  Solar parabolic trough collector technology has received significant
attention among researchers for its economic potential to meet electrical and
thermal energy demands. Furthermore, parabolic trough collector power plants
can be hybridized with fossil fuels or other renewable power plants. Improving
the efficiency of the parabolic trough collector leads to increase the
electricity production and allows the parabolic trough collector power plant to
be built in a more compact size, at reduced capital investment. This review
focuses on parabolic trough collector receivers, which uses cavity technology
to improve efficiency. The cavity receiver has shown the potential to overcome
shortages of the conventional receiver. It was seen that the thermal losses of
the cavity receiver are affected by various parameters such as aperture sizes,
emissivities, and working fluid temperature as well as mass flow rate and wind
velocity. Different cavity designs have a different effect on the solar flux
distribution along the circumference of the receiver. An efficient cavity
receiver still has the potential to minimize the losses and hence, improve the
overall efficiency. Some of the design gaps have been identified as a guide for
future work.
