![]() On the other hand, as the amount of vapor grew, it readily detached from the heated surface due to the lower centrifugal acceleration, significantly reducing the size and duration of dry patches on the heated surface. When the platform rolled up to its maximum amplitude, the vapor drifted slowly due to the effect of tangential acceleration, which acted in the opposite direction to the platform. Therefore, the observations of vapor behavior focused on the period during which the platform rolled to its maximum rolling amplitude and then rolled back down. When the platform rolled more quickly, CHF occurred earlier, while CHF occurred every time the platform rolled back after reaching its maximum rolling amplitude. It was observed that the combination of centrifugal and tangential acceleration affected the vapor behavior and occurrence of CHF. Vapor behavior and critical heat flux (CHF) mechanism under rolling motion were experimentally analyzed in the present study using a rolling platform system. Furthermore, this correlation has been enhanced to predict CHF values underwater above 50 W/cm2 by applying a genetic algorithm, and new perspectives for possible future research activities are proposed. It shows that the uncertainty band can be further narrowed down to ☑2.5% for dielectric liquids by using TME correlation. Finally, a correlation proposed by Professor Avram Bar-Cohen and his team (thermal management of electronics (TME) correlation) is compared with the experimental dataset published in previous studies. While proposed correlations for predicting CHF have been quite promising, they still have a considerable uncertainty (☒5%). A broad summary of correlations developed until now for predicting CHF is presented with their ranges of validity. The governing mechanisms are discussed separately, and various options related to the selection of appropriate working fluids are highlighted. To achieve an optimal heat removal solution for a particular problem, each of these parameters must be understood. This paper presents a critical literature review of various parametric effects on pool boiling heat transfer and critical heat flux (CHF) such as pressure, subcooling, surface topography, surface orientation, working fluid, and combined effects. Therefore, many researchers have been extensively studying over the last six decades. Pool boiling heat transfer offers high-performance cooling opportunities for thermal problems of electronics limited with high heat fluxes. Based on these results, it is apparent that the surface orientation significantly affects the ONB, CHF, and bubble dynamics on PCB in a saturated water pool. Moreover, it was observed that the bubble with the biggest departure diameter had the smallest departure frequency, and needs longer time to generate another bubble. On the other hand, bubble frequency decreased with increasing surface orientation (0° to 90°) and increased as the surface orientation went beyond 90°. ![]() Furthermore, based on the photographic and image processing, the results revealed that the approximate bubble departure diameter with the heater facing upwards (0° and 45°) including at 90° was bigger compared to that of the heater facing downwards (135° and 150°). Moreover, it was observed that the CHF began when the heater was placed horizontally facing downward (180°) as the boiling commenced at this surface orientation. ![]() Early ONB occurred when the heater was placed facing downwards (135°, 150°, and 180°). On the other hand, when the heater placed horizontally facing downward (180°), the generated vapor bubble grew and coalesced together until it ultimately covered the entire heated surface. In contrast to those orientations, at 90°, 135°, and 150°, the generated vapor bubble exhibited similar behavior except that it drifted along the heated surface before it departed at the most upper part of the heater. ![]() When the heater was placed facing upwards (0° and 45°), the generated vapor bubble grew and coalesced together to form an elongated bubble which eventually departed from the heated surface due to the buoyancy in the vertical direction of the heated surface. Results revealed that boiling commenced from downward to upward surface orientations (180° to 0°). Additionally, photographic analyses and image processing were conducted to observe the pool boiling phenomena and determine the bubble dynamics from upward to downward surface orientations (0°, 45°, 90°, 135°, 150°, and 180°). The onset of nucleate boiling (ONB) and critical heat flux (CHF) of saturated water on printed circuit board (PCB) that is immersed in a stainless steel pool were investigated at various surface orientations.
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