Biomimetic Copper Forest Wick Enables High Thermal Conductivity Ultrathin Heat Pipe

Abstract

Electronic devices with high heat flux are currently facing heat dissipation problems. Heat pipes can be used as efficient heat spreaders to address this critical problem. However, as electronic devices become smaller, the space for heat dissipation is becoming ever so limited; hence, ultrathin heat pipes are desired. This study proposes a biomimetic copper forest wick for an ultrathin heat pipe (UTHP). It is made by a simple one-step electrodeposition process and appears as a natural forest structure with abundant Ω-like grooves. Capillary rise tests with ethanol were performed to characterize the capillary force of the wick structure. Compared to traditional sintered particles, this wick structure has a much higher capillary performance parameter, K/R eff. The biomimetic copper forest wick was used to fabricate a 0.6 mm thick UTHP. The UTHP was tested at different filling ratios; the optimum filling ratio was found to be about 71%. At a heating power of 6 W, the temperature difference between the condenser and evaporator was only 1.2 °C, with an effective thermal conductivity, λ eff, up to 1.26 × 104 W m–1 K–1.

Lightweight All Graphene‐Based Two‐Phase Heat Transport Devices

“…Figure 6f compared the specific thermal conductivity of the rGO/PVA-based TPHTD with different thermal management materials and devices. [9,15,[41][42][43][44][45][46][47][48][49][50][51][52] By combining the advantages of lightweight of rGO/PVA casing material and high thermal conductivity of two-phase heat transfer, the rGO/PVA-based TPHTD generated achieves the highest specific thermal conductivity, up to 5600 W (mKg) −1 .…”

“…Such a device mainly relies on the phase change heat transfer process and takes advantage of both the large latent heat and the fast flow of the vapor from the evaporator to the condenser to realize efficient heat transfer, thus achieving high thermal conductivity, enabling its extensive use in thermal management devices. [8][9][10] So far, graphene has been used in two different ways for the TPHTD. In one way, graphene is coated on the inner wall of the metal-based casing in the TPHTD.…”

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

“…In ultra-thin heat pipes and vapor chambers, as the thickness decreases, the vapor space and wick thickness also decrease significantly, especially when the thickness is less than 0.3 mm. Even slight variations in thickness can result in a sharp increase Energies 2023, 16, 5348 2 of 14 in thermal resistance, often exponentially [4,5]. Therefore, it is essential for the wick to maintain optimal capillary performance while minimizing its thickness as much as possible.…”

“…In previous research, we discovered that the biomimetic copper forest structure, due to its abundant dendrites, exhibits superhydrophilic characteristics and high capillary features. At same time, it shows excellent heat transfer performance at boiling and in ultra-thin heat pipes [14][15][16]. Therefore, this paper combines the biomimetic copper forest structure with copper mesh to fabricate a composite ultra-thin wick with a high capillary performance.…”

Microscopic Observation of Preferential Capillary Pumping in Hollow Nanowire Bundles

“…Capillary wicking is an interfacial process that is ubiquitous in nature without the requirement of external energy. It is of vital importance in a broad range of industrial applications such as capillary-driven liquid film evaporation and boiling heat transfer, − liquid film condensation, − heat pipe, , vapor chamber, and microfluidics. − Superior wicking capability of surfaces is a major motivation to be employed in phase change heat transfer applications requiring the removal of a large amount of heat to maintain adequate performance and ensure system reliability in electronics, nuclear power generation, and aeronautics. − Numerous research efforts have been devoted to the development of wicking enhancement strategies. The wicking surfaces reported previously can be divided into three categories: microscale, − nanoscale, − and hierarchical − structures.…”