Modeling of a concentrated-solar, falling-particle receiver for ceria reduction

Modelling of solar thermochemical reaction systems

“…The expression was further used in the work of Bala Chandran et al (2015a). Oles and Jackson (2015) included a rather detailed description of mass transfer in an irradiated particle curtain by including gas diffusion and sorption by considering the particle composition in the bulk, sub-surface, and surface. von Zedtwitz and Steinfeld (2005) and von Zedtwitz et al…”

“…Falling particle receivers fall into the category of dilute fluidised STRSs because it can be approximated that the particles do not directly interact with each other. However, gas entrainment is an important phenomenon in these systems as was accounted for in (Oles and Jackson, 2015) by using a semiphenomenological approach and more rigorously in (Chen et al, 2007) for non-reactive particles. The works discussed thus far consider flows with Reynolds numbers that are-or are assumed-low enough that laminar flow modelling is sufficient.…”

“…Thus, one energy conservation equation (15) is solved for each phase. The use of local thermal non-equilibrium (LTNE) appears widely in the literature when using homogenisation Belghit, 2011a, 2011b;Groehn et al, 2016;Kenarsari and Zheng, 2014;Villafán-Vidales et al, 2011;Wang et al, 2014a;Wang et al, 2014b;Zedtwitz et al, 2007;Zedtwitz and Steinfeld, 2005) or when the phases are resolved individually (Abanades et al, 2007;Oles and Jackson, 2015), though there are examples of high solid fraction studies in fixed beds where the single temperature-or local thermal equilibrium (LTE)-assumption is made (Lapp et al, 2013;Lapp and Lipiń ski, 2014;Lu et al, 2016;Martinek et al, 2014). The approximation of LTE is valid when any local temperature differences between a fluid and a solid are much smaller than the temperature differences that appear in the whole system.…”

“…Enthalpy of reaction can be available experimentally or estimated by thermodynamic database software as demonstrated in (Villafán-Vidales et al, 2011). The temperature dependence of reaction rates is generally handled by assuming an Arrhenius-type law (see Section 3.2): Lipiń ski, 2012, 2011;Haussener et al, 2009;Lipiń ski and Steinfeld, 2004;Müller et al, 2008;Oles and Jackson, 2015;Schunk et al, 2009b;2009a;Villafán-Vidales et al, 2015;Yue and Lipiń ski, 2015a,b,c;Zedtwitz et al, 2007;Zedtwitz and Steinfeld, 2005). Fluid density, specific heat and thermal conductivity can all also be strong functions of temperature, particularly for gasses; inclusion of these effects can be found, for example, in (Kenarsari and Zheng, 2014;Lu et al, 2016;Müller et al, 2008;Wang et al, 2014b).…”

“…It has appeared in several studies, likely because of its availability in the popular simulation package from ANSYS (Abanades et al, 2007;Chen et al, 2007;Haussener et al, 2009). The zonal method-a method relying on finite volumes (zones) and the concept of exchange areas-is used in (Oles and Jackson, 2015;.…”