The benefits of using strip fin heat sinks (SFHSs) where the cross-sectional aspect ratio of the fins lie between those for plate fins (high aspect ratio) and pins fins (aspect ratio ) are explored computationally, using a conjugate heat transfer model. Results show that strip fins provide another effective means of enhancing heat transfer, especially when staggered arrangements of strip fins are used. A detailed parameter investigation demonstrates that perforating the strip fins provide additional improvements in terms of enhanced heat transfer, together with reduced pressure loss and heat sink mass. Results are also given which show that, for practical applications in micro-electronics cooling, perforated SFHSs offer important benefits as a means of achieving smaller processor temperatures for reduced mechanical power consumption.
The benefits of using notch, slot and multiple circular perforations in plate fin heat sinks (PFHSs), are investigated numerically, using a conjugate heat transfer model. Comparisons show that each type of perforation can provide significantly reduced pressure drops over PFHSs but that fins with slot perforations provide the most effective design in terms of heat transfer and pressure drop. The practical benefits of each type of perforated fin for microelectronics cooling is also explored and their capabilities of achieving low processor temperatures for reduced mechanical power consumption are quantified.
The reactivity of an oil‐miscible ionic liquid, phosphonium phosphate (PP), and the common anti‐wear additive zinc dialkyl dithio phosphate (ZDDP) with a solid surface at elevated temperature in the absence of any tribological motion is investigated. Understanding the thermal film build up, composition, and relative thickness will help in the understanding of lubrication mechanisms once tribological effects are introduced. Attenuated total reflection–Fourier transform infrared (ATR‐FTIR), scanning electron microscopy–energy dispersive spectroscopy (SEM‐EDS), and X‐ray photoelectron spectroscopy (XPS) are employed to characterise silicon surfaces before and after the experiments in terms of surface chemistry and surface morphology. The results show that both additives react with the silicon surface to produce thermal films. However, ZDDP forms a thicker film. PP reacts with the silicon and forms a thermal film, but the reaction rate is self‐limited such that an increase of time to 24 hours does not significantly increase the film thickness.
Ionic liquid (IL) lubricants are rapidly seeing increased use as either base lubricants or additives for a wide range of functionalities. This study considers the thermal stability of the ILs with the emphasis being their use as potential lubricants. The effect of IL chemistry, including anion chain length, cation chain length, anion type, and cation type, on their thermal stability is studied. The decomposition mechanism as a function of time and temperature is considered. Five ILs are studied by utilising both thermogravimetric analysis (TGA) for the dynamic thermal decomposition and Fourier transform IR spectroscopy (FTIR) for the static thermal decomposition. For static thermal decomposition, both time and temperature are varied. The results show that the variation of IL chemistry directly influences their thermal stability. The increase of either cation or anion chain length decreases their thermal stability. Both anion and cation type have a significant influence on the thermal stability.
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