Flat-plate solar collector thermal performance assessment via energy, exergy and irreversibility analysis

Abstract

This paper presents a detail exergy analysis of a flat-plate solar collector based on irreversibility rates. The governing equations of the flat-plate collector are obtained by writing energy and exergy conservation equations for glass cover, absorber plate and working fluid. The computed results of this study are in concordance with previous studies experimental data. Our findings reveal that 84.97% of total collector irreversibility are linked to the absorber plate. Increasing the flow rate to 0.0056 kg/s decreases the irreversibility rate in the absorber plate to a minimum of 579.20 W and increases the irreversibility rate in the working fluid to it maximum of 158.83 W. The maximum exergy efficiency was 33.21% for a flow rate of 0.0056 kg/s and inlet fluid temperature of 30 °C. An increase in inlet fluid temperature from 20 to 65 °C decreases the absorber plate irreversibility by 129.13 W, meanwhile the working fluid and glass cover irreversibility increase by 30.37 W and 99.39 W, respectively. An increase in number of absorber tube from one to sixteen increases the energy and exergy efficiencies respectively by 34.61% and 92.94%. Meanwhile the absorber plate irreversibility rate increases by 97.49% and the irreversibility rates of the working fluid and glass cover reduce by 72.06% and 89.01%, respectively.