Numerical investigation of porous stack for a solar-powered thermoacoustic refrigerator

Abstract

This article proposes a numerical analysis for performance improvement of the stack, which represents a crucial element on the solar-powered thermoacoustic refrigerator. The stack is considered as a saturated parallelepiped homogeneous porous media. Numerical simulation of the flow and the heat transfer in the thermoacoustic refrigerator is carried out. The physical flow is governed by the modified Darcy–Brinkmann–Forchheimer model. The governing equations are solved numerically using the lattice Boltzmann method. Furthermore, the local thermal equilibrium assumption is applied to examine heat transfer. Particular attention is paid a new form of the lattice Boltzmann equation system describing the flow and the heat transfer in porous media and fluid regions. The effects of several parameters characterizing the thermal behaviour in the porous medium are studied. The parametric results lead to the optimization of the porous media form. The presence of the viscous dissipation term in the heat transfer formulation within the thermoacoustic system is particularly highlighted, due to its significant effects introduced by the Eckert number.

CFD Modeling of Thermoacoustic Energy Conversion: A Review

“…The porous media heat transfer model for thermoacoustic applications is crucial because it can determine the success or the failure of a CFD simulation of a standing-wave device. The model built by Oumayama et al [137] is one example of a stack refrigerator treated as a homogenous porous medium with a Darcy-Forchheimer model coupled to a thermal equilibrium model. To the authors' best knowledge, successful CFD models of a standing-wave thermoacoustic engine based on a macroscopic scale have not been found in the available literature.…”

Comparison of Li2CO3-Na2CO3-K2CO3, KCl-MgCl2 and NaNO3-KNO3 as heat transfer fluid for different sCO2 and steam power cycles in CSP tower plant under different DNI conditions

“…To overcome these problems study of renewable and sustainable energy should be the top priority. [1][2][3][4] Concentrated Solar Power (CSP) technology is one of the most promising technologies that can use renewable energy to generate electricity thus meeting energy demand and sustainability of the environment. Using this technology direct sunlight is converted into renewable electricity without emission of greenhouse gasses.…”

“…CSP operation requires a lot of HTF; therefore, it is important to choose the most suitable HTF to reduce costs when it comes to performance. The most commonly used salt as HTF is usually solar salt (60% NaNO 3 -40% KNO 3 ), 32 which is used in commercial plants like the Gemasolar power plant and Crescent Dunes power plants. 19,33,34 Some salts are especially suitable for high-temperature processes to get higher efficiencies, for example, Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 , KCl-MgCl 2, etc.…”