Effects of mechanical vibration on the heat transfer performance of shell-and-tube latent heat thermal storage units during charging process

Abstract

Mechanical vibrations are unavoidable in thermal systems at certain times, but they do not only have a bad effect. This paper presents the first pioneering study of the effect of vibration on the heat transfer performance of a horizontal tubular heat exchanger. Through numerical simulation methods, by applying mechanical vibrations of different vibration frequencies and vibration amplitudes, the heat transfer enhancement effect of phase change material (PCM) under vibrational conditions are fully revealed. The results show that, under lower vibration frequencies (ω = 10 ∼ 20 Hz), which can significantly promote the mixing of melted PCM and melting heat transfer rate during charging processes. However, this heat transfer enhancement begins to weaken in the range of medium to high vibration frequencies. For all amplitudes, the heat transfer enhancement is markedly stronger than that of frequency, which is linked directly to the magnitude of the amplitude value. Furthermore, the effect on heat transfer enhancement has been discussed when there is an inclination of the vibration axis to the direction of gravity. When the inclination angle is varied from 0° to 90°, the contribution to heat transfer enhancement is greatest at θ = 30°, which is optimal inclination angle. This paper could fill the knowledge gap regarding the thermal performance of heat exchangers with different geometries under mechanical vibration and provide some guidance for future practical applications.