Saturation boiling of PF-5060 on rough Cu surfaces: Bubbles transient growth, departure diameter and detachment frequency

Scalable and Resilient Etched Metallic Micro- and Nanostructured Surfaces for Enhanced Flow Boiling

“…The departure diameter is in turn related to the wettability of the surface and the magnitude of drag force assisting bubble departure during flow. The bubble departure diameter D d of the high roughness Al etched surface decreases with contact angle (θ ∼ 0°) (see Section S10) since , where θ is the apparent receding contact angle as measured between the liquid–vapor interface and solid–liquid interface, σ is the working fluid liquid–vapor surface tension, g is the gravitational constant, and ρ 1 and ρ v are the working fluid liquid and vapor densities, respectively. , In addition, the drag and inertia forces during flow balance the capillary force ( F c ), which is the force keeping the bubble attached to the wall. The capillary force ( ) reduces with increased wetting associated with etched surfaces and therefore enables bubbles to depart the surface at smaller diameters and results in higher heat transfer coefficients.…”

“…, where θ is the apparent receding contact angle as measured between the liquid−vapor interface and solid−liquid interface, σ is the working fluid liquid−vapor surface tension, g is the gravitational constant, and ρ 1 and ρ v are the working fluid liquid and vapor densities, respectively. 55,56 In addition, the drag and inertia forces during flow balance the capillary force (F c ), which is the force keeping the bubble attached to the wall. The capillary force (…”

Recent Advances in Two-Phase Immersion Cooling with Surface Modifications for Thermal Management

“…A further increase in the wall superheat causes transition and film boiling, where the surface is covered by vapor, and then heat dissipation is reduced. Because of this risk, a cooling system is often designed at 70% of the CHF [23]. Kutateladze and Zuber [24] expressed the CHF as Equation (1).…”

“…El-Genk et al [27] created different surfaces with average roughness in the range of 0.039~1.79 µm using sandpaper with grit sizes of 120-2500, and investigated the transient growth rate, departure diameter, and frequency of bubbles [23]. The density of the active sites increased as the roughness increased.…”

A critical review of pool and flow boiling heat transfer of dielectric fluids on enhanced surfaces

“…Visualization of the bubble dynamics on these surfaces by Suszko and El-Genk [87] showed that the smooth copper surface has higher bubble growth rate, departure diameter and detachment frequency than the rougher copper surfaces and, for all surfaces, the bubble growth rates were proportional to the square root of time indicating that the bubble growth was thermally driven. In addition, based on the results obtained, it was also concluded that the enhancement in heat transfer with increasing surfaces roughness was primarily due to the increase in surface active nucleation site density.…”