Search

This study investigates the utilization of Al2O3 nanofluids in an Active Magnetic Regenerative (AMR) system, focusing on varying nanoparticle concentrations from 0.01 to 1.0%. Numerical modelling is used to analyze the effects of nanoparticle incorporation on system efficiency and cooling performance. Al2O3 nanoparticles are found to significantly increase the thermal conductivity, density, and viscosity of the base fluid while reducing specific heat capacity. Comparative analysis reveals that Al2O3 nanofluids outperform pure water in terms of cooling performance, achieving a lower final temperature and a higher temperature span after 60 min of operation. Moreover, the study highlights that cooling capacity and pumping work increase with higher nanoparticle concentrations, with a notable improvement of 64.95% in cooling capacity and 39.31% in pumping work for the 1.0% Al2O3 nanofluid compared to water. The Coefficient of Performance (COP) of the AMR system peaks at an optimal nanoparticle concentration of 0.2%, reaching 3.88, before declining due to increased pumping power requirements. [ABSTRACT FROM AUTHOR]

A comparative experimental study to examine the hydrothermal behaviors of the double tube heat exchanger with various modified twisted tape and wire coil inserts is performed using Al 2 O 3 +MWCNT hybrid nanofluid. The investigation is performed for Reynolds number of 8000–40000, nanofluid flow rate of 5–25 lpm and volume concentration of 0.01%. The effects of using various enhancers (V-cut twisted tapes and tapered wire coils) and hybrid nanofluid on the hydrothermal characteristics are assessed for different enhancer arrangements such as different twist ratios, V-cut depth ratios, V-cut width ratios, converging type (C-type) wire coil, diverging (D-type) wire coil and converging-diverging type (C-D type) wire coil. The test reveals that the pressure drop and heat transfer coefficient increase with reducing twist ratio, increasing depth ratio and reducing width ratio. D-type wire coil exhibits higher heat transfer performance with the penalty of pressure drop than that of other arrangements. V-cuts twisted tape of minimum twist ratio, maximum depth and width ratios yields maximum PEC and FOM. V-cut twisted tapes show a higher performance index than the tapered wire coil as the augmentation in pressure drop is slightly significant. D-type wire coil shows the minimum value of entropy generation among all other arrangements. • Performance of concentric tube heat exchanger is studied with inserts using hybrid nanofluid. • Experiment is performed for various V-cut twisted tape and tapered wire coil configurations. • D-type wire coil exhibits higher heat transfer performance with the penalty of pressure drop. • V-cut twisted tapes show higher hydrothermal performance as compared to tapered wire coil. • D-type wire coil exhibits minimum value of entropy generation among all the arrangements. [ABSTRACT FROM AUTHOR]

The experimental studies with a new type of enhancer, conical wire coil insertion in the concentric tube heat exchanger using water-based mono (Al 2 O 3 and CNT) and hybrid (Al 2 O 3 + CNT) nanofluids, flowing in the inner tube, are conducted to examine the effect on thermohydraulic performance. The thermohydraulic performances are studied with various conical wire coil configurations (converging, diverging and converging-diverging coils). The outcomes indicate that the diverging wire coil insert exhibits better thermohydraulic performance as compared to other wire coil arrangements. In comparison to DI water in the plain tube (without insert), the maximum Nusselt number enhancements for diverging, converging-diverging and converging wire coil inserts are 171%, 152% and 139%, respectively. Similarly, the friction factor is increased up to 106%, 92% and 72%, respectively, for diverging, converging-diverging and converging wire coil inserts. In all conditions, it is found that the entropy generation of DI water is higher than that of mono/hybrid nanofluids. The thermal performance factor is observed more than one with all mono/hybrid nanofluids and wire coil inserts, indicating a promising combination. [ABSTRACT FROM AUTHOR]