Heat transfer improvement for a filled-type compound parabolic solar collector with U-tube: Energetic and economic analysis

In this study, the thermal and economic performance of a compound parabolic collector (CPC) with a U-tube was evaluated. Different filling fluids of the evacuated tube and different mass flowrates were evaluated. A detailed analysis of the energy performance of the collector components was conducted, along with an evaluation of its optical and economic aspects. The evaluated collector presented an optical efficiency of about 63.6 %. Air achieved the highest evacuated tube temperature (160.6 °C), followed by thermal oil (84.6 °C) and water (61.3 °C). The increase in HTF mass flowrate reduced both temperature gain and thermal efficiency. Thermal oil demonstrated superior thermal performance, achieving 32.5 % higher efficiency than air and 30.0 % higher than water. Results showed the thermal oil as the most cost-effective fluid, with a leveled cost of heat of 0.034 $/kWh and a simple payback period of 2.8 years. These findings demonstrate the potential of CPC systems for efficient thermal energy applications, with thermal oil emerging as the optimal filling fluid for both thermal and economic performance. Additionally, this study provides valuable practical insights for designing more efficient and sustainable CPC-based solutions for thermal energy applications.