Coupling of a parabolic solar dish collector to finned-tube heat exchangers for hot air production: An experimental and theoretical study

[Display omitted] •A novel indirect solar air heating system was studied both experimentally and theoretically.•A cavity receiver in a parabolic dish collector system was coupled to two series finned-tube heat exchanger.•A comprehensive mathematical model was developed for the system described.•The effects of some parameters on the performance of the system were investigated.•The average daily thermal efficiency of the system can be achieved up to 60%. A new type of solar air heaters was proposed by using a parabolic dish concentrator. A cylindrical cavity with helical baffles in its annular gap located at the focal point of a parabolic dish concentrator was used as a solar receiver. The receiver captures the solar energy and transfers it to silicone oil. The heat gained by oil is transferred to the air by two series finned-tube heat exchangers embedded in a heating box. The system can produce moderate to high-temperature air for various applications with regulating air flow through the box. A comprehensive mathematical model was developed for the system. The model results were compared with the experimental data, and the results of the error analysis show that the presented model is reliable. The influence of some effective parameters on the thermal performance of the system was investigated. Results show that the oil mass flow rate, air mass flow rate and receiver aperture diameter have a significant effect on the performance of the system and the initial mass of the oil in the storage tank has negligible effect. The thermal performance of the system was investigated during various days, and at optimum values of mentioned parameters, the daily average thermal efficiency of the system can be obtained up to 60%. The performance of the present system is comparable with other types of solar air heaters.