Patent Application
20220341680
The present invention relates to a heat pipe structure, and more particularly, to a low-temperature heat pipe structure that enables latent heat exchange in a phase change of a working fluid in the heat pipe under an ambient temperature of 0° C. to -90° C.
A conventional heat pipe structure includes a hollow pipe shell, in which a water-absorbent wick structure and a working fluid, such as water, coolant, methanol, acetone and liquid ammonia, are provided. Most of the currently commercially available hollow pipe shells for the conventional heat pipe structure are made of a copper material or an aluminum material. By taking advantage of a latent heat exchange that occurs in the working fluid due to phase change of the working fluid in the hollow pipe shell, the heat pipe structure is used to transfer heat.
Currently, the heat pipe structure applied to the heat dissipation of electronic products usually includes a copper pipe and an amount of pure water filled therein to serve as the working fluid. Since the copper pipe has good heat conductivity and the pure water has good latent heat, the conventional heat pipe structure can be used in most normal environments with restriction in some applications. For example, the conventional heat pipe structure is not advantageous for use in some indoor and outdoor applications, such as for the heat dissipation of chips for 5G and 6G base stations, insulted-gate bipolar transistors (IGBTs) of outdoor photovoltaic power source and automotive chips. Further, the pure water as the working fluid tends to freeze under an ambient temperature of 0° C., and the decreased molecular force of the frozen water will cause problem in the structural strength of the heat pipe structure.
It is therefore an important target of persons skilled in the art to protect the vapor and liquid circulation in the heat pipe structure against damages due to a frozen working fluid under low temperature.
A primary object of the present invention is to effectively solve the problems in the conventional heat pipe structure by providing an improved low-temperature heat pipe structure that enables latent heat exchange in a phase change of a working fluid in a pipe thereof under a low ambient temperature.
To achieve the above and other objects, the heat pipe structure according to the present invention includes a pipe, a plurality of wick structures, and a working fluid. The pipe internally defines an airtight chamber. The wick structures includes a plurality of grooves, a wire mesh and a sintered powder metal formed in the airtight chamber of the pipe layer by layer from a radially outer side to a radially inner side.
The grooves respectively have an open side and an opposite closed side, and the open side has a width smaller than that of the closed side. The working fluid is filled in the airtight chamber of the pipe and is capable of diffusing and flowing back through the wick structures. The wire mesh is mainly used to further separate the sintered powder metal form the grooves, lest fine powder of the sintered powder metal should fall into the grooves and block the same to adversely affect the diffusion of the vapor-phase working fluid through the grooves. With the above arrangements, the heat pipe structure of the present invention is a low-temperature heat pipe structure enabling latent heat exchange in a phase change of the working fluid in the pipe under a low ambient temperature of 0° C. to -90° C.
The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein
The present invention will now be described with a preferred embodiment thereof and by referring to the accompanying drawings.
Please refer to
The pipe 11 defines an internal airtight chamber 111, and can be made of an aluminum material, a copper material, a stainless steel material, or a titanium material. In the case of an aluminum pipe 11, the aluminum materials include, but not limited to, A3003 and AL 6063 aluminum alloys. Further, the pipe 11 has a wall thickness about 0.5 mm and can be round, flat or square in cross section. The pipe 11 has an evaporator area located at one end or a middle section of the pipe 11 and a condenser area located at another opposite end of the pipe 11.
The wick structures 12 include a plurality of axial grooves 121, a wire mesh 122 and a sintered powder metal 3 provided in the pipe 11 layer by layer from a radially outer side to a radially inner side. The axial grooves 121 are circumferentially arrayed on an inner wall surface of the pipe 11 and respectively have an open side 1211 and a closed side 1212. The open side 1211 has a width smaller than that of the closed side 1212, giving the grooves 121 a substantially inverted trapezoidal, omega-shaped or inverted triangular cross section. The metal mesh 122 is provided on and connected to the inner wall surface of the pope 11 by way of sintering or diffusion bonding. The wire mesh 122 can be made of a copper material, an aluminum material, a stainless steel material, or a titanium material. In the case of an aluminum wire mesh 122, the aluminum materials include, but not limited to, A3003 and AL 6063 aluminum alloys. Further, the wire mesh 122 is preferably a #200 wire mesh without being particularly limited thereto.
The working fluid 2 is filled in the airtight chamber 111 of the pipe 11. When the heat pipe structure is in use, the working fluid 2 initially in the evaporator area in a liquid phase is heated and evaporated into a vapor phase. The vaporized working fluid 2 diffuses in the airtight chamber 111 and the grooves 121 or flows from the evaporator area to the condenser area, at where the working fluid 2 in the vapor phase releases heat and is condensed into the liquid phase again. When the vapor-phase working fluid 2 is condensed to form the liquid-phase working fluid 2 again, the liquid-phase working fluid 2 is guided by the wire mesh 122 and the sintered powder metal 3 or by a capillary action occurred at the grooves 121 to flow back to the evaporator area, i.e. an area in contact with a heat source. The grooves 121 help the condensed liquid-phase working fluid 2 to flow back to the evaporator area or help the evaporated vapor-phased working fluid 2 to diffuse to the condenser area.
The wire mesh 122 is mainly used to separate the sintered powder metal 3 from the grooves 121, lest finely powder of the sintered powder metal 3 should fall into the grooves 121 to block the same. Blocked grooves 121 would adversely affect the diffusion of the vaporized working fluid 2 through the grooves 121. With the above arrangements, the heat pipe structure of the present invention is a low-temperature heat pipe structure enabling latent heat exchange in a phase change of the working fluid in the pipe under a low ambient temperature of 0° C. to -90° C.
The wire mesh 122 has an outer peripheral surface 1221 and an inner peripheral surface 1222. The outer peripheral surface 1221 is correspondingly fitted to the open side 1211 of the grooves 121, while the inner peripheral surface 1222 has a powder sintered body 3 provided thereon. The powder sintered body 3 is a structural body formed by sintering copper powder, aluminum powder or nickel powder.
The working fluid 2 is filled in the airtight chamber 111 of the pipe 11.
In summary, the present invention provides a low-temperature heat pipe structure having multiple liquid-absorbent wick structures 12. In an embodiment, the low-temperature heat pipe structure includes a pipe 11 made of an aluminum material; a plurality of grooves 121 with an omega-shaped cross section, a wire mesh 122 made of an aluminum material, and a powder sintered body 3 are sequentially provided on an inner wall surface of the pipe 11; and a working fluid 2, such as a coolant having a liquidus temperature point of -90° C., is filled in the pipe 11 to give the heat pipe structure an operating temperature interval between -90° C. and 100° C., enabling the heat pipe structure to be applied in outdoor environments, such as being used for dissipating heat produced by 5G and 6G base station chips, insulated-gate bipolar transistors (IGBTs) of a photovoltaic power source, and automotive chips. Since latent heat exchange in a phase change of the working fluid 2 can occur in the pipe 11 under an ambient temperature of 0° C. to -90° C., the heat pipe structure of the present invention is a low-temperature heat pipe structure enabling latent heat exchange in a phase change of the working fluid at a low temperature. Therefore, the heat pipe structure of the present invention can be applied in a low-temperature environment without the problem of having a frozen working fluid in the pipe to maintain normal vapor and liquid circulation in the heat pipe.
The present invention has been described with a preferred embodiment thereof and it is understood that many changes and modifications in the described embodiment can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.
