Correction to: Effects of L-shaped fins on cooling an electronic heat sink fitted under magnetic field of CNT–water/ethylene glycol nanoliquid (original) (raw)
Correction to "Micro scale pin fin heat sinks: Parametric performance evaluation study
IEEE Transactions on Components and Packaging Technologies, 2000
A parametric study of heat transfer and pressure drop associated with forced flow of deionized water over five micro pin fin heat sinks of different spacing, arrangements, and shapes was conducted experimentally. Nusselt numbers and friction factors were obtained over Reynolds numbers ranging from 14 to 720. The thermal and hydraulic results were obtained to evaluate and compare the heat sinks performances at fixed mass flow rate, fixed pressure drop, and fixed pumping power. Two distinct regions of the Nusselt number dependency on the Reynolds number separated by a critical Reynolds number have been identified for unstreamlined pin fin devices while the streamlined device showed no slope change. The effects of spacing, shape of pin fins, and arrangement on friction factor and heat transfer were in agreement with existing literature. The results indicate that utilizing streamlined pin fin heat sinks can significantly enhance the thermal-hydraulic performance of the heat sink, but only at moderate Reynolds numbers.
Lab on a Chip, 2014
Assembled nanofin heat sinks, nanostructures which are formed via external forces in a cooling microfluidic to remove heat from hot spots, are a new concept that has recently been introduced. In this work, we investigate nanofin structures formed by CrO 2 and Fe 2 O 3 magnetic nanoparticles and compare their performance. Thermal imaging is used for comparison of three cases including: (i) DI water as the coolant liquid, (ii) suspension of magnetic particles in DI water, and (iii) suspension of magnetic particles in DI water in the presence of a magnetic field. For each case, the experiments are conducted at three different flow rates of 10, 40 and 120 μl min −1 . Our results suggest that the high thermal conductivity of the nanofins composed of CrO 2 significantly enhances the heat exchange across the microchannel. The proof-of-concept magnetophoretic system can offer a practical solution for the cooling of future compact electronics.
Promising Technology for Electronic Cooling: Nanofluidic
2013
Currently, the thermal management of microelectromechanical systems (MEMS) has become a challenge. In the present research, a micro pulsating heat pipe (MPHP) with a hydraulic diameter of 508 lm, is experimented. The thermal performance of the MPHP in both the transient and steady conditions, the effects of the working fluid (water, silver nanofluid, and ferrofluid), heating power (4, 8, 12, 16, 20, 24, and 28 W), charging ratio (20, 40, 60, and 80%), inclination angle (0 deg, 25 deg, 45 deg, 75 deg, and 90 deg relative to horizontal axis), and the application of magnetic field, are investigated and thoroughly discussed. The experimental results show that the optimum charging ratio for water is 40%, while this optimum for nanofluids is 60%. In most of situations, the nanofluid charged MPHPs have a lower thermal resistance relative to the water charged ones. For ferrofluid charged MPHP, the application of a magnetic field substantially reduces the thermal resistance. This study proposes an outstanding technique for the thermal management of electronics.
Physica A: Statistical Mechanics and its Applications, 2020
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Controlled assembly and alignment of CNTs in ferrofluid: Application in tunable heat transfer
Journal of Magnetism and Magnetic Materials, 2019
Nanofluids are new generation of heat transfer fluids with enhanced thermal properties. When using nanofluids, one of the major problems is aggregation of nanoparticles. In this study, in order to benefit from controlled aggregation of nanoparticles by application of magnetic field, we used magnetic nanoparticles (MNPs) as one of the most useful nanoparticles in recent energy and biomedical researches. To achieve a more precise insight about behavior of MNPs under magnetic field, a water-based nanofluid of Fe3O4/MWNTs was studied. Due to the importance of thermal conductivity (TC) of nanofluids, it was investigated for the mentioned nanofluid. Taking advantage of magnetic properties of magnetite nanoparticles besides high thermal conductivity of multi-wall carbon nanotubes, a water-based nanofluid of 0.1 wt.% Fe3O4/MWNT was prepared and its thermal conductivity was measured for the situations in which temperature gradient and magnetic field were either parallel or perpendicular. The findings suggested that TC was increased by 52% and 11.9% at H= 0.14 T for the two situations, respectively. This finding proved the anisotropic behavior of magnetic nanofluid. Formation of chain-like structures of MNPs was demonstrated through a novel approach. This phenomenon was found to be the reason of thermal conductivity enhancement. Our findings show that employing Fe3O4/MWNT is a promising approach for improving heat transfer efficiency of heat carriers.
The Impact of Cavities in Different Thermal Applications of Nanofluids: A Review
Nanomaterials
Nanofluids and nanotechnology are very important in enhancing heat transfer due to the thermal conductivity of their nanoparticles, which play a vital role in heat transfer applications. Researchers have used cavities filled with nanofluids for two decades to increase the heat-transfer rate. This review also highlights a variety of theoretical and experimentally measured cavities by exploring the following parameters: the significance of cavities in nanofluids, the effects of nanoparticle concentration and nanoparticle material, the influence of the inclination angle of cavities, heater and cooler effects, and magnetic field effects in cavities. The different shapes of the cavities have several advantages in multiple applications, e.g., L-shaped cavities used in the cooling systems of nuclear and chemical reactors and electronic components. Open cavities such as ellipsoidal, triangular, trapezoidal, and hexagonal are applied in electronic equipment cooling, building heating and cool...
Thermal management of water based SWCNTs enclosed in a partially heated trapezoidal cavity via FEM
International Journal of Heat and Mass Transfer, 2017
Present study, examines the phenomena of natural convection flow in a partially heated trapezoidal cavity loaded with the nanofluid in the presence of Single Wall Carbon Nanotubes (SWCNTs). A modified model for effective thermal conductivity of carbon nanotube is used to develop the governing partial differential equations. Thermal management within the cavity is controlled via two simultaneous features: one is to use the partially heated bottom wall and other is to use conductivity of Carbon particles. Most significant and physical conditions are adjusted at the inclined walls of the trapezoidal cavity to obtain the behavior of stream lines and heat management. The Gelerkin finite element method is implemented to solve the dimensionless form of PDEs. Simulations are performed for the different lengths of the heated portion ð0:3 6 L 6 0:7Þ, various choices of Raleigh number ð10 4 6 Ra 6 10 7 Þ and volume fraction ð0:0 6 / 6 0:2Þ. Flow field and thermal field are visualized through streamlines and isotherms. Moreover, results are obtained for Nusselt number over partially heated wall, temperature and velocity distribution over the mean position of the cavity. It is found that, by reducing the length of heated portion, flow filed is getting stronger but thermal depicts the opposite trend inside the cavity. Variation of Raleigh number also has significant influence on flow and thermal field. Conduction was dominant at low Ra but later on convection was found to be dominant for large choice. Fluid circulation was stronger and heat transfer rate was very slow at low viscous effects. From the graph it is clear that greater heat transfer will be occurred in the presence of nanofluid as compared to the based fluid water. Similarly velocity distribution of water is dominant as compare to the nanofluid.