Experimental study on the heat transfer performance of an oscillating heat pipe with self-rewetting nanofluid

• The self-rewetting nanofluid enhances the heat transfer performance of the OHP.
• The proposed method is effective in measuring the surface tension and thermal conductivity.
• The self-rewetting nanofluid possesses the thermal and comprehensive physics properties of their constituents.

The heat transfer performance of an oscillating heat pipe (OHP) charged with a self-rewetting nanofluid is investigated in this experimental work. The self-rewetting nanofluids are prepared by mixing self-rewetting fluids and nanofluids. The nanofluid is a graphene oxide dispersion solution, while the self-rewetting fluid is a n-butanol alcohol aqueous solution. The OHP is fabricated from a straight copper tube with an inner diameter and length of 2 mm and 600 mm, respectively. The charge ratio is 50%, while the OHP tilt angle is 90°. The effect of the mass fraction of the nanoparticles and the n-butanol on the heat transfer performance of the OHP is investigated. The thermal conductivity and surface tension of the working fluids are also measured accordingly. The experimental results show an optimum constituent concentration of the nanoparticles and the n-butanol for the self-rewetting nanofluid. The heat transfer performance of the OHP can reach a high point at this optimum constituent concentration. The maximal enhancement ratio of the self-rewetting nanofluid is about 16% to that of the self-rewetting fluid and about 12% to that of the nanofluid. The analysis of thermal physics properties indicates that the heat transfer enhancement of the OHP is caused by the comprehensive effects of high thermal conductivity and surface tension of the inverse Marangoni effect. Subsequently, a method is proposed based on the measurement of the thermal physics properties of the self-rewetting nanofluid, which can determine the optimum constituent concentration of the self-rewetting nanofluid corresponding to the best heat transfer performance of the OHP.