Numerical and experimental analysis on convective heat losses from a fully open cylindrical cascaded cavity receiver

A cavity receiver finds substantial application to improve the thermal performance of a solar parabolic dish collector. However, its limited surface area shortens the scope of utilization and bars thermal efficiency. This research has intercepted such problems by including a cascaded cavity receiver, which offers more surface area and high-temperature distributions, representing more heat absorption and utilization to convert into thermal energy. The crucial design of a cascaded receiver consists of two concentric steel cylinders with different heights attached at one end. The design is tested theoretically with the help of CFD analysis, and the heat loss results are compared with the traditional cavity receiver. Furthermore, according to design, an experimental set-up is fabricated, and experimentations are conducted in off-flux mode using an electric heater. The Pyromark coatings minimize radiation losses and implement the working conditions in the lab testing scenario. The convective heat losses estimated reduction of 4.3 % at 0°–24.8 % at 90° due to the application of coatings in the normal cavity and 3.4 % at 0°–16.4 % at 90° due to the application of coatings in the cascaded cavity. Also, the cascaded cavity receiver minimizes 6.98 %–13.93 % convective heat losses compared to traditional cavity receivers.