Experimental study on the effect of modified heated surfaces on the heat transfer performance of deionized water and ethylene glycol binary mixtures

ABSTRACT

With the development of modern industry, the demand for environmentally friendly working fluids is gradually increasing. Although binary mixtures have low global warming potential, their boiling heat transfer performance is generally lower than that of pure components. To enhance their applications in boiling heat transfer, it is of great research significance to improve the boiling heat transfer coefficient (HTC) of binary mixtures by changing the characteristics of the heated surface. This article used a mixture of 30% ethylene glycol and deionized water as the working fluid to experimentally study the effect of a series of modified heated surfaces on their boiling heat transfer performance. Including heated surfaces with different roughness polished with 320#, 800#, and 2000# sandpapers, heated surfaces covered with TiO₂ and Al₂O₃ nanoparticle coatings with varying diameters of nano particles, and two state-of-art types of microstructure heated surfaces. The experimental results indicated that most modified heated surfaces can improve the boiling performance of the working fluid. Among them, the heated surfaces that changed the roughness due to sandpaper polishing had the least improvement effect on HTC. The microstructure surfaces had the best performance in HTC improvement. The reason for this phenomenon is that the microstructure not only changes the roughness of the heated surface but also increases the heat transfer area. Although nanoparticle coatings enhanced the heat transfer performance, the TiO₂ nanoparticle coatings showed better performance than Al₂O₃, which may be related to the stability of nanoparticle coatings.

KEYWORDS:

• Binary mixture
• heat transfer
• pool boiling
• modified heated surface

Disclosure statement

No potential conflict of interest was reported by the authors.