Comparison study on two LT-PV/T systems with different tubular condensers

The concentric double-tube heat exchanger (CDTHE) proposed in our previous work addresses the limitations of the combined application of conventional loop thermosyphon photovoltaic/thermal (LT-PV/T) systems. Based on this, a novel non-concentric multi-tube heat exchanger (NMTHE) as the condenser of the LT-PV/T system was proposed in this paper, which improves the performance of system by reducing the flow resistance of the working fluid. Experimental platform was built to explore the performance difference between CDTHE-LT-PV/T and NMTHE-LT-PV/T system. Experimental results show that compared with the CDTHE-LT-PV/T system, the thermal efficiency, the electrical efficiency, the primary energy-saving efficiency and the exergy efficiency of NMTHE-LT-PV/T system relatively increase by 17.76%, 2.1%, 10.05% and 3.64%. Mathematical models for two systems are established and verified. Then the performance of the two systems under different solar radiation and ambient temperature is explored. Besides, the all-day performance of the two systems on typical winter days in four cities at different latitudes is predicted. The results show that the NMTHE-LT-PV/T has more prominent advantages in northern China at higher latitude. Furthermore, the influences of some structural parameters and operating setup on the performance of NMTHE-LT-PV/T system are discussed.

Automated summary

This study proposes a novel heat exchanger design to address the limitations of traditional photovoltaic/thermal systems, and explores its performance through experiments and mathematical modeling. The experimental results show significant advantages of the new heat exchanger in improving system efficiency, and predict performance differences under different solar radiation and ambient temperature conditions.