Computational Fluid Dynamics Analysis of Heat Transfer and Entropy Generation for a Flow in Supercritical and Dense Phases in a Baffled Evacuated Tube Solar Collector
نویسندگان
1 Department of Chemical Engineering, Faculty of Engineering, University of Sistan and Baluchestan, Zahedan, I.R. IRAN
2 Department of Chemical Engineering, Faculty of Engineering, University of Sistan and Baluchestan, Zahedan, I.R. IRAN
3 Department of Chemical Engineering, Faculty of Engineering, University of Sistan and Baluchestan, Zahedan, I.R. IRAN
doi
10.30492/ijcce.2025.2060712.7117چکیده
Natural gas heating for hydrate prevention is energy-intensive and contributes to greenhouse gas emissions. This study investigates an Evacuated Tube Solar Collector with an Inserted Baffle (ETSCIB) as a sustainable alternative. A three-dimensional CFD model, validated against experimental data with an average error below 6 percent, was employed to evaluate natural gas heating in both dense and supercritical phases. The dense phase, with 63 percent higher density and specific heat capacity, enhanced heat transfer performance. Compared with the supercritical phase, the dense phase achieved a 21 percent increase in the Nusselt number and a lower temperature difference between the heated wall and the bulk gas. Although entropy generation in the dense phase was 9 percent higher, it was primarily associated with heat transfer and resulted in improved thermal efficiency. Extending the collector length from 0.8 m to 1.2 m reduced the heat transfer coefficient and Nusselt number by 16.8 percent and 16 percent in the dense phase, and by 18.1 and 17.4 percent in the supercritical phase. These results demonstrate that ETSCIB systems using dense phase flow can achieve higher energy efficiency, thereby reducing dependence on conventional heating and lowering emissions in natural gas processing.
