The thermal non-equilibrium porous media modelling for CFD study of woven wire matrix of a Stirling regenerator S.C. Costa a,⇑ , I. Barreno a , M. Tutar b,c , J.A. Esnaola b , H. Barrutia b a CS Centro Stirling S. Coop, Avda. Alaba 3, 20550 Aretxabaleta, Spain b Mechanical and Manufacturing Department, Engineering Faculty of Mondragon University, Loramendi 4, 20500 Mondragon, Spain c IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain article info Article history: Received 5 May 2014 Accepted 8 October 2014 Keywords: Stirling regenerator Porous media Heat transfer Pressure drop CFD abstract Different numerical methods can be applied to the analysis of the flow through the Stirling engine regen- erator. One growing approach is to model the regenerator as porous medium to simulate and design the full Stirling engine in three-dimensional (3-D) manner. In general, the friction resistance coefficients and heat transfer coefficient are experimentally obtained to describe the flow and thermal non-equilibrium through a porous medium. A finite volume method (FVM) based non-thermal equilibrium porous media modelling approach characterizing the fluid flow and heat transfer in a representative small detailed flow domain of the woven wire matrix is proposed here to obtain the porous media coefficients without further requirement of experimental studies. The results are considered to be equivalent to those obtained from the detailed woven wire matrix for the pressure drop and heat transfer. Once the equiv- alence between the models is verified, this approach is extended to model oscillating regeneration cycles through a full size regenerator porous media for two different woven wire matrix configurations of stacked and wound types. The results suggest that the numerical modelling approach proposed here can be applied with confidence to model the regenerator as a porous media in the multi-dimensional (multi-D) simulations of Stirling engines. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction The Stirling engine is an attractive alternative machine for micro-cogeneration mainly for the achievable high efficiencies and the possibility to use different heat sources. Recent studies on Stirling engines are motivated by the need to reduce the energy consumption, to improve energy efficiency and to use clean energy technologies. Despite of having many theoretical advantages, Stir- ling engines still face some challenges in terms of efficiency and the design process. The recent Stirling engines studies mainly focus on the multi- dimensional (multi-D) analysis [1–7], which is based on full Stir- ling engine modelling, and can reproduce useful Stirling engine performance results in a time-frame short enough to impact design decisions [3]. In the multi-D analysis, the regenerator is a difficult component to be modelled because any numerical inaccuracies will influence the full scale Stirling simulation. In the modelling of a regenerator, an important factor is the internal geometry of the matrix and most of the regenerator models do not assume a precise geometrical shape for the elements of the regenerator. In the Stirling engine’s multi-D analysis the regenerator is usually modelled as a macro-scale porous medium, the porous media model requires the input of a friction factor and heat transfer coef- ficient which mostly are empirically obtained. There are several works on modelling of Stirling regenerator as a porous media [8–16]. Cleveland State University [8] worked on CFD to develop a multi-D computer model of a portion of the regenera- tor matrix. Park et al. [9] indicated that screen-laminate matrices can be modelled as a porous media using a local thermal non-equi- librium model. Kim [10] studied the flow friction associated with laminar pulsating flows through porous media mainly for under- standing the Stirling regenerators and pulse tube cryocoolers. Tao et al. [11] investigated the fluid flow and heat transfer perfor- mances of mesh regenerators under different mesh geometric parameters and material properties based on an anisotropic porous media. Landrum et al. [12] modelled porous media hydrodynamic parameters adjusting iteratively to match the model predictions to the experimental results. Conrad et al. [13] determined the hydrodynamic parameters of stacked discs matrices using a 2-D CFD assisted methodology, whereby the hydrodynamic resistance parameters for these fillers are specified when they are modelled http://dx.doi.org/10.1016/j.enconman.2014.10.019 0196-8904/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +34 943 037 948; fax: +34 943 792 393. E-mail address: ccosta@centrostirling.com (S.C. Costa). Energy Conversion and Management 89 (2015) 473–483 Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman