Numerical Investigation on Using MWCNT/Water Nanofluids in Photovoltaic Thermal System (PVT)

Abstract

Photovoltaic thermal systems (PVT) are solar energy conversion systems that produce both electricity and heat simultaneously. PVT systems seeking to minimize temperature of solar cells become more significant with the increased thermal and electrical efficiency of the working fluids (water and nanofluids) employed in the solar thermal system. The major objective of this research is to investigate the thermal, electrical and overall performance of the photovoltaic thermal (PVT) system with different weight fractions of MWCNT/water nanofluids (φ = 0.3%, 0.6% and 1%) and water. A sheet and tube PVT system model geometry, which has been simplified to rectangular PV cell, absorber plate, cylindrical pipe, and fluid domain geometries to investigate outlet and PV cell temperature of photovoltaic thermal (PVT) system between different weight fractions of MWCNT/water nanofluids (φ = 0.3%, 0.6% and 1%) and water with varying fluid inlet velocities from 0.02 m/s to 0.08 m/s using ANSYS FLUENT. The results show that increasing the inlet fluid velocity and weight fraction of the working fluid improves thermal and electrical efficiency. The highest improvement in thermal and electrical efficiency at 0.08m/s inlet fluid velocity for the weight fractions, φ = 1% of MWCNT/water nanofluids is 7.8% and 0.03% compared to water. In addition, the weight fractions, φ = 0.3% of MWCNT/water nanofluids is 4.46% and 0.01% and the weight fractions, φ = 0.6% of MWCNT/water nanofluid is 6.72% and 0.02%. Additionally, the maximum increase of overall efficiency at 0.08m/s inlet fluid velocity for the weight fractions, φ = 1% of MWCNT/water nanofluids is 7.83% compared to water while the weight fractions, φ = 0.3% of MWCNT/water nanofluids is 4.43% and the weight fractions, φ = 0.6% of MWCNT/water nanofluid is 6.74% at inlet fluid velocity of 0.08 m/s. As a result of the research, it was discovered that using MWCNT/water nanofluids improves the performance of PVT systems.