Energy
Farhaad Nasiri Khamesloo; Davood Domiri Ganji
Articles in Press, Accepted Manuscript, Available Online from 20 March 2024
Abstract
The dissipation of heat generated in electronic and industrial chips is essential for the health of these components. For this purpose, one of the best choices is a microchannel heatsink, which offers a lower pressure drop compared to other channels while maintaining a high heat transfer rate. In this ...
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The dissipation of heat generated in electronic and industrial chips is essential for the health of these components. For this purpose, one of the best choices is a microchannel heatsink, which offers a lower pressure drop compared to other channels while maintaining a high heat transfer rate. In this study, a fractal microchannel heatsink, introduced in recent years, has been numerically investigated. To enhance the performance of the microchannel, two types of fins have been added to the microchannel walls, resulting in the creation of two new geometries. In the first new geometry, fins are placed at the bottom of the microchannel, while in the second one, fins are placed on the sidewalls of the microchannel. It is worth mentioning that the volume of fins used is consistent across both geometries. Thermal and hydraulic parameters have been examined, revealing that both new geometries increase the Nusselt number, with the highest increase observed in the microchannel with fins on the sidewalls, amounting to 28%. Additionally, both geometries increase the pumping power, with the highest increase observed in the microchannel with fins at the bottom, reaching 120%. Finally, by evaluating the performance coefficient, it was determined that the microchannel with fins on the sidewalls increases the overall performance by 3 to 6% across different flow rates, whereas the microchannel with fins at the bottom reduces the system's performance by 7%. Therefore, for efficient dissipation of the generated heat, it is preferable to use a microchannel heatsink with fins on the sidewalls.
Nano-Biotechnology
F. Nasiri Khamesloo; D. Domiri Ganji
Abstract
The use of microchannel heat sinks is one of the most popular methods for cooling electronic components. In recent years, fractal microchannels have attracted researchers' attention, leading to increased heat transfer and reduced pressure drop compared to parallel microchannels. In this study, two hybrid ...
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The use of microchannel heat sinks is one of the most popular methods for cooling electronic components. In recent years, fractal microchannels have attracted researchers' attention, leading to increased heat transfer and reduced pressure drop compared to parallel microchannels. In this study, two hybrid nanofluids under laminar flow conditions are used for cooling inside microchannels, and simulations are conducted using COMSOL Multiphysics software. Parameters such as pumping power, maximum temperature, and performance evaluation coefficient are investigated for two hybrid nanofluids, Fe3O4-MoS2 and Fe3O4-Al2O3 (mixed 50%-50% and with a volume fraction of 1% for each nanoparticle). The results indicate that the thermal performance of Fe3O4-MoS2 hybrid nanofluid is superior, leading to a 0.5% improvement in the maximum temperature of the heat sink. On the other hand, the use of this hybrid nanofluid increases pumping power by 9% inside the microchannel. Ultimately, the overall system performance is enhanced with the use of both hybrid nanofluids, and the Fe3O4-MoS2 hybrid nanofluid improves the overall system performance by 3.2%, providing better performance and making it more suitable for cooling microchannel heat sinks.
Energy
A. Jabbari; M. Basaki; M. R. Sheykholeslami
Abstract
In this paper, an axial flux permanent magnet generator for a 30 kW direct drive wind turbine is designed and the design parameters were optimized with the aim of achieving high efficiency. In order to reduce the cogging torque and electromagnetic torque ripple components, the air core topology has been ...
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In this paper, an axial flux permanent magnet generator for a 30 kW direct drive wind turbine is designed and the design parameters were optimized with the aim of achieving high efficiency. In order to reduce the cogging torque and electromagnetic torque ripple components, the air core topology has been used, and with the aim of increasing the power capacity of the generator, a modular structure has been used. The advantage of the modular design is that each module can be considered as a generator unit and depending on the wind speed conditions, the number of units corresponding to the wind speed can be placed in the circuit and the generator will always work with maximum efficiency. First, by using the governing equations, the dimensions and performance characteristics of the generator are determined, and then a generator prototype is fabricated based on the electromagnetic design. In order to evaluate the output performance of the generator, machine simulation was performed in Maxwell finite element analysis software and the characteristic curves of voltage, current and ohmic losses were extracted. In order to evaluate the accuracy of the results, the outcomes of the analytical method have been compared with the experimental tests results.