Energy/Technology/Art
Harvesting Solar Sustainability
CFD Investigation
The use of renewable energy sources is becoming increasingly important as we look for ways to reduce our dependence on fossil fuels and combat climate change. One promising technology in this area is the solar parabolic trough collector, which uses mirrors to focus the sun’s rays onto a linear receiver tube. The heat generated in this process is then used to generate electricity. In this study, we will investigate the heat transfer performance of linear solar receiver tubes using computational fluid dynamics. By analyzing the effects of heat flux distribution and fluid flow, we aim to obtain a better understanding of the thermal characteristics of the receiver tube and optimize its performance.
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Highlighted Findings:
Key Insights from Our Investigation
- the study investigates the effects of heat flux on the heat transfer performance of linear solar receiver tubes using computational fluid dynamics (CFD)
- the analysis is performed for both uniform and non-uniform heat flux distribution on circular pipes
- the CFD model is verified by comparing the results to various turbulent flow equations and the results are in good agreement
- the study finds that the temperature distributions of the absorber surface are similar to the distributions of the solar energy flux, and that the temperature differences are mainly dependent on the heat transfer fluid (HTF) velocity
- recommendations for future work include testing different working fluids and CFD investigation with the addition of turbulence in the flow field, as well as modifying the receiver tube profile
Enhancing Solar Panel Efficiency: Exploring Surface Modifications of Receiver Tubes
Passive methods of heat transfer enhancement are gaining popularity in the design of solar receivers. One such method involves modifying the wall profile of the receiver tube, rather than using direct inserts. The modified receiver tubes feature non-uniform cross-sectional areas, such as linear cavity receivers, dimpled receivers, helical finned receivers, cavity receivers of rectangular shape, converging-diverging receivers, and helical corrugated tubes. Numerical and experimental investigations have shown that these modified tubes can significantly improve the thermal performance and efficiency of solar receivers, resulting in reduced heat losses and higher exergy effectiveness. While some modifications may result in increased pressure drop, they are often recommended for high-temperature applications.
Internal helical finned receivers have also been studied, and it was found that by increasing fin numbers and their helix angle, the pressure loss increases. However, thermal losses and temperature gradient decrease, generating higher thermal efficiency. In addition, the use of a cavity receiver of rectangular shape was investigated by Loni et al, who found that the cavity position must be located in the parabolic focal line for maximum efficiency.
Other modifications, such as changing the peripheral surface, have also been investigated. Bellos et al. discussed the use of a converging-diverging type of receiver tube case and found a 4.55% improvement in mean efficiency with receiver tube modification. However, the pressure drop occurred, and it falls in the range of 160 to 330 Pa. The helical corrugated tube has also been investigated and found to contribute to a rise in PTSC thermal performance and exergy effectiveness.
Overall, these passive methods of heat transfer enhancement have shown promising results in improving the thermal efficiency of PTSCs. Their effectiveness depends on the specific design and operating conditions of the collector, and further research is needed to optimize their performance.
