Exergy performance assessment of a linear parabolic trough photovoltaic thermal collector

Abstract

This paper presents the exergy performance assessment of a linear parabolic trough photovoltaic thermal collector. The governing equations of a concentrating photovoltaic thermal collector (CPVT) are obtained through an energy balance for the various components of the system. The electrical analysis of PV cells is carried out by a four-parameter model of current-voltage. By introducing the various exergy components in the system, the system exergy efficiency is obtained. The simulation results of present study are in good agreement with previous studies data. The results show that the exergy efficiency variation with respect to the fluid velocity and channel diameter is negligible. Increasing fluid velocity from 0.08 to 0.43 m/s increases the electrical efficiency and thermal efficiency 1.05% and 2.2%, respectively. An increase of receiver width from 0.06 to 0.2 m increases the exergy efficiency and thermal efficiency by 1.47%, and 9.4%, respectively. Increasing channel diameter from 0.017 to 0.06 m increases the thermal efficiency and electrical efficiency 2.75% and 3.9%, respectively. By increasing the collector length from 3 to 90 m initially the thermal efficiency increases to 62.5% and then decreases to 60%. The exergy efficiency has a slight change with increasing collector length. An increase of fluid inlet temperature from 20 to 90 °C increases the exergy efficiency by 8.2%. Meanwhile, the thermal and electrical efficiencies reduce by 6.5% and 3.35%, respectively. An increase of the incident beam radiation from 50 to 1000 W/m2 enhances the electrical efficiency by 6.6% and increases the exergy efficiency by 15.7%, while the thermal efficiency has an ascending/descending trend. The increase of ambient temperature increases the exergy efficiency and thermal efficiency by 7.6% and 5.1%, respectively. The impact of receiver width and ambient temperature on electrical efficiency is negligible.