_a
SolidPropertyData1
−
Solid material property data
Wm⋅K
Material_a.k is the thermal conductivity of the material of port_a
Material_a.k
Jkg⋅K
Material_a.cp is the specific heat capacity of the material of port_a
Material_a.cp
kgm3
Material_a.rho is the density of the material of port_a
Material_a.rho
Material_b
Material_b.k is the thermal conductivity of the material of port_b
Material_b.k
Material_b.cp is the specific heat capacity of the material of port_b
Material_b.cp
Material_b.rho is the density of the material of port_b
Material_b.rho
k__fluid
0.0241
The thermal conductivity of the fluid which fills void space
kf
0.0001
Apparent contact area between materials
A_const
A__cA
0.01
Area ratio A__cA (between 0 and 1)
Aratio_const
0.00005
L_const
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