Experimental study of ethylene glycol-based Al2O3 nanofluid turbulent heat transfer enhancement in the corrugated tube with twisted tapes

In this study, fluid flow of the Al2O3/ethylene glycol (EG) nanofluid in a corrugated tube fitted with twisted tapes were experimentally studied under turbulent flow conditions. The experiments with different twists ratio and different nanofluid concentration were performed under similar operation condition. The investigated ranges are (1) three different Al2O3 concentrations: 0.5, 1 and 1.5 % by volume (2) three different twist ratios of twisted tape: y/w = 2, 3.6 and 5 and (3) Reynolds number from 6000 to 30,000. Regarding the experimental data, utilization of twists together with nanofluids tends to increase heat transfer and friction factor as compared with the base fluid. In addition, heat transfer performances were weakened by using for high nanoparticle concentration. The thermal performances of the heat exchanger with nanofluid and twisted tapes were evaluated for the assessment of overall improvement in thermal behavior. Over the range studied, the maximum thermal performance factor 4.2 is found with the use of Al2O3/EG nanofluid at concentration of 0.5 % by volume in corrugated tube together with twisted tape at twist ratio of 2.