However, the critical heat flux of heat pipe is often limited by the maximum capillary-driven liquid transport rate through the wicking material. A significant number of novel porous material with complex structures have been proposed in past studies to provide enhanced capillary-driven flow without substantial reduction in pore size and porosity.
Mar 09, 2021 · The condensed working fluid inside a heat pipe is pumped from the condenser to the evaporator section to complete the operating cycle by using the capillary force generated inside the wick structure. Since the miniature heat pipes have smaller vapor cross-sectional area, the fiber wick structure is suitable for this application. Applied Thermal Engineeringstructures are at the heart of heat pipes. They are utilized as capillary-wicking medium to drive the circulation of working uid in its liquid phase, as well as evaporation-enhancement structures to release/cap-ture the working uid in its vapor phase. In heat pipe design, wick performance is often a limiting factor . Common homogeneous
LOOP HEAT PIPE ANALYSIS Loop heat pipes utilize the evaporation and condensation of fluid to transfer heat. Capillary forces develop in porous wicks and drive flow between an evaporator and, traditionally, a single condenser. Figure 7 shows a schematic of the current loop heat pipe design with multiple flat plate condensers Heat Pipe Design Guide:Different Types of Heat Pipes Nov 18, 2019 · 4. Heat Pipe Wick Material. Heat pipes consist of an outer shell and an internal structure that wicks the working fluid from the condenser to the heat source. The heat pipe's wicking type directly influences the system's capillary action potential. There are two common heat pipe wick types:grooved and sintered copper powder.
pipes. A number of studies have investigated the capillary limit-induced dryout phenomenon in porous wick structures in heat pipes. Hanlon and Ma  characterized the dependence of dryout heat flux in sintered particle structures on wick thickness, particle size, and porosity. Chun  studied the dryout Heat Pipe Technology, Working Priniciples, Wick Dec 19, 2019 · If the engineer knows that the heat pipe will be required to operate in orientations between -50 to -90 degrees, the wick structure can be optimized to increase the capillary pumping action. As seen in the chart below, a gravity optimized 6mm heat pipe now has a higher power carrying capacity (Qmax) than its non-optimized 6mm counterpart, to meet the needs of this application.
Heat Pipe 1-Piece Vapor Chamber 2-Piece Vapor Chamber 20 Heat Pipes Bend radius 3X diameter of heat pipe. Each 45 degree bend reduces Qmax by ~2.5% Flatten to 1/3 diameter of original pipe (typical) Machining if pipe wall thickness permits. Allows direct contact with heat source 1-Piece Vapor Chamber 10mm bend radius along narrow plane Heat Pipes for Electronics Cooling ApplicationsSep 01, 1996 · Heat pipe operating above designed power input or at too lowan operating temperature:Increase vapor space diameter or operating temperature:Capillary:Sum of gravitational, liquid and vapor flow pressure dropsexceed the capillary pumping head of the heat pipe wick structure:Heat pipe input power exceeds the design heat
Heat sinks with heat pipe are used to handle power from 40W to multiple KW. How Heat Pipes Work:A heat pipe is a simple device that can quickly transfer heat from one point to another. It consists of a sealed copper container whose inner surfaces have a capillary wicking material. A heat pipe is similar to a thermo siphon. Heat and Mass Transport in Heat Pipe Wick Structures May 23, 2012 · Heat and Mass Transport in Heat Pipe Wick Structures. Design and fabrication of sintered wick for miniature cylindrical heat pipe. A microscale model for thin-film evaporation in capillary wick structures. International Journal of Heat and Mass Transfer, Vol. 54, No. 1-3.
One strategy for improving heat pipe heat transport performance will be discussed in detail. Using an axially graded wick, in which the capillary pore radius is varied as a function of axial position, the liquid pressure drop can be reduced allowing for increased heat transport. Oscillating Heat Pipes ThermAvant TechnologiesOscillating heat pipes (OHPs) use pressure-driven, two-phase fluid flow to rapidly transfer heat between heat sources and heat sinks. They can be built in materials, fluids, shapes, and sizes that are not possible with conventional capillary-driven heat pipes or vapor chambers.
The mesh tries to unwrap itself leaving the wick held by this tension against the inner wall of the heat pipe. The capillary force that is generated by the mesh is determined by the size of the rectangular openings between the individual threads. Heat pipes with this type of wick structures are capable of operating in gravity-aided and Selecting capillary structures for heat pipes in The capillary wick structure, required to facilitate the fluid transport, in combination with the orientation of the embedded heat pipe determines, to a large extent, the heat pipe's performance. Important design parameters are the wick's effective pore size and permeability, together with
A high permeability wick structure for heat pipes. A thin capillary liquid transport structure is encased within relatively thick sections of a plastic bonded aluminum powder wick. The capillary structure is formed of two layers of fine mesh screen separated only by small, randomly located, powdered metal granules. The capillary liquid transport structure can be built in numerous cross Heat Pipe Wicks Advanced Cooling TechnologiesInverted Wicks:In most heat pipes, the majority of the wick is on the inner diameter of the envelope, as shown in the pictures on this webpage. In an inverted wick, the vapor space is located adjacent to the heat pipe envelope. These types of wicks are used in capillary pumped loops and loop heat pipes.