Power generation enhancement in direct methanol fuel cells using non-uniform cross-sectional serpentine channels

Hu, Xu-Qu; Yang, Qinwen; Xiao, Gang; Xiaoting, Chen; Qiu, Xiang

doi:10.1016/j.enconman.2019.03.058

Cited by 22 publications

(8 citation statements)

References 37 publications

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“…The finite element methods [ 36 ], finite difference method [ 34 ] and the finite volume method [ 35 ] are traditional macroscopic methods for Computational Fluid Dynamics (CFD) calculation. The lattice Boltzmann method (LBM) is a computational fluid dynamics method based on a mesoscope simulation scale [ 37 , 38 , 39 , 40 , 41 ]. Compared with other traditional CFD calculation methods, this method has mesoscopic model characteristics between the micro molecular dynamics model and macro continuous model.…”

Section: Dynamics Equation and Numerical Methodsmentioning

confidence: 99%

Temporal–Spatial Evolution of Kinetic and Thermal Energy Dissipation Rates in a Three-Dimensional Turbulent Rayleigh–Taylor Mixing Zone

Guo

Wei

et al. 2020

Entropy

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In this work, the temporal–spatial evolution of kinetic and thermal energy dissipation rates in three-dimensional (3D) turbulent Rayleigh–Taylor (RT) mixing are investigated numerically by the lattice Boltzmann method. The temperature fields, kinetic and thermal energy dissipation rates with temporal–spatial evolution, the probability density functions, the fractal dimension of mixing interface, spatial scaling law of structure function for the kinetic and the thermal energy dissipation rates in 3D space are analysed in detail to provide an improved physical understanding of the temporal–spatial dissipation-rate characteristic in the 3D turbulent Rayleigh–Taylor mixing zone. Our numerical results indicate that the kinetic and thermal energy dissipation rates are concentrated in areas with large gradients of velocity and temperature with temporal evolution, respectively, which is consistent with the theoretical assumption. However, small scale thermal plumes initially at the section of half vertical height increasingly develop large scale plumes with time evolution. The probability density function tail of thermal energy dissipation gradually rises and approaches the stretched exponent function with temporal evolution. The slope of fractal dimension increases at an early time, however, the fractal dimension for the fluid interfaces is 2.4 at times t/τ ≥ 2, which demonstrates the self-similarity of the turbulent RT mixing zone in 3D space. It is further demonstrated that the second, fourth and sixth-order structure functions for velocity and temperature structure functions have a linear scaling within the inertial range.

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Section: Dynamics Equation and Numerical Methodsmentioning

confidence: 99%

Temporal–Spatial Evolution of Kinetic and Thermal Energy Dissipation Rates in a Three-Dimensional Turbulent Rayleigh–Taylor Mixing Zone

Guo

Wei

et al. 2020

Entropy

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“…The re-normalization group (RNG) k-e turbulence model is used for steady simulation, and the large eddy simulation (LES) turbulence model is used for unsteady simulation [30,31]. Turbulence is inevitable in the centrifugal fan.…”

Section: Governing Equations and Turbulence Modelmentioning

confidence: 99%

Unsteady Flow Characteristics of Rotating Stall and Surging in a Backward Centrifugal Fan at Low Flow-Rate Conditions

Zhou

Yang

et al. 2020

Processes

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The steady and unsteady flow characteristics of internal flow in a backward centrifugal fan of double inlet at low flow-rate condition are investigated by computational fluid dynamics in this paper. The investigation aims to reveal insights into generation mechanisms and our physical understanding of the rotating stall and surge. The numerical results mainly demonstrate that, with decreasing flow rate, a large number of vortex flows almost increasingly occupy the internal flow of the impeller. The reverse flow and separation vortices increasingly appear near the outlet of volute, and the internal flow of the impeller is completely blocked by the separated vortex flow at low flow-rate conditions. Results indicate that, due to a synchronization of the impeller rotation and separation vortex, these separated vortices act intensely on the pressure surface of the blade with time evolution, and the interaction between the separated vortices and surface of blade increasingly yields small-scale eddies. It is further found that the amplitude of pressure and velocity fluctuations gradually increase with the decrease of flow rate in a certain range. The unsteady characteristics acting on the volute tongue gradually increase in a range of Qd to 0.3 Qd (Qd is the design volume flow rate) with the decrease of flow rate, and the unsteady characteristics acting on the volute tongue are weakened at the working condition of 0.15 Qd. These insights clearly explain the unsteady nature of the rotating stall and surge phenomenon in the double inlet backward centrifugal fan.

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“…According to results from [ 12 ], the power density (6.64 mWcm −2 ) of trapezoidal cross-section channels was nearly two times higher than the power density (3.9 mWcm −2 ) of rectangular cross-section channels at a 7 M methanol concentration. A serpentine channel with a non-uniform cross-section was designed and analyzed in [ 13 ]. Numerical results show that non-uniform converging designs enhance the peak power generation performance by as much as 12% at high-current-density operations.…”

Section: Introductionmentioning

confidence: 99%

Design and Simulation of Air-Breathing Micro Direct Methanol Fuel Cells with Different Anode Flow Fields

2021

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The design of the anode flow field is critical for yielding better performance of micro direct methanol fuel cells (µDMFCs). In this work, the effect of different flow fields on cell performance was investigated by the simulation method. Compared with grid, parallel and double-serpentine flow fields, a single-serpentine flow field can better improve the mass transfer efficiency of methanol and the emission efficiency of the carbon dioxide by-product. The opening ratio and channel length also have important effects on the cell performance. The cells were manufactured using silicon-based micro-electro-mechanical system (MEMS) technologies and tested to verify the simulation results. The experimental results show that the single-serpentine flow field represents a higher peak power density (16.83 mWcm−2) than other flow fields. Moreover, the results show that an open ratio of 47.3% and a channel length of 63.5 mm are the optimal parameters for the single-serpentine flow field.

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Power generation enhancement in direct methanol fuel cells using non-uniform cross-sectional serpentine channels

Cited by 22 publications

References 37 publications

Temporal–Spatial Evolution of Kinetic and Thermal Energy Dissipation Rates in a Three-Dimensional Turbulent Rayleigh–Taylor Mixing Zone

Temporal–Spatial Evolution of Kinetic and Thermal Energy Dissipation Rates in a Three-Dimensional Turbulent Rayleigh–Taylor Mixing Zone

Unsteady Flow Characteristics of Rotating Stall and Surging in a Backward Centrifugal Fan at Low Flow-Rate Conditions

Design and Simulation of Air-Breathing Micro Direct Methanol Fuel Cells with Different Anode Flow Fields

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