varmebroer

Varmebroer, or heat pipes, are sealed, evacuated tubes that contain a working fluid and often a wick structure lining the inner wall. They are designed to transfer heat efficiently over short or long distances with minimal temperature difference.

The operating principle relies on evaporation and condensation. At the hot end, heat causes the liquid to vaporize; the vapor travels to the cooler end, where it condenses and releases latent heat. The condensate is returned to the hot end by capillary action through the wick or by gravity and replenishes the liquid for another cycle. This closed-loop process enables rapid and efficient heat transfer with relatively small external power input and no moving parts.

Designs and variants include straight heat pipes, loop heat pipes, and pulsating heat pipes, as well as flat-plate configurations such as vapor chambers. Wick structures can be made from sintered metals or screen meshes to optimize liquid return. Materials are typically copper or aluminum shells, with working fluids selected for the target temperature range.

Common working fluids include water, ammonia, methanol, acetone, and ethanol, chosen based on operating temperature and compatibility with the container. In high-temperature or specialty applications, metals such as sodium or potassium may be used.

Applications span electronics cooling, aerospace and spacecraft thermal control, solar thermal collectors, and industrial heat recovery. Advantages include high effective thermal conductivity, passive operation, reliability, and compactness; limitations involve temperature range, potential dry-out, leakage risk, and manufacturing complexity.

Historically, heat pipes were developed in the early to mid-20th century and became widely used in electronics cooling and space applications in the latter half of the century.