Heat pipes offer extremely high thermal conductivity in their longitudinal directions. Depending on the lengths and manufacturing factors, the effective thermal conductivity of heat pipes can be 10 to 1000 times of the thermal conductivity of pure copper. When coupled with highly conductive fins or spreaders, heat pipes become a powerful tool that can quickly dissipate large quantities of heat to the environment or a location where additional cooling systems can be installed.
Fins can be assembled onto heat pipes in two methods. One is to solder fins to heat pipes, the other is to use interference fit (also called press fit or friction fit), in which the fins have holes that are slightly smaller than the diameter of the heat pipe. By pressing the fins onto the heat pipes with pressure, the heat pipe and the fins are tightly assembled. When temperature arises in working conditions, thermal expansion of the fins and heat pipes will make the assembly even more secure.
Three-dimensional simulation is extremely valuable in the design of heat pipe assemblies. Because of the complex thermodynamic process (evaporation and condensation) within a heat pipe, direct simulation of physical process is difficult and time-consuming. For most engineering designs, a simple workaround is to model the heat pipe as a super conductor with a high effective thermal conductivity. The longer the heat pipe is, the higher the effective thermal conductivity should be. The assumed effective thermal conductivity shall be corrected after prototypes are made and thermal measurements are performed.
