Authors: Nese Budak Ziyadanogullari; Suleyman Percin
Addresses: Department of Mechanical Engineering, Batman University, Batman, Turkey ' Department of Mechanical Engineering, Batman University, Batman, Turkey
Abstract: This study investigated the effects of using nanofluids prepared with hexagonal boron nitride (hBN) nanoparticles on the thermal performance and pressure drop of a concentric tube heat exchanger. Experiments were carried out with water-hBN nanofluids for stable, dispersed, 0.01%, 0.1% and 1% volume concentrations, at different flow rates and Reynolds numbers under parallel and counter-flow conditions. When the experimental results were examined, the exergy loss was higher in the parallel-flow heat exchanger compared to the counter-flow heat exchanger. The highest exergy loss value was obtained for distilled water at the highest Reynolds number (Re = 8,700) for parallel flow operation at 170 W. The exergy loss of water at the highest Reynolds number (Re = 8,700) for parallel flow operation increased by 15.7%, 24.8% and 49.8% for hBN-water concentrations of 0.01%, 0.1% and 1%, respectively. Exergy loss of water at the highest Reynold number (Re = 8,700) for counter flow operation increased by 11.3%, 17.3% and 29.2% for hBN-water concentrations of 0.01%, 0.1% and 1%, respectively. When evaluating the exergy analysis of the system, exergy losses due to pressure drops were negligible for both flows (parallel and counter).
Keywords: hexagonal boron nitride-water nanofluid; concentric tube heat exchanger; exergy efficiency; exergy loss; pump power.
International Journal of Exergy, 2021 Vol.35 No.4, pp.438 - 452
Received: 04 Mar 2020
Accepted: 06 Dec 2020
Published online: 05 Aug 2021 *