Numerical simulation of wind flow around a parabolic trough solar collector A.A. Hachicha, I. Rodríguez, J. Castro, A. Oliva ⇑ Centre Tecnològic de Transferència de Calor, Universitat Politècnica de Catalunya, ETSEIAT, Colom 11, 08222 Terrassa, Barcelona, Spain highlights " A numerical aerodynamic and heat transfer model based on LES modelling of PTC is proposed. " The numerical model is verified on a circular cylinder in a cross-flow. " The instantaneous and time-averaged flows are studied for an Eurotrough solar collector. " A comparative study of the heat transfer coefficients around the heat collector element is carried out. article info Article history: Received 20 November 2012 Received in revised form 25 January 2013 Accepted 2 February 2013 Keywords: Parabolic trough solar collector Wind flow Large eddy simulations Heat transfer coefficient abstract The use of parabolic trough solar technology in solar power plants has been increased in recent years. Such devices are located in open terrain and can be the subject of strong winds. As a result, the stability of these devices to track accurately the sun and the convection heat transfer from the receiver tube could be affected. In this paper, a detailed numerical aerodynamic and heat transfer model based on Large Eddy Simulations (LES) modelling for these equipments is presented. First, the model is verified on a circular cylinder in a cross-flow. The drag forces and the heat transfer coefficients are then validated with avail- able experimental measurements. After that, simulations are performed on an Eurotrough solar collector to study the fluid flow and heat transfer around the solar collector and its receiver. Computations are car- ried out for a Reynolds number of Re W = 3.6  10 5 (based on the aperture) and for various pitch angles (h =0°, 45°, 90°, 135°, 180°, 270°). The aerodynamic coefficients are calculated around the solar collector and validated with measurements performed in wind tunnel tests. Instantaneous velocity field is also studied and compared to aerodynamic coefficients for different pitch angles. The time-averaged flow is characterised by the formation of several recirculation regions around the solar collector and the receiver tube depending on the pitch angle. The study also presents a comparative study of the heat transfer coef- ficients around the heat collector element with the circular cylinder in a cross-flow and the effect of the pitch angle on the Nusselt number. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Parabolic trough solar collectors (PTC) constitute a proven de- vice of thermal energy for industrial process heat and power gen- eration. Currently, PTC is one of the most mature and prominent technologies for solar energy for production of electricity. The majority of the parabolic trough plants deployed operate at tem- peratures up to 400 °C using synthetic oil as heat transfer fluid (HTF) [1]. Parabolic trough collectors are built in modules that are supported from the ground by simple pedestals at either end. A PTC is basically constructed as a long parabolic trough-shaped mirror that reflects direct solar radiation and concentrates it onto a heat collector element (HCE) located in the focal line of the parabola. The HTF runs through the receiver tube and absorbs the concentrated sunlight. The surface of the absorber is covered with a selective coating which has a high absorptance for solar radiation and low emittance for thermal radiation. A glass enve- lope is used around the absorber tube to reduce the convective heat losses with vacuum in the space between the absorber and the glass cover. The PTC is aligned to the north–south axis and tracks the Sun from east to west as it moves across the sky using a tracking mechanism system. In practice, the array field of solar collectors is located in an open terrain and it is sensitive to strong winds [2]. The surrounding air is usually turbulent and can affect the optical performance and wind resistance of the PTC, as well as, the heat exchange between 0306-2619/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.apenergy.2013.02.014 ⇑ Corresponding author. Tel.: +34 93 739 8192; fax: +34 93 739 8101. E-mail address: cttc@cttc.upc.edu (A. Oliva). URL: http://www.cttc.upc.edu (A. Oliva). Applied Energy 107 (2013) 426–437 Contents lists available at SciVerse ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy