A numerical study of parabolic trough receiver with nonuniform heat flux and helical screw-tape inserts

Effect of solar incidence angle was analyzed in order to accurately simulate the heat flux distribution around the absorber tube outer surface. Helical screw-tape inserts was proposed to homogenize the absorber tube temperature distribution and improve the thermal efficiency. Three dimensional periodical models of flow and heat transfer were established and solved with the heat flux of different transversal angle (beta). The results show that beta affects the flux distribution more greatly than longitudinal angle (phi). Transversal angle (beta) of 11.567 mrad increases the relative change of heat loss (Q(loss)) as inlet temperature rises, and also increases the maximum temperature on absorber tube (T-max) and the maximum circumferential temperature difference (Delta T). But its effect reduces as Reynolds number rises. Within the range of studied Re, the helical screw-tape inserts of given geometrical parameters greatly reduce the Q(loss), T-max and Delta T, which indicates that helical screw-tape inserts is a feasible way to enhance the heat transfer inside the receiver. (C) 2014 Elsevier Ltd. All rights reserved.