Exergy and entropy analysis of heat exchanger under mechanical vibration and magnetic field

Abstract

The present study primarily investigates the exergy and entropy generation in a heat exchanger influenced by the combined effects of mechanical vibrations and magnetic fields. A rectangular channel with dimensions 40 mm in length and 4 mm in width was examined using magnets of varying strengths and subjected to vibrations and magnetic fields. The Reynolds number (Re) investigated in this study ranges from 150 to 300. Both, magnetic field and vibrations, generated intricate patterns and contours, highlighting their interaction with flow dynamics. As vibrational intensity increased, the Nusselt number amplified correspondingly. While the introduction of magnetic field also enhanced the Nusselt number (Nu), the impact of vibrations was more pronounced. A maximum Nu enhancement of 225.9% was achieved at a Re 300, under the influence of vibrations at 5 mm and 25 Hz, and a magnetic field strength of 2000 G. The study further revealed that exergy efficiency decreases progressively with increasing Re but improves with higher vibrational intensity, reaching a peak of 52.81% at 5 mm and 25 Hz. Additionally, it was observed that irreversibility (φ) decreases with increasing vibrational and magnetic strengths. The ratio of entropy generation under the vibrational and magnetic influence to that of static case peaked at a value of 2.4 under vibrational intensity of 5 mm and 25 Hz, and magnetic field strength of 2000 G.