Concentrating Solar Thermal Energy

6Numerical Simulations of Flows and Heat Transfers of Solar Receivers

Françoise BATAILLE¹, Adrien TOUTANT¹ and Dorian DUPUY^1,2

¹ PROMES-CNRS, UPVD, Perpignan, France

² CERFACS, Toulouse, France

6.1. Introduction

Solar receivers are places where turbulent flows are strongly heated in an asymmetric way (irradiated face/hidden face). It is difficult to model these flows, as they combine both dynamic aspects (the flow is turbulent) and thermal aspects (with high-temperature gradients) that are complex and amplified through their interactions. There is a literature on isothermal turbulent flows as well as on anisothermal flows where the temperature is considered as a passive scalar (its behavior does not influence the flow dynamics). An exhaustive review can be found in the books by Bailly and Comte-Bellot (2003) or Lesieur (2012), while keeping in mind that this research is in itself very difficult. On the other hand, scientific literature and studies related to strongly anisothermal turbulent flows are far less abundant.

Figure 6.1. Schematic representation of the profiles of mean and fluctuating fields. For a color version of this figure, see www.iste.co.uk/flamant/energy.zip

Most flows encountered in nature and engineering applications are turbulent. Turbulence is useful in heat exchangers, as it tends to accelerate the homogenization and mixing processes, intensifying wall ...