Evaluation of Heat Transfer Enhancement from an Oscillation Heat Sink Under Free Convection Heat Transfer

Feb 4, 2026

Journal NTU Journal for Renewable Energy

DOI https://doi.org/10.56286/2vzvbp70

Issue 1

Volume 9

Enhancing heat dissipation in passive cooling systems remains a critical challenge for modern electronic and thermal devices. This study introduces an innovative approach that integrates forced vibration with a rectangular-finned heat sink to enhance free-convective thermal performance. The research investigates the influence of vibration frequency and amplitude on the heat transfer coefficient, fin efficiency, and air mass flow rate under various heat fluxes. Experiments were conducted within a controlled vertical duct test rig equipped with a data logger, anemometer, and electrical instrumentation. Three heat flux levels, 150, 230, and 360 W/m², were examined across vibration frequencies ranging from 0 to 50 Hz and amplitudes between 0.07- and 6.99-mm. Results revealed a direct correlation between the heat transfer coefficient and the modified Rayleigh number, with maximum enhancement observed at 50 Hz. Compared to static conditions (0 Hz), the overall heat transfer coefficient increased by 160%, 59.5%, and 55.2% for the respective heat fluxes, accompanied by air mass flow rate rises of 8.8%, 12.7%, and 25%. Despite these gains, fin efficiency decreased marginally by 9.8t o11.8% due to intensified convective mixing. The findings highlight the novel contribution of mechanical vibration as an effective means to augment natural convection without additional energy input for fluid motion, offering a practical enhancement strategy for passive aluminum-finned heat sinks used in electronic cooling and thermal management systems. . A heat sink is a device used to dissipate heat generated by electrical and electronic devices; it is classified as an active or passive heat sink according to the cooling process. The present study aims to evaluate the effect of forced vibration on heat sink thermal performance. Evaluation of Heat Transfer Enhancement from an Oscillation Heat Sink Under Free Convection Heat Transfer

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Numerical study on entropy minimization in pipes with helical airfoil and CuO nanoparticle integration

Apr 6, 2024

Journal Open Engineering

Publisher Open Engineering

DOI https://www.degruyterbrill.com/document/doi/10.1515/eng-2022-0594/html

Issue 1

Volume 14

In this study, minimizing entropy generation in a horizontal pipe is numerically investigated through two passive techniques: in the first mode, the helical wire inserts in the pipe were placed at three various ratios of pitch ratio. The second mode is adding cupric oxide nanoparticles at various volume concentrations. Experiments were conducted for Reynolds numbers ranging from 4,000 to 14,000 under a uniform heat flux scenario of 25,000 W/m2. The study utilized the ANSYS 14.5 software, employing the K-omega standard model, which involves three primary governing equations: continuity, momentum, and energy. According to the data, it was determined that the helical wire placed inside the pipe with a small pitch ratio decreased the entropy generation number. Cupric oxide nanoparticles also have a substantial impact on the entropy generation number. The higher volume concentration models had lower entropy generation numbers and Bejan numbers than the other models. Comparative analyses further emphasize the substantial advantages of using cupric oxide nanofluids and helical-wire inserts, with efficiency gains ranging from 5.08 to 11.7%. Keywords: entropy generation; numerical investigation; nano‎fluids; helical airfoil; Bejan numbers

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