Chapter 1 - Basics
Overview of thermal couplings
Here is a list of the types of thermal couplings discussed up to here. A thermal conductance is defined as total Watts per Kelvin temperature difference [W/K] over a thermal interface. The heat transfer coefficient [W/(m2K)] takes surface area into account.
| Heat transfer method | Thermal conductance [W/K] | Heat transfer coefficient [W/(m2K)] | Condition |
| Conduction | TC = (k A) / L | h = k / L | unidirectional conduction (over length L, cross-section A) |
| Convection | TC = A hc | h = hconv | Typical value for laminar water flow: hconv= 1000[W/(m2K)] |
| Radiation |  | h1 = TC / A1 h2 = TC / A2 | Linearized: Valid for small deviations from nominal temperature Tnom |
| Contacting surfaces | “dry” contact: TC = A hcontact gap material: TX = A kfill / d (gap height d, filler conductivity kfill) | h = hcontact | Typical value for dry contact at moderate pressure: hcontact= 100 – 1000[W/(m2K)] |
