Abstract:
The environmental repercussions of harmful emissions caused by conventional energy fuels
such as petroleum and coal are a significant concern in today’s globe. A parabolic trough
collector (PTC) is a promising solar energy harvesting technology that provides thermal
energy. In conventional PTC receivers, solar fluxes are significantly non-uniform, which can
cause high local temperatures and large temperature gradients, posing serious challenges to
safety and efficiency. One approach for increasing the service life and dependability of a PTC
is to reduce the receiver tube’s circumferential temperature difference that increases with the
concentration ratio. This study investigates the design and development of a PTC with a
secondary reflector for medium temperature applications and its experimental performances.
Tonatiuh, a Monte Carlo ray-tracing based optical simulation tool, is used to obtain the power
output and heat flux profiles on the receiver tube surface. Response surface methodology has
been used to examine and select the desired configuration of the solar collector system, and the
findings have been analysed using ANOVA. The results showed that the uniformity of heat flux
distribution has significantly enhanced after the secondary reflector is installed in its most
suitable location, compared to the solar collector without the secondary reflector. Therminol®
55 (TH55) oil-based hybrid nanofluids with graphene nanoplatelets and alumina nanoparticles
are prepared by two-step method with different concentrations. Compared to the base fluid, the
hybrid nanofluid appears to have an 18.72% increase in thermal conductivity at 65°C. A CFD
analysis results show that at 0.1 kg/min mass flow rate, the hybrid nanofluids average
convection heat transfer coefficient has enhanced by 21.88%. The experimental results
revealed that the efficiency of the PTC with the secondary reflector obtained a greater than 6.0
% improvement over conventional PTCs. With a flow rate of 7.5 lpm, the PTC using hybrid
nanofluid demonstrated an increase of 4.05 % in average thermal efficiency compared to the
PTC using TH55. Overall this study proposes a new design approach of a solar PTC and a new
hybrid nanofluid as its heat transfer fluid for efficient operation of PTC systems
