Numerical Analysis of Microchannels Designed for Heat Sinks

Abstract

Conjugate heat transfer is numerically investigated using a three-dimensional computational fluid dynamics approach in various microchannel geometries to identify a high-performance cooling method for piezoelectric ceramic stacks and spindle units in high-precision machines. Straight microchannels with rectangular cross sections are first considered, showing the performance limitations of decreasing the size of the microchannels, so other solutions are needed for high applied heat fluxes. Next, many microchannel designs, focusing on streamwise geometric variation, are compared to straight channels to assess their performances. Sinusoidally varying channels produce the highest heat transfer rates of those studied. Thus, their optimization is considered at a channel width and height of 35 and 100 μm, respectively. Heat transfer increases as the amplitude and spatial frequencies of the channels increase due to increased interfacial surface area and enhanced Dean flow. The highest performance efficiencies are observed at intermediate levels of amplitude and frequency, with efficiency decreasing as these geometric parameters are increased further at the onset of flow separation. The sinusoidal channel geometries are then optimized with respect to minimizing the system’s pressure drop for all applied heat fluxes between 5690 and 6510 kW/m2. Doing so created an optimal geometry curve and showed that all geometries in this region had amplitudes close to 40 μm. Therefore, imposing a fixed heat flux requirement for a case study of cooling piezoelectric ceramics, the optimized sinusoidal geometry decreases the system pressure drop by 79% relative to a straight channel while maintaining a larger minimum feature size.

Investigation on high-aspect-ratio silicon carbide ceramic microchannel by using waterjet-assisted laser micromachining

“…The magnetic pump pressure, nozzle diameter and adjustable nozzle angle is 0.6MPa, 0.4mm and 0 ~ 90°, respectively. Silicon carbide (SiC) ceramic with excellent high-temperature mechanical properties was selected as the target sample in this research with a size of 50×10×2mm 3 . The characteristic parameters are presented in Table 1.…”

“…transmission and reaction etc.) are the core units in areas of new energy, intelligent sensing, etc., and have become an emerging interdisciplinary research eld recently [1][2][3]. Silicon carbide ceramic has become an important material for manufacturing microstructures such as microreactors, micronozzles, high-temperature bearings, and electronic equipment components due to its excellent high-temperature mechanical properties (e.g.…”

Effects of sperm processing techniques on IVF pregnancy rates: a mini-review

“…This method is direct, minimizing or avoiding mechanical DNA damage to sperm. For example, McCormack et al 66 developed a direct channel for assessing the fertilization capacity of semen samples using fluorescent labeling technology. Screening experiments conducted according to the World Health Organization standard demonstrate that the fluorescence signal of the system exhibited Pearson correlation coefficients of 0.79 and 0.80 with motile sperm concentration and forward motile sperm concentration, respectively.…”

“…Despite its accuracy, the high cost of the device and the complexity of the fluorescence labeling procedure restrict its widespread use. 66 Based on the same principle, Chen et al 67 have also designed a portable analyzer for sperm quality, which integrates Coulter technology to count sperm and evaluate the two indices of sperm motility and concentration. This system does not require fluorescent labeling or sample pretreatment and is a low cost and convenient operation.…”

Magnetohydrodynamic-based Internal Cooling System for a Ceramic Cutting Tool: Concept Design, Numerical Study, and Experimental Validation

“…Heat reduction in micro- and mesoscale engineering systems is critical to maintaining and developing sustainable solutions to current challenges in thermal management [ 1 ]. Micro-manufacturing operations produce heat as a by-product of machine use [ 2 ]. In precision machining applications, the excess tool wear due to the heat induced during cutting actions is a major challenge in thermal management [ 3 , 4 ].…”