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<p>In the current study, a fixed volume fraction of Al<sub>2</sub>O<sub>3</sub> in the varying composition of ethylene glycol (EG) and H<sub>2</sub>O has been used as nanofluid, in both smooth and artificially roughened ducts with the aim of increasing the heat transfer and thermal efficiency of solar heater (SH). The artificial roughness in the duct has been introduced as triangular and square ribs on the collector surface. A two-dimensional computational fluid dynamics model is developed using ANSYS Fluent, simulating flow and heat transfer over a range of Reynolds numbers (3000–18000). The computational model has been validated against empirical, numerical and experimental results to provide accurate predictions of heat transfer and friction characteristics. According to the numerical results, the ribs increase the turbulence intensity near the boundary and improve the heat transfer characteristics. The maximum heat transfer coefficient is found for the nanofluid with 40% volume concentration for EG and 60% for H<sub>2</sub>O at the Reynold number of 18,000, for triangular ribs. For the same nanofluid, an increase of 71.6% in the heat transfer coefficient between smooth and rough triangular ducts is noted. This nanofluid also corresponds to the minimum friction factor among the investigated nanofluids, whereas a high Nusselt number is obtained for 40/60% composition of EG and H<sub>2</sub>O. Moreover, triangular ribs are found to have better heat transfer rate as compared to square ribs. These findings are particularly relevant for the design of compact solar thermal systems and automotive thermal management units, where enhanced heat exchange and fluid efficiency are critical.</p>

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Synergistic effects of Al2O3–ethylene glycol/water nanofluids and artificial roughness on solar heater thermal performance

  • 期刊论文

  • 发表日期：

    2025年8月22日

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  • Umar Farooq,
  • Saif ur Rehman,
  • Hafiz Hamza Riaz,
  • Tauqir Muhammad,
  • Tzu-Chi Chan

摘要

In the current study, a fixed volume fraction of Al2O3 in the varying composition of ethylene glycol (EG) and H2O has been used as nanofluid, in both smooth and artificially roughened ducts with the aim of increasing the heat transfer and thermal efficiency of solar heater (SH). The artificial roughness in the duct has been introduced as triangular and square ribs on the collector surface. A two-dimensional computational fluid dynamics model is developed using ANSYS Fluent, simulating flow and heat transfer over a range of Reynolds numbers (3000–18000). The computational model has been validated against empirical, numerical and experimental results to provide accurate predictions of heat transfer and friction characteristics. According to the numerical results, the ribs increase the turbulence intensity near the boundary and improve the heat transfer characteristics. The maximum heat transfer coefficient is found for the nanofluid with 40% volume concentration for EG and 60% for H2O at the Reynold number of 18,000, for triangular ribs. For the same nanofluid, an increase of 71.6% in the heat transfer coefficient between smooth and rough triangular ducts is noted. This nanofluid also corresponds to the minimum friction factor among the investigated nanofluids, whereas a high Nusselt number is obtained for 40/60% composition of EG and H2O. Moreover, triangular ribs are found to have better heat transfer rate as compared to square ribs. These findings are particularly relevant for the design of compact solar thermal systems and automotive thermal management units, where enhanced heat exchange and fluid efficiency are critical.