CFD analysis of a receiving cavity suitable for a novel CSP parabolic trough receiver

The aim of this work was to study, by means of accurate 3D steady-state CFD simulations, the thermo-fluid dynamics behavior of a helically coiled heat exchanger (HCHE) constituting the receiving cavity of the novel CSP receiver based on Airlight Energy technology. In this innovative receiver design, air is used as heat transfer fluid (HTF), which, besides being inexpensive and environmentally friendly, is optimally suited for high temperature operation well beyond the limit of conventional HTFs. According to preliminary information related to the collectors orientation of the first 3.9 MWth Airlight Energy pilot plant, under construction in Ait Baha (Morocco), two reference skew angles of the incoming solar radiation were considered and the receiving cavity performance were evaluated in terms of thermal efficiency and pressure drop. Among all, one of the main requirements was to achieve, at the outlet section of the HCHE, an air temperature of 650 degrees C; hence the mass flow rate was tuned accordingly. In order to minimize the pumping power requirements, the HCHE was designed to guarantee a laminar flow regime under all the operating conditions. Navier-Stokes, energy and radiation transport equations, the latter accounted for by the Discrete Ordinates (DO) model, were numerically solved, using the finite-volume method approach, with Fluent code from ANSYS. A meticulous experimental proof of concept was then carried out in Biasca (Switzerland) by the Swiss company Airlight Energy Manufacturing SA. The analysis of the experimental results, detailed in this paper, allowed to assess the reliability and effectiveness of this novel CSP receiver design in the solar energy harvesting. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).