Numerical investigation of using different arrangement of fin slides on the plate-fin heat sink performance

Cutting fins of the plate heat sinks into multi-numbers of slides instead of one slide fin is a technique to improve the performance of the heat sink. One, two, three, and four slides have been studied numerically. The slides have been arranged in staggered arrangement. The study has been carried out on two different flow directions (impinging and parallel). The performance of the heat sink under the studied conditions has been represented through calculation of heat sink effectiveness, thermal resistance, pressure drop, pumping power, and Nusselt number. The studied range of Reynolds number is from 1333 to 5334. The results show that parallel flow gives lower thermal resistance than impinging flow for all studied cases. The pumping power required for high Reynolds number in case of parallel flow increases by around 155% with case-4 (four slides) as compared by case-1 (one slide). While it is slightly affected in case of impinging flow, using three slides with impinging flow represents an acceptable decrement in thermal resistance with low change in the required pumping power. In case of parallel flow, the resulting change in the heat sink performance, as the number of slides increases, is not proportional to the large increase in the pumping power.

Investigating the Role of Extreme Synoptic Patterns and Complex Topography During Two Heavy Rainfall Events in Crete in February 2019

During February 2019, two severe storms affected the island of Crete, located in south Greece. Both storms produced excessive rainfall, provoking severe damages, especially in the western part of Crete. The role of the prevailing synoptic patterns and the interaction of the flow with the high mountains of Crete were investigated. For this purpose, a variety of observational and numerical model data were exploited, including data from a dense rain gauge network, satellite imagery, and model analysis of various parameters describing the stability of the impinging flow. The first storm was a long-lasting event, with convective outbreaks embedded in a more stratiform rainfall pattern. The second storm was brief but mostly convection dominated. The analysis of the available data underlined the role of the low-level convergence upstream of the mountains during both storms, highlighting similarities and differences, as well as the role of the stability of the impinging flow. High soil moisture content was also evidenced as a key ingredient for the severe flooding that occurred during the second storm. This work complements similar studies on the role of Mediterranean islands and their topography on the spatial and temporal distribution of extreme rainfall.

Improving Heat Transfer of Plate-Fin Heat Sinks Using Through Rod Configurations

The performance of the heat sink has been investigated as using rods through its fins. The shear-stress transport k–ω model is selected to carry out this study. Two different flow directions have been studied. Four cases are represented, including the baseline case which has no rods through the fins. Two, four, and six rods are used through the fins. Thermal resistance, pumping power, and Nusselt number have been represented and discussed through this study. The results show that as the number of rods increases, the thermal resistance decreases while the required pumping power increases. The impinging flow direction shows higher performance as compared with the suction flow direction. As the Reynolds number increases, the Nusselt number increases for all studied cases. The optimum case along with the studied range of Reynolds number and number of rods is case-2 (has four rods through fins).

Analysis of Flow Characteristics and Pressure Drop for an Impinging Plate Fin Heat Sink with Elliptic Bottom Profiles

The performance of impingement air cooled plate fin heat sinks differs significantly from that of parallel flow plate fin heat sinks. The impinging flow situations at the entrance and the right-angled bends of the plate fin heat sink are quite involved. Flow characteristics of a plate fin heat sink with elliptic bottom profiles cooled by a rectangular impinging jet with different inlet widths are studied by numerical simulations. The results of pressure drop of numerical simulations and experimental results match quite well. The numerical results show that at the same flow rate, the pressure drop decreases with the increase of the impingement inlet width, and the pressure drop increases significantly with the increase of the fin height. The larger the impingement inlet width of air-cooled plate fin heat sink, the milder the pressure drop changes with velocity. Pressure drop for an impinging plate fin heat sink without elliptic bottom profiles is larger than that with elliptic bottom profiles at the same inlet width and velocity. Based on the fundamental developing laminar continuum flow theory, an improved model which is very concise and nice for quick real world approximations is proposed. Furthermore, this paper verifies the effectiveness of this simple impinging pressure drop model.

Temperature Profile of Thermal Impinging Flow Induced by Horizontally Oriented Rectangular Jet Flame Upon an Opposite Plate

The horizontally oriented jet flame induced by rectangular source impinging upon the opposite wall is actually common in the chemical industry, but the related studies are limited. In this paper, the computational fluid dynamics codes are carried out to investigate the temperature profile in thermal impinging flow of the horizontally oriented methane jet flame with rectangular source, which the rectangular orifice is 400 mm2 with three different aspect ratios (L/W = 1, 2, 4); besides, the jet velocities vary from 27.5 m/s to 125 m/s. As the horizontally oriented methane jet flame impinges on the vertical plate in front of the fuel orifice directly, the vertical temperature along the opposite plate is focused on. Results show that the temperature near the impingement point is the same for different jet velocities, but the temperature along the vertical direction is larger with increasing fuel jet velocity. Moreover, the orifice aspect ratio has a significant effect on the temperature, which increases with the aspect ratio at a given position for the momentum-controlled flame. The effective heat release rate on the basis of unburned fuel and ellipse flame shape hypothesis is put forward to correlate the temperature profile. Finally, a new correlation to illustrate the vertical temperature rising along the opposite plate is proposed in light of the orifice aspect ratio and fuel jet velocity, and the predictions obtained by the proposed model agree well with the numerical results, which is applicable for the horizontally oriented flame with rectangular source impinging upon the opposite wall.