Mathematical modelling and experimental investigation of solar air collectors with corrugated absorbers

This paper presents mathematical modelling and performance evaluation of solar air collectors (SACs) with corrugated absorbers for indoor space heating. Experimental tests were first conducted based on a SAC system to understand its real-time performance. A mathematical model was then developed and validated against the experimental data. A sensitivity study was further implemented to identify the key design factors and investigate their influence on the performance of the SAC. The results showed that the modelling results agreed with the experimental data. The surface absorptance and opening angle of the corrugated absorber were the most significant design variables governing the thermal efficiency of SACs. The other significant variables included the temperature setting for the outlet air from the SAC, the depth ratio of the upper air channel to the overall size of the air space, the slope and length of the SAC, the air flow rate, and the unit area mass of the absorber. Using the opening angle of 60 degrees and surface absorptance of 0.8 can result in an average effective thermal efficiency of 27.14%, which was comparable to that using the opening angle of 120 degrees and the surface absorptance of 0.96. The results obtained can be used to facilitate optimal design of SACs. (C) 2019 Elsevier Ltd. All rights reserved.