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Engineering Applications of Microscale Convective Heat Transfer
Published in C. B. Sobhan, G. P. Peterson, Microscale and Nanoscale Heat Transfer, 2008
Various fabrication techniques used to integrate microchannels into silicon substrates have been discussed in the literature. Tuckerman and Pease (1982) describe the use of the etching process and precision machining methods for fabrication of microchannels and heat sinks. Anisotropic etching of <110> silicon using KOH has originally been used in fabrication. The use of precision sawing (such as wafer dicing saw) has been used with excellent results, producing grooves as narrow as 30 μm. Very smooth finish has been obtained using 1 mm diamond grit. Precision sawing has the advantage that hard substrates can be machined by appropriate selection of the cutting material, whether the substrate is crystalline or amorphous.
Anodic bonding of mid-infrared transparent germanate glasses for high pressure - high temperature microfluidic applications
Published in Science and Technology of Advanced Materials, 2020
Julien Ari, Geoffrey Louvet, Yannick Ledemi, Fabrice Célarié, Sandy Morais, Bruno Bureau, Samuel Marre, Virginie Nazabal, Younès Messaddeq
To investigate the quality and the migration of species at the interface between the glass and the silicon wafer, scanning electron microscopy (SEM) analyses using a Quanta 3D-FEG instrument equipped with an energy dispersive X-ray (EDAX) spectrometer were carried out. First, the Si-glass assemblies were cut with a precision dicing saw to get access to the bonded region. Secondary electron imaging mode was used to obtain high-resolution images, whereas backscattered electron mode was employed to assess information related to the elemental distribution (contrast) with the samples. Energy dispersive analyses have been performed by scanning lines crossing the interface from the glass to the silicon wafer.
Enhanced Pool Boiling Performance of Microchannel Patterned Surface with Extremely Low Wall Superheat through Capillary Feeding of Liquid
Published in Nanoscale and Microscale Thermophysical Engineering, 2020
Fengxun Hai, Wei Zhu, Shiqiang Liang, Xiaoyi Yang, Yuan Deng
An experimental setup is designed and built to allow testing of different plain and enhanced copper surfaces. The pool-boiling heat transfer test system consists of a Cu test rod, a cartridge heater, an auxiliary heater, a liquid chamber, a power supply system and a data acquisition system [25]. As shown in Figure 1a, Cu test sample rod is fixed on a cartridge heater and heated by a 600 W silicon nitride ceramic heater inside the cartridge heater. The liquid chamber has a side length of 150 mm, a thickness of 5 mm and a height of 200 mm and is directly open to the ambient atmosphere. Besides, a press-fitted Teflon bushing is provided between the bottom plate opening and copper rod to ensure the leak-proof joint and prevent pool liquid from leaking into bottom heater section. An electrical resistance auxiliary heater immersed in water in the liquid chamber serves as the heat source to maintain the saturation condition of distilled (DI) water in the chamber. A copper rod with a height of 2 cm is diced by the precision dicing saw and then bolted on the cartridge heater. Three holes are drilled into the center of the copper rod at 3 mm intervals, as shown in Figure 1b. Three sheath K-type thermocouples (± 0.2 K) are installed to measure the temperature distribution in the copper rod. The steady state measurement method is used to measure the boiling heat transfer performance. All tests are performed using DI water to avoid premature bubble formation and to minimize surface contamination. The input power starts from 5 W/cm2 and is increased with the increment of 5 W/cm2 in the initial stage and 2 W/cm2 when it is close to CHF. All values of the temperature are collected by the data acquisition to determine the uncertainty of heat flux, superheat and heat transfer coefficient.