Heat pipe

A heat pipe, comprising:

• a pipe body, having a top wall and a bottom wall;
• and
• a capillary structure, installed in the pipe body, and having a liquid delivery structure which is a solid structure with porous structures, the liquid delivery structure having a top surface, two side surfaces and a bottom surface in a direction of extension of the liquid delivery structure, wherein the top surface is contacted with the top wall, and the bottom surface is contacted with the bottom wall, an outer side of the side surface of the liquid delivery structure together with the top and bottom walls forming a vapor channel, the liquid delivery structure being divided into a center portion and an outer layer, the outer layer being coupled to the center portion, and the center portion having a porosity greater than a porosity of the outer layer,
• wherein
• the pipe body is divided into an evaporation section, an insulation section and a condensation section, and the capillary structure includes a first capillary portion coupled with a first end of the liquid delivery structure, and a second capillary portion coupled with a second end of the liquid delivery structure opposite the first end, and
• the first capillary portion has a porosity smaller than or equal to the porosity of the outer layer, and the second capillary portion has a porosity greater than or equal to a porosity of the center portion.