Heat Transfer Enhancement and Entropy Generation of Nanofluids Laminar Convection in Microchannels with Flow Control Devices

Li, Ping; Xie, Yuanyuan; Zhang, Di; Xie, Gongnan

doi:10.3390/e18040134

Cited by 40 publications

(20 citation statements)

References 43 publications

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“…In the forced conductive flow with heat transfer, the entropy generation contains two parts, one caused by the heat transfer irreversibility, and the other due to the fluid frictional irreversibility [22]. The entropy generation of flow can be calculated by the following equations [23] …”

Section: Parameter Definitionmentioning

confidence: 99%

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Effects of Endwall Fillet and Bulb on the Temperature Uniformity of Pin-Fined Microchannel

Pan

et al. 2017

Entropy

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Endwall fillet and bulb structures are proposed in this research to improve the temperature uniformity of pin-fined microchannels. The periodical laminar flow and heat transfer performances are investigated under different Reynolds numbers and radius of fillet and bulb. The results show that at a low Reynolds number, both the fillet and the bulb structures strengthen the span-wise and the normal secondary flow in the channel, eliminate the high temperature area in the pin-fin, improve the heat transfer performance of the rear of the cylinder, and enhance the thermal uniformity of the pin-fin surface and the outside wall. Compared to traditional pin-fined microchannels, the flow resistance coefficient f of the pin-fined microchannels with fillet, as well as a bulb with a 2 µm or 5 µm radius, does not increase significantly, while, f of the pin-fined microchannels with a 10 µm or 15 µm bulb increases notably. Moreover, Nu has a maximum increase of 16.93% for those with fillet and 20.65% for those with bulb, and the synthetic thermal performance coefficient TP increases by 16.22% at most for those with fillet and 15.67% at most for those with bulb. At last, as the Reynolds number increases, heat transfer improvement of the fillet and bulb decreases.

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Section: Parameter Definitionmentioning

confidence: 99%

“…As for the internal microchannel flow, the entropy generating rate per unit length is calculated by [23] …”

Section: Parameter Definitionmentioning

confidence: 99%

Effects of Endwall Fillet and Bulb on the Temperature Uniformity of Pin-Fined Microchannel

Pan

et al. 2017

Entropy

Self Cite

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“…After the pioneering works by Choi [16], Eastman et al [17], Eastman et al [18], Xuan and Li [3], and Choi et al [19], nanofluids have been extensively studied experimentally, theoretically and numerically [20][21][22][23][24][25][26][27][28]. In a recent review by Lomascolo et al [29], it has been shown that the number of annual journal publications about nanofluids has been growing exponentially.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer and Flow of Nanofluids in a Y-Type Intersection Channel with Multiple Pulsations: A Numerical Study

Massoudi

Yan

2017

Energies

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Abstract:In this paper, we study pulsed flow and heat transfer in water-Al 2 O 3 nanofluids in a Y-type intersection channel with two inlets and one outlet. At the two inlets, two sinusoidal velocities with a phase difference of π are applied. We assume that the shear viscosity and the thermal conductivity of the nanofluids depend on the nanoparticles concentration. The motion of the nanoparticles is modeled by a convention-diffusion equation, where the effects of the Brownian motion, thermophoretic diffusion, etc., are included. The effects of pulse frequency, pulse amplitude and nanoparticles concentration on the heat transfer are explored numerically at various Reynolds numbers. The results show that the application of the pulsed flow improves the heat transfer efficiency (Nusselt number) for most of the cases studied. Amongst the four factors considered, the effect of the frequency seems to be the most important.

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“…The macroscopic mixture model has been widely used by many researchers to study nanofluid heat transfer with low-particle concentration as it provides reasonably accurate results with less computing power and time [21][22][23][24]32,37,38]. Thus, the macroscopic model is the best suited for the present study.…”

Section: Introductionmentioning

confidence: 99%

Constructal Design of a Rectangular Fin in a Mixed Convective Confined Environment

et al. 2018

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Extended surfaces or fins offer an efficient solution in many engineering situations that demand a higher heat transfer, including cooling gas-turbine components and electronic chips via internal convective flows. However, fins require a higher active surface area for higher heat transfer, which may not be always feasible in a confined environment. A feasible solution to enhance heat transfer from fins can be the use of nanofluids, which are the combination of a fluid base and nanoparticles. The main purpose of this study is, therefore, to optimize a rectangular fin intruded into the mixed convective confined space filled with a nanofluid and by means of constructal design. Here, a two-dimensional macroscopic numerical model has been developed for Al 2 O 3 -water nanofluid to investigate the heat transfer and fluid flow inside a square confined-space with an intruded rectangular fin and to optimize the fin geometry for maximizing the heat transfer using the constructal design method. The flow fields, temperature fields, heat transfer rates, and the transition from forced to mixed convection are examined for different values of Rayleigh and Reynolds numbers for various fin geometries in order to maximize the heat transfer from the fin to the surrounding nanofluid flow. The outcome of this study provides important insights into the constructal design method for the confined environment, which would be beneficial in developing novel fin geometries with enhanced and controlled heat-transfer for engineering problems, including cooling gas-turbine components and electronic chips.

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Heat Transfer Enhancement and Entropy Generation of Nanofluids Laminar Convection in Microchannels with Flow Control Devices

Cited by 40 publications

References 43 publications

Effects of Endwall Fillet and Bulb on the Temperature Uniformity of Pin-Fined Microchannel

Effects of Endwall Fillet and Bulb on the Temperature Uniformity of Pin-Fined Microchannel

Heat Transfer and Flow of Nanofluids in a Y-Type Intersection Channel with Multiple Pulsations: A Numerical Study

Constructal Design of a Rectangular Fin in a Mixed Convective Confined Environment

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