Abstract :
This paper describes aspects of the design methodology and heat transfer calculations for an elevated north–south
oriented linear absorber. The absorber is part of a direct steam generation solar thermal concentrating system based on
the Australian compact linear Fresnel reflector (CLFR) concept. The basic absorber design is an inverted air cavity with
a glass cover enclosing a selective surface. This arrangement has been shown previously to offer good optical and
thermal performance from measurements on a 4 kWthermal outdoor test apparatus. Two main design aims are discussed
here: Firstly to maximise the heat transfer between the absorbing surface and the steam pipes, and secondly, to ensure
that the absorber surface temperature is sufficiently uniform so as not to cause thermal degradation of the selective
surface. Results are given of the absorber temperature distribution obtained from finite element analysis. Sufficiently
low temperature differences between the fluid surface and the absorbing surface (<20 K) can be achieved with satisfactory
pipe separations and sizes, and with practical absorber plate thicknesses.
2003 Elsevier Ltd. All rights reserved
