Numerical simulation of an efficient circular solar air heater integrated with a CPC

Abstract

A numerical analysis of a solar air heater is conducted to evaluate the thermal performance of the proposed solar collector under various situations for providing high-temperature airflows. The research investigates the design of a circular solar air heater including revolving airflow combined with a compound parabolic concentrator to enhance incident radiation. The two principal components of the circular heater and the applied concentrator possess compatible geometries and are well integrated. The numerical CFD study is conducted by solving the Navier-Stokes and energy equations for the primary forced convection airflow in the circular solar air heater and the free convection airflow within the cavity of the compound parabolic concentrator. Multiple test cases with varying solar irradiation and air mass flow rates are analyzed, incorporating surface-to-surface radiation. The CFD study of the circular solar air heater is compared with the experimental results. In the analyzed test cases with an air mass flow rate of 0.01 kg/s and a solar heat flux of 1000 W/m2, the thermal efficiency is calculated to be 70 %, despite the elevated outlet air temperature reaching 120 °C. This indicates a 100 % increase in efficiency compared to conventional smooth duct solar air heaters. The research concludes that the circular solar air heater with revolving airflow, combined with a compound parabolic concentrator, results in a highly efficient heat exchanger for generating high-temperature airflow suitable for many applications.