An experimental study on the thermal performance of multi-surface compound trough solar air concentrators with dual collector tubes

A multi-surface compound trough solar air concentrator (MCTSAC) with dual collector tubes (DCTs) was developed and introduced in the paper, in order to improve the thermal performance and the air flow rate of MCTSACs with a single collector tube (SCT). In the study, the thermal performance of MCTSACs with DCTs and those with a SCT was compared using real measured data. Additionally, the influence of factors, i.e. air velocity inside the collector tube, solar radiation, inclination angle and length of the MCTSAC, on the thermal performance of MCTSACs has been evaluated. Experimental results have reflected that comparing to MCTSACs with a SCT, MCTSACs with DCTs perform significantly better in both thermal performance and air flow rate, with an increase of 18% for both mean heat collection and mean thermal efficiency. Furthermore, solar radiation has shown a positive impact on the thermal performance, whilst inlet temperature performed a negative impact. When the air velocity inside the collector tube was around 1.8m/s with the inclination angle set as 23°, the MCTSACs with DCTs performed the best.