“…In addition, the flow area is higher in rectangular microchannels when compared to square microchannels. 44 Hence, friction factor is higher in rectangular microchannels. The friction factor in square microchannels is lower by 37.55% and 32.25% compared to rectangular microchannels, at lower fluid velocities (u m = 0.5 m/s) and higher velocities (u m = 2 m/s), respectively.Figure 12.Friction factor vs. Fluid velocity of 0.1 vol.…”
The objective of this paper is to analyze the effect of hydraulic diameter and channel shape on the thermal and hydrodynamic characteristics of a microchannel cooled by Graphene-Platinum/water hybrid nanofluid for electronic cooling applications. The study was performed numerically using mathematical software called Maple 19.0. Microchannels having square and rectangular cross-sections, and hydraulic diameters ranging from 200 µm to 1000 µm were taken into consideration. Thermal resistance, heat transfer coefficient, pressure drop and friction factor were evaluated for different conditions and their corresponding graphs are presented and discussed. It was evident from the results that low thermal resistance and high heat transfer coefficient was achieved upon decreasing the hydraulic diameter, which is favorable for the cooling of electronic chips and devices. Based on the Reynolds number, the heat transfer coefficient increased by 2 to 4 times for both rectangular and square microchannels, on decreasing the hydraulic diameter from highest value (1000 µm) to lowest value (200 µm). However, friction factor and pressure drop increased for channels with lower hydraulic diameters. In addition, rectangular microchannels exhibited better heat transfer performance, while square microchannels had lower friction factor and pressure drop. Rectangular microchannels presented a maximum enhancement of 30% in heat transfer coefficient and a reduction of 18% in thermal resistance, when compared to square microchannels. The results also suggested that the performance of microchannels with 500 µm hydraulic diameter is balanced, considering both heat transfer performance and pressure drop constraints.
“…In addition, the flow area is higher in rectangular microchannels when compared to square microchannels. 44 Hence, friction factor is higher in rectangular microchannels. The friction factor in square microchannels is lower by 37.55% and 32.25% compared to rectangular microchannels, at lower fluid velocities (u m = 0.5 m/s) and higher velocities (u m = 2 m/s), respectively.Figure 12.Friction factor vs. Fluid velocity of 0.1 vol.…”
The objective of this paper is to analyze the effect of hydraulic diameter and channel shape on the thermal and hydrodynamic characteristics of a microchannel cooled by Graphene-Platinum/water hybrid nanofluid for electronic cooling applications. The study was performed numerically using mathematical software called Maple 19.0. Microchannels having square and rectangular cross-sections, and hydraulic diameters ranging from 200 µm to 1000 µm were taken into consideration. Thermal resistance, heat transfer coefficient, pressure drop and friction factor were evaluated for different conditions and their corresponding graphs are presented and discussed. It was evident from the results that low thermal resistance and high heat transfer coefficient was achieved upon decreasing the hydraulic diameter, which is favorable for the cooling of electronic chips and devices. Based on the Reynolds number, the heat transfer coefficient increased by 2 to 4 times for both rectangular and square microchannels, on decreasing the hydraulic diameter from highest value (1000 µm) to lowest value (200 µm). However, friction factor and pressure drop increased for channels with lower hydraulic diameters. In addition, rectangular microchannels exhibited better heat transfer performance, while square microchannels had lower friction factor and pressure drop. Rectangular microchannels presented a maximum enhancement of 30% in heat transfer coefficient and a reduction of 18% in thermal resistance, when compared to square microchannels. The results also suggested that the performance of microchannels with 500 µm hydraulic diameter is balanced, considering both heat transfer performance and pressure drop constraints.
In this paper, we numerically study the influence of the addition of parallelogram ribs and pie-shaped ribs in micro-channels on thermal exchange in three dimensions. We design four different silicon micro-channel heat sinks; the first and second cases without ribs, the third case with added pie-shaped ribs, and a fourth case containing parallelogram ribs. The main purpose of this research is to determine the best micro-channel heat sink in which the heat dissipation is sufficient to improve the heat exchange performance of the micro-channel, as well as to improve the cooling of the electronic components. A constant heat flux is applied to the bottom wall of the four micro-channels, and we use liquid diamond-water with a volume concentration of 5% diamond nanoparticles as a coolant, with a Reynolds number chosen between 200 and 600. The numerical results show that the Nusselt number (Nu) of the micro-channel that contains the parallelogram ribs is higher than that for the other cases, and it also yiels lower temperature values on the bottom wall of the substrate compared to the micro-channel containing pie ribs. When increasing the flow velocity, the thermal resistance of the micro-channel decreases in all cases, and we then find the largest value of the friction factor in the fourth case (with parallelogram ribs).
“…3-1-Governing equations The governing equations for this conjugated heat transfer problem can be written as follows:[8], [9] Where: Dh is the hydraulic diameter. And the pressure drop is the difference between the total pressure at the inlet and outlet.…”
Section: -Mathematical Modelmentioning
confidence: 99%
“…For calculated the thermo-physical properties of Nano fluid the following equations will be used: [9], [12] The density and specific heat are calculated by using 1-∅ ………….. (7) ……………. (8) The viscosity of the Nano fluid was calculated from the relation:…”
This study aims to study the effect of different cooling fluids (pure fluids, Nanofluids and microencapsulated phase change materials suspensions) and the cooling performance of rectangular micro-channel heat sink. Three types of Nanofluids (Al2O3-water, Cu-water,Tio2-water), three types of microencapsulated phase change materials suspensions(MEPCM) are(RT44-water, paraffin wax water, n-octed-water ) and three pure fluids ) Water, Oil ,Ethylene Glycol ) were used with constant heat flux(100 W /cm 2 ) applied on the base of heat sink. The volumetric concentrations of Nanofluids and MEPCM suspensions (1%, 3%, and 5%) and (100 to 900) is the range of Reynolds number used in this study. The results showed that, using different types of Nanofluids and MEPCM suspensions lead to enhance the cooling performance of the micro channel heat sink (MCHS), since it lead to increase the heat transfer compared with pure fluids. The heat transfer in (MCHS) for MEPCMs is higher than that for Nanofluids. Also, the performance of heat sink increases with increase the concentration of Nanofluids and MEPCMS at certain volumetric concentration. Additionally, the pressure drop for MEPCM suspensions and Nanofluids increased compared with pure fluids.
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