Experimental study on heat transfer characteristics of hybrid nanofluid impinging jets

Abstract

Silver (Ag)-multiwall carbon nanotube/water hybrid nanofluids were used as a heat transfer media. The stability of the hybrid nanofluids was tested by comparing the matching ratios of different Ag particles and multiwall carbon nanotube particles. The optimal ratio of mixed solution and deionized water were selected at different mass fractions. The experimental study analyzes conventional impinging jets (CIJs) and swirling impinging jets (SIJs) on the conditions of different heat exchange surfaces, different length to diameter (L/D) values and different swirling ratios of twisted ribbons. The analysis also includes the effects of adding different dispersants on mixed nanofluids. The results shows that the thermal conductivity of Ag-multiwall carbon nanotube/water hybrid nanofluids is higher than that of multiwall carbon nanotube nanofluids. Furthermore, the heat transfer efficiency increases with the increasing of mass fraction. Under the same experimental conditions, the effect of heat transfer by swirling impinging jets was better than that of conventional impinging jets. The arc target surface heat transfer coefficient was higher, and L/D = 4 was the best nozzle size to target the surface space ratio. Finally, y/w = 3 was the best spiral structure of the built-in twisted ribbon.