Deformation of receiver in solar parabolic trough collector due to non uniform temperature and solar flux distribution and use of bimetallic absorber tube with multiple supports

Present study aims at minimising the risk of bending in receiver of Parabolic Trough Collector (PTC) using double layered absorber held at pillars and mathematical equations are formulated. Tube is modelled for practical scenarios supported by pillars made up of movable structure that can slide to help absorber expand when heated. Ball joints at contact points enable tube to rotate. Equations are validated against the experimental measurements. Effects of placement of conductive material, focal length, PTC width, geometrical imperfections and HTF flow rate on bending and energy losses due to bending are studied. It is found that (i) single layered absorber leads to bending and energy loss of -15.1 mm and 23%. Double layered absorber with high conductivity material as inside layer reduces bending/energy loss to -10.0mm/1.0%. However, use of high conductivity as outside layer further reduces bending/energy loss to -6.1mm/0.4%, (ii) change in HTF flow rate from 0.4 kg/s to 1.4 kg/s reduces bending/energy loss from -15.1mm/2.3% to -10.2mm/1.0% for single layered absorber and -6.1mm/0.4% to -4.5mm/0.2% for double layered and (iii) focal length near to 0.7 m reduces bending/energy loss to Omm/0%. (C) 2018 Elsevier Ltd. All rights reserved.