What is a Heat Pipe?

A Heat Pipe is an evacuated sealed tube with a capillary mechanism incorporated for the return of working fluid. Introductions Heat Pipes are developed for thermal control in spacecraft, in particular in earth orbiting satellites.Importance to the specific application of Heat Pipe are due to its following characteristics.

Heat transfer :
The ability to transfer considerable quantIties of heat over a distance wih low temperature difference between source
and sink.

Isothermalisation
The ability to reduce temperature gradients within a bod or to produce a near-isothermal surface.

Heat Flux transformation:
The ability to accomodate different heat and flux at the evaporator and condensor, as a function of two surface areas.

Thermal Response time Heat Pipe V/s. Copper rod

One inch of test sample immersed in boiling water, heat sink  free convection.