Performance Evaluation of a Hybrid PV/T Solar Air Heater Enhanced with a Packed Bed

Abstract

This paper proposes and parametrically analyzes a modified hybrid photovoltaic/thermal (PV/T) solar air heater with a duct equipped with a packed bed. Based on the energy conservation principle, a steady-state, one-dimensional mathematical model is developed and implemented to specify the mechanisms governing the system's behavior using a MATLAB-based computer code. Model predictions are validated against literature data for comparable PV/T configurations, showing a good agreement and confirming the reliability of the adopted approach. Numerical simulations are specifically carried out according to a two-pronged objective. The first is to demonstrate the significance of the proposed modification and quantify the accompanying improvements. The second is to examine and analyse the effects of key design and operating parameters (such as mass flow rate, particle diameter, and bed porosity) on the system's performance and efficiency. the results show that reducing the diameter can significantly improve overall efficiency by enhancing convective heat transfer within the channel, while the optimal porosity is 0.75. The study identifies 0.01 kg/s as the optimal flow rate, as higher rates sharply reduce heat quality without significant gains in overall efficiency. A value of 0.03 m is established as sufficient insulation thickness to suppress back-wall heat losses, beyond which no appreciable improvement in collector efficiency is observed. Under similar conditions, the optimised hybrid PV/T air heater with a packed bed produces 13.9% higher overall efficiency if compared to the conventional heater. The findings provide a validated framework and practical guidelines to determine optimal trends for constructing and operating this superior hybrid system for maximum energy efficiency.