Energy and Exergy evaluation of Photovoltaic Thermal (PVT) system cooled by nanofluid and Spiral Flow Absorber.

Abstract

The performance of a nanofluid-cooled PVT collector can be represented by its electrical and thermal efficiencies. The sum of the two efficiencies, known as the overall PVT system efficiency, is used to evaluate the overall system performance. A PVT system powered by a Multi-Wall Carbon Nanotube (MWCNT) nanofluid was constructed and investigated in Baghdad-Iraq climates. Experimental results demonstrated that both efficiencies increase with increasing mass flow rate, and consequently, the overall efficiency (PVT efficiency) increases. The nanofluid-cooled PVT system equipped with a spiral-flow heat exchanger achieved overall PVT efficiencies ranging from 59% to 70%, with electrical efficiencies ranging from 12.8% to 13.5% and thermal efficiencies ranging from 46.2% to 56.5%. These efficiencies were achieved at mass flow rates ranging from 0.011 kg/s to 0.033 kg/s and a solar irradiance of from 250 to 1000 W/m². Recently, exergy analysis has been applied to evaluate PVT collector performance more comprehensively. In the study, the analyses show that the PVT exergy efficiency is between 22% and 40% with thermal exergy of 572 to 118 W and electrical exergy of 59 to 67 W.