Temperature estimation of a receiver equipped with a 3D compound parabolic concentrator

Solar Tower Power Plant (STPP) require a high concentration ratio to provide high working fluid temperatures for power generation. Three-dimensional Compound Parabolic Concentrator (3D-CPC) can be used to increase the concentration ratio in the receiver. This paper estimates the air outlet temperature of an indirectly irradiated solar receiver equipped with a 3D-CPC for STPP. For this purpose, the STPP subsystems such as the heliostat field, the 3D-CPC and the receiver are sized for an electrical power of 30 kW. An in-house Matlab code is developed and executed the configuration of the heliostats in the field. The result of the Monte Carlo ray tracing (MCRT) method is used to provide boundary conditions to the Computational Fluids Dynamics (CFD) model. The CFD model is used to simulate the conjugate heat transfer in the receiver. Based on this, a heat source is created from the solar rays absorbed in the receiver. This heat source is implemented as a volumetric heat source in Ansys Fluent by UDFs functions. Thus, the in-house Matlab code is validated by simulating the PS-10 heliostat field and the CFD model is also validated by simulating the Weizmann heliostat field. The results show that the solar field is consisted of 175 heliostats of 2 m2 surface area and 1.5 m height each. The 3D-CPC truncated at 35° increased the concentration ratio by a factor of 4.91 for an optical efficiency of 80.66 %. A receiver mesh count of 1,076,958 gave convergence of the air outlet temperature. 1.5 × 106 rays are found to get independence of the absorbed heat flux in the receiver. The temperature found on the heated solid is 1063.4 K. For a porosity of 56.02 % and a mass flow rate of 0.11 kg/s, a temperature of 1218 K is reached at the outlet of the receiver. The results show that the use of a 3D-CPC increase the concentration ratio and, consequently improve the thermal performance of the receiver. It is important to note that, parameters such as mass flow rate and porosity have a strong influence on the air outlet temperature.