Heat transfer enhancement of aluminum boiling surface with micro-grooves fabricated by laser

Abstract

Owing to recent advances in the manufacture of electronic devices, efficient cooling and heat-dissipation systems are required to achieve efficient technological performance. In this regard, looped thermosyphons have been studied with the intent of improving their heat-dissipation performance. The key technique is to improve the boiling heat transfer with a modified surface. This study presents the boiling characteristics of the selected working fluid, R1234ze(E), on a microtextured boiling surface fabricated using Laser Interference Surface Structuring (LISS). Compared with the unfabricated surface, the grid-grooved LISS-fabricated surfaces exhibit significant enhancements in the boiling heat transfer coefficients. An enhancement of 240—275% in the maximum heat transfer coefficient based on the untreated surface was observed. However, a significant heat transfer degradation was observed at higher heat fluxes. Additionally, to examine the effect of wicking induced by microgrooves on the critical heat flux, the capillary force was quantified using a dimensionless wicking number with ethanol utilized for the test boiling surfaces. The test surfaces with numerous irregular small cavities exhibited the highest values. These surfaces also exhibited the highest critical heat flux. The measured critical heat flux in the thermosyphon increased monotonically with an increasing wicking number.

Keywords

• Boiling heat transfer
• Critical heat flux
• Thermosyphon
• Laser interference surface structuring
• R1234ze(E)