Convective heat transfer in diverging and converging microchannels

Duryodhan, V. S.; Singh, Abhijeet; Singh, Suneet; Agrawal, Amit

doi:10.1016/j.ijheatmasstransfer.2014.09.042

Cited by 99 publications

(16 citation statements)

References 40 publications

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“…[1][2][3][4] Most of the earlier studies focused on microchannels with nonuniform cross-sections conducting liquid°ows. [5][6][7][8] To review works on gas°ows, one could note work of Varade et al 9 who performed an experimental and numerical study on gaseous°ow at slip regime through divergent microchannels. They showed that the pressure drop, centerline velocity, and wall shear decrease with an increase in divergence angle for their range of study.…”

Section: Introductionmentioning

confidence: 99%

On the thermally-driven gas flow through divergent micro/nanochannels

Mozaffari

Roohi

2017

Int. J. Mod. Phys. C

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A detailed study on thermally driven flows through divergent micro/nanochannels is presented. Rarefied gas flow behavior and thermal mass flow rate were investigated with different divergence angles ranging between 0[Formula: see text] and 7[Formula: see text] at two aspect ratios ([Formula: see text]) using particle-based direct simulation Monte-Carlo (DSMC) method. We compare our DSMC solutions for normalized thermal mass flow rate with the numerical solution of the Boltzmann–Krook–Walender (BKW) model and Bhatnagar–Gross–Krook (BGK) model and asymptotic theory over a wide range of Knudsen number in the transition regime. The flow field properties including Mach number, pressure, overall temperature and magnitude of shear stress are examined in detail. Based on our analysis, we observed an approximately constant velocity and pressure distribution at a microchannel with a small opening angle. Our results also demonstrate that the heat lines from weakly nonlinear form of Sone constitutive law and DSMC show good agreement at low Knudsen numbers. Moreover, we show that the effect of divergence angle is influential in increasing normalized thermal mass flow rate at early transition regime.

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Section: Introductionmentioning

confidence: 99%

On the thermally-driven gas flow through divergent micro/nanochannels

Mozaffari

Roohi

2017

Int. J. Mod. Phys. C

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“…A grid independence study is also performed and accordingly 0.45 and 1.3 million cells are selected for the fluid and solid zones respectively. Details about the grid independence study can be found in our earlier study (Duryodhan et al, 2015). Numerical results are first validated with the experimentally measured data for 8º diverging microchannel.…”

Section:  mentioning

confidence: 88%

Three-Dimensional Numerical Study of Conjugate Heat Transfer in Diverging Microchannel

Duryodhan

Singh²,

Singh³

et al. 2016

Proceedings of the Indian National Science Academy

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Increase in applications of varying cross sectional area microchannels in microdevices has provided the need to understand fluid flow and heat transfer through such flow passages. This study focuses on conjugate heat transfer study through a diverging microchannel. Three-dimensional numerical simulations are performed using commercially available package. Diverging microchannels with different geometrical configurations (i.e. varying angle: 1-8°, depth: 86-200 µm, solid-tofluid thickness ratio: 1.5-4) are employed for this purpose. Simulations are carried out for varying mass flow rate (3.3 x 10 -5 -8.3 x 10 -5 kg/s) and heat flux (2.4-9.6 W/cm 2 ) conditions. Heat distribution along the flow direction is studied to understand the effect of wall conduction. Wall conduction number (M) varies from 0.006 to 0.024 for the range of parameters selected in the study. Wall conduction is observed to be a direct function of depth and solid-to-fluid thickness ratio, and varies inversely with angle of diverging microchannel. It is observed that the area variation and wall conduction contribute separately towards redistribution of the supplied heat flux. This leads to reduced temperature gradients in diverging microchannel. The results presented in this work will be useful for designing future microdevices involving heating or cooling.

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“…studied the mechanism of enhanced heat transfer in CD tubes and found that the key parameter affecting the heat transfer performance -roughness height should be located in the flow transition zone. Meanwhile, Duryodhan [34] carried out single phase fluid flow and heat transfer in diverging and converging microchannels, and found that the heat transfer coefficient is 35% higher in converging microchannel compared with diverging microchannel. Currently, the research on CD tubes as high-efficiency enhanced heat transfer units mainly focuses on single-phase flow and convective boiling heat transfer inside and outside the tube, but rarely focuses on falling film evaporation or sensible heating.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on heat and mass transfer of falling liquid films in converging-diverging tubes with water

Huang

Deng

2018

International Journal of Heat and Mass Transfer

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To improve the heat and mass transfer performances of falling films and develop a new type of falling film evaporator, the characteristics of falling film evaporation and sensible heat and mass transfer in four different sizes of converging-diverging (CD) tubes were experimentally explored in this study. By analyzing the relationship between the heat transfer coefficient and the falling film flow rate, it was found that the CD tube is suitable for falling film evaporation and sensible heating with a large Reynolds number. For different sizes of tubes, the key factor affecting the heat transfer in falling film evaporation and sensible heating is the height of the ribs. At the same rib height and rib pitch, the longer the converging segment of the CD tube, the better the heat transfer performance. According to the comparative analysis of the evaporation and sensible heating heat transfer performances inside the four CD tubes, the CD tube 3# is best. The evaporation heat transfer coefficient (at Reynolds number of liquid films of 2356), evaporation mass transfer rate (at the perimeter flow rate of liquid films is 0.173 kgm-1 s-1), and sensible heating heat transfer coefficient (at Reynolds number of liquid films of 1635) of CD tube 3# are 62%, 38% and 63% higher than that of the smooth tube, respectively. For the same CD tube, the evaporation heat transfer coefficient is larger than the sensible heating heat transfer coefficient, but both increases as the flow rate increases. The heat transfer correlations of falling film evaporation and sensible heating in the experimental range were obtained through data fitting. It will provide a useful reference for future engineering design and industrial applications.

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Convective heat transfer in diverging and converging microchannels

Cited by 99 publications

References 40 publications

On the thermally-driven gas flow through divergent micro/nanochannels

On the thermally-driven gas flow through divergent micro/nanochannels

Three-Dimensional Numerical Study of Conjugate Heat Transfer in Diverging Microchannel

Experimental study on heat and mass transfer of falling liquid films in converging-diverging tubes with water

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