CFD analysis of heat transfer for high-pressure natural gas in a baffled evacuated tube solar collector

This study presents a three-dimensional computational fluid dynamics (CFD) investigation of the thermal performance of an evacuated tube solar collector equipped with internal baffles (ETSCIB). The simulation considered high-pressure natural gas as the working fluid, specifically examining its behavior in the dense phase. The analysis revealed that the thermophysical properties of natural gas in the dense phase—particularly density and specific heat capacity—were substantially greater than those observed in the supercritical phase. As a result, the dense phase exhibited enhanced thermal storage and heat transfer characteristics. Moreover, the temperature gradient along the flow path was consistently lower in the dense phase, indicating more effective thermal energy absorption and distribution. Across the entire range of Reynolds numbers studied, the Nusselt number in the dense phase was found to be approximately ۲۱% higher than in the supercritical phase, confirming superior convective heat transfer performance. These findings suggest that utilizing dense phase natural gas can significantly improve the efficiency of solar thermal systems, particularly under high-pressure operating conditions.

کلیدواژه ها:

Evacuated tube collector solar ، Natural gas ، Dense phase ، CFD