Convective heat transfer analysis of circular tube-annular tube systems with nanofluids: a comparative study

This study investigates the convective heat transfer performance of various fluid combinations within a circular tube-annular tube system, with a particular emphasis on the influence of nanofluids. The analysis evaluates four distinct fluid combinations: base fluid-base fluid (BW), base fluid-nanofluid (HN), nanofluid-base fluid (CN), and nanofluid-nanofluid (BN). Convective heat transfer coefficients were systematically measured across a range of mass flow rates, and the effects of varying nanoparticle concentrations (ϕ) on heat transfer efficiency were meticulously analyzed. The results indicate a general trend of increasing convective heat transfer coefficients with rising mass flow rates for most fluid combinations, particularly for BW, CN, and BN. Notably, however, a significant decrease in heat transfer efficiency is observed at higher mass flow rates in the HN combination, suggesting a potential saturation effect that may limit the effectiveness of this fluid pairing. This comparative analysis not only highlights the intricate interactions between different fluid types but also provides valuable insights into the potential of nanofluids to enhance thermal efficiency in heat exchanger applications, paving the way for future research and practical implementations in thermal management systems.