Computational investigation and parametrization of the pumping effect in temperature-driven flows through long tapered channels

Tatsios, Giorgos; Rojas-Cárdenas, Marcos; Baldas, Lucien; Colin, Stéphane; Valougeorgis, Dimitris

doi:10.1007/s10404-017-1932-5

Cited by 19 publications

(13 citation statements)

References 40 publications

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“…In recent years, with the development of materials technology and micro-machining technology, the pump structure can now be produced by using poly-silicon material, and using the inter-molecular gaps in porous materials such as aerogel membranes [ 10 , 11 , 12 ], mixed cellulose ester (MCE) [ 13 , 14 ], zeolite [ 15 , 16 ], porous ceramics [ 17 , 18 ] and Bi 2 Te 3 [ 19 , 20 ] to construct the flowing channel of the Knudsen pump. Since the rectangular Knudsen pump has been proposed, many structures for the channel were successively designed and studied ( Figure 1 ), including the sinusoidal micro-channel [ 21 ], matrix micro-channel [ 21 ], curved micro-channel with different curvature radii [ 22 ], alternately connected curved and straight micro-channel [ 23 , 24 ], tapered micro-channel [ 25 ], and ratchet micro-channel [ 26 , 27 , 28 , 29 ].…”

Section: Introductionmentioning

confidence: 99%

Study of Flow Characteristics of Gas Mixtures in a Rectangular Knudsen Pump

et al. 2019

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A Knudsen pump operates under the thermal transpiration effect or the thermal edge effect on the micro-scale. Due to the uneven temperature distribution of the walls in the channel axis direction or the constant temperature of the tips on the walls, directional thermally-induced flow is generated. In this paper the Direct Simulation Monte Carlo (DSMC) method is applied for N2–O2 gas mixtures in the ratios of 4:1, 1:1, and 1:4 with different Knudsen numbers in a classic rectangular Knudsen pump to study the flow characteristics of the gas mixtures in the pump. The results show that the changing in the gas physical properties does not affect the distribution of the velocity field, temperature fields, or other fields in the Knudsen pump. The thermal creep effect is related to the molecular mass of the gas. Even in N2 and O2 gas mixtures with similar molecular masses, N2 can be also found to have a stronger thermal creep effect. Moreover, the lighter molecular weight gas (N2) can effectively promote the motion of the heavier gas (O2).

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Section: Introductionmentioning

confidence: 99%

Study of Flow Characteristics of Gas Mixtures in a Rectangular Knudsen Pump

et al. 2019

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“…[14][15][16] Thermal creep/transpiration problems were studied by several researchers during the past [17][18][19] and recent years. 15,20,21 Alexeenko et al 15 investigated the e®ects of wall temperature distribution applied to a two-dimensional¯nite length microchannel. They examined three wall temperature distributions: linear, stepwise, and a nonmonotonic pro¯le typical for a radiantly heated Knudsen compressor's membrane and compared BGK and ES and DSMC solutions.…”

Section: Introductionmentioning

confidence: 99%

“…They reported mass°ow rate dependency on the wall temperature and derived analytical expressions for the mass°ux. Tatsios et al 21 considered the associated pumping e®ects through extended channels with linearly diverging or converging cross-sections. They parametrized mass°ow rate and the induced pressure di®erence between the channel inlet and outlet in terms of geometrical and operational data including the channel inclination and the inlet pressure.…”

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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“…Furthermore, since the length of the narrow microchannels is always much longer than the radius, the flow may be considered fully developed, i.e., the pressure varies only in the axial direction and remains constant in each cross section of the capillary. Thus, flow modeling is based on the infinite capillary theory, which is well known and established for pressure- and temperature-driven rarefied gas flows [24,25,26,27,28,29,30]. Additionally, in cases where the fully developed assumptions are not met (i.e., in the wide channels of diameter D subject to thermally driven back flow), the end effect correction is accordingly introduced [31,32].…”

Section: Kinetic Modelingmentioning

confidence: 99%

“…In addition to the temperature-driven flow, a pressure-driven flow is generated. Similar to the analysis performed in [30] for thermally driven flow through tapered channels, the net mass flow rate m˙ may be computed based on the differential equation dPdz=−truem˙υ0(z)πR3GP(δ)+GT(δ)GP(δ)P(z)T(z)dTdz, subject to the given pressures P(0) and P(L) at the channel inlet and outlet, respectively. Here, z∈[0,L] is the coordinate along which the flow is directed, υ0(z)=2RgTfalse(zfalse) is the probable molecular speed, Rg is the specific gas constant, T(z) is ...…”

Section: Kinetic Modelingmentioning

confidence: 99%

Design Guidelines for Thermally Driven Micropumps of Different Architectures Based on Target Applications via Kinetic Modeling and Simulations

et al. 2019

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The manufacturing process and architecture of three Knudsen type micropumps are discussed and the associated flow performance characteristics are investigated. The proposed fabrication process, based on the deposition of successive dry film photoresist layers with low thermal conductivity, is easy to implement, adaptive to specific applications, cost-effective, and significantly improves thermal management. Three target application designs, requiring high mass flow rates (pump A), high pressure differences (pump B), and relatively high mass flow rates and pressure differences (pump C), are proposed. Computations are performed based on kinetic modeling via the infinite capillary theory, taking into account all foreseen manufacturing and operation constraints. The performance characteristics of the three pump designs in terms of geometry (number of parallel microchannels per stage and number of stages) and inlet pressure are obtained. It is found that pumps A and B operate more efficiently at pressures higher than 5 kPa and lower than 20 kPa, respectively, while the optimum operation range of pump C is at inlet pressures between 1 kPa and 20 kPa. In all cases, it is advisable to have the maximum number of stages as well as of parallel microchannels per stage that can be technologically realized.

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Computational investigation and parametrization of the pumping effect in temperature-driven flows through long tapered channels

Cited by 19 publications

References 40 publications

Study of Flow Characteristics of Gas Mixtures in a Rectangular Knudsen Pump

Study of Flow Characteristics of Gas Mixtures in a Rectangular Knudsen Pump

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

Design Guidelines for Thermally Driven Micropumps of Different Architectures Based on Target Applications via Kinetic Modeling and Simulations

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