Performance and environment interactivity of concentric heat exchanger practicing TiO2 nanofluid and operated near heat capacity ratio of unity

Abstract

The present research aims to experimentally investigate the influence of mixing Titanium Oxide nanoparticle with distilled water on the performance and energy-environment interrelation of a concentric heat exchanger at variable cold/hot flowrate ratio and mixing percentage. The target parameters of interest include the heat capacity ratio (the flowrate ratio), the overall heat transfer coefficient, the NTU-value, the exchanger effectiveness, and the heat leak to the surrounding. Results of the study show that significant drops in the NTU-value is observed when the heat capacity ratio approaches unity, albeit noticeable enhancement in the overall heat transfer unit is discerned. Such reduction results in a 25%–29% decrease in the effectiveness of the exchanger for the range of nanofluid volume fraction selected. Heat leak factor is observed to perpetually descend with the increase in the heat capacity ratio for all volume concentration of nanofluid, including the pure water case, suggesting that this factor is apparently dominated by Reynolds number rather than capacity ratio.The enhancement in the effectiveness caused by switching the configuration from parallel to counter profile ameliorates by ∼16.5% up to ∼25.5%. In return, the heat leak factor reduces by a range of 47%–60% for the same domain of nanofluid volume fraction.

Keywords

• Concentric heat exchanger
• Nanofluid
• Heat leak factor
• Heat capacity ratio
• Heat exchanger effectiveness
• Energy