Flow and heat transfer simulation in a wall-driven porous cavity with internal heat source by multiple-relaxation time lattice Boltzmann method (MRT-LBM)

The flow and heat transfer (FHT) in porous volumetric solar receiver was investigated through a double-distributed thermally coupled multiple-relaxation-time (MRT) lattice Boltzmann model (LBM) in this study. The MRT-LBM model was first verified by simulating the FHT in Sierpinski carpet fractal porous media and compared with the results from computational fluid dynamics (CFD). Three typical porous structures in volumetric solar receivers were developed and constructed, and then the FHT in these three porous structures were investigated using the MRT-LBM model. The effects of pore structure, Reynolds (Re) number based on air velocity at inlet, the porosity, and the thermal diffusivity of solid matrix were discussed. It was found that type-III pore structure among the three typical porous structures has the best heat transfer performance because of its lowest maximum temperature of solid particles at the inlet and the highest average temperature of air at the outlet, under the same porosity and heat flux density. Furthermore, increasing the thermal diffusivity of solid particles will lead to higher averaged air temperature at the outlet. It is hoped that the simulation results will be beneficial to the solar thermal community when designing the solar receivers in concentrated solar power (CSP) applications.

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Multiple-relaxation-time lattice Boltzmann simulation of natural convection with multiple heat sources in a rectangular cavity

Canadian Journal of Physics ◽

10.1139/cjp-2019-0055 ◽

2020 ◽

Vol 98 (4) ◽

pp. 332-343

Author(s):

Peisheng Li ◽

Xiaolong Lian ◽

Yue Chen ◽

Ying Zhang ◽

Wandong Zhao ◽

...

Keyword(s):

Heat Transfer ◽

Relaxation Time ◽

Heat Exchange ◽

Heat Source ◽

Lattice Boltzmann ◽

Heat Sources ◽

Left Wall ◽

Multiple Relaxation Time ◽

Lateral Offset ◽

Heat Exchange Efficiency

Natural convection and heat transfer in a square cavity with multiple heat sources was investigated through a multiple-relaxation-time (MRT) collision model and lattice Boltzmann method (LBM) in the current work. The MRT-LBM model was verified by a former experiment and numerical findings with different Ra numbers from 103 to 105, which proved the MRT-LBM model is effective to handle the flow and transfer. The heat transfer that developed inside the cavity was analyzed under different width, height, and lateral offset of heat source in this paper. Moreover, the change of spacing between two symmetrically distributed heat sources was discussed. The results showed that the heat exchange efficiency was augmented by increasing width, height, and spacing of the heater, but it was reduced by increasing lateral offset. Specifically, the Nusselt number of the upper wall decreased by increasing height of heat source, and the left and right walls showed better heat exchange efficiency by increasing height. Additionally, the lateral position had a notable influence on the left wall surface of the heat source, and the optimum heat exchange efficiency of the heat source’s left wall existed in the condition of small lateral offset.

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Nusselt Number Prediction for Slip Flow in Confined Porous Media Based on Lattice Boltzmann Method

ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer ◽

10.1115/mnhmt2019-4192 ◽

2019 ◽

Author(s):

Ammar Tariq ◽

Zhenyu Liu ◽

Zhiyu Mu ◽

Huiying Wu

Keyword(s):

Heat Transfer ◽

Porous Media ◽

Nusselt Number ◽

Lattice Boltzmann Method ◽

Lattice Boltzmann ◽

Slip Flow ◽

Flow And Heat Transfer ◽

Prime Concern ◽

Multiple Relaxation Time ◽

Boltzmann Method

Abstract Understanding flow and heat transfer in porous media is a matter of prime concern for micro devices. In this work, slip flow and heat transfer of gaseous fluid through the confined porous media is numerically simulated using a multiple-relaxation-time lattice Boltzmann method. The method is employed using an effective curved boundary treatment based on non-equilibrium extrapolation and counter-extrapolation methods. Nusselt number prediction for varying porosity, Knudsen and Reynolds number are studied. Based on the obtained numerical results, it is proved that the current technique can be used to effectively model slip flow and heat transfer at pore-scale.

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