Parameter studies of infrasound enhanced cooling of steel plate

Abstract

This Master’s thesis studies the effect of infrasound acoustic waves on heat transfer
enhancement for industrial purposes. Previous research has demonstrated the cap
ability of infrasound to cool steel uniformly, with performance comparable to forced
convection. This opens the possibility of increasing the efficiency of the cooling process
while also enabling new potential cooling methods for different steel varieties.
This work is divided into a numerical simulation using ANSYS Fluent and an exper
imental investigation. The simulation involved calculating the pressure drop due to
f
low friction in a cooling chamber, in order to relate friction-induced pressure drops to
experimental acoustic pressure drops. The experimental part involved applying differ
ent frequencies at various pressure amplitude levels to cool a 100×200×3 mm heated
plate from 170°C to 40°C. The temperature was monitored second by second, along
with the acoustic pressure amplitude.
In the simulation, seven geometries were tested, while in the experimental work, nine
geometries were used, at frequencies of 5.7, 9.7, and 13.1 Hz, and two different pressure
amplitude levels. The relationships between geometry, frequency, pressure, acoustic
velocity, and cooling were corroborated and analyzed. Clear correlations between
geometries and heat transfer were observed; however, at higher pressure amplitudes,
these trends became less distinct.

Popular Abstract

This thesis investigates the application of infrasound as a method to enhance heat transfer in industrial applications.
Previous studies have shown that infrasound (below 20 Hz) can promote heat transfer. This effect is due to the interaction between particle vibrations and the thermal boundary layer, which results in more uniform heat distribution through the material exposed to the sound. The conditions to obtain maximum heat transfer are the use of a stationary wave and locating the objective in a node (point where pressure is always null), thereby obtaining the maximum acoustic velocity, which corresponds to the peak particle vibration and thus optimal heat transfer. The goal of this thesis is to determine the heat sink geometry that optimizes this effect.
The work is divided into two parts: Computational Fluid Dynamics (CFD) simulations to calculate the pressure drop of air through a cooling chamber, and experimental research using a pulsator to generate acoustic waves at 5.7 Hz, 9.7 Hz, and 13.1 Hz. These experiments measured the cooling time and acoustic pressure drop across different geometries. The simulated and measured acoustic pressure drops showed similar trends, although they differed in magnitude. A total of nine geometries were tested under two pressure levels, resulting in 54 individual experiments. The results demonstrated that the greatest heat transfer consistently correlates with the highest acoustic velocity obtained. This velocity is highly dependent on geometry at low pressures, while at high pressures, the influence of geometry is reduced. At low pressures, the optimal geometries are those with larger finned surface areas and higher pressure drops, whereas at higher pressures this trend shifts, and geometries with smaller surface areas become more effective. The data suggest that the system achieves higher efficiency at lower flow velocities, which may offer advantages in terms of industrial energy savings. Additionally, the frequency of the wave, within the tested range, was not found to be relevant to the performance, with the achieved acoustic velocity being the important factor, indicating that every case can adjust to the frequency that fits better its setup.
The research identifies a relationship between frictional pressure drops and acoustic pressure drops. It also reveals a trend in geometry optimization that can be extrapolated to industrial applications. Acoustic behaviour is more sensitive to changes in chamber geometry at low pressures, suggesting that in industrial applications, optimal performance can be achieved without excessive surface area.

• author: Alegre, Mario
• supervisor: Lei Wang
• organization: Department of Energy Sciences
• course: MVKM05 20251
• year: 2025
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Infrasound Cooling
• report number: ISRN LUTMDN/TMPH-25/5657-SE
• ISSN: 0282-1990
• language: English
• id: 9206001
• date added to LUP: 2025-06-26 10:53:17
• date last changed: 2025-06-26 10:53:17