A design method of an S-curved parabolic trough collector absorber with a three-dimensional heat flux density distribution

摘要

This paper presents the first study on the feasibility of an S-curved/sinusoidal absorber for a use in parabolic trough collectors (PTCs). The conventional straight absorber located along the focal line of the PTC is replaced by an S-curved/sinusoidal one for which the heat flux density distribution on the outer surface varies in both axial and azimuthal directions while it varies only in the azimuthal direction on the former. On the basis of the heat flux density distribution (q) for horizontal straight absorbers, a simplified method is proposed to generate the 3D character of q for the newly designed S-shaped absorber. The results show that for specular reflectors of perfect alignment, to collect the entire reflected solar beam, the amplitude of the sinusoidal centreline of the new absorber must not be larger than a maximum deviation, Delta(max) established with reference to the focal line. The heat flux density distributions of two newly designed S-curved pipes are performed and shape effects on the flux distribution are shown. So far, the concentrated heat flux distribution analysed in details revealed the almost homogeneous heating of the new absorber pipe. The design should achieve other indirect benefits, as the reduction of the absorber pipe deflection in consequence of a better flux distribution around the pipe. It is also established that the intercept factor of a solar collector unit equipped with the S-curved absorber should be comparatively better than that of the former equipped with the conventional straight absorber. (C) 2015 Elsevier Ltd. All rights reserved.