Hybrid parabolic dish-fresnel lens solar system with transparent dual-aperture baffle-guided receiver: Comprehensive energy and exergy analysis

This study proposes a transparent dual-aperture receiver with baffle-guided spiral flow for hybrid solar parabolic dish concentrator (PDC) and Fresnel lens (FRL) systems. Transparent walls on both faces admit the reflected and transmitted beams into the receiver's internal surfaces, while radial baffles guide the fluid across both irradiated surfaces in series. A transient framework coupling Monte Carlo ray tracing (MCRT), computational fluid dynamics (CFD), conjugate heat transfer, and exergy analysis is validated against experimental data with mean absolute percentage errors below 1.2%, within the ±1.41 °C measurement uncertainty. The flow stays laminar at pressure drops of 4.90–19.16 Pa. At 25 °C inlet temperature, a water mass flow rate of 100 kg/h, and a peak direct solar irradiance of 1050 W/m 2 , the receiver delivers 64.6% thermal efficiency, 2.08% exergy efficiency, and 4890 W peak useful heat. Reducing water flow rate from 150 to 75 kg/h improves exergy efficiency by 136%, and raising inlet temperature from 20 to 30 °C raises exergy gain by 137%, through the higher exergy of a hotter outlet. The off-focal position R PDC = 0.9 gives 72.5% thermal efficiency, 2.67% exergy efficiency, and 5424 W peak useful heat. Against a bare-type receiver of equal fluid volume, the design increases daily thermal efficiency from 45.0% to 59.3% and exergy efficiency from 2.15% to 3.98%; against a single dish, it delivers 13.3% higher thermal efficiency, 39.6% higher exergy efficiency, and 60% higher exergy gain. Although the receiver achieves high thermal efficiency, its low exergy efficiency reflects the inherent second-law penalty associated with converting concentrated solar radiation into low-temperature heat. Thus, the proposed system is better suited to higher-temperature thermal applications than to conventional low-temperature water heating.