A novel ultra-large flat plate heat pipe manufactured by thermal spray

Abstract

An ultra-large flat plate copper heat pipe (180 x 180 mm 2) was constructed using a thermal spray technique, and it was then thermally characterized. A porous copper wick was fabricated by using a flame spray torch to deposit a mixture of copper and aluminum particles onto the target substrate. A stainless-steel wire mesh acts as a mask so that the coating deposited is in the form of an array of microstructures with channels between them. After spraying, the aluminum deposit is leached away by immersing the plate in a dilute NaOH solution to produce a porous structure. A second copper plate was placed on top of the coated surface, and their edges were vacuum brazed to form a sealed enclosure. The enclosed volume was evacuated and partially filled with water to form a heat pipe. The heat pipe was centrally heated from its bottom and cooled along its top outer edge. Three liquid filling ratios and six heat fluxes from 2.5 W/cm 2 to 15 W/cm 2 were investigated. A decreasing lateral thermal resistance for an increasing applied heat flux was noted for all filling ratios until central dry-out. Central dry-out corresponds to the point where the evaporation rate outpaces the wicking of the working fluid at the centre of the heat pipe. Dry-out of the central wick results in a large thermal resistance compared to the pre-dry-out condition. Delayed dry-out onset was noted for increasing working fluid filling ratios. In the pre-dry-out condition, a peak average radial thermal conductivity of 920 W/m K was noted for a 65% filling ratio, and 7.5 W/cm 2 applied heat flux. A model was generated to calculate dry-out of the thermally sprayed porous wick for a given filling ratio and applied heat flux. The present research represents two highly novel advances in heat pipe technology. The first is the development of a new innovative manufacturing technique for the generation of a porous wick structure within a heat pipe. This new manufacturing technique enables the production of large metal vapour chambers with complex 3D geometries. When applied in conjunction with copper compatible working fluids, this techniques facilitates the realization of skin thermal conductors. Second, the fabrication of an ultra-large flat plate heat pipe that is significantly larger than that previously reported in the literature is demonstrated.

Biomimetic Copper Forest Structural Modification Enhances the Capillary Flow Characteristics of the Copper Mesh Wick

“…Comparisons of the ∆P c •K values of the MWs and the CFMWs with other wick structures are shown in Figure 8 [16,[18][19][20][21][22][23][24][25][26][27][28][29]. The CFMWs superior capillary performance at an ultra-thin thickness, especially superior sintered meshes.…”

Research on the Manufacturing Process and Heat Transfer Performance of Ultra-Thin Heat Pipes: A Review

“…This novel manufacturing method eliminates the gap between the inner wall of the evaporator and the wick, thus inhibiting vapor leakage and improving thermal leakage [ 77 ]. Feng et al [ 78 ] used a flame spraying process to inject copper powder and aluminum powder into a flame spray gun at the same time, and then, they sprayed it onto the copper substrate covered with aluminum mesh. The aluminum is removed by sodium hydroxide to form a porous copper wick, and the porosity is determined by the feeding rate of the aluminum powder [ 78 ].…”

“…Feng et al [ 78 ] used a flame spraying process to inject copper powder and aluminum powder into a flame spray gun at the same time, and then, they sprayed it onto the copper substrate covered with aluminum mesh. The aluminum is removed by sodium hydroxide to form a porous copper wick, and the porosity is determined by the feeding rate of the aluminum powder [ 78 ]. This novel fabrication method helps to reduce the production cost and simplify the manufacturing process for application in commercial manufacturing production [ 78 ].…”

“…The aluminum is removed by sodium hydroxide to form a porous copper wick, and the porosity is determined by the feeding rate of the aluminum powder [ 78 ]. This novel fabrication method helps to reduce the production cost and simplify the manufacturing process for application in commercial manufacturing production [ 78 ]. Jafari et al [ 79 ] applied additive manufacturing techniques to flexibly control the porosity and pore size, as well as the shape and size, of the wicking wick to fabricate a flat heat pipe with better heat transfer performance, using stainless steel as the raw material, as shown in Figure 15 [ 79 ].…”

Corrosive wear and electrochemical corrosion performances of arc sprayed Al coating in 3.5% NaCl solution

“…Corrosive wear becomes more severe in oxygen-rich splash zone (Melchers et al , 2007), the total mass loss in the corrosive wear process is greater than that of corrosion and wear alone (López et al , 2015; López–Ortega et al , 2018), which decreased the mechanical properties such as strength, ductility and impact strength to loss of material and ultimate failure (Popoola et al , 2013). To save the maintenance and replacement costs, coating technologies are widely used to protect from corrosion and wear, including electroless plating (Guo et al , 2016; Wang et al , 2015), thermal spraying (Fenga1 et al , 2020; Chen et al , 2020). among them, arc spraying (AS) has always been the focus of thermal spraying research studies, which provides many benefits over other coating techniques.…”